Antifungal, aflatoxin inhibition and antioxidant activity of Callistemon lanceolatus (Sm.) Sweet essential oil and its major component 1,8-cineole against fungal isolates from chickpea seeds

The present investigation reports the extent of molds and aflatoxin contamination to Avarodhi, Kabuli, Pusa 256, Radha and Samrat varieties of chickpea seeds. The study also examines the chemical composition of Callistemon lanceolatus (Sm.) Sweet essential oil and its antifungal, antiaflatoxin and antioxidant activity. During standardization of chemical profile, a total of 8 compounds constituting 0.862 mg/mL of oil composition were analyzed by GC-MS analysis where 1,8-cineole was recorded as a major component (0.56 mg/mL). The antifungal activity of EO and 1,8-cineole was evaluated by contact assay on Czapek’s dox agar. The EO (0.227-0.908 mg/mL) and 1,8-cineole (0.918 mg/mL) showed remarkable antifungal effect against all the fungal isolates of chickpea. Their minimal inhibitory (MIC) and fungicidal (MFC) concentrations for Aspergillus flavus were lower than those of the prevalent systemic fungicide Nystatin. Aflatoxin B₁ (AFB₁) production by NKD-208 isolates of A. flavus was strongly inhibited even at the lower fungistatic concentration of EO and 1,8-cineole.There was no adverse effect of EO treatment on chickpea seed germination suggesting its non-phytotoxic nature. Based on the findings of present investigation, C. lanceolatus essential oil may be recommended as botanical preservative for the enhancement of shelf life of food items in- view of the adverse effect of synthetic preservatives and its strong antifungal, aflatoxin inhibition and antioxidant activity.     

Growth inhibition and morphological alterations of Fusarium verticillioides by cinnamon oil and cinnamaldehyde

Fusarium verticillioides is a filamentous fungus and a widely distributed pathogen having the ability to infect and cause destruction in economically important crops and grains by producing fumonisin mycotoxins. In the present study, the inhibitory effect of cinnamon, citral, Litsea cubeba oil, clove, eucalyptus, anise, spearmint and camphor oils on F. verticillioides was investigated, and cinnamon oil proves to be the most effective in inhibition. The antifungal effect of cinnamon oil was studied with special reference to its mechanism of inhibition of F. verticillioides growth at the morphological and ultrastructural levels. For F. verticillioides, the minimal inhibitory concentrations (MICs) of cinnamon oil (85% cinnamaldehyde), natural cinnamaldehyde (95%), and synthetic cinnamaldehyde (99%) were 60, 50, and 45 μL/L, respectively. The antifungal activity of cinnamon oil was proportional to its cinnamaldehyde concentration. Scanning electron microscopy and transmission electron microscopy of F. verticillioides exposed to MIC of cinnamaldehyde showed irreversible deleterious morphological and ultrastructural alterations, such as lack of cytoplasmic contents, loss of integrity and rigidity of the cell wall, plasma membrane disruption, mitochondrial destruction, folding of the cell. These modifications induced by cinnamaldehyde may be due to its interference with enzymatic reactions of cell wall synthesis, thus affecting the morphogenesis and growth of the fungus. These results further emphasized the toxicity of cinnamon oil against F. verticillioides attacking grains, and that cinnamon oil could be safely used as an alternative to chemical fungicides during grain storage and in the field.     

Degradation of fumonisin B1 by cinnamon essential oil

Fumonisins are group of mycotoxins produced mainly by Fusarium verticillioides and Fusarium proliferatum. They frequently contaminate corn and corn based products, and cause several diseases in humans and animals. Fumonisin B₁ (FB₁) is the most prevalent fumonisin and is highly toxic to human and animal. The essential oils from plants offer a hope in the prevention and detoxification of these mycotoxins. The present study investigates the degradation effect of cinnamon, citral, Litsea cubeba, clove, eucalyptus, anise, spearmint and camphor oils on FB₁. The degradation level of FB₁ was determined by ELISA. Cinnamon oil proves to be effective essential oil in reducing FB₁, followed by citral, eugenol oil, eucalyptus oil, anise oil and camphor oil. The effects of incubation time, and temperature with respect to the concentration of cinnamon oil on their degradation effect on FB₁ by cinnamon oil were investigated. Results showed that at 120 h time with the 280 μg/ml concentration of cinnamon oil, under 30 °C is optimal for FB₁ reduction. Under optimal condition, FB₁ was reduced from 15.03 to 0.89 μg/ml (94.06%). Cinnamon oil could be a promising candidate in the detoxification and control of FB₁ in corn based products.     

