N. K. Dubey

Safety assessment of Zanthoxylum alatum Roxb. essential oil, its antifungal, antiaflatoxin, antioxidant activity and efficacy as antimicrobial in preservation of Piper nigrum L. fruits

The investigation deals with antifungal, antiaflatoxin and antioxidant efficacy of Zanthoxylum alatum Roxb. essential oil (EO), its two major constituents and their comparison with five commonly used organic acid preservatives. The chemical profile of EO, characterized through GC and GC-MS analysis, revealed linalool (56.10%) and methyl cinnamate (19.73%) as major components. The EO, linalool and methyl cinnamate completely inhibited the growth of a toxigenic strain of A. flavus (LHP-10) as well as aflatoxin B(1) secretion at different concentrations. Methyl cinnamate was found to be more efficacious than EO, linalool and five organic acid preservatives, showing antifungal and antiaflatoxigenic efficacy at a low concentration (0.6 μl/ml) and the nature of its toxicity was fungicidal. However, EO showed strong antioxidant activity with an IC(50) value at 5.6 μl/ml. Moreover, EO was found to have negligible mammalian toxicity as its LD(50) value, determined through oral administration on mice, was calculated to be 6124μl/kg body weight during safety profile assessment. During in vivo investigation on fruit systems, the Zanthoxylum EO, when tested as fumigant, provided 66.27% and 86.33% protection respectively at 1.25 μl/ml and 2.5 μl/ml against fungi infesting Piper nigrum L. fruits demonstrating its practical efficacy as a plant based antimicrobial for post harvest application.

In vitro and in vivo antifungal activity of essential oils of Cymbopogon martini and Chenopodium ambrosioides and their synergism against dermatophytes.

The present study was carried out to evaluate the antifungal efficacy of essential oils (EO) of Cymbopogon martini, Chenopodium ambrosioides and of their combination against dermatophytes and some filamentous fungi in vitro as well as in vivo using a guinea pig model. The minimum inhibitory concentrations of EOs and of their combination were found between 150 and 500 ppm, while those of known antifungal drugs ranged from 1000 to 5500 ppm. EO ointments were prepared and applied against induced ringworm in guinea pig model and disease removal was observed in 7–21 days, and the hair samples showed negative results for fungal culture in a time‐dependent manner after the application of EO ointments. Chemical constituents of EOs were determined by GC–MS. Both the EOs and their combination displayed strong antifungal effects. The results provide a scientific validation for the use of these EOs in the treatment of dermatophyte infections and may be recommended as an alternative to synthetic drug for topical application.

Exploitation of Natural Compounds in Eco-Friendly Management of Plant Pests

The intensive use of synthetic pesticides and their environmental and toxicological risks have generated increased global interest to develop alternative sources of chemicals to be used in safe management of plant pests. Recently, in different parts of the world, attention has been paid towards exploitation of higher plant products as novel chemotherapeutics for plant protection because they are mostly non phytotoxic and easily biodegradable. Currently, different plant products have been formulated for large scale application as botanical pesticides in eco-friendly management of plant pests and are being used as alternatives to synthetic pesticides in crop protection. These products have low mammalian toxicity and are cost effective. Such products of higher plant origin may be exploited as eco-chemical and biorational approach in integrated plant protection programmes. The current status and future prospects of botanical pesticides in eco-friendly management of different plant pests are reviewed and discussed.

Chemically characterized Cymbopogon martinii (Roxb.) Wats. essential oil for shelf life enhancer of herbal raw materials based on antifungal, antiaflatoxigenic, antioxidant activity, and favorable safety profile

The study reports antifungal and antiaflatoxigenic efficacy of chemically characterized Cymbopogon martinii essential oil (CMEO) against aflatoxigenic Aspergillus flavus causing infestation to stored herbal raw materials. In addition, the antioxidant activity and safety profile of CMEO were also assessed to recommend it as ideal preservative for stored herbal raw materials. The GC–MS of CMEO showed nerol as the major component (79.91%). CMEO inhibited growth and aflatoxin secretion of A. flavus LHPA9 at 0.5 and 0.4 μl/ml respectively, showing better efficacy over synthetic antimicrobial Propineb 70. It also exhibited broad fungitoxic spectrum against fungi causing postharvest deterioration of herbal raw materials. The TEM analysis of CMEO-treated fungal cells showed disruption of plasma-membrane and deformed cell organelles. The EO also caused inhibition of ergosterol content emphasizing plasma membrane as active site during antimicrobial action. CMEO also exhibited pronounced antioxidant activity (IC50 = 49 μl/ml) better than nerol, the major component of CMEO. The LD50 of CMEO, determined through oral administration on mice, was calculated as 2569.16 mg/kg body weight indicating its favorable safety profile as preservative. CMEO may thus be recommended as postharvest preservative in enhancement of shelf life of herbal raw materials against storage fungi, mycotoxins, and oxidative deterioration.

Assessment of chemically characterised Abelmoschus moschatus Medik. seed essential oil as shelf life enhancer of herbal raw materials based on antifungal, antiaflatoxigenic and antioxidant efficacy

Abstract The study reports fungal biodeterioration of herbal raw materials of Adhatoda vasica Nees and Withania somnifera Dunal and assessment of Abelmoschus moschatus Medik seed essential oil (AMEO) as antifungal, antiaflatoxigenic, and antioxidant. Seven fungal species belonging to three genera were isolated from Adhatoda vasica leaves and Withania somnifera roots. The minimum inhibitory, fungicidal, and aflatoxin inhibitory concentrations of AMEO were found to be 1750, 5000, and 1250 ppm, respectively, against A. flavus LHP-WS-1, isolated from W. somnifera. The effect of AMEO over ergosterol content in the plasma membrane was assessed to test the mode of action on A. flavus. AMEO also exhibited broad fungitoxicity at its minimum inhibitory concentration (MIC) and strong antioxidant property through 2,2-diphenyl-1-picrylhydrazyl (DPPH) analysis having IC50 value equal to 0.325 μL/mL. In view of strong antifungal, antiaflatoxigenic, and antioxidant activity, the AMEO may be recommended as botanical preservative for herbal raw materials in order to enhance their shelf life and to maintain their quality.

