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From the Linden Flower to Linden Honey - Volatile Constituents of Linden Nectar, the Extract of Bee-Stomach and Ripe Honey

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Abstract

Honey is produced by honeybees (Apis mellifera), which collect nectar from flowers, digest it in their bodies, and deposit it in honeycombs, where it develops into ripe honey. We studied the evolution of the volatile constituents from the nectar of linden blossoms (Tilia cordata) to honey via the ‘intermediate’ honeybee. The sampling of the contents of the honey stomach or honey sack of the bee is unique. Extracts were prepared from nectar, from the liquid of the honey stomach, and from ripe honey. The chemistry is extremely complex, and compounds spanning from monoterpenes (hydrocarbons, ethers, aldehydes, acids, and bifunctional derivatives), isoprenoids, aromatic compounds (phenylpropanoids, phenols), and products degraded from fatty acids to alkaloids, were identified. Some compounds definitely stem from the plants, whereas other interesting constituents can be attributed to animal origin. Two derivatives of decanoic acid, 9-oxodec-2-enoic acid (12) and 9-hydroxydec-2-enoic acid, identified in the honey are known to be constituents of the so-called ‘Queen's pheromone’. Two metabolites of these acids were identified in the extract of the honey stomach: 8-oxononanal (10), a new natural product, and 8-oxononanol (11). There structures were confirmed by synthesis. Nectar and honey stomach contain many aldehydes, which, due to the highly oxidative atmosphere in the honeycomb, are found as corresponding acids in the honey. Two acids were newly identified as 4-isopropenylcyclohexa-1,3-diene-1-carboxylic acid (14) and 4-(1-hydroxy-1-methylethyl)-cyclohexa-1,3-diene-1-carboxylic acid (15).

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... Így az egyébként higroszkópos méz nem tud nedvességet visszavenni a levegıbıl. A méz keletkezési folyamatairól, valamint a nektár és a méz kapcsolatáról érdekes képet ad Naefnek és munkatársainak vizsgálatsorozata (NAEF et al., 2004), melyben mintát vettek hárs-nektárból (a környéken csak hársfák virágoztak), a győjtésbıl visszatért méhek mézhólyagjából és egy hónap múlva az érett mézbıl. A nektárban talált vegyületek igen sokfélék voltak: zsírasavak bomlástermékei (nonanal, dekanal stb.), fenil-propanoidok, izoprenoidok (pl. ...
... Felismerték a mézben a méhek feromonjait is. Hársmézben a méhkirálynı feromonját alkotó 9-oxodeka-2-énsav és 9-oxodekánsav lebomlási termékeit, a 8oxononanalt és a 9-hiroxinonán-2-on nevő vegyületet mutatták ki (NAEF, 2004). A méhek a Nasonov mirigy feromonjával részint a kaptárt jelölik meg, de a nektár-forrásokat is jelzik a többi méh számára. ...
... 1878 4-(1-metiletil)-benzolmetanol 87 17.55 62 32.67 1923 3-hidroxi-benzoesav metilészter 80 5. 60 2119 4-(1-metiletil)-benzolmetanol, (p-cimén-alfa-ol) 96 3.04 81 41.369 2180 2-metoxi-4-(1-propenil)-fenol, (izoeugenol) 97 2. 37 82 41.496 2183 5-metil-2-(1-metiletil)-fenol, (timol) 93 5. 40 84 41.994 2198 5-metil-2-(1-metiletil)-fenol, (timol) 93 1. 21 85 42.503 2213 5-metil-2-(1-metiletil)-fenol, (timol) 91 3. 96 4.87 96 1. 20 37 22.587 1626 n-hexadekán 95 32. 85 48 26.174 1732 n-heptadekán 98 3.00 56 30.002 1845 n-oktadekán 93 40. 98 A vegyületnevek írásmódja információt hordoz, a jelentéstartalom megegyezik a virágfelvételeknél tárgyaltakkal. ...
... The same authors suggested an alternative theory, where bumblebee death is caused by starvation due to the unproven assumption that a significant number of the linden tree flowers are lacking nectar Surholt and Baal, 1995;Illies and Mühlen, 2007). More recently, Naef et al. indicated the presence of trace amounts of nicotine in Tilia nectar, in addition to the purine alkaloids caffeine and theophylline (Naef et al., 2004;Barachi et al., 2017;Koch and Stevenson, 2017). Baracchi et al. (2015) suggested that bumblebees may use nicotine-containing nectar for selfmedication towards microbial infections (Barachi et al., 2015). ...
... According to Naef et al. (2004) Tilia nectar contains a complex mixture of volatile constituents. Using GC-MS-methods they identified products of fatty acid degradation (nonanal, decanal and tetradec-1ene), phenylpropanoids (3-(4-methoxyphenyl)propan-1-ol, 3-(4-methoxyphenyl)propanal, 3-(4-methoxyphenyl)prop-2-enal, isoprenoids (vomifolione, vomifoliol and 3,5,5-trimethyl-4-(3-oxobutyl)cyclohex-2ene-1-one), alkaloids (caffeine, theophylline and trace amounts of nicotine), and a complex mixture of monoterpenes, among them Tilia ether and 1,8-cineole, in addition to several unknown compounds having molecular weights of 148, 150, 152, 166, 168 and 170, respectively (Naef et al., 2004). ...
... However, ethanol has not previously been found in Tilia nectar. Naef et al. (2004) screened the nectar for volatile molecules with molecular weights in the range 27-350 and did not detect ethanol. To confirm this observation nectar samples were directly diluted with the NMR solvent H 2 O-D 2 O (90:10; v/v) and analysed by high resolution NMR spectroscopy. ...
Article
For more than six decades, bumblebee death, which mainly occurs in August, has been assumed to be associated with intake of presumed toxic nectar from linden trees (Tilia spp.), a hypothesis which has been sustained by observations of a significant number of dead bumblebees under these trees during their flowering season. Several theories exist in current literature to account for these observations. The nectar has been assumed to contain compound(s) toxic to the bumblebees including the monosaccharide mannose, which cannot be metabolized by bumblebees. The presence of toxic compounds such as the alkaloid nicotine or pesticides of anthropogenic origin has also been indicated. However, none of the above suggested compounds have hitherto been properly characterized from the nectar. In the current paper we report on characterization of the composition of nectar of linden trees, under which a significant number of dead bumblebees were observed. The structure determinations were performed by selective 1D TOCSY NMR and extensive applications of 2D NMR spectroscopy. The nectar of the linden flowers was readily available in significant amounts during the entire period when dead bumblebees were observed under these trees. The nectar only contained non-toxic sugars such as α-glucopyranose, β-glucopyranose, sucrose, fructose and minor amounts of xylose. The nectar did not contain mannose, nor alkaloids or pesticides. Initial toxicity studies using brine shrimp lethality assay showed that the nectar did not exhibit any toxic effects even at concentrations higher than 1 mg/ml dry weight, providing disproving evidence against the assumption of the nectar's toxic character.
... The non-sugar chemistry of T. tomentosa nectar and pollen remains largely unstudied. Naef et al. [41] and Frérot et al. [62] described the volatile nectar constituents from the related T. cordata and found secondary compounds including terpenoids, flavonoids and a novel cyclohexa-1,3-diene-1-carboxylic acid and its b-gentiobiosyl ester. The disaccharide gentiobiose occurs in crops of honeybees foraging on T. tomentosa [63], and in linden honey [64]. ...
... terrestris) foragers emit three pheromones within the colonies that recruit idle workers to start foraging: eucalyptol, farnesol and ocimene [71]. All three compounds occur in flower volatiles or nectar of Tilia species [41,45,46]. Exposure to these volatiles either on the tree or in the colony through returning foragers with Tilia scent could exploit the bumblebees' sensory bias and increase foraging intensity even at times of low nectar production. ...
... Intriguingly, Naef et al. [41] reported caffeine (figure 1) in T. cordata nectar, and Mathon et al. [72] detected caffeine in Tilia sp. flower tea. ...
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For decades, linden trees (basswoods or lime trees), and particularly silver linden (Tilia tomentosa), have been linked to mass bee deaths. This phenomenon is often attributed to the purported occurrence of the carbohydrate mannose, which is toxic to bees, in Tilia nectar. In this review, however, we conclude that from existing literature there is no experimental evidence for toxicity to bees in linden nectar. Bee deaths on Tilia probably result from starvation, owing to insufficient nectar resources late in the tree’s flowering period. We recommend ensuring sufficient alternative food sources in cities during late summer to reduce bee deaths on silver linden. Silver linden metabolites such as floral volatiles, pollen chemistry and nectar secondary compounds remain underexplored, particularly their toxic or behavioural effects on bees. Some evidence for the presence of caffeine in linden nectar may mean that linden trees can chemically deceive foraging bees to make sub-optimal foraging decisions, in some cases leading to their starvation. © 2017 The Author(s) Published by the Royal Society. All rights reserved.
... Even though nectar collection is a common procedure, in some plant species it is a highly laborious and time-consuming task, and the amount of nectar collected is usually limited and seldom enough to perform biological tests. Unifloral honeys, on the other hand, are relatively simple to extract in large amounts and they can be used as a nectar substitute for chemical analyses (Alissandrakis et al., 2003;Naef et al., 2004;Afik et al., 2006a) or for biological assays (Hagler and Buchmann, 1993;Afik et al., 2006bAfik et al., , 2008Tan et al., 2007). Using honey as a nectar substitute should, however, be done with caution due to our limited ability to identify honey sources and due to the changes in nectar composition that occur during the process of honey ripening. ...
... Using honey as a nectar substitute should, however, be done with caution due to our limited ability to identify honey sources and due to the changes in nectar composition that occur during the process of honey ripening. Any results achieved using honey still remain to be verified through nectar analysis (Alissandrakis et al., 2003;Naef et al., 2004). ...
Article
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Unifloral honeys are honeys that are dominated by a single nectar source. Several samples of Israeli honeys were analyzed for their physicochemical characteristics and tested by pollen analysis for their botanical source. Based on pollen content, unifloral honeys were harvested only from landscapes of planted forests including: aethel (Tamarix sp.), carob (Ceratonia siliqua), and eucalyptus (Eucalyptus sp.). However, honeys extracted from agricultural landscapes should also be considered as unifloral due to pollen underrepresentation. No evidence for unifloral honeys from natural landscapes was found. Later, honeybee preference between different honeys and sucrose solution was tested and these preferences were correlated with honey traits. The preference experiment revealed that bees tend to prefer sucrose solution rather than any honey source. Among honeys, bees showed the highest preference for citrus honey and the lowest preference for avocado honey. Preference for aethel, cotton, and eucalyptus was intermediate. The electrical conductivity value of the honeys was negatively correlated with honey preference, indicating that the mineral content of honey, and probably of nectar, affects the attractiveness to bees.
... 22 Linden honey, with light amber color and distinctive intense aromatic flavor, is also highly appreciated by the consumers. Some unusual terpene acids and glycosides were identified in linden honey, 23,24 while another research explored that special "linden ether" can serve as an indicator substance for detection of linden honey. 25 It is worth noting that both acacia and linden honeys are the most consumed and exported in China, and the annual output is about 20 000 and 25 000 tons, respectively. ...