In vitro evaluation of antibacterial and antioxidant activities of the essential oil and methanol extract of endemic Zataria multiflora Boiss

The present study was conducted to evaluate in vitro antibacterial and antioxidant properties of essential oil and methanol extracts from a unique and endemic plant, Zataria multiflora Boiss. The antibacterial test results showed that the essential oil of the plant strongly inhibited the growth of all of the microorganisms studied especially the Gram-negative strains. The polar fraction of methanol extract has been effective against Gram-positive strains, while the non-polar fraction has shown activity similar to essential oil. The antioxidant potential of the samples was evaluated using two separate methods, inhibition of free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ammonium thiocyanate systems. Sub fractions of the methanol extract were able to reduce the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) with an IC₅₀ of 11.7 ± 1.58 and 16.2 ± 1.61 μg/ml, respectively for non-polar and polar ones, which the activity of the latter almost is equal to synthetic antioxidant BHA (18.2 ± 1.94 μg/ml). Inhibition values of linoleic oxidation were calculated to be 82.4% and 80.3% for the polar and non-polar fractions, respectively. The essential oil to be showed more inhibition (89.7 ± 2.5), similar to the synthetic antioxidants BHA (97.8 ± 2.94) and ascorbic acid (93.2 ± 2.1). The chemical composition of hydrodistilled essential oils of Z. multiflora was analyzed by GC/MS. A total of 25 compounds representing 99.78% of the oil were identified: thymol (37.59%), carvacrol (33.65%); para-cymene (7.72%), γ-terpinene (3.88%) and β-caryophyllene (2.06%) were the main components comprising 84.9% of the oil. Results here show that the essential oil and methanol extract of Z. multiflora possess antioxidant and antibacterial activity, and therefore it could be used as a natural preservative ingredient in food and/or pharmaceutical industries.     

Biological activities of Boswellia sacra extracts on the growth and aflatoxins secretion of two aflatoxigenic species of Aspergillus species

Aflatoxins are the most serious carcinogenic, hepatotoxic, teratogenic and mutagenic secondary metabolites which adversely affect human and animal health. This study was designed to evaluate the in vitro inhibitory effect of different concentrations of Boswellia sacra resin (2.5, 5, 7.5 and 10 g/100 ml), leaf extract (5, 7.5, 10, 12.5 and 15 ml/100 ml), and essential oil (1, 2, 3, and 4 ml/100 ml) on the growth and aflatoxins production by two species of Aspergilli, namely Aspergillus flavus (SQU21) and Aspergillus parasiticus (CBS921.7). Resin of B. sacra caused 57.9–92.1% inhibition of aflatoxin secretion by A. flavus and 43.6–95.7% for A. parasiticus. However, the mycelial dry weights were significantly increased by 20.9–52.7% for A. flavus, and 8.9–68.5% for A. parasiticus. The leaf extract of B. sacra apparently enhanced aflatoxins production by 20–50%, and mycelial dry weight by 25.5–29.1% for A. flavus and A. parasiticus. The essential oil of B. sacra at different concentrations similarly inhibited the fungal growth and aflatoxins production by 45.8–83.7% for A. flavus and 41.3–83.5% for A. parasiticus which indicates the antifungal activity of this oil. None of the B. sacra extracts detoxified pure aqueous aflatoxin B₁. We have concluded that B. sacra resin and essential oil possess biological activity against biochemical synthesis and metabolic pathway of aflatoxin production of the two Aspergillus species. Therefore, the resin and essential oil of B. sacra can be recommended as safe plant based bioreservatives to enhance shelf life of food and feed products with reference to adverse effect of physical and synthetic chemical preservatives and their antimicrobial and aflatoxins inhibition activity.     

