Archna Rani

Isolation, characterization and antifungal activity of major constituents of the Himalayan lichen Parmelia reticulata Tayl.

Antifungal activity of hexane, ethyl acetate and methanol extracts of Parmelia reticulata was evaluated against soilborne pathogenic fungi, namely, Sclerotium rolfsii, Rhizoctonia solani, R. bataticola, Fusarium udum, Pythium aphanidermatum and P. debaryanum by poisoned food technique. Maximum antifungal activity was exhibited by hexane and ethyl acetate extracts against most of the test pathogens. Secondary metabolites, namely, (±)-isousnic acid, (±)-protolichesterinic acid, atranorin, evernyl, ethyl hematommate, ethyl orsellinate, methyl hematommate (3-formyl-2,4-dihydroxy-6-methylbenzoic acid methyl ester), 2-hydroxy-4-methoxy-3,6-dimethylbenzoic acid, 1-hydroxy-3,6-dimethoxy-8-methyl-xanthen-9-one, baeomycesic acid and salazinic acid, were isolated from the above extracts and identified by 1H NMR, 13C NMR and mass spectroscopic methods. When these metabolites were tested for antifungal activity against test pathogens, maximum antifungal activity was exhibited by (±)-protolichesterinic acid against R. solani (ED50=23.09 μg mL(-1)) and P. debaryanum (ED50=16.07 μg mL(-1)) and by atranorin against S. rolfsii (ED50=39.70 μg mL(-1)). The antifungal activity of protolichesterinic acid was found to be comparable to that of hexaconazole, a commercial fungicide.

Antifungal activity of extracts of the lichens Parmelia reticulata, Ramalina roesleri, Usnea longissima and Stereocaulon himalayense

Antifungal activity of the hexane, dichloromethane, ethyl acetate, methanol and aqueous extracts of the lichens namely, Parmelia reticulata, Ramalina roesleri, Usnea longissima and Stereocaulon himalayense were evaluated against nine soil-borne pathogenic fungi namely Rhizoctonia bataticola, Sclerotium rolfsii, Alternaria alternata, Pythium debaryanum, Fusarium oxysporum, Rhizoctonia solani, Botrytis cinerea, Sclerotina sclerotium and Pythium aphanidermatum by food poison technique. ED50 (Effective dose for 50% of inhibition) was calculated using Probit analysis. Hexane and dichloromethane extracts from all the four lichen species were found most active against the test fungi while aqueous extract was found to be least effective against all the test pathogenic fungi. The highest inhibition was recorded with hexane extracts of P. reticulata, R. roesleri, U.longissima and S. himalayense against R. bataticola with ED50 25.1, 24.50, 18.91 and 51.36 μg ml−1, respectively.

Synthesis, Characterization, and Formation Mechanism of Nanoparticles and Rods of 1,5-Bis(2-Halophenyl)Penta-1,4-Dien-3-One

Synthesis, Characterization, and Formation Mechanism of Nanoparticles and Rods of 1,5-Bis(2-Halophenyl)Penta-1,4-Dien-3-One For the first time nano sized particles of 1,5-bis(2-bromophenyl) penta-1,4-dien-3-one (I) and 1,5-bis(2-flourophenyl)penta-1,4- dien-3-one(II) were synthesised by facile reverse microemulsion route. Amazingly, I & II possessed spherical morphology and fibrous morphology respectively, as revealed by FTIR, FE-SEM with EDAX, HR-TEM with SAED. The detailed mechanism has been discussed.