Article

Antifungal compounds in Geraldton waxflower tissue

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  • Kamtech Technologies Ltd
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Abstract

Geraldton waxflower is the most economically important native Australian cut flower export. Infection of waxflower by Botrytis cinerea can lead to unacceptable levels of flower abscission after harvest. An investigation was conducted into the nature and identities of constitutive antifungal compounds in flowers and leaves. Antifungal activity against B. cinerea ( pathogen) and Cladosporium cladosporioides (bioassay organism) was observed in leaf and flower extracts. Leaf tissue contained less antifungal activity than flower tissue. Four antifungal compounds were common to the three different waxflower cultivars studied. Two antifungal compounds were identified as the sesquiterpene, globulol, and the monoterpene, grandinol. At least two unidentified phenolic compounds also demonstrated strong antifungal activity. Notwithstanding general similarities in antifungal profiles, it was evident from TLC bioassays that variations exist in some antifungal compounds between different waxflower cultivars.

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... de Vries, were recovered from naturally infected strawberry cv. Elsanta fruit (Terry et al., 2003). They were cultured in 9 cm diameter Petri plates on ½ strength PDA (potato dextrose agar; 19.5 g l -1 distilled water) (Oxoid Ltd., Berkshire, UK) at 22 ±1 and 20 ±1°C, respectively. ...
... TLC plates were developed in either one or two dimensions (1-D, 2-D) at approximately 22°C in a TLC tank (20 x 20 x 10 cm) lined with filter paper to create a solvent saturated atmosphere. 1-D TLCs were developed either in 100 ml of running solvents comprised of hexane: ethyl acetate: methanol (A = 60:40:1; B = 60:40:10; C = 60:40:20; D = 60:40:30 v/v/v) (Terry et al., 2003) or in the organic phase of ethyl acetate: benzene: ethanol (4:1:1, v/v/v; Mussell and Staples, 1971). 2- D TLCs (Wedge and Nagle, 2000) were developed in solvent system A (1-D) and then solvent system D (2-D). ...
... After examination, ammonia was removed from plates by air drying for 1h. Replicate plates were sprayed with 10% w/v phosphomolybdic acid (PMA) in ethanol, and heated to about 100°C for 2 min (Terry et al., 2003). PMA is a general visualisation reagent for oxidizable compounds. ...
Article
Antifungal activity against the pathogen, Botrytis cinerea, and a bioassay organism, Cladosporium cladosporioides, declined with advancing strawberry fruit maturity as shown by thin layer chromatography (TLC) bioassays. Preformed antifungal activity was also present in flower tissue. The fall in fruit antifungal compounds was correlated with a decline in natural disease resistance (NDR) against B. cinerea in planta. Crude extracts of green stage I fruit (7 days after anthesis) contained at least two preformed antifungal compounds (Rf=0.44 and 0.37) that were not present in white and red stage fruit. These compounds were shown with TLC reagent sprays to be neither phenolics nor alkaloids. Positive reactions to Ehrlich’s reagent suggested that Rf=0.37 was a terpene. Most antifungal activity was found in the achenes of green stage I fruit. However, antifungal activity was found in all tissue types (viz. pith, cortex, epidermis) of green stage I fruit. TLC bioassays revealed that all fruit stages yielded antifungal activity at the origin (Rf=0.00). The approximate area of fungal inhibition at the origin in green stage 1 fruit extracts was 1.87- and 1.73-fold greater than in white and red stages, respectively. TLC reagent sprays showed that the antifungal compound(s) at origin included phenolics. This observation is consistent with previous reports that phenolic compounds in strawberry fruit are inhibitory to B. cinerea.
... Once the compounds have been separated, the plates are dried and spores/ conidia can then be sprayed on the surface. Compounds with antifungal activity can be identified as the area with reduced mycelial growth (Adikaram and Ratnayake Bandara, 1998; Terry et al., 2003 Terry et al., , 2004). The identity of these antifungal compounds can be determined by developing spots of known standards. ...
... Once the compounds have been separated, the plates are dried and spores/conidia can be sprayed on the surface. Compounds with antifungal activity can be identifi ed as the area with reduced mycelia growth (Adikaram and Ratnayake Bandara, 1998;Terry et al., 2003Terry et al., , 2004. The identity of these antifungal compounds can be determined by developing spots of known standards. ...
