Antimicrobial effect of crude extracts of fresh and dry leaves of Datura metel L.

Abstract

Datura metel, is native of southern China is commonly called horn of plenty, devil’s trumpet, angel’s trumpet or thornapple. It is shrubby, sprawling, short-lived, tender perennial. The aim of this work is to investigate antimicrobial activities of different crude extracts from dry and fresh leaves of Datura metel. Different organic solvents including methanol, chloroform, hexane, ethyl acetate and butanol were used to prepare the crude extract from the fresh and dry leaves. Antimicrobial activities of different crude extracts from dry and fresh leaves of Datura metel were determined by DPPH method and agar agar diffusion method with minor modification. In vitro phytochemical screening for all the crude extract from both dry and fresh leaves was tested and found positive results for alkaloid, flavonoid, saponin and tannin compound. However, all the crude extract did not show positive result for steroids and triterpenoid compounds. The antioxidant activity results of both fresh and dry crude extracts show that when gradually increasing the samples concentration, there was an increase in the absorbance. Late leaf spot (LLS) (causal agent Phaeoisariopsis personata) and rust (causal agent Puccinia arachidis) are economically important foliar diseases of groundnut and have global significance. Aqueous leaf extract of Datura metel known for high antifungal activity against P. personata completely inhibited the germination of uredospores. Extracts of Datura metel (25g/L) applied as a prophylactic spray reduce the frequency of LLS lesions and rust pustules by 65-74%. In field studies, a programme of four sprays of D. metel leaf extract at 45, 60, 75 and 90 days after showing (DAS) was partially effective against the foliar diseases (LLS and rust) upto 95 DAS. The increase in pod yield by this treatment was comparable with the sustained application of chlorothalonil. Further validation of integrated applications of D. metel extract and chlorothalonil may reduce the dependency on fungicides in groundnut cultivation.