Article

Content of potentially anticarcinogenic flavonoids of 28 vegetables and 9 fruits commonly consumed in The Netherlands

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Abstract

The content of the potentially anticarcinogenic flavonoids quercetin, kaempferol, myricetin, apigenin, and luteolin of 28 vegetables and 9 fruits was determined by RP-HPLC with UV detection. Fresh foods were purchased in a supermarket, agrocery, and a street market and combined to composites. Processed foods were purchased additionally. Sampling was carried out in spring, summer, winter, and spring of the following year. Quercetin levels in the edible parts of most vegetables were generally below 10 mg/kg except for onions (284-486 mg/kg), kale (110 mg/kg), broccoli (30 mg/kg), French beans (32-45 mg/kg), and slicing beans (28-30 mg/kg). Kaempferol could only be detected in kale (211 mg/kg), endive (15-91 mg/kg), leek (11-56 mg/kg), and turnip tops (31-64 mg/kg). In most fruits the quercetin content averaged 15 mg/kg, except for different apple varieties in which 21-72 mg/kg was found. The content of myricetin, luteolin, and apigenin was below the limit of detection (

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... Quercetin is a commonly present flavonol in different diets as it is present in many fruits, vegetables and beverages. Onion is a rich source of quercetin (0.3mg/g of fresh leaves) followed by tea, which contains 10-25mg/L [51]. Flavones (luteolin and apigenin) are less common and present in celery and sweet red pepper [51]. ...
... Onion is a rich source of quercetin (0.3mg/g of fresh leaves) followed by tea, which contains 10-25mg/L [51]. Flavones (luteolin and apigenin) are less common and present in celery and sweet red pepper [51]. The main flavan-3-ols are catechins. ...
... Gut bacteria can carry out several processes that hydrolyze glycosides, glucuronides, amides, sulfates, esters, and lactones. Ring-cleavage, reduction, decarboxylation, demethylation, and dehydroxylation reactions are also carried out by Gut bacteria [51]. The hydrolysis of glycosides ends in metabolites, which are potentially more active than their parent compounds. ...
... DPPH • color can be lost via either radical reaction (HAT) or reduction (SET) as well as unrelated reactions, and steric accessibility is a 10 Quercetin is found in a considerable quantity in various vegetables. Onions and shallots are the most important sources of quercetin [57][58][59] . Broccoli, asparagus, green peppers, tomatoes and red leaf lettuce are also great sources of ubiquitous quercetin, especially in summer 53,58,60 . ...
... Onions and shallots are the most important sources of quercetin [57][58][59] . Broccoli, asparagus, green peppers, tomatoes and red leaf lettuce are also great sources of ubiquitous quercetin, especially in summer 53,58,60 . Fruits (such as apples, strawberry, raspberry, blueberry, cranberry, black currants, etc.), green tea and wine also contain a considerable amount of quercetin 61,53,58-62 . ...
... Onions (Allium cepa) contain quercetin 4'-glucoside (6), quercetin 3-glucoside (8), quercetin dimmer (9), 3,4'-diglucoside, etc. with the content in the range of 284-486 mg/kg 58,63,64,65 . The amount of quercetin in onions varies with bulb color and type 66.67 , being distributed mostly in the outer skins and rings 68,69 . ...
Thesis
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Quercetin (Q1) is a naturally occurring polyphenolic compound having potent nutritional and medicinal value. In this study, commercially available quercetin was used to synthesize various acyl, methyl, benzyl and methylbenzyl derivatives. Quercetin on simple acylation with different stoichiometry of the reagents gave quercetin-3,3’,4’,5,7-pentaacetate (Q2) and quercetin-3,3’,4’,7-tetraacetate (Q4). Quercetin-3,3’,4’,5,7-pentaacetate (Q2) on selective deacylation using imidazole yielded quercetin-3,3’,4’,5-tetraacetate(Q3). Benzylation of quercetin afforded quercetin-3,4’,7-tribenzylether (Q5) and quercetin-3,3’,4’,7-tetrabenzylether (Q6), which were separated by silica gel column chromatography. Following with alkylation then gave three methylbenzyl derivatives, namely, quercetin-3,4’,7-tribenzyl-3’-methylether (Q7), quercetin-3,3’,4’,7-tetrabenzyl-5-methylether (Q8) and quercetin-3,4’,7-tribenzyl-3’,5-dimethylether (Q9). Debenzylation of Q7, Q8 and Q9 was carried out to obtain three methyl derivatives quercetin-3’-methylether (Q10), quercetin-5-methylether (Q11) and quercetin-3’,5-dimethylether (Q12). Quercetin-3,4’,7-trimethylether (Q13), quercetin-3,3’,4’,7-tetramethylether (Q14) and quercetin-3,3’,4’,5,7-pentamethylether (Q15) were obtained using alkylations. The structure of derivatives synthesized was established using UV-Vis shift reagent study and recording of melting point. Antioxidant activity was evaluated using DPPH free radical scavenging assay, and IC50 values of quercetin and its derivatives were calculated. Dihedral angles α of C3-C2-C1’-C6’ chain and β of O1-C2-C-1’-C2’ chain between AC and B rings of quercetin (Q1) and its derivatives (Q2-15) were calculated from energy minimized structures using Chem3D pro software. Quercetin (Q1) having dihedral angles α 11.5º and β 6.6º showed a high antioxidant property (IC50 = 47.20 µM). Quercetin-3’-methyl ether (Q10) (α 11.1º and β 6.3º) (IC50 = 52.54 µM), quercetin-5-methyl ether (Q11) (α 11.2º and β 6.4º) (IC50 = 52.24 µM) and quercetin-3’,5-dimethyl ether (Q12) (α 11.2º and β 6.3º) (IC50 = 119.27 µM) showed comparable antioxidant property. Further variations in dihedral angles α and β caused decrease in the antioxidant property as shown by quercetin-3,3’,4’,5,7-pentaacetate (Q2) (α 7.3º and β 3.9º) (IC50 = 790.57 µM) and quercetin-3,3’,4’,5-tertaacetate (Q3) (α 9.2º and β 4.6º) (IC50 = 516.26 µM).
... Flavones are found in celery (22-108 mg/kg fresh weight) and are able to lower the levels of total and lowdensity lipoprotein (LDL) cholesterol, having anti-inflammatory and anticancer activities [39]. In other vegetables, the contents are (mg/kg of luteolin and apigenin, respectively): 0.41 and 0.05 in water spinach; 0.09 and 0.03 in cucumber; 0. 16 Flavonols have been extensively studied and are widely distributed in plants [41][42][43][44][45][46][47][48][49][50]. They are frequently the conjugated form of glycosides such as kaempferol, quercetin, and myricetin ( Figure 4). ...
... They are frequently the conjugated form of glycosides such as kaempferol, quercetin, and myricetin ( Figure 4). Quercetin levels in the edible parts of most vegetables are generally (of fresh weight, mg/kg) below 10, except for onions (284-486), kale (110), broccoli (30), French beans (32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45), and slicing beans (28-30) [41]. Kaempferol could only be detected (fresh edible weight, mg/kg) in kale (211), endive , leek , and turnip tops (31-64) [41]. ...
... They are frequently the conjugated form of glycosides such as kaempferol, quercetin, and myricetin ( Figure 4). Quercetin levels in the edible parts of most vegetables are generally (of fresh weight, mg/kg) below 10, except for onions (284-486), kale (110), broccoli (30), French beans (32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45), and slicing beans (28-30) [41]. Kaempferol could only be detected (fresh edible weight, mg/kg) in kale (211), endive , leek , and turnip tops (31-64) [41]. ...
Chapter
Aroma and flavor compounds play a critical role in the quality of vegetables, medicinal and aromatic plants (MAPs), being two of the most important sensory attributes for consumer‘s preferences. Throughout the last decades, many studies have correlated the presence of bioactive compounds with consumer‘s choices or with their beneficial health properties. The purpose of this review is to provide an updated overview regarding the presence of volatile and non-volatile compounds in some of the most economically relevant vegetables and MAPs. Particular emphasis is placed on bioactive polyphenols, polyphenols as prebiotics, and discuss the most important factors that affect the content and profile of the volatile and non-volatile compounds responsible for the aromatic features of vegetables and MAPs. The new challenges and future perspectives for science will also be reported in improving and intensifying the aroma and flavors of vegetables and MAPs.
... More than 400 flavonoids have now been identified in vegetables (Michael et al. 1992;Shen et al. 2022), and they can be classified into flavones, flavonols, anthocyanins, isoflavones, chalcones, dihydroflavones, dihydroflavonols, flavonoid carbonosides, and proanthocyanidin. Structurally, flavones are distinguished by having no oxygen-containing substitution at the −3 position of the heterocyclic ring, while flavonols have a 3-hydroxyflavonoid backbone (Vogt 2010). ...
... Besides these vegetables, onions (Allium cepa) are known to have as their main flavonoids quercetin derivatives and kaempferol (Crozier et al. 1997;Park et al. 2017). Carrots (Daucus carota), lettuce (Apium graveolens), and ginger (Zingiber officinale) are all rich in kaempferol (Lako et al. 2007), while celery, bitter gourd (Momordica charantia), and lettuce (Apium graveolens L.) contain abundant apigenin (Lin, Lu, and Harnly 2007;Michael et al. 1992). Thus, consumers can choose among vegetables depending on their diet and health needs. ...
Article
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Flavonoids are the most abundant polyphenols in plants, and have antioxidant effects as well as other bioactivities (e.g., anti-inflammatory, anti-cancer, anti-allergic, and neuroprotective effects). Vegetables are rich in flavonoids and are indispensable in our daily diet. Moreover, the vegetables as chassis for producing natural products would emerge as a promising means for cost-effective and sustainable production of flavonoids. Understanding the metabolic engineering of flavonoids in vegetables allows us to improve their nutrient composition. In this review, a comprehensive overview of flavonoids in vegetables, including the characterized types and distribution, health-promoting effects, associated metabolic pathways, and applied metabolic engineering are provided. We also introduce breakthroughs in multi-omics approaches that pertain to the elucidation of flavonoids metabolism in vegetables, as well as prospective and potential genome-editing technologies. Based on the varied composition and content of flavonoids among vegetables, dietary suggestions are further provided for human health
... In addition, antioxidants are also associated with a reduced rate of heart disease mortality [46] and reduced incidents of pharynx, mouth, oesophagus, stomach, colon and lung cancers, as well as premature aging [47]. ...
Article
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Fruits and vegetables are important components of a healthy diet. They are rich sources of vitamins and minerals, dietary fibre and a host of beneficial non-nutrient substances including plant sterols, flavonoids and other antioxidants. It has been reported that reduced intake of fruits and vegetables may increase the risk of non-communicable diseases (NCDs). Chili pepper, is a common and important spice used to enhance taste and nutrition. Over the years, reports have shown its potential as antioxidant and an anti-obesity agent. Obesity is a serious health concern as it may initiate other common chronic diseases. Due to the side effects of synthetic antioxidants and anti-obesity drugs, scientists are now focusing on natural products which produce similar effects to synthetic chemicals. This up-to-date review addresses this research gap and presents, in an accessible format, the nutritional, antioxidant and anti-obesity properties of different chili peppers. This review article serves as a reference guide for use of chili peppers as anti-obesity agents.