Fungal and aflatoxin contamination of marketed spices

Fourteen spice samples were collected from local markets in Doha, Qatar, during 2012, and were surveyed for the presence of potentially harmful mycoflora and for contamination with aflatoxins B₁, B₂, G₁, and G₂ by high-performance liquid chromatography (HPLC). Among the tested spice samples, chili powder showed the highest presence of fungal propagules, while ginger, curry and garlic samples did not present any fungal contamination. A total of 120 isolates, mostly belonging to Aspergillus and Penicillium genera, were collected and 33 representative species were identified by amplification and sequencing of the internal transcribed spacer (ITS) region. Aspergillus flavus, Aspergillus nomius and Aspergillus niger were the most dominant. Thirty-seven Aspergillus strains were screened for their potential to produce aflatoxins using biochemical and molecular tools: only 9 A. flavus strains showed both fluorescence and amplification with all the three primers targeting aflP, aflM and aflR genes. Aflatoxins were detected in five spices (black pepper, chili, tandoori masala. turmeric and garam masala), and with the exception of garam masala, the tested samples of turmeric, black pepper, tandoori masala and chili powder exceeded B₁ and/or total aflatoxin maximum levels. Our results demonstrate the potential for mycotoxin biosynthesis by fungi contaminating imported spice products.     

Investigations on the essential oil of Lippia rugosa from Cameroon for its potential use as antifungal agent against Aspergillus flavus Link ex. Fries

Lippia rugosa essential oil was tested for its effectiveness against Aspergillus flavus on artificial growth media. The chemical composition of the oil was determined by gas chromatography–mass spectrometry (GC–MS). Geraniol (51.5%), nerol (18.6%) and geranial (10.4%) were the main components of Lippia oil. After 8 days of incubation on essential oil supplemented medium, mycelium growth of A. flavus was totally inhibited by 1000 mg l^?1 of L. rugosa essential oil. The effect of essential oil on aflatoxin B₁ synthesis was evaluated in SMKY broth. The medium supplemented with different essential oil concentrations, was inoculated with A. flavus mycelium and incubated at 25 °C. After 2, 4, 6 and 8 days, aflatoxin B₁ (AFB₁) was quantified in the supernatant using Enzyme Linked Immuno-Sorbent Assay (ELISA). Results showed that aflatoxin B₁ synthesis was inhibited by 1000 mg l^?1 of L. rugosa essential oil after 8 days of incubation. The effect of the EO on the H⁺-ATPase pumping membrane was also evaluated in the presence of several concentrations of oil (200–2000 mg l^?1) by monitoring glucose-induced acidification of the external medium. L. rugosa essential oil at the concentration of 2000 mg l^?1 completely inhibited the activity of this enzyme. These data suggest that the essential oil of L. rugosa is a fungicidal for A. flavus and its possible cellular target include the H⁺-ATPase.Results obtained in the present study indicate the possibility of exploiting Lippia rugosa essential oil in the fight against strains of A. flavus responsible for biodeterioration of stored foods products.     

Influence of emulsifier type on the antifungal activity of cinnamon leaf,lemon and bergamot oil nanoemulsions against Aspergillus niger

Only exiguous data are currently available on the antifungal properties of essential oil (EO) nanoemulsions against spore-forming microorganisms. The aim of this work is to develop physically stable nanoemulsion-based delivery systems for different EOs (cinnamon leaf, lemon, and bergamot), to exploit their antifungal properties against Aspergillus niger. The inhibition of mycelial radial growth and spore germination were used as indicators of antifungal activity of the nanoemulsions, which were prepared at 3 wt% EO, using non-ionic Tween 80 (T80) or anionic whey protein isolate (WPI) (1 wt%) as emulsifiers, and sunflower oil (1 wt%) as ripening inhibitor. The nanoemulsions were physically stable over seven days of accelerated aging at 35 °C.The minimal inhibitory concentration of free cinnamon leaf and of both citrus EOs were 0.35 and 5.50 μg/g, respectively. The encapsulation of cinnamon leaf EO in nanoemulsions significantly enhanced the inhibiting effect against A. niger mycelial growth and spore germination, with respect to the free EO. In contrast, for citrus EOs, the encapsulation in nanoemulsions generally decreased the antifungal activity, likely because of the nanoemulsion acting as a hydrophobic sink for the main constituents of citrus EOs. The emulsifier played a fundamental role in the resulting antifungal activity, with WPI-based nanoemulsions being more effective in inhibiting the mycelial growth and the spore germination of A. niger than T80-based ones. The antifungal action was correlated to the morphological alterations observed in A. niger, such as the loss of cytoplasm in fungal hyphae and hyphal tip. The results of this study show the importance of nanoemulsions design in the development of efficient and stable natural antifungal agents for food applications.     