... This finding is consistent with Naef's research that this compound is only present in ripe linden honey. 23 Naef's subsequent study claimed that this monoterpenic acid is present in the form of glycosides in linden honey. 24 However, in this study, we did not find the presence of lindenin glycosides in our samples, based on chromatography and mass spectrometry data. ...
Article
Honey fraud has an extensive global magnitude, and impacts both honey price and beekeeper viability. This study aimed to investigate the characteristic phytochemicals of rape, acacia, and linden honey to verify honey authenticity. We discovered methyl syringate, phaseic acid and lindenin (4-(2-hydroxypropan-2-yl) cyclohexa-1,3-diene-1-carboxylic acid) as particular or unique phytochemicals of rape, acacia, and linden honey. Methyl syringate and lindenin were the most abundant component in rape and linden honey; moreover, the average contents reached up to 10.44 and 21.25 mg/kg, respectively. The average content of phaseic acid was 0.63 mg/kg in acacia honey. To our knowledge, the presence of phaseic acid in honey is a novel finding. Furthermore, we established the HPLC fingerprints of three monofloral honeys. We offered assessment criteria and combined characteristic components with standard fingerprints to evaluate the authenticity of commercial rape, acacia, and linden honeys. For uncertain commercial honey samples, genuine pure honeys constituted nearly 70%. We differentiate the adulteration of acacia and linden honeys with low-price rape honey. Our results reveal that 10% of commercial honeys were pure syrups. Overall, we seem to propose a novel and reliable solution to assess the authenticity of monofloral honey.
... Honey aroma compounds are derived from the transfer of volatile substances from plants, metabolic transformations of plant constituents by bees, the metabolism of bees, changes that occur during honey processing, and the action of microorganisms (NAEF et al, 2004;BARONI et al., 2006;RIBEIRO et al., 2008;dE-MElO et al., 2018). ...
... Benzaldehyde was observed in the flowers and in samples H1-H4, H6, and H10, whereas toluene was only transferred from the flowers of B. verticillata to samples H1-H3 (Tables 2 and 3). However, there was no transfer of skatole, possibly because this substance originated from the metabolic processes of bees or from microorganisms associated with bees or with B. verticillata (BARONI et al., 2006;NAEF et al., 2004;RIBEIRO et al., 2008). There are no reports of the presence of skatole in honey from Brazil or other countries (BARONI et al., 2006;DE MARIA & MOREIRA, 2003;KRUŽÍK et al., 2017;PATRIGNANI et al., 2018), but it has been described in off-flavor meat products. ...
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Climatic conditions in the mid-northern region of Mato Grosso State in Brazil are favorable for beekeeping. However, since 2011, the honey production chain has suffered losses because the production of off-odor honey has made it impossible to market the honey. Reports from beekeepers indicated a relationship between the off-odor in the honey and the nectar of Borreria verticillata (L.) G. Mey (Rubiaceae). In this study, the botanical origins and volatile profiles of ten off-odor honeys (H1-H10) and flowers of B. verticillata were evaluated. Palynological and sensorial analyses of the honeys were performed; a scale from 1 to 4 was applied for the sensorial analysis, in which 1 indicates no off-odor and 4 indicates extreme off-odor. Analysis of volatile was performed by using headspace solid-phase microextraction and gas chromatography-mass spectroscopy methods. The honeys investigated were classified with very high to intense off-odors, except H4 and H5, which did not differ from the control honey (no off-odor). Palynological analyses showed that honeys H1-H4, H7, and H9 were monofloral from B. verticillata, whereas in H5, H6, H8, and H10 this pollen were accessory. However, there was no quantitative correlation between the B. verticillata pollen content and the off-odor attributes of the honeys. Skatole was identified in all of the honeys except H4, H5, and the control honeys, suggesting that skatole contributed to the off-odor attributes of the products. However, further studies are required to investigate the origin of the skatole because it is not transferred directly from B. verticillata flowers to the honey.
... On returning to the hive, the content of the honey-sac is regurgitated into the honeycomb and ripened into honey. Under the honeycomb oxidative atmosphere sensitive honey organic compounds can undergo oxidation [28]. There are only a few studies in which the organic extractives of the honey-sac have been correlated with those of the corresponding honey. ...
... There are only a few studies in which the organic extractives of the honey-sac have been correlated with those of the corresponding honey. The comparison of the components of the extracts of Linden honey and honey-sac contents showed that nectar and honey-sac contents contain many aldehydes which were found as corresponding acids in the honey, while the aliphatic compounds, isoprenoids and the alkaloids remained unchanged [28]. In another research, the major identified terpene in the honey-sac was 3,7-dimethylocta-1,5-dien-3,7-diol (terpendiol I) and it was found in Mentha spp. ...
Article
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Headspace solid-phase microextraction (HS-SPME) and ultrasonic solvent extraction (USE), followed by GC-MS/FID, were applied for monitoring the nectar (NE)/honey-sac (HoS)/honey (HO) pathways of the headspace, volatiles, and semi-volatiles. The major NE (4 varieties of Citrus unshiu) headspace compounds were linalool, α-terpineol, 1H-indole, methyl anthranilate, and phenylacetonitrile. Corresponding extracts contained, among others, 1H-indole, methyl anthranilate, 1,3-dihydro-2H-indol-2-one and caffeine. The major HoS headspace compounds were linalool, α-terpineol, 1,8-cineole, 1H-indole, methyl anthranilate, and cis-jasmone. Characteristic compounds from HoS extract were caffeine, 1H-indole, 1,3-dihydro-2H-indol-2-one, methyl anthranilate, and phenylacetonitrile. However, HO headspace composition was significantly different in comparison to NE and HoS with respect to phenylacetaldehyde and linalool derivatives abundance that appeared as the consequence of the hive conditions and the bee enzyme activity. C. unshiu honey traceability is determined by chemical markers: phenylacetaldehyde, phenylacetonitrile, linalool and its derivatives, as well as 1H-indole, 1,3-dihydro-2H-indol-2-one, and caffeine.
... This compound has been previously reported as main component of linden (T. cordata) nectar and honey [14] and has been detected in lower amounts in chestnut and fir honeys. Authors proposed that this type of glycosides is stored in the nectar. ...
... On the contrary, a monoterpene glycoside (6), a small phenolic glycosides (8, p-coumaroyl-4-O-gentobioside) have been detected for the first time in this species. Furthermore, traces of caffeine and theophylline previously reported in linden nectar [14] were isolated and identified by NMR. All the characteristic constituents which contribute to the quality of Tiliae flos have been identified and quantified by our validated analytical method. ...
Article
In the present study extensive HPLC-DAD, HPLC-ESI-MS and NMR analyses were undertaken in the aqueous preparations (decoctions, infusions) and tinctures of Tilia platyphyllos Scop inflorescences. The aim of this work was to examine in depth the qualitative and quantitative profile of the investigated preparations, which find until today wide applications in pharmaceutical and cosmetic industry, and to propose a validated method for their quality control. An HPLC-DAD-ESI-MS method was developed and optimised for the quantitative determination of the constituents. Marker constituents of Tiliae flos are the flavonoids, while the volatile content is also used for the quality control. However, the analyses of the non-volatile fraction gave complex chromatographic fingerprints containing simple phenolics and low molecular weight procyanidins. The use of different HPLC columns permitted a good separation of the constituents and enabled their quantitation, while HPLC-MS analyses permitted the detection of procyanidin oligomers. Overall, 31 constituents were detected and identified. Extensive preparative chromatographic investigations and 2D-NMR analyses allowed the characterisation of procyanidins as epicatechin derivatives. Finally, the HPLC method was validated and complied with ICH guidelines. This is the first report of detailed analysis of the chemical composition of Tiliae flos.
... Previously, nonanal has been found in both flowers of Castanea sativa and Eucalyptus globulus and the honeys produced from these flowers (Alissandrakis et al. 2011). Naef et al. (2004 showed that nonanal exists in both nectar and the content of the bee honey stomach. Here, we examined nonanal in flowers and honeybee colonies simultaneously, and our results showed that nonanal existed both in nectar droplets (Fig. 3 and Table 1) and honey samples (Table 1). Therefore, these indicate that nonanal is present within nect ...
... ers and honey samples (Jorgensen et al. 2000;Schade et al. 2001;Alissandrakis et al. 2007Alissandrakis et al. , 2011Jerkovi et al. 2009;Bianchi et al. 2011;Bayraktar and Ur 2011;Twidle et al. 2018). Nonanal has been found in both flowers of Castanea sativa and Eucalyptus globulus and the honeys produced from these flowers (Alissandrakis et al. 2011). Naef et al (2004 showed that nonanal exists in both nectar and the content of the bee honey stomach, suggesting that nonanal can be transferred from nectar into honey in beehives. In addition, nonanal can also be found in indoor air but the concentration is lower than 100 μg/m 3 (Daisey and Hopke 1991;Iwashita and Hibino 2011;Iwashita and Tokunaga 2012) ...
Article
Full-text available
Volatile odors from flowers play an important role in plant-pollinator interaction. The honeybee is an important generalist pollinator of many plants. Here, we explored whether any components of the odors of a range of honeybee-pollinated plants are commonly involved in the interaction between plants and honeybees. We used a needle trap system to collect floral odors, and GC–MS analysis revealed nonanal was the only component scent detected in 12 different honeybee-pollinated flowers and not present in anemophilous plant species. For Ligustrum compactum, blooming flowers released significantly more nonanal than buds and faded flowers. For Sapium sebiferum, nonanal release through the day correlated with nectar secretion. Experimentally increasing nectar load in flowers of Sapium sebiferum, Ligustrum compactum, and Castanea henryi increased nonanal levels also. Nonanal was also detected in flower nectar and honeys from experimental colonies. Electroantennogram recordings and behavioral observations showed that untrained honeybees could detect and were strongly attracted to nonanal. We argue that nonanal persists in both honey and nectar odors facilitating a learned association between nonanal and food reward in honeybees.
... It is not unusual that plants produce secondary metabolites that can be poisonous for pollinators (Adler, 2000). Nearly 500 chemical compounds have been found in the nectar of the small-leaved linden (Naef et al., 2004). The biological effects of all these compounds alone or in combination are not well known, but currently no compounds poisonous for bumblebees are known (Fossen et al., 2019;Jacquemart et al., 2018). ...
... The alkaloid caffeine has, in experiments, been shown to do this (Couvillon et al., 2015). Naef et al. (2004) found caffeine and several other alkaloids in nectar from small-leaved lime (Tilia cordata), while ...
Article
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Linden trees (Tilia spp.) have for a long time been associated with bumblebee (Bombus spp.) mortality in Europe and North America. Several explanations have been suggested for this phenomenon. This study aimed to explore to which extent the factors of predation, ageing, starvation, and poisonous nectar serve as explanations for bumblebee mortality in association with linden trees. Starvation, ageing, and predation all contributed to mortality of bumblebees found under flowering linden trees. The mean weight of a dead wild bumblebee found under linden trees was found to be close to the weight of a starved bumblebee of the same size. This indicated that starvation was the main driver for many of the deaths. A significant proportion of the dead bumblebees collected under linden trees had injuries indicating predation. The authors suggest that predation may serve as a secondary explanation for the bumblebee mortality, after weakening by starvation or other factors. A small proportion of the bumblebees may have died from physical degradation or age. The present study did not support the poisonous nectar hypothesis. It is necessary to explore the covariation between the suggested hypotheses more closely, to better understand the interplay between the different factors. In addition, there is a need to investigate alternative hypotheses for the association between bumblebees and linden trees. The authors of the article suggest that three different factors contribute in different proportions to the deaths of the bumblebees. A fourth explanation is rejected. The study's findings indicate that starvation was the main driver for many of the deaths of the bumblebees found under flowering linden. The authors suggest that predation may serve as a secondary explanation for the bumblebee mortality, after weakened by starvation or other factors. A small proportion of the bumblebees may have died from physical degradation or age. The present study did not support the poisonous nectar hypothesis.