... Rutin (3,3 ′ ,4 ′ ,5,7-pentahydroxy flavones-3-rutinoside) ( Fig. 1), which was also named vitamin P, eldrin, melin, sophorin, and violaquercitrin, is a typical glycoside of the natural flavonoids widely distributed in plants 1 . Rutin is slightly soluble in water and has a higher solubility in organic solvent such as methanol 2 . ...
Article
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Three simple, rapid, accurate precise and economic spectrophotometric methods (A, B and C) have been developed for estimation of rutin in several herbal formulations. Method A and B are based on the complexation of rutin with cobalt (II) nitrate and nickel (II) chloride to give colored complexes. The absorption maxima, λ max , are at 359.70 nm for method A, 347.85 nm for method B and 340.90 nm for method C respectively. Beer's law was obeyed in the concentration range of 0.004-0.04 mg mL-1 for all methods. Developed methods are validated as per ICH guidelines and could be successfully adopted for the routine estimation of rutin.
... We focussed our analyses on kaempferol and its 3′-hydroxy derivative, quercetin, because a study by Austel et al. (2016) showed that a kaempferol derivative is detrimental to elm leaf beetle larvae. To determine the total concentration of the flavonol core structures, rather than the concentration of each of their various glycosides, we subjected the crude elm leaf extract to acidic hydrolysis according to a modified protocol from Hertog et al. (1992) and Mattila et al. (2000). A volume of 700 µL leaf crude extract was transferred into a 2 mL centrifuge tube and evaporated to dryness under reduced pressure at 40 °C (Eppendorf Concentrator 5301). ...
Article
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Main conclusion Elms, which have received insect eggs as a ‘warning’ of larval herbivory, enhance their anti-herbivore defences by accumulating salicylic acid and amplifying phenylpropanoid-related transcriptional and metabolic responses to hatching larvae. Abstract Plant responses to insect eggs can result in intensified defences against hatching larvae. In annual plants, this egg-mediated effect is known to be associated with changes in leaf phenylpropanoid levels. However, little is known about how trees—long-living, perennial plants—improve their egg-mediated, anti-herbivore defences. The role of phytohormones and the phenylpropanoid pathway in egg-primed anti-herbivore defences of a tree species has until now been left unexplored. Using targeted and untargeted metabolome analyses we studied how the phenylpropanoid pathway of Ulmus minor responds to egg-laying by the elm leaf beetle and subsequent larval feeding. We found that when compared to untreated leaves, kaempferol and quercetin concentrations increased in feeding-damaged leaves with prior egg deposition, but not in feeding-damaged leaves without eggs. PCR analyses revealed that prior insect egg deposition intensified feeding-induced expression of phenylalanine ammonia lyase ( PAL ), encoding the gateway enzyme of the phenylpropanoid pathway . Salicylic acid (SA) concentrations were higher in egg-treated, feeding-damaged leaves than in egg-free, feeding-damaged leaves, but SA levels did not increase in response to egg deposition alone—in contrast to observations made of Arabidopsis thaliana . Our results indicate that prior egg deposition induces a SA-mediated response in elms to feeding damage. Furthermore, egg deposition boosts phenylpropanoid biosynthesis in subsequently feeding-damaged leaves by enhanced PAL expression, which results in the accumulation of phenylpropanoid derivatives. As such, the elm tree shows similar, yet distinct, responses to insect eggs and larval feeding as the annual model plant A. thaliana.
... The data obtained in this work are difficult to compare to those found in literature for different reasons. There are huge differences in vegetables polyphenol quantification depending on seasonal harvesting (Arabbi et al., 2004;Hertog et al., 2007), different cultivar (Heimler et al., 2007;Koh et al., 2009), the climate where they grow (Podsedek, 2007), the cultivation site (D'Acunzo et al., 2017) endogenous circadian rhythms (Soengas et al., 2018), soil and pest-control treatment (Valverde et al., 2015). Moreover, the use of solvent is a variable that greatly affects the extraction efficiency. ...
... Tendo em vista esses dados coletados da literatura e sabendo que alguns dos íons presentes nas frações em acetato de etila e aquosa já foram descritos, foram realizados experimentos de fragmentação de alguns íons. Liu et al., (1989), Hertog et al., (1992), Colombo et al., (2008), que relatam que a fragmentação de ligações O-glicosídicas com perda de 146 Da correspondem a ramnose. Ferreira O composto descrito na proposta acima, pertence à classe dos flavonóides glicosilados que se destacam por apresentar diversas propriedades terapêuticas como antioxidadante, antiocarcinogênico, cardioprotetora e hepatoprotetora (Behling, 2004). ...
Article
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A espécie Kalanchoe laetivirens é uma suculenta proveniente de áreas tropicais como a África e Ásia. Devido ao clima favorável, esta planta foi introduzida no Brazil onde é utilizada como alternativa medicinal para o tratamento de doenças como infecções, inflamações, diarréia e cicatrização de ferimentos. Os compostos presentes neste organismo pertencem, em sua grande maioria, a classe dos flavonoides com atividades antioxidante, gastroprotetora, antiúlcera, cálculos renais, infecções bacterianas e virais. Sendo assim, o objetivo deste trabalho foi investigar os compostos químicos presentes nos extratos brutos e das suas frações bem como verificar seu potencial antimicrobiano. Para isso, a amostra vegetal foi submetida à extração com etanol 70% sendo fracionada em seguida com hexano, clorofórmio e acetato de etila. Tais extratos foram analisados em cromatografia líquida de alta eficiência acoplada ao espectrômetro de massas para verificar os íons presentes nas amostras. Foi encontrado composto 3,7-di-O-ramnosil-cianidina, a uma cianidina glicosilada. Sua atividade antimicrobiana foi determinada como sendo negativa frente aos patógenos testados.
... Quercetin is the most common flavonoid in nature and can be found in fruits and vegetables including onions, kale, and apples. Quercetin in onion peel has higher bioavailability than that of apple peel [247]. It is one of the most investigated polyphenols exhibiting various health-promoting properties, for example, antimicrobial, antioxidative, anti-inflammatory, and metabolic effects [248]. ...
Article
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The gut microbiota has been designated as a hidden metabolic ‘organ’ because of its enormous impact on host metabolism, physiology, nutrition, and immune function. The connection between the intestinal microbiota and their respective host animals is dynamic and, in general, mutually beneficial. This complicated interaction is seen as a determinant of health and disease; thus, intestinal dysbiosis is linked with several metabolic diseases. Therefore, tractable strategies targeting the regulation of intestinal microbiota can control several diseases that are closely related to inflammatory and metabolic disorders. As a result, animal health and performance are improved. One of these strategies is related to dietary supplementation with prebiotics, probiotics, and phytogenic substances. These supplements exert their effects indirectly through manipulation of gut microbiota quality and improvement in intestinal epithelial barrier. Several phytogenic substances, such as berberine, resveratrol, curcumin, carvacrol, thymol, isoflavones and hydrolyzed fibers, have been identified as potential supplements that may also act as welcome means to reduce the usage of antibiotics in feedstock, including poultry farming, through manipulation of the gut microbiome. In addition, these compounds may improve the integrity of tight junctions by controlling tight junction-related proteins and inflammatory signaling pathways in the host animals. In this review, we discuss the role of probiotics, prebiotics, and phytogenic substances in optimizing gut function in poultry.
... The presence of phenolic compounds in plant extracts contributes significantly to their antioxidant potential (Dudonné et al., 2009). Part of this AOA comes from flavonoids, low molecular weight polyphenolic compounds distributed in fruits and vegetables (Hertog et al., 1992). For their part, betalains are powerful free radical scavengers that act as efficient antioxidants in biological models (Cano et al., 2017). ...
Article
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Postharvest quality, quantification of betalains, phenolic compounds, and antioxidant activity of peel, pulp, and juice of fruits of three prickly pears (Opuntia ficus-indica L. Mill.) cultivars of Colegio de Postgraduados in México, were measured. The red and orange cultivars showed outstanding features of postharvest quality (size, texture, TSS and pulp and juice content) highest content of betalains and phenolic compounds. Therefore, highest antioxidant activity. In general, the highest content of bioactive compounds was detected in the peel, besides the content in pulp and juice did not show statistically significant differences. Phenolic content is very high in comparison with other fruits. Antioxidant activity was measured by three assays: FRAP, ABTS, and DPPH. Three cultivars showed a high correlation between antioxidant activity and phenolic compounds. The methodologies used in this work are a very useful tool for the quantification of bioactive compounds in O. ficus-indica fruit tissues.
... Phenols were determined according to Hertog et al. (1992), with some modifications. Freeze dried samples, in powder form (1 g), were weighed into 50 mL plastic centrifuge tubes and homogenised for 1 min in 10 mL of extraction solution containing methanol/water/ hydrochloric acid (80:19.5:0.5, v/v/v) using a vortex mixer (Fisherbrand TM Analog, Thermo Fisher Scientific, Pty, Ltd, Johannesburg, South Africa). ...
Article
Sweet potatoes are key to food security, nutrition and income generation in sub-Saharan Africa, and orange-fleshed sweet potato contributes towards pro-vitamin A intake. This study investigated the changes in phytonutritional components and antioxidant activity in six sweet potato cultivars with varying flesh colour in fresh form and during different postharvest thermal treatments; conventional cooking (boiled), drying in hot-air convection oven dryer (14 h at 60°C) as well as blanched and unblanched indirect solar drying (at 20-60°C for 48 h). Overall thermal processing enhanced the retention of total protein content, Zn, total phenols, epicatechin, protocatechuic acid, and 2-caffeoyl-L-tartaric acid in all six cultivars compared to the fresh form. However, vanillic acid was not detected in most of the cultivars after cooking except in ‘C5-1. Hot-air convection oven drying significantly increased the total phenolic content in all six cultivars compared to the fresh form and other drying methods, while hot-air oven dried ‘Monate’ contained the highest total phenols and protocatechuic acid. Similarly, hot-air oven dried ‘C5-1’ showed the highest epicatechin and vanillic acid content compared to the fresh form and other drying methods. Cooking increased the 2-caffeoyl-L-tartaric acid in all six cultivars, compared to the fresh form and the highest content was detected in cooked ‘Bophelo’. Blanching and solar drying improved the β-carotene content in orange cultivars ‘Beauregard’, ‘Bophelo’ and ‘C5-1’, of which ‘C5-1’ showed the highest β-carotene content. Cooking increased the antioxidant power (FRAP activity) in all six cultivars and increased the protein content and Zn content in ‘Ndou’ and ‘199062.1’ respectively. The study provided novel information on the changes in phytonutritional components of different sweet potato cultivars including the cream cultivars ‘Monate’ and ‘Ndou’ and orange cultivars ‘Bophelo’ and ‘C5-1’ bred locally in South Africa, using different processing methods.
