Salimuzzaman Siddiqui, HI, MBE, SI, FPAS, FRS (Urdu: سلیم الزّماں صدّیقی [səˈliːmʊzːəmaːn sɪˈd̪ːiːqi]; 19 October 1897 – 14 April 1994) was a Pakistani organic chemist specialising in natural products, and a professor of chemistry at the University of Karachi.

[1] On return to British India, he worked at the Tibbia College Delhi and the Indian Council for Scientific and Industrial Research.

He later co-founded the Pakistan Academy of Sciences, and after retirement from the government, he founded the Hussain Ebrahim Jamal Research Institute of Chemistry.

[1] Siddiqui is credited with pioneering the isolation of unique chemical compounds from the Neem (Azadirachta indica), Rauvolfia, and various other flora.

[2][3] During his career, Siddiqui published more than 300 research papers and obtained 40 patents mainly from the field of natural product chemistry.

[4] He received his early education from Lucknow, both in the Urdu and Persian languages, and soon developed interest in literature, poetry, and calligraphy from his father Sheikh Muhammad Zaman.

Many years later, as a successful scientist in Pakistan, Siddiqui repaid Hakeem Ajmal Khan's kindness by dedicating his discoveries to him.

[1] On his return, he established the Ayurvedic and Unani Tibbi Research Institute at the Tibbia College Delhi, under the guidance of Hakim Ajmal Khan.

In 1940, he joined Indian Council for Scientific and Industrial Research where he worked until 1951 when he migrated to Pakistan on the request of Prime Minister Liaquat Ali Khan.

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.

[2] Later on, Siddiqui also extracted other alkaloids from Rauvolfia serpentina that included Ajmalinine, Ajmalicine (C21H24N2O3), Isoajmaline, Neoajmaline, Serpentine and Serpentinine.

[9] 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.

Siddiqui identified nimbidin as the main active antibacterial ingredient, and the highest yielding bitter component in the neem oil.

[2] In his later career, Siddiqui continued to discover and isolate numerous unique anti-bacterial compounds from various parts (leaves, bark, etc.)

[7] In due time, Siddiqui transformed the institute into a distinguished centre of international excellence in the field of chemistry and natural products.

In March 1975, he headed the National Commission for Indigenous Medicines[16] His tireless efforts for the promotion of science and technology earned him Hilal-e-Imtiaz by the Government of Pakistan in 1980.

During his stay in Germany, he also translated Rainer Maria Rilke's poetry into Urdu, which was published in the journal of Jamia Millia Islamia.