... To verify this, researchers should check for breakdown products in honey as well as the original compounds. Whether this detoxification occurs in the bees or the hive environment (Naef et al. 2004;Liu et al. 2007) is not clear. use the term 'social detoxification' for various honeybee behaviours that may reduce the need for enzymatic detoxification: collecting from diverse pollen and nectar sources to dilute particular toxins, and subsequent food processing may lead to their degradation. ...
Article
The ecological function of secondary metabolites in plant defence against herbivores is well established, but their role in plant-pollinator interactions is less obvious. Nectar is the major reward for pollinators, so the occurrence of defence chemicals in the nectar of many species is unexpected. However, increasing evidence supports a variety of potential benefits for both plant and pollinator from these compounds. Beneficial effects may include: a) mediating specialization in plant-pollinator interactions, b) protecting nectar from robbery or larceny, and c) microbial activity including preservation of nutrients in nectar from degradation and reduction of disease levels in pollinators. Secondary metabolites in nectar can be toxic or repellent to flower visitors, but equally they can go undetected or even make nectar more apparent or attractive. These biological effects are concentration dependent so must considered at a range of ecologically relevant doses. For example, caffeine occurs in nectar and improves honeybee memory for odours associated with food rewards which enhances pollen transfer at naturally occurring concentrations but is repellent to honeybees at higher concentrations. This review synthesises evidence from recent literature that supports selection for secondary metabolites in floral nectar as an adaptation that drives the co-evolution between plants and their pollinators. However, their presence in nectar could still simply be a consequence of their defensive role elsewhere in the plant (pleiotropy). We highlight the need for more studies demonstrating measurable benefits to the plant, the importance of exposure levels and effects on target species beyond the current emphasis on alkaloids and bees. This article is protected by copyright. All rights reserved.
... Ripe honey is a kind of natural sweet food with strong aroma and, is produced by honeybee colonies until most cells in the honeycomb are sealed (Naef et al., 2004). As suggested by previous reports, ripe honey is viscous and has water content lower than 22%, which is not favorable for the growth of microorganisms; as such, the shelf life of ripe honey is prolonged (Aparna & Rajalakshmi, 1999). ...
Article
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Beekeepers who manage migratory beekeeping in China preferred to produce non-ripe honey rather than natural ripe honey in short flowering seasons, to obtain higher honey yield and profits. To explore an alternative method for production of ripe honey, we fed Apis cerana cerana colonies with non-ripe honey produced from Apis mellifera ligustica colonies to produce re-ripe honey. The production rate of re-ripe honey was 29.06%, which led to a high market profit considering price factors. The contents of glucose and fructose in re-ripe honey didn’t change significantly, and small amounts of sucrose and maltose were detected. The amylase activity (39.06 mL/(g*h) in re-ripe honey significantly increased, compared with that (34.86 mL/(g*h)) in non-ripe honey. The types and relative content of volatile organic components, namely, alcohols and esters, in re-ripe honey were lower than those in non-ripe honey, indicating the milder and non-irritating aroma of the former. Overall, the method raised by us is a practical approach to produce honey with high quality and economic values and could be easily accepted by the market.
... Generally, the analysis of conversion of nectar into honey has not been studied sufficiently. To our best knowledge, three studies reporting volatile compounds occurring in the nectar and honey sac in comparison to the corresponding honey were conducted by Naef, Jaquier, Velluz, and Bachofen (2004) investigating the volatile constituents of Tilia cordata nectar, bee-stomach extract and honey, and Jerković , Hegić , Marijanović , and Bubalo (2010), investigating organic extractives from Mentha spp. honey and honey sac content, as well as Citrus unshiu nectar/honey-sac/ honey pathways of the headspace, volatiles, and semi-volatiles (Jerkovic et al., 2016). ...
Article
Samples of Satsuma mandarin (Citrus unshiu Marc.) nectar, honey sac content and honey were analyzed by FTIR-ATR spectroscopy and reference methods. The spectral analysis allowed detection of the major chemical constituents in C. unshiu nectar-to-honey transformation pathway thus providing information on the intensity and location of the compositional changes occurring during this process. The preliminary results showed that in average more than one-third of sugar-related nectar-to-honey conversion takes place directly in the honey sac; the average sugar content (w/w) was 17.93% (nectar), 47.03% (honey sac) and 79.63% (honey). FTIR-ATR results showed great spectral similarity of analyzed honey samples and small degree variations in both sugar and water content in nectar samples. The spectral data revealed distinctive differences in the chemical composition of individual honey sac contents with the most intensive and complex absorption envelope in the spectral region between 1175 and 950 cm⁻¹ (glucose, fructose and sucrose absorption bands).
... A second experiment was designed to test whether the alkaloid is able to influence associative learning in bees. In this second experiment, naïve bumblebees (n = 60) were presented with an array of two types of flowers, either unrewarding (water only) or rewarding in independent tests, the reward being sucrose solution only (control), or sucrose solution plus 1-ppm nicotine, or sucrose solution plus 2.5-ppm nicotine, or sucrose solution plus 50-ppm nicotine (1-ppm and 2.5-ppm nicotine occur in natural range and 50-ppm above it 12,15,29 ). We found that the presence of the alkaloid in nectar significantly boosts associative learning performance of bees, enhancing flower constancy once a flower type has been memorised. ...
Article
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Many plants defend themselves against herbivores by chemical deterrents in their tissues and the presence of such substances in floral nectar means that pollinators often encounter them when foraging. The effect of such substances on the foraging behaviour of pollinators is poorly understood. Using artificial flowers in tightly-controlled laboratory settings, we examined the effects of the alkaloid nicotine on bumblebee foraging performance. We found that bumblebees confronted simultaneously with two equally rewarded nicotine-containing and nicotine-free flower types are deterred only by unnaturally high nicotine concentrations. This deterrence disappears or even turns into attraction at lower nectar-relevant concentrations. The alkaloid has profound effects on learning in a dose-dependent manner. At a high natural dose, bees learn the colour of a nicotine-containing flower type more swiftly than a flower type with the same caloric value but without nicotine. Furthermore, after experiencing flowers containing nicotine in any tested concentration, increasing numbers of bumblebees stay more faithful to these flowers, even if they become a suboptimal choice in terms of reward. These results demonstrate that alkaloids enhance pollinator flower constancy, opening new perspectives in co-evolutionary process between plants and pollinators.
... Caffeine is hypothesized to have evolved as a deterrent to herbivorous insects (Nathanson 1984), and has been shown at high concentrations (0.01 M) to have negative effects on pollinator behavior Tiedeken et al. 2014). Caffeine, however, is present at low concentrations in the flowers of linden, citrus (10 −5 M) and coffee (10 −4 M) plants (Kretschmar and Baumann 1999;Naef et al. 2004;Maze et al. 2006;Wright et al. 2013) and at these concentrations causes nectar to be preferred by honeybees (Singaravelan et al. 2005), enhances honeybee learning and memory (Si et al. 2005;Wright et al. 2013), and increases bumblebee response to floral odors (Arnold et al. 2021). It has therefore been proposed that low concentrations of caffeine in nectar have positive repercussions for plant pollination, but this has not been studied directly. ...
Article
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Caffeine and ethanol are naturally occurring compounds in floral nectar. We examined how these compounds influenced pollinator behaviors including floral preference, floral constancy, and social behavior using bumblebees, Bombus impatiens, which were given prior experience foraging on either human blue or human white (hereafter blue and white) artificial flowers. Because flower color influenced bee behavior, with strong preferences for blue, we focused on the interaction between nectar chemistry and flower color. Bees that had experience with blue flowers preferred blue regardless of nectar chemistry. In contrast, for bees that had prior experience with white flowers, only the control treatment preferred white, while bees exposed to caffeine and ethanol showed no preference. The effects of nectar compounds may therefore only occur when bees are already foraging on a less-preferred color. We also examined the impact of nectar chemistry on the social behavior of joining other bees at flowers. In the same treatments for which bees showed a preference for previously experienced flower colors (all of the blue treatments and only the white control), bees also preferentially visited unoccupied flowers. In the treatments where bees showed no color preference, however (the white caffeine and ethanol treatments), bees showed no preference for unoccupied flowers. We show that the impacts of field-realistic levels of caffeine and ethanol in nectar on pollinator behavior depend on flower color, highlighting that the potential costs and benefits of nectar chemistry to plants are likely to be dependent on bee behavioral biases for other floral traits. Significance statement Flower nectar often contains toxic compounds hypothesized to impact pollination, but little research has shown their effects on the behavioral decisions of free-flying bees. Caffeine and alcohol occur in the nectar of some flowers. We found that bee response to these nectar compounds depends on the flower color. Bees preferentially visited blue flowers regardless of nectar chemistry, but the presence of caffeine or alcohol reduced bee color preference when bees had experience foraging on white flowers. The bumblebee’s social behavior of joining other bees at flowers showed related effects; in treatments where bees showed a preference for flower type, they also preferred to forage alone. This research highlights that bees make decisions based on the interaction between multimodal cues including nectar chemistry, and therefore the strength of selection on nectar chemistry is dependent on bee behavioral biases for other floral traits.
... Clover honey lacked any apparent signature markers, but was distinguished by its low levels of glucose. The known linden marker, 1-O-β-gentiobiosyl (6-O-(β-D-glucopyranosyl)-β-D-glucopyranosyl) ester of 4-(1hydroxy-1-methylethyl)cyclohexa-1,3-diene-1-carboxylic acid was present (Naef, Jaquier, Velluz, & Bachofen, 2004;Schievano et al., 2013). Gentiobiose was the most abundantly present in the linden honey. ...
Article
The Finnish varietal honeys are valued specialty foods with unique characteristics, owing to their botanical origin. 1H NMR metabolomics was applied to examine the compositional differences and origin-related markers of naturally complex boreal honeys (buckwheat, clover, dandelion, heather, Himalayan balsam, honeydew, linden, lingonberry, multifloral). Special focus was on the metabolites in aqueous samples. Chloroform extracts of selected samples were also analyzed for additional metabolic evidence.
... Contrarily to our results, trace amounts of nicotine have been indicated to occur in Tilia nectar (Naef et al. 2004). Nevertheless, Singaravelan et al. (2006) concluded that honeybees can cope with naturally occurring concentrations of nicotine, even when consumed in large quantities (up to 50 ng/μL). ...
