| The defatted MeOH extract of Aster pilosus Willd. (Asteraceae) was found to exhibit significant anti-inflammatory activity in rats at oral doses of 25, 50 and 100 mg/kg in the carrageenin-induced pedal edema and adjuvant-induced arthritis assays. Bioassay-guided fractionation of the active CHCl 3-soluble fraction resulted in the isolation of six new triterpenes, hop-17 (21)-en-3β-ol (1), hop-17 (21)-en-3β-ol ( 2), adianene-3β-ol (10), 23-hydroxymelaleucic acid (12), 24-acetoxyl-2α3α-dihydroxyurs-12-en-28-oic (13) and asterpilosin F (16). Also isolated from this fraction were the known compounds friedelin (3), epifriedelanol (4), friedelanol (5), friedelanol-3α-yl-acetate (6), α-spinasterol (7), α-spinasterol-3β-yl-acetate (8), α-spinasterol-3-O-β-D-glucopyranoside (9) and bauerenyl acetate (18). It is noteworthy that oleanolic acid (15), friedelin (3), friedelanol (5), epifriedelanol (4) and friedelanol-3α-yl-acetate (6) have previously been reported to be active in the carrageenin-induced rat pedal edema assay.; During the course of a large scale re-isolation of the cancer chemopreventive lignan secoisolariciresinol diglucoside (SDG, 23) from flaxseed [(Linus usitatissimum L. Linaceae], a new flavonoid glycoside, herbacetin 3,8-O-diglucopynanoside (26), the known flavonoids, herbacetin 3,7-O-dimethyl ether ( 28), kaempferol 3,7-O-diglucopynanoside (29 ), and the known lignan, (−)-pinoresinol diglucoside ( 30) were obtained. The stereochemistry of SDG (23) was defined for the first time by use of extensive 1D- and 2D-NMR spectral analyses and [α]D measurements. The isolates 26, 28, 29, 30, as well as the aglycone 27 of 26 were evaluated for antioxidant activity with the non-glycosylated herbacetin (27) and herbacetin 3,7- O-dimethyl ether (28) showing potent antioxidant activity.; A new ent-kaurene diterpene, megathyrin B (35 ), 1α,7β,11β,15β-tetrahydroxy- ent-7α,20-oxido-kaur-16-ene, was isolated from the cytotoxic MeOH extract prepared from the leaves of Isodon megathyrisus (Diels) H. W. Li (Labiatae).; A novel alkaloid, (1R, 2S)-(−)-mangochinine (38), possessing a rare dibenzopyrrocoline nucleus in its structure, was isolated from Manglietia chingii Dandy (Magnoliaceae). Its stereochemistry was determined on the basis of optical rotation measurements and extensive 1D- and 2D-NMR spectral analyses on its diacetylated derivative.; Finally, a unique inseparable epimeric diterpene pair was isolated from the stems and leaves of Isodon irrarata (Forrest) Hara (Labiatae) and was named irroralactone (39). Its structure in the crystalline state was unambiguously determined by X-ray crystallography. Compound 39 was shown to have very different epimeric ratios and conformation in MeOH-d4, C5D5N, DMSO- d6 and CDCl3 solutions. |
