ISOLATION AND STRUCTURAL STUDIES ON THE CHEMICAL CONSTITUENT OF MEDICAL PLANTS SKIMMIA LAUREOLA AND WITHANIA COAGULANTS

Abstract

This dissertation describes the phytochemical investigations one the two medicinally important plant of Pakistan namely Withania Coagulans and Skimmia Laureola. Phytochemical studies on the whole plant of W. coagulans have led to the isolation often new withanolides,(+)-coagulin F (48) (+)-coagulin H (49), (+)-coagulin I (50), (+)-coagulin J(51), (+)-coagulin K(52), (+)-coagulin L(53), (+)-coagulin M(54), (+)-coagulin N(55), (+)-coagulin O(56), (+)-coagulin P(57) (48) J.Nat. Prod., 1998,61,812-814 (49)Heterocycles, 1998,48,1801-1811. (50)Heterocycles,1998,48,1801-1811. (51) Heterocycles,1998,48,1801-1811. (52) Heterocycles,1998,48,1801-1811. (53) Heterocycles,1998,48,1801-1811. (54) Chem. Pharm.Bull., 1998(in press) (55) Chem. Pharm.Bull., 1998(in press) (56) Chem. Pharm.Bull., 1998(in press) (57)Heterocycles, 1998(Submitted) Studies on the chemical constituents of Skimmia Laureola have yielded a triterpendiod (+)-taraxerone (82), three coumarins (+)-Oxypeucedanin hydrate(83), (+)-ulopterol(84), 2-H-1-benzopyrane-2-one(68), two esters: (E)-3(4-hydroxypheny1)-2propenoic methyl ester(85), (E)-3(4-hydroxypheny1)-2 propenoic methyl ester(86), and two quinoline alkaloids: (+)-edulinine(87) and (±)-ribalinine(88). Compounds 82-88 have been isolated for the first time from this source compounds 68,84 and 88 have shown antimicrobial activities against a number of human pathogenic bacteria and fungi. The structure of (+)-taraxerone (82)was unambiguously identified by single-crystal X-ray diffraction methods. The structure of these new and known natural product were determined on the basis of extensive spectroscopic studies including one-, two- and inverse two dimensional NMR experiments (such as COSY, HOHAHA, HMQC HMBC etc.) chemical dramatizations.