Combined analytical and microbiological tools to study the effect on Aspergillus flavus of cinnamon essential oil contained in food packaging

Cinnamon essential oil has been used for centuries to protect food from microbiological infection, and in the last ten years cinnamon essential oil is also incorporated into food packaging materials as antimicrobial agent. However, very little is known about the real effect that it has on the microorganism cells. This study combines analytical and microbiological tools to elucidate cell damage produced on Aspergillus flavus. First, antifungal activity of cinnamon essential oil was evaluated at 10³,10⁴, 10⁵ and 10⁶ CFU/mL. Minimal Inhibitory Concentration (MIC) and Minimal Fungicidal Concentration (MFC) were determined by macrodilution in direct contact with the mold. A strong activity was obtained, with a MIC of 0.05–0.1 mg/mL, and a MFC of 0.05–0.2 mg/mL, both ranges depending on the initial fungal suspensions.Polyethylene terephthalate films containing cinnamon essential oil were tested in vapor phase, without direct contact with the mold. Active PET started showing activity at 2% CIN EO load and produced total inhibition at 4% CIN EO. SEM and FTIR were used to study the cell damage on the mold exposed to the cinnamon essential oil. Evident damage and a strong decrease in sporulation were found by SEM, while biochemical changes in conidia could be suggested from the FTIR spectra analysis. Two deposition techniques were used to prepare the samples for FTIR. The results obtained are shown and discussed.     

In vitro and in vivo activity of essential oil from dill (Anethum graveolens L.) against fungal spoilage of cherry tomatoes

The objectives of present study were to determine the antifungal activity in vitro of the essential oil extracted from the seeds of dill (Anethum graveolens L.) and to evaluate its antifungal activity in vivo as a potential food preservative. The antifungal activity of this oil was tested by poisoned food technique against Aspergillus flavus, Aspergillus oryzae, Aspergillus niger and Alternaria alternata. The wet and dry mycelium weight of the tested fungi was also determined in a liquid culture to evaluate the antifungal activity. The minimum inhibitory concentration of oil for the four tested fungi was found to be 2.0 μl/ml, and the mycelial growth inhibition was determined at day 9. Observations on the microstructure of A. niger using light and scanning electron microscopes revealed degenerative alterations in the conidial heads and hyphal morphology after oil treatment, including distorted conidial heads, decreased hyphal diameters, shriveled hyphal aggregates, and swelling of the hyphal wall. The effect of the essential oil on inhibition of decay development on cherry tomatoes was tested in vivo by exposing inoculated and control fruit to essential oil vapor at 120 μl/ml and 100 μl/ml concentrations, respectively. Thus, the essential oil of dill could be used to control food spoilage as a potential source of food preservative.     

Synergistic action between fractions of essential oils from Cymbopogon citratus, Ocimum gratissimum and Thymus vulgaris against Penicillium expansum

Penicillium expansum is a mould that causes the rotting of several fruits and vegetables, especially apples onto which it also synthesizes some dangerous mycotoxins. The degree of synergism between fractions of essential from Cymbopogon citratus, Ocimum gratissimum and Thymus vulgaris was evaluated against two mycotoxin producing strains of P. expansum. The antifungal activity determined by dilution method and expressed as a Number of Decimal Reduction of the colony forming units per ml (NDR cfu) showed that the essential oils extracted from O. gratissimum was significantly (P < 0.05) more active against P. expansum than those extracted from C. citratus and T. vulgaris. Fractions enriched with oxygenated terpenes were significantly (P < 0.05) more active than their respective essential oils, whereas most of the fractions enriched with terpene hydrocarbons, were significantly (P < 0.05) less active. The fungicidal activity of mixtures of fractions from the same essential oils or from two different essential oils showed that there exist synergistic, additive and antagonistic effects between fractions of the three essential oils tested against both fungal strains. The synergistic effects observed could be exploited in order to maximize the antimicrobial activity of essential oils and to minimize the concentrations of essential oil required to produce a given antimicrobial effect without any alteration of the food test.     