Article
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To investigate whether Tilia trees are poisonous or valuable resources for bee visitors, we determined the nectar and pollen quantities and composition of the four main Tilia species planted in Western Europe (T. cordata, T. platyphyllos, T. tomentosa, and T. × europaea). We developed a new method to detect nicotine in nectars. We observed insect visitor diversity and abundance. We also assessed bumblebee death when individuals were only fed with Tilia flowers. No traces of mannose or nicotine, incriminated in the Tilia toxicity, have been detected in the nectars of the studied species. Huge numbers of insect visitors, mainly bees and syrphids, visited the trees which offer large numbers of flowers, plenty of sugar rich nectar, and protein-rich pollen. Bumblebees only fed with Tilia flowers did not present any particular mortality. We discuss the different hypotheses of the supposed toxicity and propose future research to solve this debate.
... Crane (1977) attributed these deaths to the presence in nectar of the sugar mannose, but Krasenbrink et al. (1994) failed to find mannose in Tilia nectar. Another explanation could be the presence of nicotine in lime nectar (Singaravelan et al. 2006;Naef et al. 2004). Mannose was not quantified in this study and evaluation of the toxicity of Tilia and Aesculus nectar need further investigations. ...
Article
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Urbanization affects the availability and diversity of floral resources (pollen and/or nectar) for wild pollinating insects. For example, urban green areas are characterized by an abundance of ornamental plant species. Increasingly, trees are planted to improve the aesthetics of urban streets and parks. These urban trees might offer important floral resources to pollinating insects. To examine the suitability of urban trees as resources for pollinating insects, we investigated the chemical composition of pollen and nectar as well as the amount of nectar produced by the nine major insect-pollinated tree species planted in cities of Western Europe, namely Acer pseudoplatanus, Aesculus carnea, A. hippocastanum, Robinia pseudoacacia, Tilia cordata, T. x euchlora, T. x europaea, T. platyphyllos and T. tomentosa. The analyses revealed that globally the Tilia trees provide pollen with lower contents of polypeptides, amino acids and phytosterols compared with the other species. Urban tree flowers offer abundant nectar with relatively high sugar contents (0.16–1.28 mg/flower); sucrose was the predominant sugar in all nectars. The investigated tree species could therefore be considered in future city plantings.
... Honey is a natural product that is produced by honeybees from the nectar of flowers [1]. It has nutritional, cosmetic, and therapeutic value [2,3], and it is considered one of the most important natural products that has been used by humankind since ancient times [4,5]. ...
Article
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Background: The goals of the current study were to address a new concept termed a health benefits' index (HBI) and to verify the type of correlation between the pricing of honey and its HBI/medicinal properties. Diverse types of honey from different origins and places were investigated for their antioxidant and antimicrobial activity. Methods: We have utilized a modified protocol of the DPPH assay for measuring free radical scavenging and the microdilution test for the determination of antibacterial/antifungal minimum inhibitory concentrations (MICs). MICs were determined against Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, and Candida albicans microorganisms. Employing a "combined benefits approach" enabled us to attach to each honey type a unique number of HBI that correlate with honey health and medicinal values. Results: The various types of honey demonstrated significant but variable antioxidant, antibacterial, and antifungal activities. Types of wildflower-labeled honey were found to have a wide range of HBI values and medicinal properties, probably due to their containing different nectar contents/phytochemicals. Moreover, an inconsiderable correlation was detected between the market prices of different types of honey and their HBIs. Conclusions: The proposed index of health benefits could be recalculated/updated following measurement of more and more medicinal properties, such as anti-inflammatory, antidiabetic, and anticancer activities. This index could be used as an effective tool for consumers of honey to evaluate the real value of the purchased product.
... DHLLE extracts retained particularly high percentages of less volatile terpenic acids: 4-isopropenylcyclohexa-1,3diene-1-carboxylic acid (22.83; 15.05; 23.64%) and 4-(2-hydroxy-2-propanyl)cyclohexa-1,3diene-1-carboxylic acid (29.27; 18.35; 22.37%). These compounds were previously reported as a markers of linden honey found in its SPE extracts [19]. Interestingly, the percentage of these compounds was higher in the boiled meads than in the not boiled ones. ...
Article
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Volatile profiles of unifloral honeys and meads prepared in different ways (boiled-saturated, not boiled-unsaturated) were investigated by headspace solid-phase micro extraction (HS-SPME) and dehydration homogeneous liquid–liquid extraction (DHLLE) followed by GC-FID/MS analyses. The obtained data were analyzed by principal component analysis (PCA) to evaluate the differences between the investigated products. The volatile profiles of honey as well as the boiled and the not boiled meads prepared from it showed significant discrepancies. The meads contained more aliphatic acids and esters but fewer monoterpenes and aliphatic hydrocarbons than the honey. Significant/substantial differences were found between the boiled (more aliphatic alcohols and acids) and the not boiled meads (more aliphatic hydrocarbons and esters). Some compounds related to yeast metabolism, such as tryptophol, may be considered markers of honey fermentation. This research allowed us to identify chemical markers of botanical origin, retained and detectable in the meads: 4-isopropenylcyclohexa-1,3-diene-1-carboxylic acid and 4-(1-hydroxy-2-propanyl)cyclohexa-1,3-diene-1-carboxylic acid for linden; valeric acid, γ-valerolactone, p-hydroxybenzoic acid for buckwheat; 4-hydroxybenzeneacetic acid, homovanillic acid and trans-coniferyl alcohol for honeydew; and methyl syringate for canola.
... A recent targeted GC-MS search by Jacquemart et al. [45] for nicotine in linden nectar did not detect it. However, in a study by Naef et al. [56] trace amounts of both nicotine and caffeine were detected. It is possible that production of alkaloids varies among individuals; it may be temporal or an induced response to factors not yet determined. ...
Article
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Linden (Tilia spp.), a profusely flowering temperate tree that provides bees with vital pollen and nectar, has been associated with bumble bee (Bombus spp.) mortality in Europe and North America. Bee deaths have been attributed, with inadequate evidence, to toxicity from mannose in nectar or starvation due to low nectar in late blooming linden. Here, we investigated both factors via untargeted metabolomic analyses of nectar from five T. cordata trees beneath which crawling/dead bumble bees (B. vosnesenskii) were observed, and of thoracic muscle of 28 healthy foraging and 29 crawling bees collected from linden trees on cool mornings (< 30°C). Nectar contained the pyridine alkaloid trigonelline, a weak acetylcholinesterase inhibitor, but no mannose. Principal component analysis of muscle metabolites produced distinct clustering of healthy and crawling bees, with significant differences (P<0.05) in 34 of 123 identified metabolites. Of these, TCA (Krebs) cycle intermediates were strongly represented (pathway analysis; P<0.01), suggesting that the central metabolism is affected in crawling bees. Hence, we propose the following explanation: when ambient temperature is low, bees with energy deficit are unable to maintain the thoracic temperature required for flight, and consequently fall, crawl, and ultimately, die. Energy deficit could occur when bees continue to forage on linden despite limited nectar availability either due to loyalty to a previously energy-rich source or trigonelline-triggered memory/learning impairment, documented earlier with other alkaloids. Thus, the combination of low temperature and nectar volume, resource fidelity, and alkaloids in nectar could explain the unique phenomenon of bumble bee mortality associated with linden.
... Extracts were analysed via HPLC-MS (Velos-Pro; Thermo Fisher Scientific; with a photodiode array (PDA)) and highresolution electrospray-ionization mass spectrometry (HR-ESI-MS) on a Thermo Fisher Scientific LTQ Orbitrap, with 5 µl injection volume onto a Phenomenex Luna C18(2) column (150 × 3 mm, 3 µm particle size) held at 30°C, and a linear mobile phase gradient of 10-100% aqueous MeOH containing 0.1% formic acid over 20 min. We focused our analyses on a major secondary metabolite from Tilia honey: 1-[4-(1-hydroxy-1-methylethyl)-1, 3-cyclohexadiene-1-carboxylate]-6-O-β-D-glucopyranosyl-β-D-glucopyranose [26,27] (to which we assign the trivial name tiliaside) and a major component of A. unedo honey: the isoprenoid unedone (2-(1,2-dihydroxypropyl)-4,4,8-trimethyl-1-oxaspiro [2.5] oct-7-en-6-one) [28]. We quantified unedone and tiliaside with peak areas recorded at their UV absorbance maxima (unedone: 245 nm; tiliaside: 308 nm) and compared with calibration curves from pure standards between 1 and 1000 ppm (see electronic supplementary material, data). ...
Article
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Antimicrobial nectar secondary metabolites can support pollinator health by preventing or reducing parasite infections. To better understand the outcome of nectar metabolite–parasite interactions in pollinators, we determined whether the antiparasitic activity was altered through chemical modification by the host or resident microbiome during gut passage. We investigated this interaction with linden ( Tilia spp.) and strawberry tree ( Arbutus unedo ) nectar compounds . Unedone from A. unedo nectar inhibited the common bumblebee gut parasite Crithidia bombi in vitro and in Bombus terrestris gynes. A compound in Tilia nectar, 1-[4-(1-hydroxy-1-methylethyl)-1,3-cyclohexadiene-1-carboxylate]-6- O -β- d -glucopyranosyl-β- d -glucopyranose (tiliaside), showed no inhibition in vitro at naturally occurring concentrations but reduced C. bombi infections of B. terrestris workers. Independent of microbiome status, tiliaside was deglycosylated during gut passage, thereby increasing its antiparasitic activity in the hindgut, the site of C. bombi infections . Conversely, unedone was first glycosylated in the midgut without influence of the microbiome to unedone-8- O -β- d -glucoside, rendering it inactive against C. bombi , but subsequently deglycosylated by the microbiome in the hindgut, restoring its activity. We therefore show that conversion of nectar metabolites by either the host or the microbiome modulates antiparasitic activity of nectar metabolites. This article is part of the theme issue ‘Natural processes influencing pollinator health: from chemistry to landscapes’.
... These chemical structures are particularly related to the composition of cuticular waxes and less to pheromones. The cuticular waxes contain aliphatic compounds from C 18 to C 54 dominated by hydrocarbons [18]. "Queen's pheromone", a well-equilibrated cocktail of fatty acids and aromatic compounds, is one of the most important sets of pheromones in the bee hive [19]. ...
Article
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The GC and GC/MS analyses of the solvent organic extractive from the stomach of the bees, having collected Mentha spp. nectar, revealed the presence of methyl syringate (6.6%), terpendiol I (5.0%) and vomifoliol (3.0%) that can be attributed to the plant origin. Other major compounds from the bee-stomach were related to the composition of cuticular waxes and less to pheromones. Organic extractives from Mentha spp. honey were obtained by solvent-free headspace solid-phase microextraction (HS-SPME) and ultrasonic solvent extraction (USE) and analyzed by GC and GC/MS. The major honey headspace compounds were hotrienol (31.1%-38.5%), 2-methoxy-4-methylphenol (0.5-6.0%), cis- and trans-linalool oxides (0.9-2.8%), linalool (1.0-3.1%) and neroloxide (0.9-1.9%). Methyl syringate was the most abundant compound (38.3-56.2%) in the honey solvent extractives followed by vomifoliol (7.0-26.6%). Comparison of the honey organic extractives with the corresponding bee-stomach extractive indicated that methyl syringate and vomofoliol were transferred to the honey while terpendiol I was partially transformed to hotrienol in ripened honey.
