Ravindra Shukla

Chemical profile, antifungal, antiaflatoxigenic and antioxidant activity of Citrus maxima Burm. and Citrus sinensis (L.) Osbeck essential oils and their cyclic monoterpene, dl-limonene

The study deals with antifungal, antiaflatoxigenic and antioxidant activity of Citrus maxima and Citrus sinensis essential oils (EOs) and their phytochemical composition. The EOs were obtained by hydrodistillation and their chemical profile was determined through GC and GC-MS analysis. Both the EOs and their 1:1 combination showed broad fungitoxic spectrum against different food contaminating moulds. The EOs and their combination completely inhibited aflatoxin B(1) (AFB(1)) production at 500 ppm, whereas, DL-limonene, the major component of EOs showed better antiaflatoxigenic efficacy even at 250 ppm. Both the oils exhibited antioxidant activity as DPPH free radical scavenger in dose dependent manner. The IC(50) for radical scavenging efficacy of C. maxima and C. sinensis oils were to be 8.84 and 9.45 microl ml(-1), respectively. The EOs were found non-mammalian toxic showing high LD(50) for mice (oral, acute). The oils may be recommended as safe plant based antimicrobials as well as antioxidants for enhancement of shelf life of food commodities by checking their fungal infestation, aflatoxin production as well as lipid peroxidation.

Chemical composition, antifungal and antiaflatoxigenic activities of Ocimum sanctum L. essential oil and its safety assessment as plant based antimicrobial

The study deals with the efficacy of Ocimum sanctum essential oil (EO) and its major component, eugenol against the fungi causing biodeterioration of food stuffs during storage. O. sanctum EO and eugenol were found efficacious in checking growth of Aspergillus flavus NKDHV8; and, their minimum inhibitory concentrations (MICs) were recorded as 0.3 and 0.2 microl ml(-1), respectively. The O. sanctum EO and eugenol also inhibited the aflatoxin B1 production completely at 0.2 and 0.1 microl ml(-1), respectively. Both of these were found superior over some prevalent synthetic antifungals and exhibited broad fungitoxic spectrum against 12 commonly occurring fungi. The LD50 value of O. sanctum EO on mice was found to be 4571.43 microl kg(-1) suggesting its non-mammalian toxic nature. The findings of present study reveals the possible exploitation of O. sanctum EO and eugenol as plant based safe preservatives against fungal spoilage of food stuffs during storage.

Efficacy of chemically characterized Piper betle L. essential oil against fungal and aflatoxin contamination of some edible commodities and its antioxidant activity.

The study investigates fungal contamination in some dry fruits, spices and areca nut and evaluation of the essential oil (EO) of Piper betle var. magahi for its antifungal, antiaflatoxigenic and antioxidant properties. A total of 1651 fungal isolates belonging to 14 species were isolated from the samples and Aspergillus was recorded as the dominant genus with 6 species. Eleven aflatoxin B(1) (AFB(1)) producing strains of A. flavus were recorded from the samples. Eugenol (63.39%) and acetyleugenol (14.05%) were the major components of 32 constituents identified from the Piper betle EO through GC and GC-MS analysis. The minimum inhibitory concentration (MIC) of P. betle EO was found 0.7 microl/ml against A.flavus. The EO reduced AFB(1) production in a dose dependent manner and completely inhibited at 0.6 microl/ml. This is the first report on efficacy of P. betle EO as aflatoxin suppressor. EO also exhibited strong antioxidant potential as its IC(50) value (3.6 microg/ml) was close to that of ascorbic acid (3.2 microg/ml) and lower than that of the synthetic antioxidants such as butylated hydroxytouene (BHT) (7.4 microg/ml) and butylated hydroxyanisole (BHA) (4.5 microg/ml). P. betle EO thus exhibited special merits possessing antifungal, aflatoxin suppressive and antioxidant characters which are desirable for an ideal preservative. Hence, its application as a plant based food additive in protection and enhancement of shelf life of edible commodities during storage and processing is strongly recommended in view of the toxicological implications by synthetic preservatives.

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.

The 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 Czapeks-dox agar. The EO (0.25-1 microL/mL) and its two constituents (1 microL/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 B(1) (AFB(1)) 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.

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.

Efficacy of essential oils of Lippia alba (Mill.) N.E. Brown and Callistemon lanceolatus (Sm.) Sweet and their major constituents on mortality, oviposition and feeding behaviour of pulse beetle, Callosobruchus chinensis L.

BACKGROUND Pulse beetle, Callosobruchus chinensis L., is the most destructive insect pest of pulses under storage in Asia and Africa. Keeping in view the negative impacts of synthetic insecticides and the demands of botanical pesticides, the present investigation explores the repellents, antifeedants, ovicidal, larvicidal and pupaecidal activity of two plant essential oils (EOs) and their major components, geranial and 1,8-cineole, when applied as fumigants for the management of the pulse beetle. RESULTS EO of Callistemon lanceolatus (Sm.) Sweet caused 100% repellency of pulse beetle in a Y-shaped olfactometer at a dose of 150 µL, while Lippia alba (Mill.) N.E. Brown EO and 1,8-cineole showed 76 and 74.7% repellency at the same dose. At 0.1 µL mL(-1) , both the oils and 1,8-cineole provided 100% insect mortality. The EO of C. lanceolatus was recorded as the most effective fumigant, showing 96.03% oviposition deterrency and 100% antifeedant activity at 0.1 µL mL(-1) . The LD(50) of L. alba (11049.2 µL kg(-1) ) and C. lanceolatus (14 626.3 µL kg(-1) ) exhibited their favourable safety profiles when recorded on mice. CONCLUSION EOs of L. alba and C. lanceolatus exhibited significant biological activity on the mortality and reproductive behaviour of pulse beetle. Based on their high LD(50) values, the oils could be safely recommended as non-mammalian toxic fumigants in management strategies for pulse beetle.

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.

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.