Fabrication, characterization and practical efficacy of Myristica fragrans essential oil nanoemulsion delivery system against postharvest biodeterioration.

The present study deals with encapsulation of Myristica fragrans essential oil (MFEO) into chitosan nano-matrix, their characterization and assessment of antimicrobial activity, aflatoxin inhibitory potential, safety profiling and in situ efficacy in stored rice as environment friendly effective preservative to control the postharvest losses of food commodities under storage. Surface morphology of MFEO-chitosan nanoemulsion as well as encapsulation of MFEO was confirmed through SEM, FTIR and XRD analysis. In vitro release characteristics with biphasic burst explained controlled volatilization from nanoencapsulated MFEO. Unencapsulated MFEO exhibited fungitoxicity against 15 food borne molds and inhibited aflatoxin B1 secretion by toxigenic Aspergillus flavus LHP R14 strain. In contrast, nanoencapsulated MFEO showed better fungitoxicity and inhibitory effect on aflatoxin biosynthesis at lower doses. In situ efficacy of unencapsulated and nanoencapsulated MFEO on stored rice seeds exhibited effective protection against fungal infestation, aflatoxin B1 contamination, and lipid peroxidation. Both the unencapsulated and nanoencapsulated MFEO did not affect the germination of stored rice seeds confirming non-phytotoxic nature. In addition, negligible mammalian toxicity of unencapsulated MFEO (LD50 = 14,289.32 µL/kg body weight) and MFEO loaded chitosan nanoemulsion (LD50 = 9231.89 µL/kg body weight) as revealed through favorable safety profile recommend the industrial significance of nanoencapsulated MFEO as an effective green alternative to environmentally hazardous synthetic pesticides for protection of food commodities during storage.

Assessment of chemically characterised Myristica fragrans essential oil against fungi contaminating stored scented rice and its mode of action as novel aflatoxin inhibitor.

The study reports chemically characterised Myristica fragrans essential oil (MFEO) as plant based food preservative against fungal and aflatoxin B1 (AFB1) contamination of scented rice varieties. The chemical profile of MFEO revealed elemicin (27.08%), myristicine (21.29%) and thujanol (18.55%) as major components. The minimum inhibitory and minimum aflatoxin inhibitory concentrations of MFEO were 2.75 and 1.5 mg/ml, respectively. The MFEO was efficacious against a broad spectrum of food deteriorating fungi. MFEO caused decrease in ergosterol content of fungal plasma membrane and enhanced leakage of cellular ions, depicting plasma membrane as the site of action. The MFEO caused reduction in cellular methylglyoxal content, the aflatoxin inducer. This is the first report on MFEO as aflatoxin suppressor. The essential oil may be recommended as plant based food preservative after large scale trials and reduction in methylglyoxal suggests its application for development of aflatoxin resistant varieties through green transgenics.

GC-EIMS analysis, antifungal and anti-aflatoxigenic activity of Capsicum chinense and Piper nigrum fruits and their bioactive compounds capsaicin and piperine upon Aspergillus parasiticus.

GC-EIMS analysis, antifungal- and anti-aflatoxigenic activities of the ethanolic extract of Capsicum chinense and Piper nigrum fruits and their main bioactive compounds were evaluated upon Aspergillus parasiticus. The GC-EIMS analysis showed capsaicin (50.49%) and piperine (95.94%) as the major constituents in C. chinense and P. nigrum, respectively. MIC50 values revealed that capsaicin (39 µg/mL) and piperine (67 µg/mL) were lower than those from fruit extracts of C. chinense (381 µg/mL) and P. nigrum (68 µg/mL). Extracts and bioactive compounds showed anti-aflatoxigenic activity. Maximum aflatoxin inhibition occurred at 150 µg/mL of extracts and compounds. The present study showed satisfactory results concerning the effects of ethanolic extract of C. chinense and P. nigrum fruits upon A. parasiticus, showing the capabilities of inhibiting fungal growth development and altering aflatoxins production.

Preparation, characterization and anti-aflatoxigenic activity of chitosan packaging films incorporated with turmeric essential oil.