... This cycle of ingestion and regurgitation from one bee to another continues several times until the honey finally achieves the desirable qualities. 7 The milks from specific mammals can also be considered a bio-processed food product, as they are produced with the aid of the rumen, the main digestive organ in cows, goats, sheep, camels, etc. The ingested food materials are transformed into precursors in the rumen (the main digestive organ) by bacteria and yeasts in an anaerobic environment, which are then used in the bio-synthesis of milk in the mammary gland. ...
Chapter
Food processing uses tissues or by-products of biological origins in the production of food for human consumption, a technique that has been used by ancient human societies to produce many staples that still remain in the human diet today. In the world of delicacies, however, many of the world’s exquisite delicacies result from using very unique ‘bio-processing’ methods, and these methods use living mammals, birds, insects, or arachnids in the processing methods. The most accurate description of these is ‘digestive bio-processing’, and this processing may involve the use of a biological system fully (such as the full digestive system, from the salivary glands to the gastrointestinal tract), or only a part of a particular organ. While the vast majority involves the use of animals, a delicacy that is plant bio-processed also exists, and this method involves predation of a plant on a living animal. Most delicacies use rather unique and limited bio-processing methods and hence are both expensive and rare. For these delicacies, demand is increasing and ingredients availability is dwindling, and unsuspecting consumers are purchasing and consuming food delicacies that have been deliberately adulterated or falsified. Despite the uniqueness of these food delicacies, a combination of observational and analytical investigative techniques, some usable in the field, can be used to determine the authenticity of these very special bio-processed foods.
... Caffeine has been found in the nectar of several plant species including coffee, citrus, and linden with a concentration range of 1 to 100 μM (Kretschmar and Baumann 1999;Naef et al. 2004;Wright et al. 2013). In free-flying honey bees, the addition of ecologically relevant concentrations of caffeine to a feeder increases the number of visits compared to sucrose alone (Couvillon et al. 2015;Singaravelan et al. 2005). ...
Article
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As well as sugars to entice pollinators, nectar contains many other chemicals including amino acids and plant secondary compounds such as phenolics, alkaloids, and glycosides. Rather than simply the byproducts of plant metabolism or contamination by compounds meant to deter herbivory, it is clear that these chemicals may have important roles in nectar. Proposed functions of non-sugar components of nectar include pollinator nutrition, reducing nectar robbing, and defense against microbes. Additionally, some of these compounds are able to interact directly with the nervous system via binding to receptor proteins found on the surface of neurons. Thus, these neuroactive components of nectar may be able to manipulate pollinator behavior. To increase our ability to analyze the many functions of nectar, it is important to understand how specific components may interact with neurons. This review examines the neurotransmitter receptors that are targets of some of the chemicals present in nectar. Although these compounds also affect the nervous systems of vertebrates, the focus of this review is on the interactions between nectar and insect pollinators.
... Previously, the average amounts of these compounds found in USE (with dichloromethane) extracts of this variety were 2.3%, 0.7%, and 2.0%, respectively [21]. A particularly high percentage of less volatile terpenic acids: 4-isopropenylcyclohexa-1,3-diene-1-carboxylic acid and 4-(2-hydroxy-2-propanyl)cyclohexa-1,3-diene-1-carboxylic acid, which are reported as markers of linden honey extracted by SPE [24], were found in the DHLLE extract of linden honey (15.6% and 29.5%) but also in smaller amounts in a few other nectar honey samples and fir honeydew honey (1.6% and 6.6%). This is in accordance with previous findings reporting slight amounts of glycosidic precursors of these compounds also in fir honeydew [25]. ...
Article
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Recently, we proposed a new sample preparation method involving reduced solvent and sample usage, based on dehydration homogeneous liquid–liquid extraction (DHLLE) for the screening of volatiles and semi-volatiles from honey. In the present research, the method was applied to a wide range of honeys (21 different representative unifloral samples) to determine its suitability for detecting characteristic honey compounds from different chemical classes. GC-FID/MS disclosed 130 compounds from different structural and chemical groups. The DHLLE method allowed the extraction and identification of a wide range of previously reported specific and nonspecific marker compounds belonging to different chemical groups (including monoterpenes, norisoprenoids, benzene derivatives, or nitrogen compounds). For example, DHLLE allowed the detection of cornflower honey chemical markers: 3-oxo-retro-α-ionols, 3,4-dihydro-3-oxoedulan, phenyllactic acid; coffee honey markers: theobromine and caffeine; linden honey markers: 4-isopropenylcyclohexa-1,3-diene-1-carboxylic acid and 4-(2-hydroxy-2-propanyl)cyclohexa-1,3-diene-1-carboxylic acid, as well as furan derivatives from buckwheat honey. The obtained results were comparable with the previously reported data on markers of various honey varieties. Considering the application of much lower volumes of very common reagents, DHLLE may provide economical and ecological advantages as an alternative sample preparation method for routine purposes.
... While several approaches can be used during experimental planning, the best approach is selected based on the type of evaluation or response. Thus, planning can be carried out using the factorial model, the fractional factorial, the Doehlert, the central compound (Central Composite Design -CCD), the Box-Behnken (Box-Behnken Design -BBD), among other approaches [31]. ...
Article
The growing consumption of illicit drugs in Brazil is becoming increasingly problematic for society. It is therefore critical to develop technologies to combat drug trafficking that allow for rapid, non-invasive evaluation of drug samples. Microfluidics is a technology that manipulates and studies small amounts of fluids, using structures with dimensions from ten to hundreds of micrometers (microdevices). The main advantages of microfluidic approaches are its low cost, speed, and ability to provide results in loco. Here, paper microfluidics were developed to perform the modified Scott test to calculate the cocaine hydrochloride content in seized samples of cocaine (n = 30) and crack (n = 30). A smartphone with the Photometrix® app was used to construct a model for quantifying the samples. A factorial model was developed to optimize microfluidic analytical parameters such as spot size (6, 8 and 10 mm), reagent content (50, 75, and 100% cobalt thiocyanate II), cocaine hydrochloride concentration (4, 6 and 8 mg mL-1) and response time (or analyte detection; t = 0, 0.5 1, 12 and 24 h). After experimental planning, a diameter of ΜPADs = 8 mm - [Co(SCN)2] = 100% and a 1 h response time were identified as the best conditions. We observed that the cocaine hydrochloride concentration did not influence the model. A sample concentration of 15 mg mL-1 was used to quantify cocaine hydrochloride in street samples apprehended by the Forensic Police of Espírito Santo state (with n = 60). The quantification curve constructed to determine the cocaine hydrochloride concentration showed a determination coefficient, R2, of 0.98246 and RMSEC (root mean squares error calibration - mean square error of the calibration) of 0.39480, with a LOD and LOQ of 0.09 and 0.30 mg mL-1, respectively. For the crack samples, the cocaine hydrochloride concentrations ranged from 2.5 to 60.8 wt% with an average purity content of 21.3 ± 13.3 wt%. For the seized cocaine samples, variation in hydrochloride content from 1.2 to 22.6 wt% was observed with a mean percentage of 14.19 ± 6.92 wt%. Finally, chemometric tools such as principal component analysis were used to assess the similarity among the samples.
... It has been detected in the floral nectar and pollen of Citrus (Sapindales: Rutaceae) and other plants from sub-tropical regions (Kretschmar & Baumann, 1999;Sano et al., 2013;Wright et al., 2013), but also in the yaupon Ilex vomitoria (Celastrales: Aquifoliacae) (Power & Chesnut, 1919) and the linden Tilia spp. (Malvales: Tiliaceae) (Naef et al., 2004) in temperate regions. Caffeine effects are well documented on the animal brain and body, including on arthropods (Mustard, 2014;Thomson et al., 2015). ...
Article
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Secondary metabolites are central to understanding the evolution of plant-animal interactions. Direct effects on phytophagous animals are well-known, but how secondary consumers adjust their behavioral and physiological responses to the herbivore's diet remains more scarcely explored for some metabolites. Caffeine is a neuroactive compound that affects both the behaviour and physiology of several animal species, from humans to insects. It is an alkaloid present in nectar, leaves and even sap of numerous species of plants where it plays a role of chemical defenses against herbivores and pathogens. Caffeine effects have been overlooked in generalist herbivores, that are not specialized on coffee or tea plants. Using a host-parasitoid system, we show that caffeine intake at relatively low dose affects longevity and fecundity of the primary consumer, but also indirectly of the secondary one, suggesting that this alkaloid and/or its effects can be transmitted through trophic levels and persist in the food chain. Parasitism success was lowered by ≈16% on hosts fed with caffeine, and parasitoids of the next generation that have developed in hosts fed on caffeine showed a reduced longevity, but no differences in mass and size were found. This study helps at better understanding how plant secondary metabolites, such as caffeine involved in plant-animal interactions, could affect primary consumers, could have knock-on effects on upper trophic levels over generations, and could modify interspecific interactions in multitrophic systems.
... Volatiles are usually analyzed by methods other than HplC, such as GC, GC-MS, and GC-olfactory analyses. These volatiles, too, are promising chemotaxonomic markers for the assessment of the botanical origin of honey [99,[121][122][123]. ...
... This can lead to internal parasites being exposed to metabolites that differ substantially from those found in the uningested floral product. Furthermore, in bee species that collect and store nectar and pollen, phytochemicals may also change pre-ingestionfor example in stored pollen (Loper et al., 1980) and nectar/honey (Liu et al., 2005;Naef et al., 2004) of social corbiculate bees, and potentially in pollen provisions for larvae of solitary bees (Steffan et al., 2019). While recognizing this potential, for the rest of this section we focus on post-ingestion processes. ...
Article
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Floral nectar and pollen commonly contain diverse secondary metabolites. While these compounds are classically thought to play a role in plant defense, recent research indicates that they may also reduce disease in pollinators. Given that parasites have been implicated in ongoing bee declines, this discovery has spurred interest in the potential for ‘medicinal’ floral products to aid in pollinator conservation efforts. We review the evidence for antiparasitic effects of floral products on bee diseases, emphasizing the importance of investigating the mechanism underlying antiparasitic effects, including direct or host-mediated effects. We discuss the high specificity of antiparasitic effects of even very similar compounds, and highlight the need to consider how nonadditive effects of multiple compounds, and the post-ingestion transformation of metabolites, mediate the disease-reducing capacity of floral products. While the bulk of research on antiparasitic effects of floral products on bee parasites has been conducted in the lab, we review evidence for the impact of such effects in the field, and highlight areas for future research at the floral product-bee disease interface. Such research has great potential both to enhance our understanding of the role of parasites in shaping plant-bee interactions, and the role of plants in determining bee-parasite dynamics. This understanding may in turn reveal new avenues for pollinator conservation.