... The data obtained in this work are difficult to compare to those found in literature for different reasons. There are huge differences in vegetables polyphenol quantification depending on seasonal harvesting (Arabbi et al., 2004;Hertog et al., 2007), different cultivar (Heimler et al., 2007;Koh et al., 2009), the climate where they grow (Podsedek, 2007), the cultivation site (D'Acunzo et al., 2017) endogenous circadian rhythms (Soengas et al., 2018), soil and pest-control treatment (Valverde et al., 2015). Moreover, the use of solvent is a variable that greatly affects the extraction efficiency. ...
Article
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Food systems have the potential to support human health, respecting the environmental sustainability principles. Food sustainability, enclosed in the concept of environmental sustainability, involves different aspects, including the recycling of food waste derived from the agri-food production chain, the use of biotechnologies ensuring the sustainability of the recovery processes of bioactive compounds from food waste and, last but not least, the awareness of having to consume and waste less food. Food loss and waste is generated during the whole supply chain, from production to household utilization. The utilization of agricultural wastes as an abundant, renewable and low-cost source for the production of high value-added products is currently explored. The bioactive compounds present in these sources have been proved to possess a wide range of biological activities; therefore, research is needed into the application of environmentally friendly traditional and advanced techniques with low production costs in the extraction, isolation and purification of phytochemical compounds from agricultural wastes in high yields and at maximal quality. Authors of this manuscript propose and discuss an innovative and sustainable extraction system of polyphenols from vegetable waste, based on an enzymatic pre-treatment coupled with a solid-liquid extraction by using a particular extractor (Naviglio Estrattore®). This extraction system, organic solvent free, allowed to extract relevant amount of polyphenols (flavonoids in particular) from several vegetable waste products.
... Although the number of aglycones is limited, there are more than 200 sugar conjugates of kaempferol (447). There is information on the flavonol content of commonly consumed fruits, vegetables, and beverages with sizable differences in the amounts found in seemingly similar produce, possibly due to local growing conditions, seasonal changes, and varietal differences (94,194,195,298). Yellow and red onions (Allium cepa) are especially rich source of flavonols containing high concentrations of quercetin-4¢-O-glucoside and quercetin-3,4¢-O-diglucoside. ...
... Several therapeutic properties have been studied mainly in quercetin, which is the main flavonoid in the human diet. Flavonoids don't only have antioxidant and anti-cancer potential, but also protect the kidney, cardiovascular and liver systems [18][19][20][21][22]. Recently, dietary polyphenols have been suggested as potential candidates to protect the skin from the harmful effects of UV rays. ...
Article
Excessive exposure to the sun is a major cause that augment the skin cancer, erythema, edema, abnormal pigmentation and finally suppress the immune system. due to stratospheric ozone depletion and climate change UV levels are increasing, there is an urgent need to protect human skin from the harmful effects of UV. Compounds with photo- protection activity are very useful in reducing the effect of ultraviolet rays. For this reason, today’s sunscreens that contain one or more different types of chemical filters are used to protect the skin from ultraviolet rays. In the market, several synthetic, UV filter molecules are available, but they have limited use because these active molecules may create adverse effects on human skin such as, cancer, estrogenic activity, or photosensitivity reactions, contact dermatitis, mutations. Therefore, the development of formulations containing plant extracts and algae that may be potentially safer is being extensively studied. For this purpose, we can refer to polyphenol compounds such as flavonoids, which are a branch of natural substances that act as catalysts in the optical phase of photosynthesis, and act as anti-stress agents in plants by removing oxygen free radicals. Natural flavonoids have light and direct protection potential due to their ability to absorb ultraviolet rays and due to their antioxidant ability, as well as anti-inflammatory and immune modulating agents. In this article, the sun photoprotection properties of compounds with polyphenolic structure such as flavonoids derived from plant extracts or algae, as well as new methods in optimizing skin protection products against UV radiation have been investigated.
... Morin is widely distributed in vegetables, fruits, and several Chinese herbs. The contents of morin in foodstuffs have been reported in range of 2-250 mg kg −1 in fruits, 3-13 mg L −1 in fruit juices, 0-100 mg kg −1 in vegetables, 4-16 mg L −1 in red wine, 10-25 mg L −1 in tea, and 200-600 mg kg −1 in onions, respectively (Hertog et al. 1992(Hertog et al. , 1993. Considering these properties, it is of great importance to develop a fast and reliable technique for the analysis of this compound in various samples such as biological, food, fruit, and vegetable. ...
Article
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A new air-assisted liquid-liquid microextraction method based on alkanol nanostructured supramolecular solvents coupled to spectrometric analysis was developed for extraction, preconcentration, and spectrophotometric determination of morin. Al(III)-morin complex was performed at pH 4.5. Four different alkanol-based SUPRAS (supramolecular solvents) were prepared for the separation and preconcentration of Al-morin complex from aqueous solution by using vortex and centrifugation. Effect of analytical variables and tolerance limit of matrix ions were investigated. Under the optimum conditions, detection limit, quantification limit, relative standard deviation, preconcentration factor, and enhancement factor were found as 3.5 µg L-1, 10 µg L-1, 3.1%, 120, and 95, respectively. The accuracy of the method was performed with standard addition. The obtained results demonstrated the applicability of the method for the separation, preconcentration, and determination of morin in fruit and beverage samples. The method also complies with green chemistry principles as it uses green solvents, reduces reagent volumes, and produces low amounts of waste. Supplementary information: The online version contains supplementary material available at 10.1007/s12161-021-02111-3.
... Besides onions, the best sources are apples and tea. 10,11 Flavones are mainly represented in the diet by apigenin and luteolin, 9 which are rich in herbs and many vegetables such as celery, parsley, and artichokes. 12 Flavanols are the most popular group of flavonoids that include catechins and procyanidins found in red wine, grapes, tea and cocoa in high concentrations. ...
Chapter
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This chapter discusses Microbial Metabolism of Polyphenols and Health
... In the US, tea, onion, apple and red wine contribute more flavonol to the human diet while average kaempferol and quercetin uptake is about 3.5 and 5.4 mg/day, respectively [11,28]. Generally, the level of processed flavonoids is reduced by 50% compared to fresh foods, therefore fresh foods should be prepared [29]. ...
Article
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Plant secondary metabolites, especially flavonoids, are major metabolites widely found in plants that play several key roles in plant defence and signalling in response to stress conditions. The most studied among these flavonoids are kaempferol and quercetin due to their anti-oxidative potential and their key roles in the defence system, making them more critical for plant adaptation in stress environments. Kaempferol and quercetin in plants have great therapeutic potential for human health. Despite being well-studied, some of their functional aspects regarding plants and human health need further evaluation. This review summarizes the emerging potential of kaempferol and quercetin in terms of antimicrobial activity, bioavailability and bioactivity in the human body as well as in the regulation of plant defence in response to stresses and as a signalling molecule in terms of hormonal modulation under stress conditions. We also evaluated the safe use of both me-tabolites in the pharmaceutical industry.
... For example, the acid hydrolysis for 2 h at 80 • C with 1.2 HCl efficiently produced flavonoid aglycones from glycosides, which were no longer detectable after the 2 h hydrolysis [36]. Degradation of quercetin, due to increasing reaction time, has also been reported [37]. Therefore, compared to the other examined procedures, method A.3 was shown to be superior. ...
Article
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Green coffee (Coffee arabica and Coffee robusta) is one of the most commonly traded goods globally. Their beans are enriched with polyphenols and numerous health benefits are associated with their consumption. The main aim of this work was to develop a new and fast analytical HPLC-MS/MS method to simultaneously determine six flavonoid polyphenolic compounds (quercetin, rutin, isorhamnetin, quercetin-3-glucouronide, hyperoside, and quercitrin) in 22 green coffee samples from six different geographical origins (Ethiopia, Brazil, Guatemala, Nicaragua, India and Colombia). In addition, by adjusting pH, temperature, solvent type, and extraction duration, several extraction methods such as acidic and alkaline hydrolysis, and extraction without hydrolysis were evaluated. The optimal extraction procedure in terms of recovery percentages (78.67–94.09%)was acidic hydrolysis at pH 2, extraction temperature of 60 °C, extraction solvent of 70% ethanol, and extraction duration of 1.5 h. Hyperoside (878–75 μg/kg) was the most abundant compound followed by quercitrin (408–38 μg/kg), quercetin (300–36 μg/kg), rutin (238–21 μg/kg), and quercetin-3-glucouronide (225–7 μg/kg), while isorhamnetin (34–3 μg/kg) showed the lowest amount. Overall, green coffee beans are rich in flavonoid polyphenolic compounds and could be used as part of a healthy diet.
... Our findings indicate that DO can significantly reduce HFD-induced body weight gain, body fat, and hepatic lipid accumulation and that 5DO was more efficacious than quercetin. The quercetin content of fresh onions was reported to be approximately 284-486 mg/kg [20]. Additionally, the moisture content of fresh onions ranged from 84% to 91% [21]; thus, the quercetin content in our dried onion was approximately 250 mg/100 g dried onion, which was comparable to previous findings. ...
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Onion (Allium cepa L.), rich in flavonoids (particularly quercetin), reportedly has anti-obesity properties, but the underlying mechanisms and associated health issues remain unclear. In this study, we compared the effects of dried onion powder (DO) with that of quercetin on high-fat diet (HFD)-induced obesity, nonalcoholic fatty liver disease, and retinal neovascularization. Briefly, rats (n = 9–10 per group) were divided into control, HFD alone (43% fat), HFD + DO (1% DO), HFD + 5DO (5% DO, w/w), and HFD + quercetin (180 mg/kg). After 12 weeks, body fat, markers of metabolism, fatty liver, steatohepatitis, and retinopathy were analyzed. The results revealed that DO and 5DO dose-dependently suppressed body weight, visceral and subcutaneous fat accumulation, and epididymal adipocyte in HFD-fed rats. DO also decreased HFD-induced ALT, AST, free fatty acid, glucose, proinflammatory cytokines, and oxidative stress. DO and 5DO groups had lower triglycerides, total cholesterol, proinflammatory cytokine levels, and ACC-α (a fatty acid synthesis–associated enzyme) expression but higher hepatic antioxidant enzyme activities and fecal lipids. 5DO exhibited better or similar efficacy to quercetin. Both 5DO and quercetin increased fecal levels of acetic acid and butyric acid similarly. They also reduced lipid peroxidation of the eye, retinal adiposity, and neovascularization. However, quercetin resulted in a more apparent decrease in regulation of the Raf/MAPK pathway than DO in eye specimens. Conclusively, DO suppresses visceral, subcutaneous, and liver fat accumulation better than quercetin likely due to higher fecal fat excretion and lower oxidative stress, proinflammatory cytokine levels, and ACC-α expression. Quercetin regulating signal pathways is better than DO at reducing retinal adiposity and neovascularization.
... The flavonoids are in many foods, such as fruits and vegetables [93][94][95][96], nuts (walnuts and legumes) [97][98][99][100], spices, and drinks (red wine and tea) [101,102]. Chemically, flavonoids have a polyphenol structure, which gives them antioxidant activity. ...