Here, we studied the preparation, characterization, anti-aflatoxigenic activity, and molecular mechanism in vitro of chitosan packaging films containing turmeric essential oil (TEO). First, we took the mechanical properties as the evaluation Index, screened for the optimum preparation conditions of packaging films with 1.5 µL/cm2 TEO using single factor and orthogonal experiments, and characterized the film properties. We found that the addition of TEO affected the microcosmic structure of films and advanced water resistance capacity. In addition, we investigated the inhibitory effects of pure chitosan films and packaging films containing 1.5 µL/cm2 or 3.0 µL/cm2 TEO on the growth and conidial formation of Aspergillus flavus (A. flavus, CGMCC 3.4410), as well as the accumulation of aflatoxin over the course of seven days. We found that the packaging films possessed a prominent antifungal activity on A. flavus. Finally, we discuss preliminary results surrounding gene expression of packaging films which inhibit aflatoxin biosynthesis. The expressions levels of 16 genes related to aflatoxin biosynthesis were found to be either completely or almost completely inhibited. Therefore, the addition of the natural antifungal agent TEO in chitosan packaging films represent a remarkable method to significantly promote the development and application of antifungal packaging materials.

Efficacy of feed additives to reduce the effect of naturally occurring mycotoxins fed to turkey hen poults reared to 6 weeks of age.

Corn with naturally occurring aflatoxin (AF), wheat with naturally occurring doxynivalenol (DON), and barley with naturally occurring zearalenone (ZEA) were used to make rations for feeding turkey hen poults to 6 weeks of age. Control rations with equal amounts of corn, wheat, and barley were also fed. The control rations did contain some DON while both sets of rations contained ZEA. Within each grain source, there were 4 treatments: the control ration plus 3 rations each with a different feed additive which were evaluated for the potential to lessen potential mycotoxin effects on bird performance and physiology. The additives were Biomin BioFix (2 lb/ton), Kemin Kallsil (4 lb/ton), and Nutriad UNIKE (3 lb/ton). The mycotoxin rations reduced poult body weight (2.31 vs. 2.08 ± 0.02 kg) and increased (worsened) poult feed conversion (1.47 vs. 1.51 ± 0.01) at 6 wk. Feeding the poults the mycotoxin feed also resulted in organ and physiological changes typical of feeding dietary aflatoxin although a combined effect of AF, DON, and ZEA which cannot be dismissed. The feed additives resulted in improved feed conversion to 6 wk in both grain treatment groups. The observed physiological effect of feeding the additives was to reduce relative gizzard weight for both groups and to lessen the increase in relative kidney weight for the birds fed the mycotoxin feed. In conclusion, the feed additives used in this study did alleviate the effect of dietary mycotoxins to some degree, especially with respect to feed conversion. Further studies of longer duration are warranted.

Aflatoxin biosynthesis control produced by Aspergillus flavus in layer hens feed during storage period of six months.

Aflatoxins (AFTs) are a group of closely related toxins that are produced by different fungus species. Food and feed contamination with AFT is a worldwide health-related problem. As a result of fungal attack, the food and feed resulted in a principal socioeconomic loss and toxins produced in feed and food items harm the humans and animals in different ways. The anti-aflatoxigenic effect Psidium guajava, Ficus benghalensis, Gardenia radicans, Punica granatum and Ziziphus jujuba leaves were evaluated against aflatoxins (AFTs), produced by Aspergillus flavus in layer feed during storage. Among the investigated medicinal plant leaves, P. granatum showed highly promising anti-aflatoxigenic activity and completely inhibited the AFTs (B1 and B2) production over storage period without compromising the nutritive quality of feed (ash, protein, fat, fiber, Fe, Ca, P and K contents). Leaves of F. benghalensis and Z. jujuba were also effective however, higher concentration (15%) inhibited the AFTs production up to 99% and also maintained nutritive quality of feed. G. radicans was found least effective in controlling the AFTs production. Results revealed that all plant leaves were effective in controlling AFTs production in layer feed over the storage period of six months and these plants are potential candidate to replace the fungicides used to protect feed and other agricultural commodities from AFTs production during storage.

Influence of the antimicrobial compound allyl isothiocyanate against the Aspergillus parasiticus growth and its aflatoxins production in pizza crust.