Essential oils to control Alternaria alternata in vitro and in vivo

The inhibitory effects of five essential oils (thyme, sage, nutmeg, eucaptus and cassia) against Alternaria alternata were tested at different concentrations (100–500 ppm) in vitro. The cassia oil and thyme oil both exhibited antifungal activity against A. alternata. The cassia oil inhibited completely the growth of A. alternata at 300–500 ppm. The thyme oil exhibited a lower degree of inhibition 62.0% at 500 ppm. Spore germination and germ tube elongation of the pathogens in potato dextrose broth was strongly inhibited in the presence of 500 ppm cassia oil. Irreversible inhibition of fungal growth could be caused by exposure to 300 ppm and 400 ppm cassia oil for 6 days and 500 ppm cassia oil for 3 days. Cassia oil at 500 ppm reduced the percentage of decayed tomatoes. The experiments on reducing natural decay development of tomatoes gave similar results. Therefore, essential oils could be an alternative to chemicals for control of postharvest phytopathogenic fungi on fruits or vegetables.     

Antifungal activities and effect of Lactobacillus casei AST18 on the mycelia morphology and ultrastructure of Penicillium chrysogenum

The antifungal effects of Lactobacillus casei AST18 on Penicillium chrysogenum. were investigated. Viable bacteria were used to detect the minimum inhibitory concentration of lactic acid bacteria (10² CFU/mL) to inhibit the growth of P. chrysogenum. Results showed that L. casei AST18 inhibited the growth of P. chrysogenum. The mycelial morphology was also altered. The scanning electron microscopy images of P. chrysogenum exposed to L. casei AST18 further showed that the mycelia were collapsed and appeared transparent. Numerous clots were also observed in the fungal cytoplasm. The tip of the hypha was deformed and exhibited a moniliform or inflated shape. The transmission electron microscopy images of L. casei AST18-exposed P. chrysogenum showed the occurrence of autophagy and death of fungal cells. Changes in the morphological characteristics of P. chrysogenum were observed in the antifungal activity experiment with viable bacteria, but such changes were not evident in the cell-free culture filtrate of L. casei AST18. This bacterial strain showed high antifungal activities and could be used as a fungal inhibitor in food and medicine.     

Chemical composition and in vitro antimicrobial,antifungal and antioxidant properties of essential oils obtained from some herbs widely used in Portugal

The aim of this study was determine (i) the chemical composition (ii) the antimicrobial activity (antibacterial and antifungal) and (iii) the antioxidant activity by means of four different antioxidant tests (DDPH, FIC, FRAP and TBARS) of the EOs of three aromatic herbs, Coriander (Coriandrum sativum), celery (Apium graveolens) and bush-basil (Ocimum minimum) widely used in Portugal.There is a great variability of the compounds presented in the three tested essential oils. Bush-basil EO had the highest total phenolic content (794.9 mg GAE/L) while coriander EO had the lower total phenolic content (52.3 mg GAE/L). Since bush-basil had the highest TPC it was expected to present a very high antioxidant profile, which was verified in 3 of the 4 assays (DPPH inhibition of 95.9%; FRAP values of 2.7 mmol Trolox/L; TBARS inhibition of 87.2%); coriander, despite the low TPC showed the highest inhibition in the FIC assay (94.1%).The bush-basil EO showed the highest antimicrobial activity, with MIC ranging between 0.6 and 5 μL/mL against bacteria and 0.04–2.5 μL/mL against yeasts. Both celery and coriander EO had a very similar antimicrobial activity against all the tested strains. The antifungal activity was higher in the bush-basil EO against Mucor racemosus and Penicillium chrysogenum since it was the only EO that showed growth inhibition on all the tested concentrations. Alternaria alternata showed great resistance against all the tested essential oils.     

