Study On Chemical Constituents And Antioxidant Activity Of Desmodium Styracifolium Seeds

Desmodium styracifolium(Osbeck) Merr. is the genuine regional drug of Guangdong and Guangxi provinces. The aerial part of this plant possessed effects of clearing heat and diuretic, relieving stranguria and expelling stone. It can be used for the treatment of urinary system infection and lithiasis. Owing to shortage of wild drugs, the amount of cultivated D. styracifolium had been increased year by year. The plant of D. styracifolium propagated by seeds. There are a large number of seeds surplus every year. This paper aimed to extend medicinal parts and promote resource utilization through systematic study on chemical constituents and antioxidant activity of D. styracifolium seeds. The content of this paper was as followed:1. By the methods of silica gel, sephadex LH-20, polyamide column chromatography, preparatived thin layer chromatography and semi-preparative liquid chromatography, 25 compounds were isolated from seeds of D. styracifolium, 11 monomers were identified by physicochemical property, MS and NMR data. These compounds are as followed: tetracosanoic acid(I), stigmasterol(II), undecane(III), benzoic acid(IV), p-methoxycinnamic acid(V), kaempferol(VI), cis-15-tetracosenoic acid(VII),(+)-catechin 5-O-β-D-glucopyranoside(VIII),(+)-catechin(IX),(+)-catechin 7-O-β-D-glucopyranoside(X), quercetin-3-O-α-L-rhamnopyranoside(XI). The above compounds were firstly isolated from seeds of D. styracifolium except compound II.2. The content of total flavonoids in different extracts from seeds of D. styracifolium was determined by ultraviolet spectrophotometry. Results showed that the flavonoids content of extracts in descending order is n-butanol extract > chloroform extract > water extract. Antioxidant activity of the seeds extract was evaluated by DPPH assay. The results showed the clearance ability of the extract to DPPH free radical from high to low order is chloroform extract > water extract > n-butanol extract. Therefore, there was no coincident relevance between flavonoids content in different extracts and antioxidant activity. It might be due to various kinds of flavonoids and other substances with antioxidant activity.