Two Kinds Of Chemical Composition And Biological Activity Of Medicinal Plants

This dissertation is composed of four chapters, in which the chemical constituents of two medicinal plants, Epimedium brevicornum and Rhododendron spinuliferum, have been studied. Moreover, the effects of fractions and compounds from E. brevicornum were evaluated for their anti-inflammatory activity in vitro. In addition, the postulated biogenetic routes of three flavonols from E. brevicornum were discussed.(1) The genus Epimedium (Berberidaceae) comprises about 40 species, which have been utilized since ancient as tonic in China. Crude extracts of Epimedium brevicornum have been shown to display a number of interesting biological activities, such as anti-inflammatory, estrogenic, antidepressant-like, anti-aging, anti-osteoporosis and angiogenesis activity. As a part of our research program to identify natural compounds with potential anti-inflammatory, the whole plants of E. brevicornum was chosen for more detailed investigation of its chemical constituents. Repeated column chromatography of an EtOAc extract of E. brevicornum led to the isolation of sixteen compounds, including two new flavonols,2"-hydroxy-3"-en-anhydroicaritin (1) and 2"-hydroxy-β-anhydroicaritin (2), and a new aryltetralin-type lignan, cyclo-olivil formaldehyde condensate (5), along with thirteen know ones, anhydroicaritin (3), (+)-cyclo-olivil (4), (-)-olivil monoacetate (6), 4-hydroxybenzeneethanol (7), methyl-3,4-dihydroxybenzoate (8),3,4-dimethoxy-7-one-phenylpropanol (9),4-hydroxy-ethyl phenylacetate (10), cis-2,4-dihydroxy-2-(2-hydro-xyethyl) cyclohex-5-en-l-one (11), (4S,6R)-4-hydroxy-4,8,8-trimethyl-9-oxabicyclo [4.2.1]-non-l-l-en-3-one (12), (-)-(7R,8S)-dihydrodehydrodiconiferyl alcohol (13), daucosterol (14), ursolic acid (15) andβ-Stitosterol (16). Their structures were elucidated on the basis of spectroscopic analysis. Compounds 1-2,5-6,8-13 and 15 were obtained from this plant for the first time.(2) The effects of compounds 1-3 and 5 on cytokine productions in vitro were investigated. Compound 1 can significantly downregulate tumor necrosis factor-a (TNF-a), and increase interleukin-10 (IL-10) production. These results suggested that compound 1 may have anti-inflammatory activity in lipopolysaccharide (LPS)-stimulated mouse macrophages. However, compounds 2,3 and 5 showed weak effects on TNF-a and IL-10. (3) In addition, the biogenetic relationships among compounds 1-3 are discussed.(4) The chemical constituents of R. spinuliferum have not been reported. The phytochemical study on the EtOAc soluable fraction of the 70% acetone-water extract from leaves and stems of this plant result in the isolation of a new flavonoid, quercetin-3-O-[3",4"-O-(isopropylidene)-β-D-xylopyranoside] (17), together with seven known ones, taxifolin (18), taxifolin 3-O-β-D-xylopyranoside (19), isoengeletin (20), astilbin (21), proanthocyanidin A-2 (22), daucosterol (23) andβ-sitosterol (24). They were isolated by chromatographic methods and identified on the basis of spectroscopic data.