Aflatoxins (AFs) are secondary metabolites produced by different species of Aspergillus, such as Aspergillus flavus and Aspergillus parasiticus, which possess mutagenic, teratogenic and carcinogenic activities in humans. In this study, active packaging devices containing allyl isothiocyanate (AITC) or oriental mustard flour (OMF) + water were tested to inhibit the growth of A. parasiticus and AFs production in fresh pizza crust after 30 d. The antimicrobial and anti-aflatoxin activities were compared to a control group (no antimicrobial treatment) and to a group added with commercial preservatives (sorbic acid + sodium propionate). A. parasiticus growth was only inhibited after 30 d by AITC in filter paper at 5 µL/L and 10 µL/L, AITC sachet at 5 µL/L and 10 µL/L and OMF sachet at 850 mg + 850 µL of water. However, AFs production was inhibited by all antimicrobial treatments in a dose-dependent manner. More importantly, AITC in a filter paper at 10 µL/L, AITC sachet at 10 µL/L, OMF sachet at 850 mg + 850 µL of water and sorbic acid + sodium propionate at 0.5-2.0 g/Kg completely inhibited AFs formation. The use of AITC in active packaging devices could be a natural alternative to avoid the growth of mycotoxinogenic fungi in refrigerated bakery products in substitution of common commercial preservatives.

Effects of Tarantula cubensis D6 on aflatoxin-induced injury in biochemical parameters in rats.

INTRODUCTION: Aflatoxins are toxic fungal metabolites that have adverse effects on humans and animals. Tarantula cubensis D6 is used as a homeopathic medicine for different purposes. The present study investigates the effects of Tarantula cubensis D6 on the oxidant-antioxidant balance and some biochemical parameters against exposure to aflatoxin. METHODS: Thirty-two Sprague-Dawley female rats were used and evenly divided into four groups. Group 1 served as control. Groups 2, 3, and 4 received 200 µl/kg.bw/day Tarantula cubensis D6 (applied subcutaneously), 400 µg/kg.bw/day total aflatoxin (approximately 80% AF B1, 10% AF B2, 6 %AF G1, and 4% AF G2), and 200 µl/kg.bw/day Tarantula cubensis D6 plus 400 µg/kg.bw/day total aflatoxin, respectively, for 28 days. At the end of 28 days, blood samples and some organs (liver, kidney, brain, and spleen) were taken from all the animals. Oxidative stress markers (MDA, SOD, CAT, GSH-Px) and some biochemical parameters (glucose, triglyceride, cholesterol, BUN, creatinine, AST, ALT and ALP, total protein, albumin) were evaluated in blood samples and tissues. RESULTS: Aflatoxin caused negative changes in all oxidative stress parameters and some biochemical parameters (glucose, triglyceride, cholesterol, creatinine, AST, ALT, ALP, total protein, albumin). Administration of Tarantula cubensis D6 partly alleviated aflatoxin-induced negative changes. CONCLUSIONS: Our results indicated that Tarantula cubensis D6 partially neutralized the deleterious effects of aflatoxin.

Mycotoxin-contaminated diets and deactivating compound in laying hens: 1. effects on performance characteristics and relative organ weight.

The current experiment was conducted to determine the effect of mycotoxin-contaminated diets with aflatoxin (AFLA) and deoxynivalenol (DON) and dietary inclusion of deactivation compound on layer hen performance during a 10-wk trial. The experimental design consisted of a 4 × 2 factorial with 4 toxin levels: control, low (0.5 mg/kg AFLA + 1.0 mg/kg DON), medium (1.5 mg/kg AFLA + 1.5 mg/kg DON), and high (2.0 mg/kg AFLA + 2.0 mg/kg DON) with or without the inclusion of deactivation compound. Three hundred eighty-four 25-wk-old laying hens were randomly assigned to 1 of the 8 treatment groups. Birds were fed contaminated diets for a 6-wk phase of toxin administration followed by a 4-wk recovery phase, when all birds were fed mycotoxin-free diets. Twelve hens from each treatment were subjected to necropsy following each phase. Relative liver and kidney weights were increased (P < 0.05) at the medium and high toxin levels following the toxin phase, but the deactivation compound reduced (P < 0.05) relative liver and kidney weights following the recovery period. The high toxin level decreased (P < 0.05) feed consumption and egg production during the toxin period, whereas the deactivation compound increased (P < 0.05) egg production during the first 2 wk of the toxin phase. Egg weights were reduced (P < 0.05) in hens fed medium and high levels of toxin. An interaction existed between toxin level and deactivation compound inclusion with regard to feed conversion (g of feed/g of egg). High inclusion level of toxins increased feed conversion compared with the control diet, whereas deactivation compound inclusion reduced feed conversion to a level comparable with the control. These data indicate that deactivation compound can reduce or eliminate adverse effects of mycotoxicoses in peak-performing laying hens.