Impact of Pediococcus pentosaceus strain L006 and its metabolites on fumonisin biosynthesis by Fusarium verticillioides

The aim of this work was to study the effectiveness of a Pediococcus pentosaceus strain L006, isolated from maize leaf and previously characterised for its high antifungal efficiency, on fumonisin biosynthesis by Fusarium verticillioides. Studies performed in GYEP medium supplemented with amylopectin showed a significant increase in fumonisin production when the F. verticillioides strain was simultaneously co-inoculated with the P. pentosaceus strain or inoculated in a three-day-old culture of this lactic acid bacteria. Our studies also demonstrated that some extracellular metabolites produced in MRS medium by the P. pentosaceus strain L006 were able to significantly reduce fumonisin production in liquid medium as well as on maize kernels. Fumonisin yields by F. verticillioides inoculated on autoclaved maize kernels were reduced by a factor ranging from 75% to 80% after 20 days of incubation. Our results illustrate the potential risk linked to the use of an antagonistic bacterial agent to manage fumonisin contamination, while emphasizing the potential use of bacterial metabolites to counteract fumonisin accumulation in kernels.     

Essential oils composition and bioactivities of two species leaves used as packaging materials in Xishuangbanna,China

This study reports the essential oils chemical composition and antioxidant and antimicrobial potentials of the leaves of Phrynium pubinerve Blume and Thysanolaena latifolia (Roxb. ex Hornem.) Honda, which are used as natural packaging materials by ethnic groups in Xishuangbanna, southwest China. GC–MS analysis identified 46 and 21 components, representing 88.6% and 93.4% of the essential oils of P. pubinerve and T. latifolia, respectively. The major constituents for P. pubinerve were (Z)-3-hexen-1-ol (17.31%), (E)-2-hexenal (9.01%) and 1-hexanol (8.61%). The major constituents for T. latifolia were (Z)-3-hexen-1-ol (28.79%), phytol (12.30) and (E)-β-ionone (9.54%). Both the essential oils and ethanol extracts showed antioxidant activity in DPPH test (IC₅₀ values = 192.47–706.07 μg/ml), ABTS assay (IC₅₀ values = 35.54–134.97 μg/ml) and FRAP assays. The essential oils showed considerable antimicrobial activity against pathogenic bacteria and spoilage organisms, with MIC and MBC values in the ranges of 64–3072 μg/ml and 64–4096 μg/ml, respectively. The bioactivities of these two plant species validate the traditional use of these two plants, suggesting that both could be new sources of natural antioxidant and antimicrobial agents for the packaging, medical and functional food industries.     

Radiosensitization of Aspergillus niger and Penicillium chrysogenum using basil essential oil and ionizing radiation for food decontamination

Stored products may be contaminated by pathogenic fungi such as Fusarium, Aspergillus and Penicillum. Fumigation with plant essential oil (EO) and irradiation treatment are options to control spoilage organisms. Basil essential oil and irradiation were tested alone and in combination for their antifungal effects in rice. Minimum Inhibitory Concentration (MIC) of basil EO was found to be 0.1% (v/v) against Aspergillus niger and Penicillium chrysogenum after 48 h. Radiosensitization of A. niger and P. chrysogenum in presence of 1% or 2% (v/v) basil EO was evaluated in vitro and in situ. At 1 and 2% of basil EO, the in vitro D₁₀ value was 0.43 and 0.31 kGy respectively for A. niger and 0.44 and 0.34 kGy respectively for P. chrysogenum. In inoculated rice, D₁₀ values for controls (sample without EO) were 0.67 and 0.63 kGy for A. niger and P. chrysogenum respectively, and the values were decreased at higher EO concentrations. For A. niger, a 2% (v/wt) basil EO alone caused a 0.42 to 1.18 log reduction on days 1 and 14 respectively, whereas treatment with 2 kGy radiation alone caused a 2.18 log reduction. The combined treatments resulted in a 4.6 log reduction of A. niger after 14 days of storage. For P. chrysogenum, 2% basil EO alone caused a 0.76 and a 1.12 log reduction on days 1 and 14 respectively, whereas a 2 kGy radiation dose caused a 2.41 log reduction. The combined treatments resulted in a 5.0 log reduction of P. chrysogenum after 14 days of storage. The findings demonstrated the potential of basil EO as antifungal agent and its efficacy to increase the radiosensitivity of A. niger and P. chrysogenum during irradiation treatment.     