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Plant-based foods are becoming an increasingly frequent topic of discussion, both scientificandsocial, due to the dissemination of information and exchange of experiences in the media. Plant-based diets are considered beneficial for human health due to the supply of many valuable nutrients, including health-promoting compounds. Replacing meat-based foods with plant-based products will provide many valuable compounds, including antioxidants, phenolic compounds, fibers, vitamins, minerals, and some ω3 fatty acids. Due to their high nutritional and functional composition, plant-based foods are beneficial in acute and chronic diseases. This article attempts to review the literature to present the most important data on nutrients of plant-based foods that can then help in the prevention of many diseases, such as different infections, such as Corona virus disease, pneumonia, common cold flu, asthma, and bacterial diseases, such as bronchitis. A properly structured plant-based diet not only provides the necessary nutrients but also can help in the prevention of many diseases.
... Quercetin is found in nature in different forms either as a composite molecule bound to additional molecules, such as sugars, sulfates and methyl groups, or in its simple form. According to the above studies, however, by recording the frequency and quantity of quercetin in a typical diet, it seems that quercetin intake is low, either due to a diet poor in organic products or the consumption of foods with low in quercetin [120][121][122][123][124][125][126]. The distribution of quercetin content in a wide range of foods occurs mainly from little to moderate concentrations. ...
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Quercetin belongs to the broader category of polyphenols. It is found, in particular, among the flavonols, and along with kaempferol, myricetin and isorhamnetin, it is recognized as a foreign substance after ingestion in contrast to vitamins. Quercetin occurs mainly linked to sugars with the most common compounds being quercetin-3-O-glucoside or as an aglycone, especially in the plant population. The aim of this review is to present a recent bibliography on the mechanisms of quercetin absorption and metabolism, bioavailability, and antioxidant and the clinical effects in diabetes and cancer. The literature reports a positive effect of quercetin on oxidative stress, cancer, and the regulation of blood sugar levels. Moreover, research-administered drug dosages of up to 2000 mg per day showed mild to no symptoms of overdose. It should be noted that quercetin is no longer considered a carcinogenic substance. The daily intake of quercetin in the diet ranges 10 mg-500 mg, depending on the type of products consumed. This review highlights that quercetin is a valuable dietary antioxidant, although a specific daily recommended intake for this substance has not yet been determined and further studies are required to decide a beneficial concentration threshold.
... Dari 29 sayuran dan buah-buahan yang diteliti dalam suatu survei, bawang bombay merupakan tanaman dengan kandungan quercetin tertinggi. Quercetin (3', 4'dihydroxyflavonol) adalah flavonoid dalam kelompok flavonol dan dianggap sebagai fitokimia flavonoid dengan kapasitas antioksidan terkuat (Hertog et al., 1996). ...
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Degenerative diseases can be triggered by free radicals. The disease can be inhibited by antioxidant compounds that can neutralize and destroy free radicals. The content of antioxidant compounds can be found in the genus Allium, one of which is the Indian red onion. Knowing the antioxidant activity, total phenolics, and total flavonoids of Indian shallot extract was the aim of this study. The extraction process was carried out from three solvents, namely dichloromethane, ethyl acetate, and 96% ethanol, using the multilevel maceration method with different levels of polarity. The samples tested included testing antioxidant activity using the DPPH method, total phenolics using the Folin Ciocalteu method, and total flavonoids using the aluminum chloride calorimetric method. The results showed that there were no phenolic and flavonoid compounds that had the potential as antioxidants in the dichloromethane and ethyl acetate extracts. Total phenolics, total flavonoids, and IC50 values in the ethanol extract were 2,381 mg GAE/g extract, respectively; 0.330 mg QE/g extract, and 297.8689 ppm. The IC50 value obtained is classified as a weak antioxidant.
... Control of planting date has an important role to play in improving the quality traits for the used seeds (31). Several factors influence the accumulation of flavonoids in plants, including genetic factors as well as ultraviolet radiation 27 and seasonal variations (16). It is well known that plant spacing plays an important role in crop production. ...
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Two field experiments were conducted in the field of medicinal plants belonging to College of Agriculture, the University of Basra during the agricultural seasons (2015/2016 and 2016/2017) with clay loam soil. The study included six treatments which are the combination between two planting dates (1/11 and 1/12), the cultivating with three plant densities (20, 30, 40 kg.ha-1) and their interactions in the activity of methanolic extract for the leaves and seeds of the flax plant (Linum usitatissimum L.) as Anti-inflammatory and antioxidant. The highest anti-inflammatory effect in vitro for the methanolic extract for the leaves and cultivated seeds of the plant at 1/11 with a plant density of (20 kg.ha-1), which amounted of (97.80, 94.78, 98.0, 96.3), respectively, and anti-oxidant activity amounted to (98.04, 95.67, 66.58, 55.11%), respectively. Treatment with Flavonoids for the leaves or seeds of flax plant had an anti-inflammatory effect in vivo that was close to the activity of Diclofenac drug. ‫الكتان‬ ‫نبات‬ ‫بذور‬ ‫و‬ ‫ألوراق‬ ‫الحيوية‬ ‫الفعالية‬ ‫في‬ ‫النباتية‬ ‫الكثافة‬ ‫و‬ ‫الزراعة‬ ‫موعد‬ ‫تأثير‬ Linum usitatissimum L. ‫مطرود‬ ‫الكريم‬ ‫عبد‬ ‫سميرة‬ 1 ‫رمضان‬ ‫حامد‬ ‫اسامة‬ 2 ‫حمزة‬ ‫كاظم‬ ‫رشا‬ 3 1 ‫الطبية‬ ‫النباتات‬ ‫وحدة‬ ‫والعطرية‬-‫الزراعة‬ ‫كلية‬-‫البصرة‬ ‫جامعة‬-‫/العراق‬ ‫البصرة‬ 2 ‫السريرية‬ ‫المختبرية‬ ‫العلوم‬ ‫فرع‬-‫الصيدلة‬ ‫كلية‬-‫البصرة‬ ‫جامعة‬-‫/العراق‬ ‫البصرة‬ 3 ‫الحدائق‬ ‫وهندسة‬ ‫البستنة‬ ‫قسم‬-‫الزراعة‬ ‫كلية‬-‫البصرة‬ ‫جامعة‬-‫/العراق‬ ‫البصرة‬ ‫الخالصة‬ ‫النباتات‬ ‫حقل‬ ‫في‬ ‫حقليتين‬ ‫تجربتين‬ ‫نفذت‬ ‫الزراعة‬ ‫لكلية‬ ‫التابع‬ ‫الطبية‬ / ‫الزراعيين‬ ‫الموسمين‬ ‫أثناء‬ ‫البصرة‬ ‫جامعة‬ 2015 / 2016 ‫و‬ 2016 / 2017 ‫طينية‬ ‫مزيجية‬ ‫بتربة‬ ، ‫زراعة‬ ‫موعدي‬ ‫بين‬ ‫التوافيق‬ ‫عن‬ ‫عبارة‬ ‫وهي‬ ‫عامليه‬ ‫معامالت‬ ‫ست‬ ‫تضمنتا‬ ‫إذ‬ 1 / 11 ‫و‬ 1 / 12 ‫نباتية‬ ‫كثافات‬ ‫بثالث‬ ‫والزراعة‬ 20 ‫و‬ 30 ‫و‬ 40 ‫هكتار‬ ‫كغم.‬-1 ‫الكتان‬ ‫نبات‬ ‫وبذور‬ ‫ألوراق‬ ‫الميثانولي‬ ‫المستخلص‬ ‫فعالية‬ ‫في‬ ‫وتداخالهما‬ Linum usitatissimum L. ‫لألكسدة‬ ‫والمضادة‬ ‫لاللتهابات‬ ‫المضادة‬. ‫الحي‬ ‫الجسم‬ ‫خارج‬ ‫لاللتهابات‬ ‫مضادة‬ ‫فعالية‬ ‫أعلى‬ ‫إن‬ ‫في‬ ‫المزروعة‬ ‫النباتات‬ ‫وبذور‬ ‫ألوراق‬ ‫الميثانولي‬ ‫للمستخلص‬ 1 / 11 ‫النباتية‬ ‫بالكثافة‬ 20 ‫كغم‬. ‫هكتار‬-1 ‫بلغت‬ 97.80 ‫و‬ 94.78 ‫و‬ 98.0 ‫و‬ 96.3 ‫بلغت‬ ‫لالكسدة‬ ‫المضادة‬ ‫الفعالية‬ ‫و‬ ‫التوالي‬ ‫على‬ , 98.04 ‫و‬ 95.67 ‫و‬ 66.58 ‫و‬ 55.11 ‫المعاملة‬ ‫وان‬ ‫التوالي.‬ ‫على‬ ,% ‫عقار‬ ‫فعالية‬ ‫من‬ ‫أقتربت‬ ‫الحي‬ ‫الجسم‬ ‫داخل‬ ‫لاللتهابات‬ ‫مضادة‬ ‫فعالية‬ ‫لها‬ ‫كان‬ ‫الكتان‬ ‫نبات‬ ‫بذور‬ ‫او‬ ‫أوراق‬ ‫بفالفونيدات‬ ‫الدايكلوفيناك.
... Many studies on the phenolic profile of different onion cultivars reported that the only phenolic compound found in detectable quantities was Quercetin (Hertog et al., 1992;Miean and Mohamed (2001); Sultana and Anwar, 2008;and Zill-e-Huma et al., (2011). Quercetin and Gallic acid were the two phenol compounds found in the hydrolyzed extract of garlic and onion (Soto et al., 2016). ...
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The Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) pandemic has become a global challenge based on its replication within the host cells that relies on non-structural proteins, protease (Mpro). Flavonoids, an important class of naturally occurring compounds with medicinal importance, are frequently available within fruits and vegetables. Herein, we report the in silico studies on naturally occurring flavonoids consisting of molecular docking studies and evaluation of theoretical kinetics. In this study, we prepared a library of nine different classes of naturally occurring flavonoids and screened them on Autodock and Autodockvina. The pharmacokinetic properties of most promising compounds have been predicted through ADMET SAR, inhibition constants, ligand efficiency and ligand fit quality have been worked out theoretically. The results revealed that naturally occurring flavonoids could fit well in the receptor's catalytic pocket, interact with essential amino acid residues and could be useful for future drug candidates through in vitro and in vivo studies. Moreover, MD simulation studies were conducted for two most promising flavonoids and the protein-ligand complexes were found quite stable. The selected natural flavonoids are free from any toxic effects and can be consumed as a preventive measure against SARS CoV-2.
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Fruits and vegetables play an important part in the diets of global human population. During processing, the unused residues such as peels, stalks, rinds, stem, leaves etc. come out as waste. Due to the high moisture content of these perishable wastes, they undergo rapid decomposition that leads to foul odour and growth of pathogens. Almost, 30% of the loss occurs at the supply, retail, consumer, post-harvest and processing level. The perishable waste like peels, pomace, seeds etc. act as threat for the environment and degrade pollution-free model. The wastes are rich in protein, carbohydrates, minerals, vitamins and other phytochemicals and bioactive compounds such as pigments, dietary fibre, essential oils etc. Recent researches have shown that there is an increase in the utilization of these wastes for the extraction of value-added products such as bioactive compounds, bio-colorants, organic acids, Single cell protein (SCP), organic minerals, enzymes and others. The present review paper deals with the recent studies conducted on valorisation of the fruit & vegetable waste.