Effects of mycotoxin-contaminated diets and deactivating compound in laying hens: 2. effects on white shell egg quality and characteristics.

An experiment was conducted to determine the effect of dietary inclusion of Mycofix Select (Biomin GmbH, Herzogenburg, Austria) on discrete egg parameters and quality characteristics of hens fed mycotoxin-contaminated diets (aflatoxin; AFLA) and deoxynivalenol (DON)) during a 10-wk trial. A 4 × 2 factorial design was used with 4 contamination levels: control, low (0.5 mg/kg of AFLA + 1.0 mg/kg of DON), medium (1.5 mg/kg of AFLA + 1.5 mg/kg of DON), and high (2.0 mg/kg of AFLA + 2.0 mg/kg of DON) with or without the inclusion of mycotoxin deactivating compound. Three hundred and eighty-four 25-wk-old laying hens were housed 3 per cage. Birds were fed contaminated diets for a 6-wk phase of toxin administration followed by a 4-wk recovery phase, when all birds were fed mycotoxin-free diets. Parameters evaluated included egg weight, Haugh unit value, specific gravity, eggshell thickness, egg shape index, and relative albumen and yolk weights. Albumen height and Haugh unit value were depressed (P < 0.05) at the high mycotoxin level 2 wk postinclusion. Egg weight was significantly reduced (P < 0.05) with the high toxins level by the third week of toxin administration and remained throughout the study during toxin administration. Egg shape index indicated a variation (P < 0.05) in shape with all toxin levels compared with the control. Relative yolk weight was decreased (P < 0.05) by the high toxin level. An interaction existed between the deactivating compound inclusion and toxins level with regard to specific gravity. Following the toxin phase, the deactivating compound inclusion increased (P < 0.05) egg specific gravity in the control and low toxin groups whereas a decrease (P < 0.05) was observed at the high toxin level. These data indicate that mycotoxins present in feed can reduce egg quality, size, yolk weight, and alter egg shape and that inclusion of a mycotoxin deactivating compound can ameliorate some of the negative effects of mycotoxin consumption.

Inhibition of aflatoxin production and growth of Aspergillus parasiticus by Cuminum cyminum, Ziziphora clinopodioides, and Nigella sativa essential oils.

Aflatoxins are highly toxic and carcinogenic metabolites produced by Aspergillus parasiticus on food and agricultural commodities. Natural products may control the production of aflatoxins. The aims of this study were to evaluate the effects of the essential oils (EOs) of Cuminum cyminum, Ziziphora clinopodioides, and Nigella sativa on growth and aflatoxins production by A. parasiticus. Minimal inhibitory concentrations (MICs) and minimal fungicidal concentrations (MFCs) of the EOs were determined and compared with each other. Determination of aflatoxins (AFB(1), AFB(2), AFG(1), and AFG(2)) was performed by immunoaffinity column extraction using reverse phase-high performance liquid chromatography. The major oil components were α-pinene (30%) in C. cyminum, pulegone (37%) in Z. clinopodioides, and trans-anthol (38.9%) in N. sativa oils. In broth microdilution method, C. cyminum oil exhibited the strongest activity (MIC(90): 1.6; MFC: 3.5 mg/mL), followed by Z. clinopodioides (MIC(90): 2.1; MFC: 5.5 mg/mL) and N. sativa (MIC(90): 2.75; MFC: 6.25 mg/mL) oils against A. parasiticus (p<0.05). Aflatoxin production was inhibited at 0.25 mg/mL of C. cyminum and Z. clinopodioides oils, of which that of C. cyminum was a stronger inhibitor. C. cyminum EO caused significant reductions in values of 94.2% for AFB(1), 100% for AFB(2), 98.9% for AFG(1), 100% for AFG(2), and 97.5% for total aflatoxin. It is concluded that the EOs of C. cyminum, Z. clinopodioides, and N. sativa could be used as natural inhibitors in foods at low concentrations to protect from fungal and toxin contaminations by A. parasiticus.

Efficacy of turmeric (Curcuma longa), containing a known level of curcumin, and a hydrated sodium calcium aluminosilicate to ameliorate the adverse effects of aflatoxin in broiler chicks.