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The presence of antimicrobial secondary metabolites in nectar suggests that pollinators, which are threatened globally by emergent disease, may benefit from the consumption of nectars rich in these metabolites. We tested whether nicotine, a nectar secondary metabolite common in Solanaceae and Tilia species, is used by parasitized bumblebees as a source of self-medication , using a series of toxicological, microbiological and behavioural experiments. Caged bees infected with Crithidia bombi had a slight preference for sucrose solution laced with the alkaloid and behavioural tests showed that the parasite infection induced an increased consumption of nicotine during foraging activity, though nicotine had an appetite-reducing effect overall. When ingested, nicotine delayed the progression of a gut infection in bumblebees by a few days, but dietary nicotine did not clear the infection, and after 10 days the parasite load approached that of control bees. Moreover, when pathogens were exposed to the alkaloid prior to host ingestion, the protozoan’s viability was not directly affected, suggesting that anti-parasite effects were relatively weak. Nicotine consumption in a single dose did not impose any cost even in starved bees but the alkaloid had detrimental effects on healthy bees if consistently consumed for weeks. These toxic effects disappeared in infected bees, suggesting that detoxification costs might have been counterbalanced by the advantages in slowing the progression of the infection. Nicotine consumption did not affect bee lifespan but the reduction in the parasite load may have other likely unexplored subtle benefits both for individual bees and their colony. Potential evidence for self-medication is discussed. The contention that secondary metabolites in nectar may be under selection from pollinators, or used by plants to enhance their own reproductive success, remains to be confirmed.
Article
AIM: To examine the possible effects of honey supplementation on hepatic damage due to obstruction of the common bile duct in an experimental rat model. METHODS: The study was performed with 30 male rats divided into three groups: a sham group, an obstructive jaundice group, and an obstructive jaundice plus honey group. At the end of the study period, the animals were sacrificed, and levels of nitric oxide (NO), and NO synthase (NOS) activities were measured in liver tissues, and levels of adenosine deaminase (ADA) and alanine transaminase (ALT) activities were measured in serum. RESULTS: Blood ALT and ADA activities were significantly elevated in the jaundice group as compared to those of the sham group. In the obstructive jaundice plus honey group, blood ALT and ADA activities were significantly decreased as compared to those of the jaundice group. In erythrocytes and liver tissues, NO levels were found to be significantly higher in the obstructive jaundice plus honey group compared to those of the sham group. Additionally, NO levels were found to be significantly higher in liver tissues from the animals in the obstructive jaundice plus honey group than those of the jaundice group. CONCLUSION: Honey was found to be beneficial in the prevention of hepatic damage due to obstruction of the common bile duct.
Article
The major developments and concepts in the study of terpenes (mainly monoterpenes) as well as C9-, C10-, C13-, C14- and C15- norisoprenoids in honey are summarized. Their occurrence and biosynthetic correlations (terpene transformations, particularly the generation of linalool derivatives as well as carotenoid degradation and the corresponding variety of norisoprenoids) are discussed considering the plant/nectar/bee-stomach composition and hive conditions (e.g. warm and acidic conditions that can lead to oxidative degradation of compounds). Terpenes up to C15 have been found as major compounds of the essential oils, but honeys from the same plant sources exhibit only partial similarity to the oil composition (e.g. lavender, sage or citrus essential oils/honeys). The formation of heat-derived or prolonged storage artefacts in honey (mainly the products of Maillard reactions and Strecker degradation reactions) influence the honey composition, and hotrienol is particularly labile among the chemical groups discussed. Stimulated by the challenges of fingerprinting methods and structure identification, exploratory studies (including our published results) on terpenes and norisoprenoids are summarized with emphasis on identifying specific or nonspecific chemical markers of the botanical origin of honey. In general, nonspecific biomarkers dominate in different honey types (e.g. monoterpenes: linalool, linalool oxide isomers or lilac alcohol/aldehyde isomers; norisoprenoids: isophorone and vomifoliol derivatives) while only a few specific biomarkers are found (e.g. anhydrolinalool oxide isomers, 3,4-dihydro-3-oxoedulan isomers, 3-oxo-retro-α-ionol isomers, kamahine A-C or meliracemoic acid).
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Although persimmon fruit is grown in various countries and is increasingly appreciated for its nutritional value, health benefits and rich flavour, surprisingly little research has been conducted to uncover the components responsible for its unique flavour. An aroma extract of persimmon fruit (Diospyros kaki L., var. Triumph) was obtained by hydrodistillation under vacuum followed by solid phase extraction. Gas chromatography–mass spectometry (GC-MS) analysis of the extract led to the positive identification of 50 compounds, among which aldehydes emerged as the most important class of volatile compounds. Thirty-two compounds were determined to have aroma-impact, by gas chromatography–olfactometry analysis of the aroma extract. The six most intense aroma-impact compounds were methional, (E)-2-hexenal, phenylacetaldehyde, (E,Z)-2,6-nonadienal, hexanal and Furaneol®. Their aroma qualities largely explain the aroma character of persimmon fruit, which was described as fresh peach, a touch of orange, sweet, woody, floral, green and potato. Unambiguous identification of trace aroma-impact compounds (E,E,Z)-2,4,6-nonatrienal and (E,Z,Z)-2,4,7-decatrienal by GC-MS was achieved by applying a solid phase extraction procedure for selective isolation of carbonyl compounds. Copyright © 2011 John Wiley & Sons, Ltd.
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The presence of antimicrobial secondary metabolites in nectar suggests that pollinators, which are threatened globally by emergent disease, may benefit from the consumption of nectars rich in these metabolites. We tested whether nicotine, a nectar secondary metabolite common in Solanaceae and Tilia species, is used by parasitized bumblebees as a source of self-medication , using a series of toxicological, microbiological and behavioural experiments. Caged bees infected with Crithidia bombi had a slight preference for sucrose solution laced with the alkaloid and behavioural tests showed that the parasite infection induced an increased consumption of nicotine during foraging activity, though nicotine had an appetite-reducing effect overall. When ingested, nicotine delayed the progression of a gut infection in bumblebees by a few days, but dietary nicotine did not clear the infection, and after 10 days the parasite load approached that of control bees. Moreover, when pathogens were exposed to the alkaloid prior to host ingestion, the protozoan's viability was not directly affected, suggesting that anti-parasite effects were relatively weak. Nicotine consumption in a single dose did not impose any cost even in starved bees but the alkaloid had detrimental effects on healthy bees if consistently consumed for weeks. These toxic effects disappeared in infected bees, suggesting that detoxification costs might have been counterbalanced by the advantages in slowing the progression of the infection. Nicotine consumption did not affect bee lifespan but the reduction in the parasite load may have other likely unexplored subtle benefits both for individual bees and their colony. Potential evidence for self-medication is discussed. The contention that secondary metabolites in nectar may be under selection from pollinators, or used by plants to enhance their own reproductive success, remains to be confirmed.
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Lime flower is used worldwide for its sedative and antispasmodic properties. Traditionally it is used for migraine, hysteria, feverish colds, and for raised arterial pressure associated with arteriosclerosis and nervous tension [1]. Besides flavonols, little is known for the rest of the phenol content. In the present study extensive HPLC-DAD, HPLC-ESI-MS and HPLC-MS/MS analyses were undertaken in the aqueous preparations of Tilia platyphyllos Scop. influorescences. An HPLC-DAD-ESI-MS method was developed and optimised for the quantitative determination of the constituents. Analyses of the ethanol extracts confirmed the predominance of flavonol glycosides and protocatechuic acid. In contrast, both decoction and infusion, which are nevertheless the traditional herbal preparations, were more complex, containing polar simple phenolics and low molecular weight procyanidins. The use of different HPLC columns permitted a good separation of the constituents and enabled their quantitation. The method showed good linearity, (r2 0.9999 for tiliroside and catechin and 0.9986 for quercetin-3-O-glucoside), intra/inter-day variability (%RSD <1.56 and 1.33) and real sample repeatability (%RSD <4.0). Preparative chromatographic investigations (Sephadex LH-20) and NMR analyses revealed the presence of procyanidin B4, while HPLC-MS/MS analyses enabled the identification of procyanidin trimers and tetramers. Overall, 20 constituents were detected and identified, belonging mainly to three classes of compounds: phenolic acid derivatives, condensed tannins and flavonol glycosides. Aqueous extracts contain a higher amount of procyanidins (strong chelating properties) than flavonols and caution should be taken upon frequent use of the drug. This is the first report of detailed analysis of the chemical composition of Tiliae flos. References: 1. Barnes J, Anderson LA, Phillipson JD. (2007) Herbal Medicines, Pharmaceutical Press.
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Caffeine acts as a weak psychostimulant and is known to cause trouble with sleeping. Therefore, the presence of caffeine in sleep-aid herbal teas was somewhat surprising, and confirmatory investigations were conducted to exclude any possible misidentification. The botanicals of the sedative mixtures were analysed individually by ultra performance liquid chromatography (UPLC) coupled with a time-of-flight high-resolution mass spectrometer (TOF-HRMS), and caffeine was detected in linden (Tilia spp.) extracts. The presence of caffeine was unambiguously confirmed by means of its characteristic mass spectrum acquired during direct analyses of powdered linden by thermal desorption coupled to a GC×GC-TOF-MS. Caffeine content was determined in 11 linden-based samples, with a validated UPLC-MS/MS method using two mass transitions. Concentrations were between traces and 110 mg kg–1 in the herbal material while those in the corresponding prepared sleep-inducing hot beverages ranged from traces to 226 μg per cup.
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S)-(−)-p-Mentha-1,3-dien-9-ol (3) has been synthesized and fully characterized, using dill ether as the starting material. Dill ether is a common constituent of the essential oil of dill weed, Anethum graveolens L. In the first step, (8S)-(−)-p-mentha-1,3-dien-9-yl acetate was prepared by treating dill ether with anhydrous magnesium bromide, followed by the addition of acetic anhydride. Hydrolysis of this mixture with potassium hydroxide led to the formation of alcohol 3, with p-cymen-9-ol as the main by-product. The chemical identity of compound 3 has been confirmed by GC/MS, IR, one- and two-dimensional NMR. Chiral analysis has shown that it consists of enantiomerically pure (8S)-(−)-p-mentha-1,3-dien-9-ol. This has been corroborated by selective oxidation of p-mentha-1,3,8-triene found in the essential oil of curly leaf parsley, Petroselinum crispum (Mill.) Fuss., to give a racemic mixture of p-mentha-1,3-dien-9-ol. Other esters (propionate, butyrate and valerate) of alcohol 3 have been prepared in a similar way by treating dill ether with the corresponding acid anhydride. Olfactory evaluation of alcohol 3 revealed a floral character while its esters gave a range of fruity and herbaceous notes.
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Conventionally, floral nectar has been conceived as a simple sugar solution. But recent studies contradict it by warranting nectar as a complex biological fluid containing significant biochemistry with an array of potential functions. Quantitatively, nectar is about 90% sugar by dry weight; the other 10% embraces a myriad of compounds like amino acids, lipids, antioxidants, mineral ions, and secondary compounds. Alkaloids, glycosides and phenolic substances are the most common secondary compounds (SC hereafter) in nectar, often reported to be toxic and/or deterrent. SC are not uncommon in floral nectar and were found in 9%-55% of the surveyed species. The relatively widespread existence of SC-laden (so called) 'toxic nectar' is puzzling, given that the general function of nectar, with its array of sugars and amino acids, is to attract pollinators. Why then would SC, which are usually toxic and/or repellent, be present in a structure whose function is to attract mutualists? This has drawn relatively little attention from ecologists. Several adaptive hypotheses have been proposed to explain the possible ecological and evolutionary role of SC in mediating plant-pollinator interactions. These hypotheses have grounded several evolutionary reasons why SC show up in nectar? Prominent among those are; a) to deter illegitimate floral visitors like nectar robbers b) to attract specialist pollinators over generalists, c), to alter pollinator movements and d) to aid antimicrobial functions and thereby ensuring a better fitness of both plants and pollinators. Though, evidences began endorsing the hypotheses, all of which appeared to have dealt with one side coin of the tale about SC in nectar. This chapter is intended to expose the other side of the coin, which uncovers the hitherto unexplored facts and posers. Major issues discussed in this chapter are: 1) How can nectar SC be adaptive? 2) Does SC's presence in nectar depend on the compound's presence in other parts of the plant like leaves, flower base, corolla, pollen etc; or, does SC appear in nectar regardless of its presence or absence in other parts of the plant? 3) Do plants use psychoactive alkaloids in nectar to addict pollinators? 4) Impact of nectar SC on pollinators' memory and central nervous system (CNS), 5) How do floral visitors cope with toxic SC? Foregoing issues are addressed based on empirical studies and excerpts from an extensive review of literature.