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Exudates were prepared using sucrose from the edible parts of sea tangle, aloe, onion, maesil (Prunus mume fruit) and kale. Changes in the amount of sugar and organic acid were investigated during 12-month storage of the exudates in hangari (a traditional Korean jar) and stainless-steel containers. Dominant lactic acid-producing bacteria were isolated and identified. Lactic acid was the major organic acid in the exudates of sea tangle, onion, and aloe, whereas citric acid and acetic acid were the major organic acids in maesil and kale exudates, respectively. In addition, it was confirmed that container type affected the composition of each exudate. Overall, the pH of these exudates decreased without any significant changes in acidity. As the storage time increased, viable bacterial counts decreased, and the number of acid-producing bacteria also decreased or disappeared. A total of 18 dominant species of lactic acid-producing bacteria were screened and classified into Lactobacillus homohiochii, Lactobacillus plantarum, and Bacillus megaterium based on 16S rRNA gene sequencing. Lactobacillus spp. showed high sugar tolerance and multiplied even at sucrose concentrations of 20-50%. Depending on the strain, these dominant bacteria hydrolyze sucrose to glucose and fructose, with lactic acid as the final product. The dominant type of lactic acid-producing bacteria differed depending on the type of sugaring exudate. Further research on the role of these microorganisms in the food industry, such as preparing exudates using bacterium as a starter material, is required.
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Summery Quercetin which belongs to the class flavonols, one of the five subclass of flavonoid compounds. Flavonoid observed in vegetables, fruits, tea, and wine. Quercetin is ubiquitously present in foods such as onions, berries, nuts, tea, cauliflower, and cabbage. Flavonoids occur in foods primarily as glycosides or aglyconesform which breaks down to various extents in thedigestive column. Quercetin is usually found in the in the glycoside form. Quercetin act as a potent antioxidant molecule and may exerts beneficial effects on its free radical scavenging function which prevent the formation of stabilized phenoxyl radicals. Quercetin plays important role in improvement of cancer disease, heart-related disease, diabetes, asthma and allergy and much more. Quercetin metabolism occurred in the small intestine, the kidney and the liver which sufficiently reduce plasma oxidant status. Quercetin and its compound based on the flavan nucleus and positions, numbers and type of substitutions affect radical scavenging activity.
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Virtual screening is a computational technique widely used for identifying small molecules which are most likely to bind to a protein target. In the present work, a molecular docking study is carried out to propose potential candidates for preventing the RBD/ACE2 attachment. These candidates are sixteen different flavonoids present in the peppermint leaf. Results showed that Luteolin 7-O-neohesperidoside is the peppermint flavonoid with a higher binding affinity regarding the RBD/ACE2 complex (about −9.18 Kcal/mol). On the other hand, Sakuranetin presented the lowest affinity (about −6.38 Kcal/mol). Binding affinities of the other peppermint flavonoids ranged from −6.44 Kcal/mol up to −9.05 Kcal/mol. The binding site surface analysis showed pocket-like regions on the RBD/ACE2 complex that yield several interactions (mostly hydrogen bonds) between the flavonoid and the amino acid residues of the proteins. This study can open channels for the understanding of the roles of flavonoids against COVID-19 infection.
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Tart cherries (Prunus cerasus L.) are the richest in phenolic compounds, among all the members of drupe family of fruits. To reduce the inherent sourness of the cherries, thermal processing or filtration steps are used. These processes lead to changes in pH, and exposure to temperature enhances oxidation leading to degradation of polyphenols. In the present study, Megatron® and high-pressure homogenization (HPH) were employed to produce micronized puree, which was analyzed for polyphenolic, flavonoid and anthocyanin contents using various assays. Both methods of micronization lead to breakage of cell wall structure facilitating enhanced release of bioactives from the cellular matrix and thus higher antioxidant release. The presence of functional groups was corroborated by FTIR spectrophotometric analysis, and reversed phase HPLC for the presence and relative amounts of various polyphenols and anthocyanins. There was a significant increase (p<0.05) of in the extractability of polyphenols with HPH (285.05 GAE μg/g) in comparison with the non-micronized samples (166.80 GAE μg/g). The changes in anthocyanins and flavonoids were also significant (p<0.05), thus confirming the impact of micronization on the antioxidant release in tart cherries.
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Onion skins are agricultural byproducts that contain high levels of antioxidants, including quercetin and protocatechuic acid. The solubility of extracts can affect their antioxidant capacity in food oil matrices. The antioxidative properties of onion skin extracts with different polarity were compared and the chemical profiles of the extracts were identified by GC‐MS. Highly lipophilic, moderately hydrophilic, and highly hydrophilic onion skin extracts (HLE, MHE, and HHE, respectively) were prepared and their antioxidant properties were tested using in vitro assays and bulk oil or oil‐in‐water (O/W) emulsions. The most abundant phenolic compounds in the onion skin extracts were quercetin and protocatechuic acid. The lipophilicity levels of HLE, MHE, and HHE were 0.674, 0.394, and ‐1.225, respectively. HLE showed higher antioxidant capacity in bulk oil and O/W emulsion matrices compared to MHE and HHE. The antioxidant capacity of HLE was higher in the O/W emulsion than in the bulk oil system. Therefore, highly lipophilic onion skin extracts can be used as effective natural antioxidants in oil matrices, especially O/W emulsions.
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The Globe is marching towards the development of the telecommunication field which leads to increment of non-ionizing radiation in the environment which affects all living beings including plants grown nearby to communication base stations. The present research was focused on physiological and biochemical alterations of tomato plants exposed to high-frequency radiation. The overall plant health was analyzed by physiological changes viz., plant height, size of leaves, length to the root system, and rate of germination upon exposure of radiation and shown significant reduction (p < 0.05) compared to control. Consecutively, radiation also negatively affects the photosynthetic pigment content of leaves which has shown significant reduction. Yet another confirmation of stress on exposed plant tissue was reported by obtaining higher H2O2 content within exposed plant leaf than the control. The morphological alterations viz. curling of leaves, discoloration, and size reduction became more prominent with an increase in the exposure time. The significant outcomes denoted according to 95% confidence limit. There was a significant decline in total phenolic content (37.06%), flavonoid content (71.38%), Vitamin C content (72.45%), and DPPH (59.32%) as well as total antioxidant assays (71.89%) which revealed significant deteriorative effects on such waves on secondary metabolites and the antioxidant potential of tomato plants. The lycopene content was continuously increasing up to 73.13% upon radiation of 120 h and such raise was the direct indication of harmful effect on fruit skin and release of lycopene due to softening of the fruit tissue. Thus, the presented findings illustrated the negative effects of such waves on the quality of tomato plants. The limited insight of metabolic pathways involved in plant responses to such non-ionizing radiation makes such investigation worth in agricultural application. Additionally, mobile communication agencies should be informed and installation of base stations for mobile communication towers should be prohibited at agricultural lands.
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Although quercetin (Que) has many beneficial therapeutic effects on the human body, its oral bioavailability is poor because of its low water solubility. Herein, we describe the preparation of casein hydrolysate (Pepcas) and its use as a dispersant to enhance the water dispersibility of Que resulting in an improvement of its bioavailability. By complexation with Pepcas, the apparent solubility of Que in the complex (Que@Pepcas) was significantly increased under acidic and neutral conditions. Que@Pepcas was pre‐digested in vitro using a simulated digestive juice, and a Caco‐2 cell monolayer permeation assay was performed to evaluate the oral bioavailability of Que. The cumulative amount of Que that permeated the monolayer using Que@Pepcas after 8, 16, and 24 h was increased compared with a blank sample (Que@Blank), and the apparent permeation coefficient Papp of Que@Pepcas was approximately 2.6‐fold better than that of Que@Blank. Pepcas can be used as a high absorption supplement and food additive, and our Pepcas complexation technique should be widely applicable to not only Que but also to other poorly water‐soluble substances.
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The present review aims to describe an overview of quercetin with its various pharmacological effects. Quercetin is used as antioxidant, anticancer, antibacterial and antimicrobial, anti-inflammatory, antidiabetic, antihypertensive, antifungal, anti-allergic and antiproliferative agents, which are described in the manuscript. It is mainly obtained from plant resources, which is also described in the manuscript. The manuscript also focuses on describing the various studies related to quercetin which shows various pharmacological activities. It is concluded from the study that quercetin has shown an efficacious effect on various diseases.
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The number of cancer cases worldwide keeps growing unstoppably, despite the undeniable advances achieved by basic research and clinical practice. Urologic tumors, including some as prevalent as prostate, bladder or kidney tumors, are no exceptions to this rule. Moreover, the fact that many of these tumors are detected in early stages lengthens the duration of their treatment, with a significant increase in health care costs. In this scenario, prevention offers the most cost-effective long-term strategy for the global control of these diseases. Although specialized diets are not the only way to decrease the chances to develop cancer, epidemiological evidence support the role of certain plant-derived foods in the prevention of urologic cancer. In many cases, these plants are rich in antiangiogenic phytochemicals, which could be responsible for their protective or angiopreventive properties. Angiogenesis inhibition may contribute to slow down the progression of the tumor at very different stages and, for this reason, angiopreventive strategies could be implemented at different levels of chemoprevention, depending on the targeted population. In this review, epidemiological evidence supporting the role of certain plant-derived foods in urologic cancer prevention are presented, with particular emphasis on their content in bioactive phytochemicals that could be used in the angioprevention of cancer.
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The human gastrointestinal tract is home to trillions of microbes. Gut microbial communities have a significant regulatory role in the intestinal physiology, such as gut motility. Microbial effect on gut motility is often evoked by bioactive molecules from various sources, including microbial break down of carbohydrates, fibers or proteins. In turn, gut motility regulates the colonization within the microbial ecosystem. However, the underlying mechanisms of such regulation remain obscure. Deciphering the inter-regulatory mechanisms of the microbiota and bowel function is crucial for the prevention and treatment of gut dysmotility, a comorbidity associated with many diseases. In this review, we present an overview of the current knowledge on the impact of gut microbiota and its products on bowel motility. We discuss the currently available techniques employed to assess the changes in the intestinal motility. Further, we highlight the open challenges, and incorporate biophysical elements of microbes-motility interplay, in an attempt to lay the foundation for describing long-term impacts of microbial metabolite-induced changes in gut motility.
