Chemical and biological studies of some medicinal plants used by the small ethnic community people of Chittagong hill tracts

Abstract

This dissertation describes the isolation and characterization of compounds from the leaves of Murraya koenigii (L.) Spreng (Fam.- Rutaceae) and Baliospermum montanum Willd. (Fam.- Euphorbiaceae) as well as the isolation of constituents of Plumbago indica L. (Fam.-Plumbaginaceae) and Alpinia conchigera Griff.( Fam.- Zingiberaceae). In addition, the crude methanol extract of leaves of M. koenigii, B. montanum and Perilla ocymoides L. (Fam.- Lamiaceae) along with crude methanol extract and different partitionates, i.e. n-hexane and chloroform soluble fractions of P. indica and A. conchigera were subjected to screenings for different biological activities. A total of 30 compounds were isolated, 14 from M. koenigii, 8 from B. montanum, 5 from P. indica and 3 from A. conchigera by using repeated column chromatography, TLC, PTLC and HPLC techniques. The structures of the 16 purified compounds were solved by extensive analysis of their high resolution NMR spectroscopic data as well as by comparison with published values and co-TLC with authentic sample whenever possible. The structures of the remaining compounds could not be solved due to unavailability of spectral data. The petroleum ether soluble fraction of methanol extract of leaves of M. koenigii upon gel permeation chromatography over lipophilic Sephadex LH-20 provided two alkaloids (MK-2, MK-8), seven coumarins (MK-1, MK-4, MK-5, MK-6, MK-7, MK-11 and MK12) and one flavonoid (MK-9). Further purification of the petroleum ether soluble partitionate by HPLC afforded two additional coumarins (MK-3 and MK-10). The isolated compounds MK-1, MK-2, MK-3, MK-4, MK-5, MK-6, MK-7, MK-8, MK-9, MK-10, MK-11 and MK-12 were characterized as murracarpin (1), arborinine (2), murpanidin (3), epoxyosthol (4), isomeranzin (5), meranzin hydrate (6), murrangatin (7), mahanimbine (8), 3,3′,4′,5′,5,6,7,8-octamethoxyflavone, (exoticin, 9), demethylisomeranzin (10), 8-acetyl-7-hydroxycoumarin (11) and 7-methoxy-8hydroxycoumarin (12), respectively.On the other hand, the dichloromethane soluble Kupchan partitionate of methanol extract of leaves of B. montanum upon gel permeation chromatography over Sephadex LH-20 yielded two flavonoids (BM-1 and BM-2) while the petroleum ether soluble fraction yielded another two flavonoids (BM-3 and BM-4), which were identified as syringetin (13), 5,6,4′,5′-tetramethoxy-7,3′-dihydroxy-8-methylflavone (14), 4′,5,7-trihydroxy-3′,5′dimethoxyflavone (tricin, 15) and 3,5,7,3′,4′,5′-hexahydroxyflavone (myricetin, 16), respectively. Among these, to the best of our knowledge, compounds 10 and 11 appear to be new, whereas compound 3 is the first report of its occurrence from M. koenigii. On the other hand, compound 14 appear to be new, whereas compounds 13, 15 and 16 are the first report of their occurrence from B. montanum. Acquisition of additional spectroscopic data, including MS is in process to confirm the structure of compounds 10, 11 and 14.