Chapter
Food processing uses tissues or by-products of biological origins in the production of food for human consumption, a technique that has been used by ancient human societies to produce many staples that still remain in the human diet today. In the world of delicacies, however, many of the world’s exquisite delicacies result from using very unique ‘bio-processing’ methods, and these methods use living mammals, birds, insects, or arachnids in the processing methods. The most accurate description of these is ‘digestive bio-processing’, and this processing may involve the use of a biological system fully (such as the full digestive system, from the salivary glands to the gastrointestinal tract), or only a part of a particular organ. While the vast majority involves the use of animals, a delicacy that is plant bio-processed also exists, and this method involves predation of a plant on a living animal. Most delicacies use rather unique and limited bio-processing methods and hence are both expensive and rare. For these delicacies, demand is increasing and ingredients availability is dwindling, and unsuspecting consumers are purchasing and consuming food delicacies that have been deliberately adulterated or falsified. Despite the uniqueness of these food delicacies, a combination of observational and analytical investigative techniques, some useable in the field, can be used to determine the authenticity of these very special bio-processed foods.
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In this study, VOC profiles of acacia flowers, honey samples at different processing stages and related comb wax samples were studied using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry. It was found that some monoterpene compounds like α-pinene, myrcene, cis-β-ocimene and 4-terpinelol were common for acacia flower and all acacia honey samples, and the presence of verbenone and ocimene was firstly established in acacia honey. The most enriched VOC profile was obtained for raw honey before cell capping, where the final composition of lactones was achieved. On the contrary, number of alcohols, esters, and variety of terpenes, as well as their concentration in the honey samples decrease through ripening processes. Strained honey was characterized by the absence of camphor, α-bisabolol, 3-carene, while isophorone, and hexanoic acid were identified only in this type of honey. The composition of final VOC profile of honey was also influenced by the age of comb wax. The additional aromatic and lactone compounds e.g. phenol, 1-phenylethanol, δ-hexalactone, γ-heptalactone were observed for honey maturated in old dark comb wax. This article is protected by copyright. All rights reserved.
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The presence of antimicrobial secondary metabolites in nectar suggests that pollinators, which are threatened globally by emergent disease, may benefit from the consumption of nectars rich in these metabolites. We tested whether nicotine, a nectar secondary metabolite common in Solanaceae and Tilia species, is used by parasitized bumblebees as a source of self-medication, using a series of toxicological, microbiological and behavioural experiments. Caged bees infected with Crithidia bombi had a slight preference for sucrose solution laced with the alkaloid and behavioural tests showed that the parasite infection induced an increased consumption of nicotine during foraging activity, though nicotine had an appetite-reducing effect overall. When ingested, nicotine delayed the progression of a gut infection in bumblebees by a few days, but dietary nicotine did not clear the infection, and after 10 days the parasite load approached that of control bees. Moreover, when pathogens were exposed to the alkaloid prior to host ingestion, the protozoan’s viability was not directly affected, suggesting that anti-parasite effects were relatively weak. Nicotine consumption in a single dose did not impose any cost even in starved bees but the alkaloid had detrimental effects on healthy bees if consistently consumed for weeks. These toxic effects disappeared in infected bees, suggesting that detoxification costs might have been counterbalanced by the advantages in slowing the progression of the infection. Nicotine consumption did not affect bee lifespan but the reduction in the parasite load may have other likely unexplored subtle benefits both for individual bees and their colony. Potential evidence for self-medication is discussed. The contention that secondary metabolites in nectar may be under selection from pollinators, or used by plants to enhance their own reproductive success, remains to be confirmed.
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The plant kingdom produces an extraordinary diversity of secondary metabolites and the majority of the literature supports a defensive ecological role for them, particularly against invertebrate herbivores (antagonists). Plants also produce secondary compounds in floral nectar and pollen and these are often similar to those produced for defense against invertebrates elsewhere in the plant. This is largely because the chemical armoury within a single plant species is typically restricted to a few biochemical pathways and limited chemical products but how their occurrence in floral rewards is regulated to mediate both defence and enhanced pollination is not well understood. Several phytochemicals are reviewed here comparing the defensive function alongside their benefit to flower visiting mutualists. These include caffeine, aconitine, nicotine, thymol, linalool, lupa-nine and grayanotoxins comparing the evidence for their defensive function with their impacts on polli-nators, their behaviour and well-being. Drivers of adaptation and the evolution of floral traits are discussed in the context of recent studies. Ultimately more research is required that helps determine the impacts of floral chemicals in free flying bees, and how compounds are metabolized, sequestered or excreted by flower feeding insects to understand how they may then affect the pollinators or their parasites. More work is also required on how plants regulate nectar and pollen chemistry to better understand how secondary metabolites and their defensive and polli-nator supporting functions are controlled, evolve and adapt.
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Honey is a natural product that could be easily adulterated with various cheaper sweeteners. In the present study, matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was applied for the detection of honey adulteration based on oligosaccharide and polysaccharide profiles. MS-based strategy could reveal the presence of polysaccharides with higher degree of polymerization (DP ≥ 13) and abnormal trends of saccharides in adulterated honey samples, which could be used as indicators for the identification of honey adulteration with high-fructose corn syrup and corn syrup. MS/MS-based strategy was proposed to characterize the difference in the composition of oligosaccharide isomers between honey samples and adulterated ones with corn syrup or invert syrup, in which the [M+Cl]− of disaccharides, trisaccharides and tetrasaccharides were fragmented to give diagnostic product ion pairs. The method is effective and robust for the high-throughput monitoring of honey adulteration, and provides a new perspective for the identification of other high-carbohydrate foods.
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According to legislation, unifloral honeys are characterized by their organoleptic, physicochemical, and microscopic properties. Melissopalynology is the established method for identifying the pollen taken up with the floral nectar by forager bees and is used for authentication of the nectar sources in honey. For cornflower honey (Centaurea cyanus), the pollen input does not correlate with the nectar input, because the nectar is produced both in floral and in extrafloral nectaries. The well-known cornflower marker lumichrome has now also been detected in the extrafloral nectar. Therefore, lumichrome is a suitable marker substance for cornflower honey. Four different methods for the sole analysis of lumichrome in honey were validated and compared. Studies over nine years have shown that unifloral cornflower honey should contain approximately 35 mg/kg lumichrome. For a further differentiated cornflower honey specific verification, other nonvolatile compounds like 7-carboxylumichrome and volatiles, such as 3,4-dihydro-3-oxoedulan I and 3,4-dihydro-3-oxoedulan II, should be analyzed. This enables a more specific accuracy for the classification of unifloral cornflower honey.
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Plant secondary metabolites found in floral nectar can affect the behaviour of pollinating insects, but how these changes benefit plants directly is little understood. An experimental study with bumblebees shows that recalling a caffeine-enhanced odour memory can increase flower visitation.
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Honey maturity, a critical factor for quality evaluation, is difficult to detect in the current industry research. The objective of this study was to explore the changes in the composition and find potential maturity indicators of rape honey at different maturity stages through evaluating physicochemical parameters (moisture, sugars, pH, electrical conductivity, total protein, total phenols, total flavonoids, proline, and enzyme activity), the antioxidant capacity, and volatile components. The relevant results are as follows: 1. As the maturity increased, the moisture, sucrose, and maltose content of rape honey gradually decreased, while the glucose, fructose, and total protein content gradually increased. The activities of diastase, invertase, and β-glucosidase showed a significant increase with the elevation of ripening days, and the activity of glucose oxidase reached the highest before completely capping. 2. The antioxidant capacity of honey increased with the increase in honey maturity. There is a significant and strong correlation between the bioactive components of rape honey and antioxidant capacity (p < 0.01, |r| > 0.857). 3. Thirty-five volatile components have been identified. Nonanal, benzaldehyde monomer, and benzaldehyde dimer can be used as potential indicators for the identification of honey maturity stages. Principal component analysis (PCA) based on antioxidant parameters and volatile components can identify the maturity of honey.
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The essential oil isolated by hydrodistillation from flowers and root bark of Gochnatia polymorpha (Less) Cabr. ssp floccosa Cabr. (Asteraceae) was analyzed by capillary GC/MS. Thirty components were identified in oil of flowers. The composition depends on the stage of flowering. At the beginning of flowering, the main components were (E)-nerolidol (20,4%) and eugenol (17,9%) whereas at the end they were phenylacetaldehyde (14,6%) and tricosane (12,0%). In the essential oil of root bark ten sesquiterpenes were identified. The major components were b-bisabolene (31,0%) and b-bisabolol (21,5%). This paper describes for the first time the composition of essential oil in the genus Gochnatia.
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The allocation of purine alkaloids within citrus flowers was studied and found to be linked to anthesis, with 99% of the total flower caffeine confined to the androecium. The main alkaloid is caffeine accompanied by considerable (up to 30% of caffeine) concentrations of theophylline. In the anther, these purine alkaloids reach altogether a concentration of 0.9% dry wt which is close to the caffeine content of the Arabica coffee bean. The pollen alkaloid concentration is in the same range. Much lower but still marked concentrations were found in the nectar. A considerable breakdown of alkaloids during honey production is assumed. The biological significance of this particular secondary compound allocation as well as possible effects on the key pollinator, the honey-bee, are discussed.