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Methicillin-resistant Staphylococcus aureus is one of the leading causes of community and nosocomial infections, which has created the urgent need for innovative anti-infective agents to control MRSA-associated infections. A conserved serine protease, caseinolytic peptidase P (ClpP) in Staphylococcus aureus is highly associated with pathogenicity and has been claimed to be a novel antimicrobial target. We aim to search suitable inhibitors of ClpP to attenuate the virulence of MRSA and combat their infections in vivo. Over 500 natural compounds were pre-screened via fluorescence resonance energy transfer using the Suc-LY-AMC substrate. The binding of myricetin to ClpP was determined and the mechanism of action was elucidated by thermal shift assay, surface plasmon resonance, and molecular dynamics simulations. The therapeutic effects of myricetin on S. aureus infection were further investigated using a S. aureus-induced pneumonia model. We revealed that myricetin could effectively block the activity of ClpP without disturbing the growth of the bacteria and the Gln-47 and Met-31 residues were necessary for myricetin binding to ClpP. Importantly, myricetin attenuated the pathogenicity of S. aureus in vivo, while improving the efficacy of the traditional antibiotic oxacillin against MRSA infection and protecting mice from fatal lung infections caused by MRSA. These findings indicate that myricetin has the potential to be applied in the pharmaceutical industry as a promising therapeutic agent.
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For the first time, quercetin-3-β-ᴅ-glucuronide, quercetin-3-β-ᴅ-glucoside, quercetin-3-(O-malonyl) -β-ᴅ-glucoside and luteolin-7-/9-ᴅ-glucuronide were isolated from lettuce and kaempferol-3-β-D-glucuronide and kaempferol-3-β-ᴅ-glucoside from endives as crystals. The flavonol glucuronides are the main glycosides. Moreover a glycoside was found in endives which is very probably identical with kaempferol-3-(O-malonyl) -β-ᴅ-glucoside.
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The "French paradox" (apparent compatibility of a high fat diet with a low incidence of coronary atherosclerosis) has been attributed to the regular drinking of red wine. However, the alcohol content of wine may not be the sole explanation for this protection. Red wine also contains phenolic compounds, and the antioxidant properties of these may have an important role. In in-vitro studies with phenolic substances in red wine and normal human low-density lipoprotein (LDL) we found that red wine inhibits the copper-catalysed oxidation of LDL. Wine diluted 1000-fold containing 10 mumol/L total phenolics inhibited LDL oxidation significantly more than alpha-tocopherol. Our findings show that the non-alcoholic components of red wine have potent antioxidant properties toward oxidation of human LDL.
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An HPLC isocratic elution procedure which allows the separation of flavonol aglycones in wine without interference from other phenolics of low molecular weight is described. The method has been applied to the separation, identification and quantitative estimation of flavonol aglycones in ether extracts of different Spanish wines (red and white table wines and Sherry finos). The results suggest that these determinations, associated with other analyses, would permit the chemical characterization of wines.
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Keys, A. (84060 Pioppi (SA), Italy), A. Menotti, M. J. Karvonen, C. Aravanis, H. Blackburn, R. Buzina, B. S. Djordjevlc, A. S. Dontas, F. Fldanza, M. H. Keys, D. Kromhout, S. Nedeljkovic, S. Punsar, F. Seccareccia, and H. Toshima. The diet and 15-year death rate In the Seven Countries Study. Am J Epidemiol 1986; 124:903–15 In 15 cohorts of the Seven Countries Study, comprising 11,579 men aged 40-years and “healthy” at entry, 2,288 died In 15 years. Death rates differed among cohorts. Differences In mean age, blood pressure, serum cholesterol, and smoking habits “explained” 46% of variance in death rate from all causes, 80% from coronary heart dIsease, 35% from cancer, and 45% from stroke. Death rate differences were unrelated to cohort differences in mean relative body weIght. fatness, and physical activity. The cohorts differed in average dIets. Death rates were related positively to average percentage of dIetary energy from saturated fatty acids, negatively to dietary energy percentage from monounsaturated fatty acids, and were unrelated to dietary energy percentage from polyunsaturated fatty acids, proteins, carbohydrates, and alcohol. All death rates were negatively related to the ratio of monounsaturated to saturated fatty acids. Inclusion of that ratio with age, blood pressure, serum cholesterol, and smokIng habits as inde pendent variables accounted for 85% of variance In rates of deaths from all causes, 96% coronary heart dIsease, 55% cancer, and 66% stroke. Oleic acid accounted for almost all dIfferences In monounsaturates among cohorts. All- cause and coronary heart disease death rates were low In cohorts with olive oil the main fat Causal relationshIps are not claimed but consideration of characteristics of populations as well as of Individuals withIn populations is urged evaluating risks.
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Approximately 200 studies that examined the relationship between fruit and vegetable intake and cancers of the lung, colon, breast, cervix, esophagus, oral cavity, stomach, bladder, pancreas, and ovary are reviewed. A statistically significant protective effect of fruit and vegetable consumption was found in 128 of 156 dietary studies in which results were expressed in terms of relative risk. For most cancer sites, persons with low fruit and vegetable intake (at least the lower one-fourth of the population) experience about twice the risk of cancer compared with those with high intake, even after control for potentially confounding factors. For lung cancer, significant protection was found in 24 of 25 studies after control for smoking in most instances. Fruits, in particular, were significantly protective in cancers of the esophagus, oral cavity, and larynx, for which 28 of 29 studies were significant. Strong evidence of a protective effect of fruit and vegetable consumption was seen in cancers of the pancreas and stomach (26 of 30 studies), as well as in colorectal and bladder cancers (23 of 38 studies). For cancers of the cervix, ovary, and endometrium, a significant protective effect was shown in 11 of 13 studies, and for breast cancer a protective effect was found to be strong and consistent in a meta analysis. It would appear that major public health benefits could be achieved by substantially increasing consumption of these foods.
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There is convincing evidence that cellular prooxidant states--that is, increased concentrations of active oxygen and organic peroxides and radicals--can promote initiated cells to neoplastic growth. Prooxidant states can be caused by different classes of agents, including hyperbaric oxygen, radiation, xenobiotic metabolites and Fenton-type reagents, modulators of the cytochrome P-450 electron-transport chain, peroxisome proliferators, inhibitors of the antioxidant defense, and membrane-active agents. Many of these agents are promoters or complete carcinogens. They cause chromosomal damage by indirect action, but the role of this damage in carcinogenesis remains unclear. Prooxidant states can be prevented or suppressed by the enzymes of the cellular antioxidant defense and low molecular weight scavenger molecules, and many antioxidants are antipromoters and anticarcinogens. Finally, prooxidant states may modulate the expression of a family of prooxidant genes, which are related to cell growth and differentiation, by inducing alterations in DNA structure or by epigenetic mechanisms, for example, by polyadenosine diphosphate-ribosylation of chromosomal proteins.
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Gastric infection with Helicobacter pylori seems to be a risk factor for gastric cancer. We have conducted a multicentre epidemiological study to investigate this relation further. Our study was designed to look at the relation between the prevalence of H pylori infection and gastric cancer rates in 17 populations from 13 countries, chosen to reflect the global range of gastric cancer incidence. In each centre, about 50 males and 50 females in each of the two age groups 25-34 years and 55-64 years were selected at random from the local population and provided blood samples. Serum samples were assayed for the presence of IgG antibodies to H pylori in a single laboratory. Prevalence rates of H pylori seropositivity were related to local gastric cancer incidence and mortality rates using linear regression. There was a statistically significant relation between the prevalence of seropositivity and cumulative rates (0-74 years) for both gastric cancer incidence and mortality with regression coefficients of 2.68 (p=0.001) and 1.79 (p=0.002), respectively. Our findings are consistent with an approximately six-fold increased risk of gastric cancer in populations with 100% H pylori infection compared with populations that have no infection.
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Quercetin inhibited soybean lipoxygenase-1-dependent linoleic acid peroxidation. Two to three μM quercetin was required for 50% inhibition. During the inhibition, quercetin was oxidized. The oxidation was observed as an absorbance decrease at about 380 nm and an absorbance increase at about 335 nm. Inhibition of linoleic acid peroxidation by quercetin seems to be due to reduction by the reagent of the linoleic acid radical formed as an intermediate during lipoxygenation. Quercetin oxidation was suppressed by ascorbate under conditions when ascorbate did not affect lipoxygenase-dependent linoleic acid peroxidation. The results suggest that ascorbate can reduce the quercetin oxidized by the linoleic acid radical back to quercetin. Based on the results, the significance of a redox reaction between oxidized quercetin and ascorbate is discussed.
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The rates of hydrolysis of more than a hundred flavonoid glycosides have been measured, using N HCl, β-glucosidase, β-glucuronidase or anthocyanase. The results show that such measurements are useful (α) in distinguishing O- from C-glycosides, (b) in characterizing flavonoids having sugars attached to more than one hydroxyl group, and (c) for determining suitable conditions for the isolation of intermediate glycosides. Flavonols with glucuronic acid or glucose attached to the 7-hydroxyl are readily distinguished from those having rhamnose attached by their resistance to acid hydrolysis; times for complete hydrolysis are 180, 25 and 5 min respectively. β-Glucosidase attacks the 3-, 7- and 4′-O-glucosides of quercetin at the same rate, but preferentially removes glucose from the 7-hydroxyl group of quercetin 7-glucoside-3-sophoro-side. Anthocyanase hydrolyses anthocyanidin 3-galactosides, 3-glucosides and 3-(diglycosides) much more rapidly than 3-rhamnosides, 3-arabinosides and acylated glycosides.These procedures have been applied, in combination with other methods, to the identification of flavonol glycosides present in species Allium, Helleborus, Lathyrus, Matthiola, Potentilla and Tulipa. New glycosides now characterized are: the 7-glucuronide-3-rutinosides of kaempferol and quercetin, the 7-rhamnoside-3-lathyroside and 7-rhamnoside-3-(rhamnosylarabinoside) of kaempferol, and the 7-glucoside-3-(xylosyl-glucoside), the 3,4′-diglucoside, the 3,7-diglucuronide and the 7-glucoside-3-(caffeoylsophoroside) of quercetin.
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• Contains additional discussion and examples on left truncation as well as material on more general censoring and truncation patterns. • Introduces the martingale and counting process formulation swil lbe in a new chapter. • Develops multivariate failure time data in a separate chapter and extends the material on Markov and semi Markov formulations. • Presents new examples and applications of data analysis.
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Qualitative identification and quantitative determination of flavonols and flavonesThe method described is suitable for the quantitative determination of flavonols and flavones in plant material and foods. Concentrations of 10 mg/kg fresh weight and higher are determined. The macerated plant material is completely extracted with methanol; the combined extracts are extracted with petroleum ether (b.p. 40–70°) and purified on a polyamide column. Then the glycosides are hydrolysed with I% H2SO4 in methanol and the aglycones formed are identified by thin-layer chromatography. For quantitative determination the hydrolysed extract is carefully applied to cellulose plates in the form of a narrow band and separated in chloroform-formic acid-water (50:45:5). The substances removed can be determined photometrically.ZusammenfassungDie mitgeteilte Methode ermöglicht es, Flavonole und Flavone in Nutzpflanzen und Lebensmitteln in Konzentrationen bis zu 10 mg/1000 g Frischsubstanz exakt quantitativ zu bestimmen. Die zerkleinerten Pflanzenteile werden mit Methanol erschöpfend extrahiert, die Extrakte mit Petroläther (Sdp. 40–70°) ausgezogen und anschliessend mit Hilfe einer Polyamid-Säule gereinigt. Danach erfolgt eine Hydrolyse der Glykoside mit 1%iger methanolischer Schwefelsäure und ein qualitativer dünnschichtchromatographischer Nachweis der enthaltenen Aglykone. Eine für quantitative Arbeiten ausreichende Trennung der Flavon(ol)e wird nach strichförmigem Auftragen auf Cellulose-Platten in Chloroform-Ameisensäure-Wasser (50:45:5) erzielt. Die abgelösten Substanzen können dann photometrisch bestimmt werden.