Chapter
Since it is widely recognized that the benefi cial infl uence of fruit on human health is linked with the presence of specifi c phytochemicals, the determination of the nature of these com-pounds in different commodities and the infl uence of preharvest, postharvest and pro-cessing treatments has been a main area of research (Espín et al., 2007; Frankel, 2007). Antioxidants can be measured as individual compounds or as a total capacity, yet some methods which quantify total antioxidant activ-ity are thought to take into account compounds not classed as antioxidants, for instance, reduc-ing sugars (Huang et al., 2005). This chapter summarizes the wide variety of extraction and characterization techniques which are used to quantify individual or total antioxidants, as well as other bioactive compounds. 18.2 Sample Preparation Fruit and vegetables contain a complex pro-fi le of bioactive compounds, of which most are labile to heat, air and/or light (Brat, 2008). To extract bioactive compounds effectively from fresh tissue, samples are usually cut into small pieces and then snap-frozen immediately in liquid nitrogen since chopped material is much more unstable. Failure to prepare sam-ples in this way can result in enzymatic browning, as well as undesirable molecular, biochemical and physiological changes. Sam-ples are often freeze-dried before extraction takes place to remove water. Lyophilization aids sample grinding, which benefi ts extrac-tion by increasing solvent penetration due to greater sample surface area. Puupponen-Pimiä et al. (2003) have investigated the effects of freezer storage on fresh vegetables. After being frozen quickly to –40°C (method not stated), frozen vegetables were then stored at –20°C for 6, 12 and 18 months. The authors found that different bioactives were affected by long-term freezer storage in dif-ferent vegetable groups. A decrease in α-and β-carotene was observed in processed carrots yet not in peas between 6 and 12 months at –20°C. Similarly, over twofold reductions of quercetin and kaempferol content were observed in caulifl ower and broccoli over the same period. It is therefore important, espe-cially when comparing different fruit and veg-etable groups, that analyses are undertaken as soon as possible after sample preparation and ideally that samples are kept at or below –40°C. Differences among the literature may indeed be due to sample preparation and subsequent storage.
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The leaf essential oil of Dendropanax gonatopodus from Monteverde, Costa Rica, has been obtained by hydrodistillation and the chemical composition determined by GC-MS. The major components in the leaf oil were (E)-2-hexenal (16.9%), terpinolene (14.8%), δ-cadinene (13.5%), (E)-caryophyllene (9.9%), and α-copaene (7.3%). Minor amounts of the aromadendrane sesquiterpenoids aromadendrene (0.3%), alloaromadendrene (0.3%), spathulenol (0.6%) and globulol (0.6%) were also detected. An ab initio investigation of the aromadendrane sesquiterpenoids has been carried out using both density functional (B3LYP/6-31G*) and post Hartree-Fock (MP2/6-31G**) methods. The calculated relative energies of the aromadendranes belie their relative concentrations generally observed in essential oil compositions.
Chapter
Origins and economic importanceGeneral fruit anatomyFruit developmentFruit ripeningPost-harvest handlingSelective gaseous atmosphere storagePost-harvest diseaseGenetic transformationConclusion
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(+)-Aromadendrene ( 1 ) is a sesquiterpene present in the distillation tail of the oil of Eucalyptus globulus . This distillation tail is commercially available in large quantities at low price and is an interesting starting material for the synthesis of other chiral products. A fair amount of research has already been carried out on aromadendrene (Chapter 1). This research was mainly focussed on transformation and isomerization of the double bond, opening of the cyclopropane ring, oxidations of derivatives of aromadendrene, and rearrangement of the aromadendrene skeleton. In this thesis, the possibilities to use aromadendrene for other synthetic strategies were explored and the first interest was the development of an economically feasible route toward the fragrance compound 167 (Chapter 2). Ledene epoxide ( 154 ), easily available from aromadendrene, was selected as the starting material for this route, and rearrangements of this b -epoxide were investigated. The formation of products with the cubebane ( 159 ) and cadinane skeleton ( 160 ) indicates that bridgehead carbocations are the prefered intermediates in these rearrangements. From these experiments it was concluded that the synthetic route toward 167 as published by Gijsen is the most efficient route known so far. Scheme 1 Synthesis of guaiane-type compounds by opening the cyclopropane ring in aromadendrene has proven to be difficult. In Chapter 3 it was shown that the conversion of isoledene ( 107 ), a double bond isomer of aromadendrene, to compounds with the guaiane skeleton can be performed in a fairly easy way. The synthesis of the blue colorant guaiazulene ( 35 ) in 22% isolated yield over two steps from isoledene is an improvement of the existing methods for the dehydrogenation with sulfur of aromadendrane or guaiane type sesquiterpenes. Figure 1 A number of guaianes, for example the cyclic ethers 198 and 200 , were synthesized from isoledene epoxide ( 193 ). Isoledene epoxide can be converted by (Lewis) acid to a stabilized cyclopropylcarbinyl cation, which undergoes opening of the cyclopropane ring to a guaiane skeleton. When no water is present during the reaction, ether 198 is obtained and the presence of water leads to formation of ether 200 . Several functionalized derivatives of 198 have been prepared. These compounds were tested for their use as fragrances, but unfortunately they were not suitable as such. Scheme 2 A relatively new method for crop protection is the use of pheromone traps for monitoring or mass trapping of insects. By using these pheromone traps, the amount of insecticides often can be reduced considerably, which is more environmentally friendly and more selective. In Chapter 4 a method is described for the conversion of aromadendrene to methyl-branched linear pheromones. These pheromones ( R )-224 , ( S )-298 , and meso -306 were all synthesized from the common linear intermediate 290 . One of the key steps in the synthesis of 290 is the Baeyer-Villiger reaction of bromide 284 , and opening of the lactone ring in a one-pot reaction to give the hydroxy ester 286 . Via a Grob fragmentation using NaOEt in the presence of NaBH <sub>4</sub> and catalytic hydrogenation, 286 was then converted to compound 290 . In Chapter 5 investigations towards the synthesis of dimethyl-branched linear pheromones have been described. It was shown that it is possible to convert aromadendrene to the dimethyl-branched linear intermediate 308 , following a route similar to the one described in Chapter 4. Scheme 3
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This study investigated treatment of mango (Mangifera indica L.) fruit with 2 host defence-promoting compounds for suppression of anthracnose disease (Colletotrichum gloeosporioides). Cultivar 'Kensington Pride' fruit were treated at concentrations of up to 1000 mg/L with either potassium phosphonate or salicylic acid. Applications were by various combinations of pre- and postharvest dips and vacuum infiltration. Postharvest treatments at up to 2000 mg/L salicylic acid were evaluated in a second fruiting season. Fruit were either uninoculated or inoculated with the fungal pathogen. Colour, firmness and disease-severity were assessed during shelf life at 23 degreesC. There were no significant (P>0.05) effects of potassium phosphonate or salicylic acid on anthracnose disease severity in the first season. Moreover, phosphonate or salicylic acid treatment did not significantly affect fruit colour or firmness changes. There were significant (P<0.05) reductions in anthracnose severity in the second season, especially at the highest concentration of 2000 mg/L salicylic acid. Mango fruit skin colour and firmness changes were also slowed down significantly (P<0.05). These effects of salicylic acid were attributed to inhibition of mango fruit skin ripening (senescence).
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A new bioassay has been developed combining the simplicity of direct bioautography with the improved chromatographic resolution of 2D-TLC. Mixtures of structurally diverse antifungal agents were tested to establish the validity and utility of this method in the discovery of new natural products with activity against agriculturally important fungal pathogens.
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Strategies for control of Botrytis cinerea on Geraldton waxflower flowers The University of Queensland A review of the flower characteristics of Geraldton waxflower and factors affecting their abscission from harvested stems
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  • Dr
Beasley DR (2001) 'Strategies for control of Botrytis cinerea on Geraldton waxflower flowers'. PhD Thesis, The University of Queensland. Beasley DR, Joyce DC (2002) A review of the flower characteristics of Geraldton waxflower and factors affecting their abscission from harvested stems. Australian Journal of Experimental Agriculture 42, 519–525.
The antifungal ethyl acetate fraction was partitioned three times with hexane and ethanol (80% v/v) and evaporated to dryness. 1-D TLC C. cladosporioides bioassays were run for hexane and ethanol fractions
  • D Tlc
D TLC bioassays were performed on each extract. The antifungal ethyl acetate fraction was partitioned three times with hexane and ethanol (80% v/v) and evaporated to dryness. 1-D TLC C. cladosporioides bioassays were run for hexane and ethanol fractions (5 PL;
Fungicides fight flower drop
  • Dc Joyce
  • Ah Wearing