Antifungal activity and chemical composition of neem seed extract (Azadirachta indica A.)

Abstract

The antifungal activities and chemical composition of neem seed extract (Azadirachta indica) were investigated. An agar diffusion assay showed that neem seed extract (optimum concentration: 10%) inhibited the growth of Trametes versicolor and Gloeophyllum trabeum. The minimum inhibitory concentration and minimum fungicidal concentration were 2% and 4%, respectively, against the two fungal species. Scanning electron microscopy revealed severe morphological damage to fungal hyphae, including reduction of spores and hyphal shriveling. Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry analyses identified 17 compounds that represented 80.3% of the total extract, including astaxanthin (34.3%), cinobufagin (16.9%), anodendro-side A (6.65%), 16-acetoxy-4,8,14-trimethyl-3,11-dioxo-, methyl ester (5.09%). Furthermore, T. versicolor-infected wood and G. trabeum-infected wood treated with 10% neem seed extract displayed mass decreases of 11.4 ± 5.8% and 25.8 ± 7.5%, respectively, compared with distilled water treatment (21.6 ± 4.2% and 46.9 ± 4.3%, respectively). These findings suggest the potential use of neem seed extract for antifungal wood protection.