Article
Quercetin and kaempferol rhamnodiglucosides are characteristic compounds of Camellia sinensis. Their structures were determined as quercetin-and kaempferol-3-O-[β-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 6)-β-D-glucopyranosides]. Reversed phase HPLC methods for preparative isolation and analytical separation of both compounds were developed. The structural elucidation of the compounds by means of NMR spectroscopy, fast atom bombardment MS and GC-MS of the sugar moieties is described. Black tea contains 0–0·95 g kg−1 quercetin rhamnodiglucoside and 0·05–1·25 g kg−1 kaempferol rhamnodiglucoside.
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THE bracken plant (Pteridium aquilinum) is known to contain radiomimetic activity. Ingestion by cattle of the whole plant, or of extracts, produces a syndrome in which there is panmyeloid bone-marrow damage, pyrexia, and often gut-lining damage and ulceration1; also typical are the widespread petechial haemorrhages2.
Article
The quercetin and kaempferol contents of eight onion varieties (Allium cepa L.) were determined. The dry skins, outer rings, and inner rings were separated and extracted with methanol to obtain flavonol glycosides that were then hydrolyzed to aglycons. Flavonols were detected and quantified by thin-layer chromatography, high-performance liquid chromatography, and spectrophotometric analyses. The quercetin content of onion tissue decreased from the dry skin to inner rings. The skin of all varieties contained quercetin, both as the aglycon and as glycosides; with some varieties, the skin also contained small amounts of kaempferol. Outer rings of all varieties except Red Hamburger contained small amounts of quercetin while those of Early Yellow Globe, Sweet Spanish Hybrid, and Walla Walla contained small amounts of kaempferol as well. Traces of these flavonols also were detected in the inner rings. The highest quercetin content found in the edible portion of these samples was about 60 mg/kg fresh weight. Small quantities of quercetin and kaempferol were present in scallion leaves but not in bulb tissue. Myricetin was not detected in any sample.
Article
Representative varieties of highbush blueberries, cranberries, and thornless blackberries were compared to determine the extent of differences in the distribution of quercetin, kaempferol, and myricetin. Quantitation was by HPLC using an external standard method. Fruits of four highbush blueberry varieties contained quercetin (24-29 mg/kg, fresh weight) but not kaempferol or myricetin. All three flavonols were found in cranberry fruits, the range for dark-colored fruit of six varieties being 112-250 mg/kg with quercetin, 11-24 mg/kg with myricetin, and 0-3 mg/kg with kaempferol. Within varieties, flavonol contents were smaller in the less highly pigmented berries. Ripe (black-colored) fruits of 12 thornless blackberry varieties and selections contained quercetin (5-35 mg/kg) and kaempferol (1-3 mg/kg). Flavonol and anthocyanin contents were smaller in less ripe fruits. No correlation was seen between the total anthocyanin content and the amounts of flavonols in these cultivars.
Article
The quercetin and kaempferol contents of 13 varieties of lettuce were determined. Leaf lettuce varieties contained 2-54 mg of quercetin/kg, while head lettuce varieties contained 1-28 mg/kg, more in the outer leaves than in the inner leaves. These samples also contained 0-2 mg of kaempferol/kg. Chives contained 55 mg of kaempferol and 9 mg of quercetin per kg in green portions and lesser amounts in white portions, while leek contained 20 mg of kaempferol/kg in green portions and no detectable quercetin in either portion. Two varieties of kale contained 7-20 mg of quercetin and 13-30 mg of kaempferol per kg. Other vegetables examined contained lesser amounts of these flavonols. No myricetin was detected in these samples.
Article
Thirty-four French red wines originating from six different grape varieties and three different production areas were analysed in duplicate for 15 anthocyanins, ten flavonoids and three colour parameters, F-statistics, principal component analysis and stepwise discriminant analysis were used to identify and to explain differences among samples.Clear difference between wines made from different varieties were mainly related to anthocyanin 3-acylglucosides. Malvidin and peonidin 3-acetylglucosides were found in increasing concentrations in wines made respectively from Grenache, Carignan, Cinsault, Merlot, Carbernet Sauvignon and Cabernet Franc grapes; the concentrations of peonidin and malvidin 3-p-coumarylglucosides were higher in the Cinsault wines studied.Cabernet Sauvignon and Merlot wines made near Bordeaux had a less intense colour and a higher malvidin 3-glucoside content than wines from the same varieties produced near Narbonne. Wines made from Merlot, Cabernet Sauvignon and Cabernet Franc grapes contained more catechin, epicatechin and myricetin when produced in the south than in the north (Narbonne, Bordeaux, Angers).Of the samples analysed, 96%, and all of the nine extra wines, were correctly classified according to the variety of the grapes using four anthocyanins and catechin selected by step wise discriminant analyses.
Article
Low molecular weight phenolic compounds were separated by high performance liquid chromatography on hydrocarbon-bonded reverse phase packings, with a water-methanol elution gradient. Phenolic compounds were extracted from wine with ethyl acetate. A first extraction at pH 7 enabled isolation of neutral molecules (catechins, procyanidins, flavonols, aromatic alcohols); a second extraction at pH 2 was performed to extract phenolic acids. Successive injections of these two extracts in the chromatograph gave the distribution of the different phenolic compounds in the wine under analysis. Analytical data are given for low molecular weight phenolic compounds present in young red Bordeaux wines from different vine cultivars.
Article
The non-volatile, water-soluble constituents of black tea were studied by using reversed-phase HPLC with a photodiode-array detector, using a linear gradient developed for this purpose. The data generated by this detector from one injection of a black tea liquor allowed information on the nature and purity of the constituents to be obtained. The following constituents were identified by the spectral data and the retention times given by reference compounds: caffeine, theobromine, (−)-epicatechin gallate, (−)- epigallocatechin gallate, gallic acid, chlorogenic acid (5-O-caffeoylquinic acid), p-coumaroylquinic acid, quercetin 3-glucoside, quercetin 3-rhamnosylglucoside, kaempferol 3-rhamnosylglucoside, and theaflavin digallate. Other peaks were classified by spectral data, but without reference compounds conclusive assignments could not be made. Finally, a group of peaks could be classified as coloured phenolic pigments, and tentatively assigned as thearubigins.
Article
We studied the effect of quercetin (Q) on the proliferation of HT-29, WiDr, COLO 201, and LS-174T human colon cancer cell lines. Q, between 10 nM and 10 μM, exerted a dose-dependent, reversible inhibition of cell proliferation. Cell-cycle analysis revealed that the growth-inhibitory effect of Q was due to a blocking action in the G0/G1 phase. Using a whole-cell assay with 17β-[3H]-estradiol as tracer, we demonstrated that all these cell lines contain type-II estrogen-binding sites (type-II EBS). By using Q and other chemically related flavonols (3,7-4′-trimethox- yquercetin, 3,7,3,4′-tetramethoxyquercetin, kaempferol, morin, and rutin), we observed that the affinities of these compounds for type-II EBS are correlated with their growth-inhibitory potential. Furthermore, the Q sensitivity of the colon cancer cell lines was correlated with the number of type-II EBS/cell. Then Q could regulate colon cancer cell growth through a binding interaction with type-ll EBS. This mechanism could also be active in vivo as we have observed that cytosolic type-II EBS are present in primary colorectal cancers and that Q is effective in inhibiting the in vitro bromodeoxyuridine incorporated by neoplastic cells in these cancers.
Article
The mutagenicities of 61 flavonoids (naturally occurring flavonoid aglycones and flavonal glycosides and synthetic flavonoids) and those of 11 compounds structurally related to flavonoids were tested with Salmonella typhimurium strains TA100 and TA98. Among the 22 flavone derivatives tested, only wogonin was strongly mutagenic, while five derivatives, apigenin triacetate, acacetin, chrysoeriol, pedalitin, and pedalitin tetraacetate, were only weakly mutagenic. Two bisflavonyl derivatives, neither of which has a 3-hydroxyl group, were not mutagenic. Of the 16 flavonol derivatives tested, all except 3-hydroxyflavone and the tetra- and penta-methyl ethers of quercetin were mutagenic. Of the five flavanone derivatives tested, only 7,4-dihydroxyflavanone was mutagenic, showing weak activity. Of the four flavanonol derivatives tested, hydrorobinetin and taxifolin were weakly mutagenic. Of the six isoflavone derivatives tested, tectorigenin was weakly mutagenic. Of the 11 compounds in the miscellaneous group structurally related to flavonoids, only iso-liquiritigenin was mutagenic, showing weak activity. For the emergence of strong mutagenicity, the double bond between positions 2 and 3 and the hydroxyl group at position 3 are required, except in wogonin, which does not have a hydroxyl group at position 3 but is strongly mutagenic to TA100. The 3-O-acetyl ester of flavonol, quercetin, was mutagenic with S9 mix, but 3-O-methyl ethers were not. Six flavonol glycosides, three quercetin glycosides and three kaempferol glycosides were mutagenic after preincubation with “hesperidinase,” a crude extract of Aspergillus niger. Of 66 flavonoid agylcones and compounds structurally related to flavonoids, quercetin was the strongest mutagen. The carcinogenicity of this compound should be clarified because it is ubiquitously found in vegetables.
Article
Free flavonol aglycones, potentially mutagenic, were determined in vegetable infusions, in fresh and pickled vegetables and in vegetables exposed to mold growth. None of the infusions tested contained any considerable amount of free mutagenic aglycones, but some vegetables, such as red onions and cucumbers, had appreciable amounts of free flavonol aglycones, especially in the external layers. The treatment used in the production of pickled vegetables did not change the quality and quantity of the flavonols but the presence of molds altered the quantity of flavonol aglycones and glycosides.
Article
In this review the qualitative and quantitative occurrence of flavonols and flavones, particularly in fruit and vegetables, are considered. They occur practically in all plants. Their formation normally depends on light so that they are mainly concentrated in the outer tissues. the concentration of flavonols in free standing leaves exceeds that in other parts of the same plant considerably, except in onions.Flavonols act as antioxidants and protect the ascorbic acid from auto-oxidation, for example in fruit juices. On the other hand, flavonols can lead to discolourations. Beneficial effects on the human organism have also been described.