A 3-wk feeding study was conducted to evaluate the efficacy of turmeric (Curcuma longa) powder (TMP), containing a known level of curcumin, and a hydrated sodium calcium aluminosilicate (HSCAS; Improved Milbond-TX, IMTX, an adsorbent, Milwhite Inc., Houston, TX) to ameliorate the adverse effects of aflatoxin B(1) (AFB(1)) in broiler chicks. Four pen replicates of 5 chicks each were assigned to each of 7 dietary treatments, which included the basal diet not containing TMP, HSCAS, or AFB(1) (control); basal diet supplemented with 0.5% food grade TMP that contained 1.48% total curcuminoids (74 mg/kg); basal diet supplemented with 0.5% HSCAS; basal diet supplemented with 1.0 mg/kg AFB(1); basal diet supplemented with 0.5% TMP and 1.0 mg/kg AFB(1); basal diet supplemented with 0.5% HSCAS and 1.0 mg/kgAFB(1); and basal diet supplemented with 0.5% TMP, 0.5% HSCAS, and 1.0 mg/kg AFB(1). The addition of TMP to the AFB(1) diet significantly (P < 0.05) improved the weight gain of chicks, and the addition of HSCAS to the AFB(1) diet significantly (P < 0.05) improved feed intake and weight gain, and reduced relative liver weight. The addition of TMP or HSCAS and TMP with HSCAS ameliorated the adverse effects of AFB(1) on some of the serum chemistry parameters (total protein, albumin, cholesterol, calcium). Further, decreased antioxidant functions in terms of level of peroxides, superoxide dismutase activity, and total antioxidant concentration in liver homogenate due to AFB1 were also alleviated by the inclusion of TMP, HSCAS, or both. The reduction in the severity of hepatic microscopic lesions due to supplementation of the AFB(1) diet with TMP and HSCAS demonstrated the protective action of the antioxidant and adsorbent used in the present study.

Inhibitory effects of Satureja hortensis L. essential oil on growth and aflatoxin production by Aspergillus parasiticus.

In an effort to screen the essential oils of some Iranian medicinal plants for novel aflatoxin (AF) inhibitors, Satureja hortensis L. was found as a potent inhibitor of aflatoxins B1 (AFB1) and G1(AFG1) production by Aspergillus parasiticus NRRL 2999. Fungal growth was also inhibited in a dose-dependent manner. Separation of the plant inhibitory substance(s) was achieved using initial fractionation of its effective part (leaf essential oil; LEO) by silica gel column chromatography and further separation by reverse phase-high performance liquid chromatography (RP-HPLC). These substances were finally identified as carvacrol and thymol, based on the interpretation of 1H and 13C NMR spectra. Microbioassay (MBA) on cell culture microplates contained potato-dextrose broth (PDB) medium (4 days at 28 degrees C) and subsequent analysis of cultures with HPLC technique revealed that both carvacrol and thymol were able to effectively inhibit fungal growth, AFB1 and AFG1 production in a dose-dependent manner at all two-fold concentrations from 0.041 to 1.32 mM. The IC50 values for growth inhibition were calculated as 0.79 and 0.86 mM for carvacrol and thymol, while for AFB1 and AFG1, it was reported as 0.50 and 0.06 mM for carvacrol and 0.69 and 0.55 mM for thymol. The results obtained in this study clearly show a new biological activity for S. hortensis L. as strong inhibition of aflatoxin production by A. parasiticus. Carvacrol and thymol, the effective constituents of S. hortensis L., may be useful to control aflatoxin contamination of susceptible crops in the field.

Biocontrol of aflatoxins B1, B2, G1, G2, and fumonisin B1 with 6,7-dimethoxycoumarin, a phytoalexin from Citrus sinensis.