Essential oils composition,antioxidant and antimicrobial activity of the leaves and flowers of Chaerophyllum macropodum Boiss

This study reports the essential oils chemical composition and in vitro antioxidant and antimicrobial potentials of the leaves and flowers of Chaerophyllum macropodum. GC and GC/MS analysis of the plant essential oils led to the identification of 49 components making 98.3–99.4% of its oils. The main constituents of the essential oils were trans-β-farnesene, trans-β-ocimene, β-pinene, limonene, spathulenol and myrcene constituting 49.6–73.1% of the oils. The extracts from the leaves and flowers showed moderate antioxidant activities in 1,1-diphenyl-2-picrylhydrazyl (DPPH) test (IC₅₀ values = 196.8 and 167.1 μg/ml respectively) and β-carotene/linoleic acid assay (inhibitions percentages = 69.9% and 62.7% respectively), but the essential oils were almost inactive in these tests. On the other hand, only the essential oils of the plant showed considerable antimicrobial activity against most of the tested microorganisms.     

Aflatoxin production by Aspergillus flavus in rumen liquor and its implications

Cow milk in infant and human nutrition is very significant. However, contamination of milk with aflatoxins is considered as a potential risk for human health. Aflatoxin is one of the major etiological factors in the development of hepatocellular carcinoma and is also found in the milk of lactating animals which could have consumed it through contaminated feedstuffs. Thus, exploration to isolate and identify the pathogenic microbe present in the rumen liquor were carried out. The screened fungal organism was identified as Aspergillus flavus by phenotypic (morphology and extrolite profiles) and molecular (β-tubulin gene sequences) characters. Fungal toxin was extracted using immuno-affinity column (IAC) and quantified by High Performance Liquid Chromatography (HPLC). The organism had potential to grow under aerobic and anaerobic conditions and also produce aflatoxin B_1. The aflatoxin B₁ production under aerobic condition was 0.902 ± 0.08 μg/ml culture broth and anaerobic condition was 0.925 ± 0.2 μg/ml culture broth. Aflatoxin B₂ was more compared to aflatoxin B₁ and the quantity was 14.472 ± 1 under aerobic condition and 1.467 ± 0.3 under anaerobic condition. The rumen liquor from which the isolation was carried out also showed the presence of aflatoxin B₁ (3.964 ± 0.5 μg/ml) and B₂ (1.170 ± 0.6 μg/ml). However, aflatoxin G₁ and G₂ were not present. Hence, the study suggests the ability of microbial ecosystem present inside the rumen to produce aflatoxin. This report on the aflatoxin production under aerobic and anaerobic conditions provides insights about the possibility of aflatoxin in cow milk thereby effecting human health. It is vital to reduce exposure of milking animals to contaminated moldy feed and take precautions to prevent fungal contaminations in the feed.     

Effect of Hibiscus sabdariffa extract and Nigella sativa oil on the growth and aflatoxin B1 production of Aspergillus flavus and Aspergillus parasiticus strains

This study was undertaken to evaluate the inhibitory effect of Hibiscus sabdariffa calyx extract at concentrations of 5, 7.5, 10 and 12.5 g/100 ml and Nigella sativa oil at concentrations of 1, 2 and 3 ml/100 ml on the growth and aflatoxin B₁ production by Aspergillus parasiticus (CBS 921.7) and Aspergillus flavus (SQU 21) strains. The inhibition of aflatoxin B₁ production by the different concentrations of H. sabdariffa calyx ranged between 91.5-97.9% and 87.1-93.3% for A. flavus and A. parasiticus strains, respectively, whereas the inhibition by different concentrations of N. sativa oil ranged between 47.9 and 58.3% for A. flavus and 32-48% for A. parasiticus strains. The different concentrations of H. sabdariffa calyx and N. sativa oil had no significant effect on the growth of either Aspergillus species. Neither H. sabdariffa calyx nor N. sativa oil detoxified pure aqueous aflatoxin. Our results suggest that H. sabdariffa calyx and N. sativa oil extracted from seeds had metabolic effects on aflatoxin biosynthesis pathway of both Aspergillus species and can be used as an effective biocontrol and non-toxic biopreservatives in food industry against aflatoxin contamination.