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The foliar essential oils of Pimenta racemosa (Miller) J. Moore var. grisea (Kiaerskov) Fosb. are dominated by geraniol (0–85.52%), methyl eugenol (0.30–92.60%), and/or trans-methyl isoeugenol (0–86.32%). The foliar essential oils of Pimenta racemosa var. hispaniolensis (Urban) Landrum are dominated by 1,8-cineole (0.05–37.96%), methyl chavicol (0–22.61%), methyl eugenol (0–63.88%), γ-terpinene (0–16.67%), terpinen-4-ol (0.08–28.98%), and/or thymol (0–44.02%). The foliar essential oils of Pimenta racemosa var. ozua (Urban & E. Ekman) Landrum are dominated by 1,8-cineole (47.24–55.93%), limonene (3.62–30.07%), and/or α-terpineol (6.68–15.12%). The commercial bay oil (P. racemosa var. racemosa) is dominated by chavicol (
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Aroma extract dilution analysis of linden honey volatiles resulted in 21 odour compounds having high factors of dilution (FD); 18 of these compounds were identified as 1-hexen-3-one, 2-acetyl-1 -pyrroline, dimethyl trisulphide, methional, phenylacetaldehyde, 2-phenylethanol, linalool, p-cresol, 3,9-epoxy-lpmenthene, 4-methylacetophenone, 3,9-epoxy-1,4(8)-p-menthadiene (linden ether), 1,3 p-menthadien-7-al, p-anisaldehyde, 4vinylguaiacol, (E)-p-damascenone, eugenol, vanillin andcis-rose oxide. Linden ether andcis-rose oxide, which were also found in an extract obtained from the blossoms of the lime tree (Tifa cordata), were absent in honeys of other botanical origin. These two odourants and the odourlesstrans-limonene-1,2-diol are proposed as indicators for linden honey. The odour thresholds (in air) of the 18 aroma compounds are reported.Die Aromaextrakt-Verdnnungs-analyse der flchtigen Verbindungen aus Lindenhonig ergab 21 Geruchsstoffe mit hohen FD-Faktoren; 18 davon wurden identifiziert: l-Hexen-3-on, 2-Acetyl-1 -pyrrolin, Dimethyltrisulfid, Methional, Phenylacetaldehyd, 2-Phenylethanol, Linalool, p-Kresol, 3,9-Epoxy-1 p-menthen, 4-Methylacetophenon, 3,9-Epoxy-1,4(8)p-menthadien (Lindenether), 1,3 -p-Menthadi-en-7-al,p-Anisaldehyd, 4-Vinylguajacol, (E)--Da-mascenon, Eugenol, Vanillin undcis-Rosenoxid. Lindenether undcis-Rosenoxid, die auch in einem Extrakt von Lindenblten (Tilla cordata) vorkamen, fehlten in Honigen anderer botanischer Herkunft. Diese beiden Aromastoffe und das geruchlosetrans-Limonen-1,2-diol werden als Indikatoren fr Linden honig vorgeschlagen. Die Geruchsschwellen (in Luft) der 18 Aromastoffe wurden bestimmt.
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This paper will briefly review the biochemistry, molecular biology and functionality of alpha-dioxygenases from tobacco, Arabidopsis, cucumber, pea, rice and algae. Alpha-dioxygenase treated in this review has emerged as a third group of fatty acid dioxygenases along with lipoxygenases and endoperoxide synthases.
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The study of the volatile fraction of cheese plays an important role in evaluating aroma. Two varieties of Quartirolo, a typical Italian mountain cheese, during 5 processing steps (milk, curd, mould, salting and 45 d of ripening) were examined in order to isolate and identify flavour volatile compounds. Simultaneous distillation extraction was carried out using methylene chloride added with n-nonadecane as internal standard. After 2 h, the procedure was stopped and the extract dried over anhydrous sodium sulphate. Aroma compounds were analysed by gas chromatography and detected by mass spectrometry. About 70 compounds were identified by comparing GC retention times with those of known standards and by mass spectra; they included 12 aldehydes, 13 ketones, 19 free fatty acids (FFA), 11 alcohols, 6 hydrocarbons, 1 sulfur compound and 5 furans. These compounds increased during the cheese making process and reached their maximum at the end of ripening. These changes were evaluated and discussed.
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The biosynthesis of purine alkaloids in flower buds of tea plants was investigated. More than 25% of total radioactivity of [8-14C]adenine taken up by stamens isolated from tea flower buds was found to have been incorporated into purine alkaloids, namely, theobromine and caffeine, 24 h after administration of the labelled compound. Pulse-chase experiments indicated that [8-14C]adenine taken up by the stamens was converted to adenine nucleotides and subsequently incorporated into theobromine and caffeine. Since 5 µM coformycin, an inhibitor of AMP deaminase, inhibited the incorporation of radioactivity into the purine alkaloids, synthesis of caffeine from adenine nucleotides seems to be initiated by the reaction of AMP deaminase. Although most of the radioactivity from [8-14C]inosine was recovered as CO2 and ureides, considerable amounts of radioactivity were recovered as purine alkaloids. The incorporation of radioactivity from [8-14C]inosine into the purine alkaloids was not affected by coformycin. The five enzymes involved in synthesis of 5-phosphoribosyl-1-pyrophosphate from glucose were present in the stamens and petals of tea flower buds. From present and previous results, the pathway for the biosynthesis of caffeine from adenine nucleotides in flower buds of tea is discussed.Copyright 1993, 1999 Academic Press
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The reaction of various types of organic halides with electron deficient olefins under the influence of NiCl2 × 6 H2O in the presence of zinc and pyridine leads to formal addition products of hydrocarbons to CC-double bonds in good yield.
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Simple Synthesis of the Enantiomeric (E)-9-Hydroxy-2-decenoic Acids The enantiomeric (E)-9-Hydroxy-2-decenoic acids (1), components of the swarm settling pheromone in Apis mellifica L. (honey bee) have been synthesized. The lithium derivative of 1-hexyne was treated with (R)-(+)-methyloxirane (2), (S)-(−)-2 or (±)-2 to give the alkynols (R)-(−)-3, (S)-(+)-3 or (±)-3, which could be isomerized with the sodium salt of 1,3-propanediamine to give (R)-(−)-8-nonyn-2-ol (4) and (±)-4. These were methoxycarbonylated to produce the esters (R)-(−)-5, (S)-(+)-5 or (±)-5. Selective hydrogenation in pyridine with Pd/BaSO4 as catalyst gave the (Z)-esters (R)-(−)-6, (S)-(+)-6 or (±)-6 which could be isomerized with photochemically generated phenylthio radicals to produce the (E)-esters (R)-(–)-7, (S)-(+)-7 or (±)-7. The acids present in the pheromone (R)-(−)-1, (S)-(+)-1 and (±)-1 could be obtained by basic hydrolysis of the esters. The minor but important component 8 of the swarm settling pheromone has been synthesized by treating the Grignard reagent obtained from 5-bromo-guaiacol benzyl ether with ethylene oxide to give 9 in high yield. Hydrogenolytic removal of the benzyl group in 9 produced 8 directly.
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The volatile fraction of honey is believed to facilitate satisfactory discrimination between honeys of different botanical origin. A new methodology for extracting volatile compounds was developed, using n-pentane:diethylether organic solvent and a water bath with ultrasound assistance. Analysis of the extracts of four Citrus species’ flowers showed linalool to be the predominant compound (11.3% in lemon, 51.6% in orange, 80.6% in sour orange and 75.2% in tangerine). The extracts from citrus honey were predominated by an array of linalool derivatives (more than 80% of the total extract). (E)-2,6-dimethyl-2,7-octadiene-1,6-diol was the predominant compound (44.7%), while significant proportions of 2,6-dimethyl-3,7-octadiene-2,6-diol (15.4%) and (Z)-2,6-dimethyl-2,7-octadiene-1,6-diol (7.2%) were also present.
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Aldehydes are reduced to alcohols with sodium formate in subcritical water at temperatures and pressures below those required to reduce cyclic ketones. Acyclic ketones afford only minor amounts of alcohol with sodium formate even under more forcing conditions.
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The levels of extractable organic substances in some New Zealand thyme and willow honeys have been determined. Substances detected include aromatic acids and phenols, aliphatic acids and diacids, and degraded carotenoids. Among the degraded carotenoids 1-(3-oxo-1-butenyl)-2,6,6-trimethyl-1,2-epoxycyclohexan-4-ol (two isomers) and 1-(3-oxo-trans-1-butenyl)-2,6,6-trimethylcyclohexane-trans,cis-1,2,4-triol were detected in thyme honey extracts while trans,cis-abscisic acid and trans,trans-abscisic acid were detected in willow honey extracts. The GC profiles of thyme and willow honeys readily distinguish them from other New Zealand unifloral honeys.
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Hotrienol (3,7-dimethyl-1,5,7-octatrien-3-01, 11) is the principal aroma component detected by headspace analysis in leatherwood (Eucryphia lucida) honey. It arises from the dehydration of 2,6-dimethyl-3,7-octadiene-2,6-diol (I), the principal terpene in methylated and unmethylated ether extracts of leatherwood honey. The diol I was detected in leatherwood plant extracts. Methylated ether extracts of the honey also contained methyl 2-hydroxy-2-(4-methoxyphenyl)acetate (1111, which has not been previously reported in honey, in addition to many other aromatic substances. Compound I11 was a major component of the acidic fraction of the plant extract. A methylated extract of unripe leatherwood honey collected after 1 week in the hive was found to contain methyl 2-hydroxy-3-phenylpropionate (N) and an unidentified compound [m /z 91 (loo), 1801 as the principal components. The unidentified compound found in immature honey was not detected in the plant extracts.
Article
Some new methods of synthesis and some improvements in the known methods of preparation of the powerful gastric secretory stimulants, 3-β-aminoethylpyrazole (1) and 4-β-aminoethylpyrazole (II), are described. A key intermediate, 3-hydroxymethylpyrazole, has been made by lithium aluminum hydride reduction of n-butyl 3-pyrazolecarboxylate and also by condensation, under acidic conditions, of hydrazine with the acetylene compounds, 4,4-diethoxy-2-butyne-1-ol and 2-(4′,4′-diethoxy-2′-butynyl)-oxytetrahydropyrane. 3-β-Aminoethylpyrazole was prepared by catalytic hydrogenation of 3-pyrazoleacetaldehyde hydrazone which, in turn, was obtained quantitatively by the reaction of hydrazine with γ-pyrone. 4-,β-Aminoethylpyrazole was prepared from 4-β-hydroxyethylpyrazole which was obtained by the reaction of hydrazine with 2-ethoxy-3-tetrahydrofuranaldehyde diethyl acetal. A new method of preparation of ethyl 4-pyrazolecarboxylate and a number of related new pyrazole derivatives are described.
Article
A novel class of odorants is described where the odor is associated with the interaction of two functional groups, one being an H-donor (AH function), and the other an H-acceptor (B function). Generally, odor occurs only if the distance between the two structural elements (AH/B system) is less than 3 Å. Bifunctional derivatives of the p-menthane and iridane series served as models for deriving this rule. The stereospecificity of odor perception was an important prerequisite for its establishment.
Article
This present work characterizes the fatty acid constituents of the lipid fraction of royal jelly. Among the organic acids found after fractionation by thin layer chromatography of the corresponding methyl esters, the following compounds were identified by combined GC-MS: saturated and unsaturated linear fatty acids, saturated and unsaturated linear and branched dicarboxylic acids, mono-and dihydroxy acids. The most common characteristic of the organic acids was that most contained 8 or 10 carbon atoms, whether saturated or unsaturated, linear or branched.
Article
Extracts of mandibular glands taken from adult queens of the honey bee, Apis mellifera carnica, were analysed by gas chromatography-mass spectroscopy. More than 100 compounds could be identified among which oxygenated fatty acids with six, eight, 10 and 12 carbon atoms are particularly interesting since they show structural relationships to the queen substance, (E)-9-oxo-2-decenoic acid. Changes in the patterns of volatiles were followed up from emergence until the full dominant status of an egg-laying queen in a strong colony. Generally, the amount of volatiles per gland was found to increase with age. The final level of queen substance (9-ODA) content is reached at the postmating stage about 10 days after emergence. Ontogenetic patterns of concentrations were determined for those components regarded to predominantly contribute to the royal pheromone. Characteristic compositions of signals, possibly involved in the premating, mating and postmating dominance status of a honey bee queen are discussed. © 1997 Elsevier Science Ltd. All rights reserved
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