Article
Flavonol and flavone glycosides occur in common vegetables, mainly as the quercetin or kaempferol glycosides and less frequently as the luteolin or apigenin glycosides. Their formation normally depends on light, so they are mainly concentrated in the outer tissues. Their concentration in free-standing leaves is considerably greater than that in any other part of the same plant, with the exception of the onion.Flavonol- und Flavon-glykoside kommen in allen Gemsearten vor, hauptschlich als Quercetin- oder Kmpferol- und weniger hufig als Luteolin- oder Apigenin-glykoside. Da ihre Bildung lichtabhngig ist, sind sie im ueren Gewebe angereichert. Die Konzentration ist in freistehenden Blttern mit Ausnahme der Kchenzwiebel erheblich hher als in anderen Teilen der gleichen Pflanze.
Article
The first Dutch National Food Consumption Survey (DNFCS) was conducted in 1987–1988. This report describes the design and methods of the Dutch nutrition surveillance system. The rationale for the use of an existing panel and a two-day record is given, and some potential pitfalls are discussed. The DNFCS data are compared with data from the Dutch national food balance sheets. Data from both individual and household levels are presented and discussed. An example regarding risk group identification is given.
Article
Photosensitized hemolysis of human erythrocytes by hematoporphyrin was suppressed by flavonols such as quercetin and rutin at submillimolar concentrations. The suppression of photohemolysis was accompanied by inhibition of lipid peroxidation by the reagents. Quercetin and rutin were photooxidized in the presence of hematoporphyrin and the photooxidation was partially suppressed by 1 mM NaN3, a quencher of singlet molecular oxygen. Flavonols were also oxidized by radicals formed during degradation of lauroyl peroxide. These results indicate that flavonols can function as antioxidants in biological systems by terminating radical chain reactions and removing singlet molecular oxygen. A pharmacological function of flavonols, decrease of the increased permeability and gragility of capillary, was discussed in relation to their antioxidative functions.
Article
A rapid method based on RP-HPLC with UV detection is presented for the quantitative determination of five major flavonoid aglycons, viz. quercetin, kaempferol, myricetin, luteolin, and apigenin, in freeze-dried vegetables and fruits, after acid hydrolysis of the parent glycosides. Completeness of hydrolysis and extraction have been optimized by testing systematically different conditions such as acid concentration, reaction period, and methanol concentration in the extraction solution using samples containing various types of flavonoid glycosides. Optimum hydrolysis conditions are presented for flavonol glucuronides, flavonol glucosides, and flavone glycosides. Identity of the flavonoids was confirmed with diode array. Repeatability of the method was good, with coefficients of variation of 2.5-3.1 % for quercetin, 4.6-5.6 % for kaempferol, 4.6 % for myricetin, 3.3 % for luteolin, and 2.8 % for apigenin. CV of the within-laboratory reproducibility was less than 2 times the CV of repeatability. Recoveries of the flavonols quercetin, kaempferol, and myricetin ranged from 77 to 110 %, and recoveries of the flavones apigenin and luteolin ranged from 99 to 106 %. The method presented allows a fast, quantitative, and reproducible determination of five flavonoids in freeze-dried foods.
Article
The content of the potentially anticarcinogenic flavonoids quercetin, kaempferol, myricetin, apigenin, and luteolin of commonly consumed beverages was determined by RP-HPLC with UV detection. Flavonoid levels in beer, coffee, chocolate milk, and white wine were below 1 mg/L. Twelve types of tea infusion, six types of wine, apple juice, tomato juice, grape juice, orange juice, grapefruit juice, and lemon juice were analyzed. No luteolin or apigenin were detected in any of the beverages. In red wines and in grape juice quercetin and myricetin levels varying from 4 to 16 mg/L and from 7 to 9 mg/L, respectively, were detected. Quercetin levels in fruit juices were generally below 5 mg/L except for lemon juice (7 mg/L) and tomato juice (13 mg/L). In black tea infusions quercetin (10-25 mg/L), kaempferol (7-17 mg/L), and myricetin (2-5 mg/L) were detected. Flavonoid levels in green tea were comparable to those in black tea. The flavonoid content of tea prepared with tea bags was generally higher than that of tea prepared with loose leaves. Together with data on the flavonoid content of vegetables and fruits published previously (Hertog et al. J. Agric. Food Chem. 1992, 40, 2379-2383), these data provide a base for an epidemiological evaluation of the potentially anticarcinogenic effects of flavonoids.
Article
The mutagenic activities of several flavonoids and flavonoid metabolites were examined by means of Salmonella typhimurium mutants that reveal base-pair substitution and frameshift mutagens. Of the compounds tested (naringin, rutin, neohesperetin, hesperetin, dihydroquercetin, quercetin, quercetin pentaacetate, permethylquercetin, m-hydroxyphenylacetic acid, and m,p-dihydroxyphenylacetic acid), only quercetin was mutagenic without microsomal activation. With activation, however, the mutagenic activity of quercetin was increased significantly and that of quercetin pentaacetate was revealed. The health implications of these findings and aspects of flavonoid structural requirements for mutagenic activity are discussed.
Article
Indole-3-carbinol, 3,3'-diindolylmethane, and indole-3-acetonitrile, three indoles occurring in edible cruciferous vegetables, have been studied for their effects on 7,12-dimethylbenz(a)anthracene-induced mammary tumor formation in female Sprague-Dawley rats and on benzo(a)pyrene-induced neoplasia of the forestomach in female ICR/Ha mice. When given by p.o. intubation 20 hr prior to 7,12-dimethylbenz(a)anthracene administration, indole-3-carbinol and 3,3'-diindolylmethane had an inhibitory effect on mammary tumor formation, but indole-3-acetonitrile was inactive. Indole-3-carbinol when added to the diet for 8 days prior to challenge with 7,12-dimethylbenz(a)anthracene inhibited mammary tumor formation, whereas indole-3-acetonitrile did not. Dietary administration of all three indoles inhibited benzo(a)pyrene-induced neoplasia of the forestomach in ICR/Ha mice. The identification of dietary constituents that can inhibit chemical carcinogens ultimately may be of value in understanding the balance of factors that determines the neoplastic response to these cancer-producing agents in the environment.
Article
The pharmacokinetics of quercetin, a flavonoid, have been studied in 6 volunteers after single intravenous (100 mg) and oral (4 g) doses. The data after iv administration were analyzed according to a two compartment open model with half lives of 8.8 +/- 1.2 min for the alpha phase and 2.4 +/- 0.2 h for the beta phase (predominant half life), respectively. Protein binding was greater than 98%. The apparent volume of distribution was small at 0.34 +/- 0.03 1/kg. Of the intravenous dose 7.4 +/- 1.2% was excreted in urine as a conjugated metabolite, and 0.65 +/- 0.1% was excreted unchanged. After oral administration no measurable plasma concentrations could be detected, nor was any quercetin found in urine, either unchanged or in a metabolized form. These results exclude absorption of more than 1% of unchanged drug. Recovery in faeces after the oral dose was 53 +/- 5%, which suggests extensive degradation by microorganisms in the gut. The data obtained show that oral administration of flavonoids may be of questionable value.
Article
Oxidative modification of LDL renders it immunogenic and autoantibodies to epitopes of oxidised LDL, such as malondialdehyde (MDA)-lysine, are found in serum and recognise material in atheromatous tissue. However, there has been no prospective study to assess the importance of oxidised LDL among patients with vascular disease. We compared the titre of autoantibodies to MDA-modified LDL and native LDL in baseline serum samples of 30 eastern Finnish men with accelerated two-year progression of carotid atherosclerosis and 30 age-matched controls without progression. Neither group had specific antibody binding to native LDL. A titre was defined as a ratio of antibody binding to MDA-LDL/binding to native LDL. Cases had a significantly higher titre to MDA-LDL (2.67 vs 2.06, p = 0.003). Cases also had a greater proportion of smokers (37% vs 3%), higher LDL cholesterol (4.2 mmol/l vs 3.6 mmol/l), and higher serum copper concentration (1.14 mg/l vs 1.04 mg/l). Even after adjusting for these variables and the severity of baseline atherosclerosis, the difference in antibody titre remained significant in a multifactorial logistic model (p = 0.031). Thus, the titre of autoantibodies to MDA-LDL was an independent predictor of the progression of carotid atherosclerosis in these Finnish men. Our data provide further support for a role of oxidatively modified LDL in atherogenesis.
Article
Recently, we and others showed that the components of green tea may be useful cancer chemopreventive agents. It has been suggested that (-)-epigallocatechin-3-gallate (EGCG), the major constituent in green tea, may possess antitumor-promoting and/or anticarcinogenic effects in rodent tumor bioassay systems. During the chemical analysis of various green tea products, we found a traditionally preserved preparation of green tea used by tribes in the Himalayan region of Sikkim, India that was rich in EGCG. EGCG was isolated from this tea product, and its inhibitory effects were evaluated against the binding of topically applied 3H-labeled polycyclic aromatic hydrocarbons (PAHs) to epidermal DNA and 12-O-tetradecanoylphorbol-13-acetate (TPA) caused induction of epidermal ornithine decarboxylase (ODC) activity in Sencar mice, the short-term markers of tumor initiation and tumor promotion, respectively. Preapplication of EGCG resulted in significant inhibition (p less than 0.05) in the binding of [3H]PAH to epidermal DNA. Similarly, the topical application of EGCG resulted in significant inhibition (p less than 0.005) in TPA-caused induction of epidermal ODC activity. In further studies, we assessed the anti-skin tumor-initiating effect of EGCG in Sencar mice in an initiation-promotion protocol. The application of EGCG before challenge with 7,12-dimethylbenz[a]anthracene as tumor initiator resulted in significant reduction both in percentage of mice with tumors and number of tumors per mouse compared with a non-EGCG-pretreated group of animals. The results of the present study suggest that the green tea preparation from Sikkim may be a good source for the isolation of EGCG and that this compound may have significant potential as a cancer chemopreventive agent.
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No doubt can remain that the flavonoids have profound effects on the function of immune and inflammatory cells as determined by a large number and variety of in vitro and some in vivo observations. That these ubiquitous dietary chemicals may have significant in vivo effects on homeostasis within the immune system and on the behavior of secondary cell systems comprising the inflammatory response seems highly likely but more work is required to strengthen this hypothesis. Ample evidence indicates that selected flavonoids, depending on structure, can affect (usually inhibit) secretory processes, mitogenesis, and cell-cell interactions including possible effects on adhesion molecule expression and function. The possible action of flavonoids on the function of cytoskeletal elements is suggested by their effects on secretory processes. Moreover, evidence indicates that certain flavonoids may affect gene expression and the elaboration and effects of cytokines and cytokine receptors. How all of these effects are mediated is not yet clear but one important mechanism may be the capacity of flavonoids to stimulate or inhibit protein phosphorylation and thereby regulate cell function. Perhaps the counterbalancing effect of cellular protein tyrosine phosphatases will also be found to be affected by flavonoids. Some flavonoid effects can certainly be attributed to their recognized antioxidant and radical scavenging properties. A potential mechanism of action that requires scrutiny, particularly in relation to enzyme inhibition, is the redox activity of appropriately configured flavonoids. Finally, in a number of cell systems it seems that resting cells are not affected significantly by flavonoids but once a cell becomes activated by a physiological stimulus a flavonoid-sensitive substance is generated and interaction of flavonoids with that substance dramatically alters the outcome of the activation process.