STUDIES ON THE CHEMICAL CONSTITUENTS WITHANIA COAGULANS AND BOSWELLIA DALZIELLI

Abstract

This dissertation describes phytochemical studies on Withania coagulans and Boswellia dalzielli. The present work on these plants has resulted in the isolation of five new natural products. In addition to these, seven known compounds have been isolated and characterized for the first time from Withania coagulans, along with eight known compounds. The new constituents isolated from Withania coagulans were (22R), 20B-hydroxy-1-oxowitha-2, 5, 24-trienolide (90), coagulin J (91) [82], coagulin R (92) and coagulin U (93). Compounds 90 and 91 have also been isolated by our colleagues Dr. Dur-e-Shahwar Makhdoom and Dr. Muhammad Yousaf, respectively. The known compounds isolated from Withania coagulans for the first time were (22R)-14, 20-epoxy-17B-hydroxy-l-oxowitha-3, 5, 25-trienolide (96), (22R)-14, 20- epoxy-17B-hydroxy-1-oxowitha-5,24-dienolide-3B-(O-B-D-glucopyranoside) (94), ajugin A (102), methyl-4- benzoate (103), B-sitosterol (105), B-sitosterol glycoside (106) and B-amyrin (104). The known withanolides isolated were coagulin K (95), coagulin C (97), coagulin E (98), coagulin D (99), coagulin F (100) and coagulin B (101). A new compound isolated from Boswellia dalzielli was trans-3, 5-dihydroxy-4-methoxystilbene-3B-[O-B-D-glucopyranosyl (1-6)-a-L-rhamnopyranoside] (18). This compound was also found to be significantly active against the enzyme phosphodiesterase I. The structure elucidation of all compounds was carried out using different spectroscopic techniques including 1H- and 13C-NMR spectroscopy (HMQC, HMBC, COSY 45°, nOe, NOESY, HOHAHA etc.), mass spectrometry (E1, -ve and +ve FAB MS, FDMS etc.), 1R, UV, etc.