Chemical-biological study of Azadirachta indica A. Juss.

INTRODUCTION As part of a search for new bioactive metabolites from plants belonging to the Meliaceae family, Azadirachta indica A. Juss leaves a phytochemical study was carried out. A. indica is native to India, where the plant is variously known as “Sacred Tree,” “Heal All,” “Nature’s Drugstore,” “Village Pharmacy” and “Panacea for all diseases but it is cultivated widely in tropical and sub-tropical areas of the world. Branches, fruits and leaves of the Neem tree have been used as food, medicine, cosmetics and insecticides since ancient times. Many bioactive constituents including tetranortriterpenoids (limonoids) have been isolated and identified from Neem tree 1,2. A. indica, elaborates a vast array of bioactive compounds that exhibit potent medicinal properties: immunomodulatory, antiinflammatory, antimutagenic 3 . Recently, gedunin a tetranortriterpenoid isolated Azadirachta indica has been shown to have potential in vitro antineoplastic properties 4. METHODOLOGY A.indica leaves were defatted with n-hexane and successively extracted for 48 h, CHCl3, CHCl3-MeOH (9:1) and MeOH. The study of the extracts was carried out using different chromatographic techniques such as Sephadex LH-20, Silica gel, MPLC and reversed-phase HPLC. The study led to isolation of some pure compounds whose structures were elucidated by 1D- and 2D-NMR Spectroscopy (1 H, 13C, 13C DEPT, DQF-COSY, HSQC, HMBC, ROESY) and confirmed by mass spectrometry. RESULTS From chloroform extract were isolated six new compounds and the known terpenoids such as: deacetilsalannin 5, azadirachtol 6, azadirachtolide 7, gedunin 7, dehydronimonol 8, nimonol 8 and 1,3-diacetylvilasinin 9. On the basis of literature data, the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of A. indica extracts was studied. The studies were conducted using the dilution-in-broth method (Mueller Hinton) according to the Clinical Laboratory Standard Institute (CLSI, 2011). MIC was determined in the range of 0.012– 128 mg/mL All the extract were subjected to screening for antimicrobial activity. CHCl3:MeOH (9:1) extract of leaves of A.indica showed antibacterial activity against Gram-positive bacteria (S. aureus 29213, E. faecalis 904 and S. aureus 906 with a MIC 0.25 mg/mL, and Gram-negative bacteria (E. coli 25922, S. Heidelberg 175, K. pneumoniae 128, E. coli 913 with a MIC 0.5 mg/mL