Amritesh C. Shukla

Use of essential oil as botanical-pesticide against post harvest spoilage in Malus pumilo fruit

During antifungal screening of the essentialoils of some angiospermic plants, oil ofCymbopogon flexuosus showed potentbioactivity against dominant post harvestfungal pathogens. The minimum bioactiveconcentrations with fungicidal action of theoil was found to be 0.2 µl ml−1 for Alternaria alternata, 0.4 µlml−1 for Aspergillus flavus, A.fumigatus, A. niger, A. parasiticus,Cladosporium cladosporioides, Colletotrichumcapsici, C. falcatum, Curvularia lunata,Fusarium cerealis, F. culmorum, F. oxysporum,F. udum, Gloeosporium fructigenum, Penicilliumexpansum, P. italicum, P. implicatum, P. digitatum,P. minio-luteum, P. variable,and 0.5 µl ml−1 forBotrytis cinerea, Helminthosporium oryzae, H.maydis, Phoma violacea, Rhizopus nigricans.The oil exhibited potency against heavy doses(30 mycelial disc, each of 5 mm in diameter) ofinoculum at 1.0 µl ml−1 concentrations.The bioactivity of the oil was thermostable upto 100°C and lasted up to 48 months.The oil preparation did not exhibit anyphytotoxic effect on the fruit skins ofMalus pumilo up to 50 µlml−1 concentrations. In vivo trials of theoil as a fungicidal spray on Malus pumilofor checking the rotting of fruits, it showedthat 20 µl ml−1 concentration controls100% infection by pre-inoculation treatment,while in post-inoculation treatment, 30 µlml−1 concentration of fungicidal spraywas required for the 100% control of rotting.The fungicidal spray was found to be costeffective (INR 15/l), has long shelf life (48month) and was devoid of any adverse effects.Therefore, it can be used as a potential sourceof sustainable eco-friendly botanicalpesticide, after successfulcompletion of wide range trials.

Broad spectrum herbal therapy against superficial fungal infections

Skin disease associated with keratinized tissues in animal and human beings has been investigated. The essential oil of Eucalyptus pauciflora in vitro showed strong antifungal activity at 1.0 μl/ml against human pathogenic fungi, viz. Epidermophyton floccosum, Microsporum audouinii, M. canis, M. gypseum, M. nanum, Trichophyton mentagrophytes, T. rubrum, T. tonsurans and T. violaceum. The oil has heavy doses of inoculum potential at 1.0 μl/ml. Moreover, it did not exhibit any adverse effects on mammalian skin up to 5% concentrations. Further, we formulated the oil in the form of ointment ‘BSHT’ (broad spectrum herbal therapy) (1% v/v) and subjected it to topical testing on patients attending the outpatient department of M.L.N. Medical College, Allahabad. Fifty patients were selected on the basis of KOH-positive results and diagnosed as either tinea pedis, tinea corporis or tinea cruris. After the second week of treatment, all patients were KOH-negative. At the end of medication, 60% of patients recovered completely and 40% showed significant improvement from the disease. No KOH-negative cases of relapse were observed when patients were re-examined after 2 months following the end of treatment. Thus, the ointment can be exploited commercially after undergoing successful multicenter clinical trials, which are in progress.

Modified Spore Germination Inhibition Technique for Evaluation of Candidate Fungitoxicant (Eucalyptus spp.)

The technique of spore germination inhibition has been modified by introducing the mathematical model for standardization of inoculum, reducing the cost as well as observation period thereby making the technique simple and no chance of contamination for the evaluation of candidate fungitoxicant(s). The present technique is compared with prevalent poisoned food technique and we found that quantitative results are almost the same. Amongst the candidate essential oils extracted from Eucalyptus citriodora, E. dalrympleana, E. laveopinea, E. pauciflora, only the oil of E. citriodora at 1000 mg/ml showed complete inhibition of spore germination of the storage spoilage test fungus Penicillium italicum. The oil of E. dalrympleana and E. laveopinea showed fungistatic toxicity against the test fungus at 3000 mg/ml but the oil of E. laveopinea showed partial inhibition at 3000 mg/ml. The oil of E. citriodora at 1000 mg/ml exhibited fungicidal nature and withstood heavy inoculum. Since the oil at sublethal concentration exhibited no abnormalities at morphological level, the total picture can be drawn only after undertaking the work on cytological and at enzymatic level against the test fungus.