Phytoalexins (stress-induced compounds) from Citrus sinensis cultivar Valencia were screened for antifungal and antimycotoxic activity against a test organism (Cladosporium cladosporoides) and mycotoxin-producing fungi Fusarium verticillioides and Aspergillus parasiticus. The active compound, a member of the coumarin family of compounds, has antifungal and antimycotoxic activities and was chemically identified. High-performance liquid chromatography results indicated that Valencia oranges contain a trace amount (0.36 microg/g) of scoparone in untreated fruit, but concentrations increased in UV-irradiated fruit (15.2 microg/g). Infection with Penicillium digitatum, a natural spoilage mold of citrus fruit, caused a 35.51-microg/g increase in the phytoalexin. UV absorption, infrared absorption, and 1H nuclear magnetic resonance spectroscopy revealed that this phytoalexin is identical to 6,7-dimethoxycoumarin. This is the first report indicating that the stress-induced compound, 6,7-dimethoxycoumarin, isolated from P. digitatum-infected Valencia fruit confers resistance against the mycotoxigenic fungi A. parasiticus and F. verticillioides and causes a reduction in production of fumonisin B1 and aflatoxins G1, G2, B1, and B2.

Protective effect of L-carnitine against oxidative damage caused by experimental chronic aflatoxicosis in quail (Coturnix coturnix).

This study was designed to evaluate the effect of L-carnitine supplementation on the plasma malondialdehyde (MDA) and whole blood reduced glutathione (GSH) concentrations in experimentally-induced chronic aflatoxicosis in quails. For this purpose, a total of 80 quails up to 8 weeks old were divided into four equal groups. Group I served as control, Group II was given L-carnitine at the dose of 200 mg/litre in the drinking water for 60 days, Group III was given 60 microg total aflatoxin/kg diet for 60 days, and Group IV was given both 60 microg total aflatoxin/kg diet and 200 mg L-carnitine/litre in the drinking water for 60 days. Aflatoxin treatment caused a significant increase in plasma MDA and a significant decrease in blood GSH concentrations. On the other hand, there was a significant decrease in plasma MDA and a significant increase in whole blood GSH in the L-carnitine-supplemented group. The present study demonstrated that L-carnitine brought about the inhibition of lipid peroxidation by enhancing antioxidant capacity in quails with chronic aflatoxicosis.

Morphological alterations in toxigenic Aspergillus parasiticus exposed to neem (Azadirachta indica) leaf and seed aqueous extracts.

The mode of action of the extracts prepared from neem plant i.e., Azadirachta indica on aflatoxin formation in toxigenic Aspergillus species is not well understood. Aflatoxin production by A. parasiticus was suppressed depending on the concentration of the plant aqueous extract (0, 1.56, 3.12, 6.25, 12.5, and 50% v/v) added to the culture media at the time of spore inoculation. Aflatoxin production in fungal mycelia grown for 96 h in culture media containing 50% neem leaf and seed extracts was inhibited by approximately 90 and approximately 65% respectively. Under similar conditions, culture media amended with 1.56% of leaf or seed extract caused approximately 23 and approximately 7% inhibition respectively. Mycelial samples exposed to selected concentrations of the plant extract (1.56 or 50% v/v) collected and processed for morphological studies. Semi-thin longitudinal and cross sections prepared from control (untreated) and treated mycelia (1.56% v/v) revealed that alterations are limited to the vacuolation of the mycelial cytoplasm. Nevertheless, exposure to high concentration i.e., 50% v/v of the extract resulted in vacuolation of the mycelial cytoplasm and vesicle deformation causing attenuation of cell wall at variable intervals. Herniation of the cytoplasmic contents that was protruding from the mycelium was associated with deformation of the mycelium. Some mycelia showed a cleft between the cell wall and cytoplasm. Association of aflatoxin production with morphological changes suggest that probably integrity of the cell barriers particularly cell wall is critical in regulation of aflatoxin production and excretion.

Antiaflatoxigenic and antioxidant activities of Garcinia extracts.

The effect of hexane and chloroform extracts from the fruit rinds of Garcinia cowa and Garcinia pedunculata on the growth and aflatoxin production in Aspergillus flavus was studied using peanut powder as a model food system. The growth of A. flavus was completely inhibited by the hexane and chloroform extracts from G. cowa and chloroform extract from G. pedunculata at 3000 ppm concentration, which was considered as the minimum inhibitory concentration (MIC). The MIC for the hexane extract of G. pedunculata was at 4000 ppm. Both the extracts from G. cowa inhibited aflatoxin B1 production upto 100% at a lower concentration of 2000 ppm. It was observed that, at lower concentration of the extracts from G. cowa and G. pedunculata, the degree of inhibition of aflatoxin production was much higher than the inhibition of fungal growth. The hexane and chloroform extracts from G. cowa and G. pedunculata were also studied for their antioxidant capacity by the formation of phosphomolybdenum complex at 100 ppm concentration and reducing power by potassium ferricyanide reduction method at various concentrations. Hexane and chloroform extracts from G. cowa showed higher antioxidant capacity than G. pedunculata extracts. Similarly, both the extracts from G. cowa showed higher reducing power than the extracts from G. pedunculata. The antiaflatoxigenic activities of the extracts from G. cowa and G. pedunculata may be due to their effective antioxidative properties, which could suppress the biosynthesis of aflatoxin.