A new NBS/oxone promoted one pot cascade synthesis of 2-aminobenzimidazoles/2-aminobenzoxazoles: a facile approach

A new strategy for the synthesis of 2-aminobenzimidazoles via a reaction of α-halogenated cyclohexanone with guanidine is reported. It provides a facile N-bromosuccinimide (NBS) mediated transition metal free, sustainable path for the synthesis of 2-substituted azoles. NBS along with the oxone promotes in situ halogenation of cyclohexanone, which in turn, when allowed to react with guanidine, afforded 2-aminobenzimidazoles (2-ABI). This eco-friendly protocol provides a competent laboratory synthesis method associated with significant advantages such as greater selectivity, cost-efficiency, mild reaction conditions, absence of chromatographic purification, clean reaction profile, and a simple work-up procedure to furnish high yields. The structures of all the synthesized compounds were confirmed on the basis of IR, 1H and 13C NMR, mass spectrometry, and elemental analyses data. In addition, we have also extended the scope of this strategy for obtaining 2-amino substituted benzoxazoles.

Efficacy of Essential Oil of Amomum subulatum as a Novel Aflatoxin B1 Suppressor

ABSTRACT Essential oils from different parts of 12 plants belonging to eight angiospermic families were extracted and tested for activity against two toxigenic strains of Aspergillus flavus link. through the poisoned food technique. The oil of the spice plant Amomum subulatum Roxb. (Fam. Zingiberaceae) was found effective against two strains of A. flavus, completely inhibiting their mycelial growth at 750 μg mL−1. This level of activity was superior to that of the synthetic fungicides tested. In addition, the oil exhibited a broad fungitoxic spectrum against all the tested fungi (A. niger, A. fumigatus, A. terreus, Alternaria alternata, Cladosporium herbarum, Curvularia lunata, Fusarium oxysporum, Helminthosporium oryzae, and Trichoderma viride), significantly inhibiting their growth at 750 μg mL−1. The essential oil displayed excellent antiaflatoxigenic efficacy, completely inhibiting aflatoxin B1 production at 500 μg mL−1. Hence, A. subulatum oil may be recommended as a novel, botanical antimicrobial and aflatoxin suppressor as an alternative to synthetic preservatives.

Clay-Supported Cu(II) Catalyst: An Efficient, Heterogeneous, and Recyclable Catalyst for Synthesis of 1,4-Disubstituted 1,2,3-Triazoles from Alloxan-Derived Terminal Alkyne and Substituted Azides Using Click Chemistry

Abstract A novel series of alloxan-derived 1,4-disubstituted 1,2,3-triazoles was synthesized in excellent yields under catalytic conditions using a click reaction strategy through 1,3-dipolar cycloaddition. Their structures have been ascertained on the basis of spectroanalytical and elemental analysis data. Synthesis of hybrid compounds with varying substitutions in the triazole ring was achieved by reaction between alloxan-derived terminal alkyne and a pertinent azide derivative in the presence of clay-Cu(II) as the catalyst in methanolic medium. Also, comparative evaluation of various catalytic systems [viz., CuI, CuSO4, CuI-zeolite, K10Ti, and clay-Cu(II)] was investigated. Of these catalytic systems, clay-Cu(II) was observed to be the best. The catalyst was recyclable for several runs without showing significant loss in its activity. The good selectivity, cost-efficiency, short reaction time, milder reaction conditions, and simple workup procedure are the added salient features of this synthetic protocol. GRAPHICAL ABSTRACT

Green Chemistry in Agricultural Pest Management Programmes

The article deals with recommendation of plant products as eco-friendly alternative of syntheticpesticides in agricultural pest management programme and emphasizes plant based green pesticides as important component in achieving ever green revolution in view of their high efficacy and favourable safety profile.

Assessment of Essential Oil of Acorus calamus L. and its Major Constituent β-Asarone in Post Harvest Management of Callosobruchus chinensis L.

Abstract Acorus calamus essential oil (EO) and its major constituent β-asarone were subjected to insect repellant, mortality, oviposition deterrent and antifeedant efficacy on Callosobruchus chinensis L. The EO showed greater efficacy against all the test parameters than the β-asarone. The repellency experiments were carried out in a glass Y- shaped olfactometer having 60 ml aerial volume At 150 μl, the EO showed 97.3% repellency of C. chinensis while it was only 74.7% in case of β-asarone. The EO caused 100% mortality of C. chinensis at 0.05 μl/ml after 24 h exposure, while β-asarone could exhibit only up to 46.5%. In addition, the EO was found more efficacious in terms of oviposition, ovicidal, larvicidal and pupaecidal activity than the β- asarone. The fumigant activity of A. calamus EO and β-asarone against adults of C. chinensis was determined through impregnated paper assay in plastic jars of 500 ml capacity .At 0.15 μl/ml EO caused 100% antifeedant activity, thereby, completely protecting the chickpea seeds from insect damage and weight loss. EO also exhibited non phytotoxic nature on treated chickpea seed germination. The findings recommend A. calamus essential oil as a safe alternative of synthetic insecticides and as suitable candidate for pest management strategy against losses of food commodities caused by C. chinensis.