Phytochemical investigation of seeds of Azadirachta indica and its evaluation for antimicrobial activities

Abstract

Natural products isolated from plants have been providing noble and clinically active drugs. The traditional medicinal system continues to play an essential role in health care, with about 80% of the world’s inhabitants relying mainly on traditional medicines for their primary health care. Thus, the main objective of this study was to isolate and characterizes bioactive natural products from the seeds of Azadirachta indica. The plant material was collected from Gambella region of Pugnewdo district and was allowed to dry in the shade area, and then powdered using pestle and mortar. The powdered material was extracted by maceration method first using petroleum ether followed by chloroform/methanol (1:1).The extract was then filtered and evaporated using a rotary evaporator. The isolation of pure compound was made by Column chromatography controlled by TLC using petroleum ether in increasing amount of ethyl acetate for polarity. This led to the isolation of two compounds, characterized as, Azadiradione and Epoxyazadiradione: which their structures were established based on their NMR data comparison with values in the literature. 100mg/ml the crude extract and isolated compounds were evaluated for antibacterial and antifungal activity against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, penicillium and Aspergillus flavus to show zone of inhibition ranging from (15-29 mm). Highest activity was recorded against Escherichia coli (29 mm) and least for Aspergillus flavus (15 mm). Compound A has better activity than compound B against Staphylococcus aureus but the two compounds have similar activity for fungal species. Generally two triterpenoids Meliaceae family were isolated and characterized from seeds of Azadirachata indica. The PE/EA (96:4) affords 166 mg of compound A a known triterpenoids azadiradione and (80:20) gives 186 mg of the second triterpenoids, compound B as epoxy derivative of compound A and assigned the name, 14, 15-epoxyazadiradione. However, further study on chemical compotation recommended including the usable seed of Azadirachata indica for future use is important for the development and production of new drugs and the biological activity should be also done on another bacterial and fungal strain.