PCSIR Islamabad

Founder

Dr. Salimuzzaman Siddiqui, Founder of PCSIR

Salimuzzaman Siddiqui;19 October 1897 – 14 April 1994),HI, MBE, SI, DPhil, FPAS, FRS, was a Pakistani organic chemist, versatile scholar, and a leading scientist in the natural product chemistry. He is credited for pioneering the isolation of unique chemical compounds from the Neem (Azadirachta indica), Rauwolfia, and various other flora. As the founder director of H.E.J. Research Institute of Chemistry, he revolutionised the research on pharmacology of various domestic plants found in South Asia to extract novel chemical substances of medicinal importance.

In addition to his scientific talents, Siddiqui was also an avid painter, a poet, and a great connoisseur of Western music. His paintings were exhibited in the United States, Germany, India, and Pakistan.

Pioneering research

Siddiqui's first breakthrough in research came when he successfully isolated an antiarrhythmic agent in 1931 from the roots of Rauwolfia serpentina. He named the newly discovered chemical compound as Ajmaline, after his mentor Hakim Ajmal Khan who was one of the illustrious practitioners of Unani system of medicine in South Asia. Later on, Siddiqui also extracted other alkaloids from Rauwolfia serpentina that included Ajmalinine, Ajmalicine (C₂₁H₂₄N₂O₃), Isoajmaline, Neoajmaline, Serpentine and Serpentinine. Many of these are still used worldwide for treatment of mental disorders and cardiovascular ailments, especially as antiarrhythmic agents in Brugada syndrome.

Discoveries from Neem

Siddiqui was the first scientist to bring the anthelmintic, antifungal, antibacterial, and antiviral constituents of the Neem tree to the attention of natural products chemists. In 1942, he extracted three bitter compounds from neem oil, which he named as nimbin, nimbinin, and nimbidin respectively. The process involved extracting the water-insoluble components with ether, petrol ether, ethyl acetate and dilute alcohol. The provisional naming was nimbin (sulphur-free crystalline product with melting point at 205 °C, empirical composition C₇H₁₀O₂), nimbinin (with similar principle, melting at 192 °C), and nimbidin (cream-coloured containing amorphous sulphur, melting at 90–100 °C). Siddiqui identified nimbidin as the main active antibacterial ingredient, and the highest yielding bitter component in the neem oil. These compounds are stable and found in substantial quantities in the Neem. They also serve as natural insecticides.

In acknowledgement of these revolutionary discoveries, he was awarded the Order of the British Empire in 1946.

In his later career, Siddiqui continued to discover and isolate numerous unique anti-bacterial compounds from various parts (leaves, bark, etc.) of the Neem and other plants. He had more than 50 chemical compounds patented in his name in addition to those discovered as a result of his joint research with other colleagues and students. Most of these discoveries still remain vital natural ingredients of various medicines as well as biopesticides.