2009
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PublicationArticle Efficacy of Lippia alba (Mill.) N.E. Brown essential oil and its monoterpene aldehyde constituents against fungi isolated from some edible legume seeds and aflatoxin B1 production(2009) Ravindra Shukla; Ashok Kumar; Priyanka Singh; Nawal Kishore DubeyThe present study deals with evaluation of antifungal properties of Lippia alba essential oil (EO) and two of its monoterpene aldehyde constituents against legume-contaminating fungi. Seventeen different fungal species were isolated from 11 varieties of legumes, and aflatoxigenic isolates of Aspergillus flavus were identified. Hydrodistillation method was used to extract the EO from fresh leaves. The GC and GC-MS analysis of EO revealed the monoterpene aldehydes viz. geranial (22.2%) and neral (14.2%) as the major components. The antifungal activity of EO, geranial and neral was evaluated by contact assay on Czapek's-dox agar. The EO (0.25-1 μL/mL) and its two constituents (1 μL/mL) showed remarkable antifungal effects against all the fungal isolates (growth inhibition range 32.1-100%). Their minimal inhibitory (MIC) and fungicidal (MFC) concentrations for A. flavus were lower than those of the systemic fungicide Bavistin. Aflatoxin B1 (AFB1) production by three isolates of A. flavus was strongly inhibited even at the lower fungistatic concentration of EO and its constituents. There was no adverse effect of treatments on seed germination, and rather, there was enhanced seedling growth in the EO-treated seeds. It is concluded that L. alba EO and two of its constituents could be safely used as effective preservative for food legumes against fungal infections and mycotoxins. © 2009 Elsevier B.V. All rights reserved.PublicationArticle Use of essential oil from Mentha arvensis L. to control storage moulds and insects in stored chickpea(2009) Ashok Kumar; Ravindra Shukla; Priyanka Singh; Amit K. Singh; Nawal K. DubeyBackground: Fungal contamination and Callosobruchus infestation results in qualitative and quantitative losses of chickpea seeds during storage. Most of the synthetic chemicals used as preservatives have adverse effects. Therefore, the antifungal and insecticidal potential of Mentha arvensis essential oil was evaluated to determine whether this could be an eco-friendly substitute of synthetic preservatives. Results: The stored chickpea seeds were dominated by Aspergillus flavus (46.1%) and 30% isolates among them were found toxigenic. The MIC of Mentha oil against A. flavus was recorded at 400 μL L-1 and it exhibited broad fungitoxic activity against 14 storage fungi. The oil was found superior to some prevalent synthetic fungicides. Mentha oil showed potent insecticidal activity against Callosobruchus chinensis at different concentrations and exposure times. The oviposition by C. chinensis was completely checked at 10 μL L-1 while F-1 emergence was completely inhibited at 200 μL L-1. During in situ experiments,94.05% protection of the chickpea from C.chinensis by Mentha oil showed superiority over the organophosphate insecticide malathion, where 90.75% protection was recorded. Conclusion: The Mentha EO showing potent fungitoxic and insecticidal efficacy and may be recommended as a plant-based preservative in the management of fungal and insect infestation of chickpea and other pulses during storage. © 2009 Society of Chemical Industry.PublicationArticle Evaluation of changes in oil cells and composition of essential oil in lemongrass (Cymbopogon citratus (D.C.) Stapf.) due to supplemental ultraviolet-B irradiation(2009) Rima Kumari; S.B. Agrawal; Abhijit SarkarField grown lemongrass (Cymbopogon citratus (D.C.) Stapf.) was exposed for a short duration (3 h/day) to supplemental ultraviolet-B (sUV-B) to evaluate its effect on oil cells and chemical composition of essential oils. Histochemical studies showed an increase in number of oil cells in tissues under sUV-B treatment. Estimation of essential oil content also demonstrated an increase of 25.7% in sUV-B treated plants over its control. Gas chromatography-mass spectrometric (GC/MS) analysis of essential oils demonstrated significant variations in qualitative and quantitative expression of oil constituents of sUV-B exposed plants. sUV-B irradiation induced the formation of major compound z-citral within the investigated oil samples by 117.56% as compared to oil obtained from nonirradiated plants. Geraniol formate, pulegol, linalyl formate and other compounds also showed significant variations after sUV-B treatment. Results suggest that sUV-B exposure stimulated the production of oil cells vis-à-vis positive change in quality and percentage of essential oil contents of lemongrass. The results suggest some future prospects for better economical utilization of lemongrass after irradiation with low doses of sUV-B for its commercial exploitation.PublicationArticle Efficacy of Artabotrys odoratissimus oil as a plant based antimicrobial against storage fungi and aflatoxin B1 secretion(2009) Bhawana Srivastava; Priyanka Singh; Anjil Kumar Srivastava; Ravindra Shukla; Nawal Kishore DubeyThe essential oil of Artabotrys odoratissimus R.Br. was evaluated for antifungal activity against some storage fungi causing contamination of food stuffs. Minimum inhibitory concentration of the oil was found to be 750 μL L-1 against Aspergillus flavus Link. It was found superior over different prevalent synthetic fungicides which inhibited the growth of A. flavus between 1000-5000 μL L-1. The oil exhibited broad fungitoxic spectrum against fourteen different storage fungi. Aspergillus fumigatus was inhibited at 1000 μL L-1 whereas Cladosporium cladosporioides, Curvularia lunata, Fusarium oxysporum, Helminthosporium oryzae, Macrophomina phaseolina, Microsporum gypseum, Mucor racemosus, Penicillium italicum, Pythium debaryanum, Rhizoctonia solani, Sclerotium rolfsii and Trichoderma viride at 500 μL L-1. Aspergillus niger was found to be inhibited only 84.9% at 1000 μL L-1. In addition, the oil showed significant efficacy in arresting aflatoxin B1 secretion by the toxigenic strain (Navjot 4NSt) of A. flavus at 750 μL L-1. The efficacy of A. odoratissimus oil as aflatoxin suppressor is being reported for the first time. © 2009 Institute of Food Science and Technology.PublicationArticle Supplemental ultraviolet-B induced changes in essential oil composition and total phenolics of Acorus calamus L. (sweet flag)(2009) Rima Kumari; S.B. Agrawal; Suruchi Singh; N.K. DubeyThe effect of supplemental UV-B radiation (sUV-B) was evaluated on the essential oil contents of sweet flag (Acorus calamus L.), a medicinal plant grown under natural field conditions. After the emergence of two leaves, plants were exposed to sUV-B radiation of 1.8 kJ m-2 above the ambient level of UV-B. The level of essential oil and phenol contents increased with exposure to sUV-B. Exposure of sUV-B resulted in significant increase in p-cymene and carvacrol contents of essential oil. Decrease in the level of major component beta-asarone due to sUV-B treatment is of prime importance, because of its toxicological concern to human health. © 2009 Elsevier Inc. All rights reserved.