The use of powder and essential oil of Cymbopogon citratus against mould deterioration and aflatoxin contamination of "egusi" melon seeds.

Experiments were carried out to determine the potential of using the powder and essential oil from dried ground leaves of Cymbopogon citratus (lemon grass) to control storage deterioration and aflatoxin contamination of melon seeds. Four mould species: Aspergillus flavus, A. niger, A. tamarii and Penicillium citrinum were inoculated in the form of conidia suspension (approx. 10(6) conidia per ml) unto shelled melon seeds. The powdered dry leaves and essential oil from lemon grass were mixed with the inoculated seeds at levels ranging from 1-10 g/100 g seeds and 0.1 to 1.0 ml/100 g seeds respectively. The ground leaves significantly reduced the extent of deterioration in melon seeds inoculated with different fungi compared to the untreated inoculated seeds. The essential oil at 0.1 and 0.25 ml/100 g seeds and ground leaves at 10 g/100 g seeds significantly reduced deterioration and aflatoxin production in shelled melon seeds inoculated with toxigenic A. flavus. At higher dosages (0.5 and 1.0 ml/100 g seeds), the essential oil completely prevented aflatoxin production. After 6 months in farmers' stores, unshelled melon seeds treated with 0.5 ml/ 100 g seeds of essential oil and 10 g/100 g seeds of powdered leaves of C. citratus had significantly lower proportion of visibly diseased seeds and Aspergillus spp. infestation levels and significantly higher seed germination compared to the untreated seeds. The oil content, free fatty acid and peroxide values in seeds protected with essential oil after 6 months did not significantly differ from the values in seeds before storage. The efficacy of the essential oil in preserving the quality of melon seeds in stores was statistically at par with that of fungicide (iprodione) treatment.

Phytochemical inhibition of aflatoxigenicity in Aspergillus flavus by constituents of walnut (Juglans regia).

Tulare walnut, a cultivar highly resistant to aflatoxin formation, was investigated for endogenous phytochemical constituents capable of inhibiting aflatoxigenesis in Aspergillus flavus. The activity, located entirely in the pellicle (seed coat), was extractable to various degrees with polar solvents, although some activity remained unextractable, indicating that the bioactivity resided in a complex of hydrolyzable tannins. These tannins can be hydrolyzed by a fungal tannase present in A. flavus, yielding gallic acid and ellagic acid, testing of which showed that only gallic acid had potent inhibitory activity toward aflatoxin biosynthesis. Comparison of the gallic and ellagic acid content in the pellicle of Tulare and Chico cultivars, over the 2002 and 2003 growing seasons, showed that the gallic acid content increased rapidly with maturation of the nut and was 1.5-2 times higher in Tulare than in Chico. Gallic acid content in the pellicle at maturity of a series of commercial English walnut cultivars, and two black walnut species, was determined as an indicator of potential for inhibition of aflatoxigenesis. Regulation of gallic acid levels in the hydrolyzable tannins of walnuts by conventional breeding or genetic manipulation has the potential to provide new cultivars with high resistance to aflatoxigenesis.

Aflatoxin in detannin coffee and tea and its destruction.

The aflatoxins produced byAspergillus parasiticus var. globosus IMI 12090 in detannin-caffeinated coffee and black tea were five times more concentrated than in regular coffee and tea. The activity of caffeine and tannin on the fungus growth and aflatoxin production in liquid broth was tested at three levels: viz. 0.1, 0.3, and 0.6%. Tannin and caffeine induced 95% inhibition in aflatoxins at 0.3% and 0.6%, respectively. The antiaflatoxigenic properties of regular coffee and tea appear to be due to tannin, followed by caffeine. The roasting of contaminated coffee beans at 200 degrees C for 20 min is effective in the destruction of aflatoxins.