Pioneering research Salimuzzaman Siddiqui

an average neem tree 15 meters high crown s diameter 15–20-meter

siddiqui first scientist bring anthelmintic, antifungal, antibacterial, , antiviral constituents of neem tree attention of natural products chemists. in 1942, extracted 3 bitter compounds neem oil, named nimbin, nimbinin, , nimbidin respectively. process involved extracting water-insoluble components ether, petrol ether, ethyl acetate , dilute alcohol. provisional naming nimbin (sulphur-free crystalline product melting point @ 205 °c, empirical composition c7h10o2), nimbinin (with similar principle, melting @ 192 °c), , nimbidin (cream-coloured containing amorphous sulphur, melting @ 90–100 °c). siddiqui identified nimbidin main active antibacterial ingredient, , highest yielding bitter component in neem oil. these compounds stable , found in substantial quantities in neem. serve natural insecticides.

in acknowledgement of these revolutionary discoveries, awarded order of british empire in 1946.

in later career, siddiqui continued discover , isolate numerous unique anti-bacterial compounds various parts (leaves, bark, etc.) of neem , other plants. had more 50 chemical compounds patented in name in addition discovered result of joint research other colleagues , students. of these discoveries still remain vital natural ingredients of various medicines biopesticides.