Antimicrobial activities of Azadirachta indica Juss leaves extracts and fractions on selected wood fungi and bacteria

Abstract

Antimicrobial activities of A. indica leaves extracts and fractions on selected wood fungi and bacteria was investigated. Fresh neem leaves were collected washed, air-dried at 37°C for 2 weeks, and finely powdered. Extracts were prepared using2g of leave powder to 1800 ml of solvent for 24-72 hours. Column chromatography was performed on the extracts. Fractions were collected, dried, and analyzed by TLC and NMR. Antimicrobial activity of the methanol extracts and fractions was tested against wood using media.Nonacosane was characterized from AIE12; palmitic acid from AIE26 and Tridecanoic acid from AIE60 fractions. The antibacterial activity of the fractions showed inhibition zones (ZoI) of 22-26 mm against Bacillus Subtilis, 20-26 mm against Pseudomonas aeruginosa, 25 -30 mm against Serratia marcescens, 23-27 mm against Enterobacter sp, 24-29 mm against Rhanella sp, and 23-30 mm against Pectobacterium carotovorum, Sparfloxacin showed ZoI values of 27-31 mm. Also, fractions exhibited antifungal activity with ZoI values from 26 mm (AIE-54 against Fibroporia vaillantii and Rhizopus sp.) to 29 mm (AIE-52 against Fomitopsis pinicola and AIE-54 against Fusarium sp.), and MIC values of 50-100 mg/mL and MFC values from 100-200 mg/mL. A. indica methanol extract showed fungicidal activity with ZoI values from 19 - 22 mm against Serpula lacryman, Coniophora puteana, Aspergillus flavu, Fibroporia vaillantii, Rhizopus sp., Tricoderma sp and Fusarium sp. and MIC of 2.5-5 mg/mL and MFC of 10 mg/mL against fungi. These results suggest that A. indica leaves have potential as natural antimicrobial agents against a range of bacteria and fungi.