Indian Journal of Natural Products and Resources Vol. 3(3), September 2012, pp. 395-406 Substrate suitability of neem seed kernel for the growth and elaboration of aflatoxins by Aspergillus parasiticus (NRRL 2999) Kosuri Tanuja, Godugu Kavitha, Rupula Karuna and R B Sashidhar* Department of Biochemistry, University College of Science Osmania University, Hyderabad-500 007, Andhra Pradesh, India Received 18 July 2011; Accepted 4 July 2012 Neem seed kernels artificially infested with Aspergillus parasiticus (NRRL 2999) was evaluated for aflatoxin elaboration and fungal growth, and compared with groundnut, a high risk commodity for aflatoxin contamination. At optimal moisture content (10-12%) the total, individual toxins (AFB 1 , AFB 2 , AFG 1 and AFG 2 ) and ergosterol content increased and showed maximum levels on day 9. Crude protein and polyphenols increased while, fat and total sugar content decreased during the period of infection. The protein content correlated positively (r = 0.734) with total toxin levels, whereas fat content (r = -0.761) and total sugars (r = -0.891) showed negative correlation and they were all statistically significant (p<0.01). The polyphenols showed negative and non-significant correlation with total toxin levels. Azadirachtin one of the major active principles of neem seed kernel showed significant decrease on day 3 ( P<0.05) and day 6 (P<0.01). Neem seed kernel has shown 54 and 74% less aflatoxin production on day 9 and 12, respectively in comparison to groundnut seeds. Ergosterol content also showed 60% decrease on day 9, conferring it a poor substrate for fungal growth and aflatoxin elaboration. Keywords: Aflatoxin, Aspergillus parasiticus, Azadirachtin, Neem seed kernel, Polyphenols, Proximate composition. IPC code; Int. cl. (2011.01)  A61K 36/58, A61K 131/00, A61P 31/10 Introduction Aflatoxins are a group of highly toxic, mutagenic and carcinogenic polyketide compounds 1 synthesized by the fungi Aspergillus flavus, A. parasiticus and A. nominus 2 . These fungi grow rapidly on a variety of natural substrates 3 and consumption of food products contaminated with toxigenic fungi causes serious health hazards to human and animals. Aflatoxins are also well known for their hepatotoxico-carcinogenic effects 4 . Neem (Azadirachta indica A. Juss.) a tree belonging to Meliaceae family is familiar in India as one of the most versatile medicinal plants having a wide spectrum of biological activities. It has been extensively used in Ayurveda, Unani and Homoeopathy and the tree is still regarded as ‘village dispensary’ in India. It is known for its pesticidal activity against more than 400 insect pests 5 and has many pharmacological activities, such as anti- inflammatory 6 , anti-malarial, anti-fertility, anti-acne 7 , ascaricidal 8 and nematicidal 9 . Further, several studies have shown the antimicrobial activity of neem 10-12 . The extracts from different parts of neem tree have shown antifungal activity 13-16 . In a recent review by Reddy et al 3 on the control of mycotoxigenic fungi by different plant derived products, neem materials (leaves, seed /kernel and oil) were proposed to be the most economical option that showed fungal growth but inhibited mycotoxin production. Earlier studies have shown significant antifungal effects of neem leaf and seed extracts on aflatoxin-producing fungal strains 17-21 . Aflatoxin inhibition activity of neem leaf and seed extracts has been associated with morphological alterations in the mycelia of the aflatoxigenic fungus 22 . Among different parts of the tree, neem seed kernel is the most active part, which has the maximum number of bioactive terpenoids 23 such as nimbidin and gedunin with proven antifungal activity 24-25 . Extracts from neem seed kernel were reported to be effective against few human pathogenic fungi 26 . The moisture content required for growth and aflatoxin contamination varies with the natural substrates. A moisture content of 10-12% in groundnuts, 17-19% in wheat, corn and sorghum grains was found to be optimum 27 . Variation among different sorghum genotypes stored in traditional containers in India with respect to percent mycotoxin contamination was observed by Sashidhar et al 28 . —————— *Correspondent author: E-mail: sashi_rao@yahoo.com; Tel / FAX #: 091 040 27097044