Natural Products from Polygala hongkongensis

Xanthone glycosides from herbs of Polygala hongkongensis Hemsl and their antioxidant activities.[Pubmed: 18636380]

Two new xanthone O-glycosides, polyhongkongenosides A (1) and B (2), together with four known xanthone glycosides, were isolated from the herbs of Polygala hongkongensis Hemsl. Their structures were elucidated on the basis of UV, IR, NMR, and MS spectral data. The antioxidant in vitro activities of 1-6 were determined by the scavenging activities against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and hydroxyl radicals and their reductive activities to Fe3+. Mangiferin, one of the four known xanthone glycosides, showed potential scavenging effect on DPPH and hydroxy radicals and reductive activity to Fe3+ with IC50 values of 4.7, 13.9, 23.7 microM, respectively.

[The chemical constituents of Polygala hongkongensis Hemsl].[Pubmed: 17882961]

Polygala hongkongensis Polycalaceae is mostly distributed in southern China, such as Guangdong, Jiangxi, Fujian and Sichuan provinces. And its herbs is used as a remedy of heat-clearing and detoxicating, removing food retention, promoting blood flow and expelling phlegm to arrest coughing in the folk medicine. Previous phytochemical investigations on Polygala plants have reported that the main chemical constituents are sapaonins, xanthones and oligosaccharide esters. To the best of our knowledge, there is no chemical report on the Polygala hongkongensis Hemsl. yet. In order to search and make use of natural resources from Polygala and to find the bioactive compounds and new compounds, we carried out studies on chemical constituents of this plant. The herbs of P. hongkongensis were extracted with 70% MeOH. The extract was combined and evaporated in vacuum to residue, which was suspended in water and successively partitioned with EtOAc and n-BuOH. Part of the n-BuOH extract was isolated and purified by various column chromatographs such as a macroporous resin, silica gel, Sephadex LH-20 column and semipreparative HPLC. The structures of isolated and purified compounds were determined by spectral analysis such as UV, IR, HRESI-MS, ESI-MS, 1H NMR, 13C NMR, HMQC, HMBC, H-H COSY, NOESY and physico-chemical property. Six compounds were identified as polyhongkonggaline (1), 3, 6'-di-O-sinapoyl-sucrose (2), tenuifoliside A (3), glomeratose D (4), cis-syringin (5), syringaresinol-4'-O-beta-D-monoglucoside (6). Compounds 1 is new compound, and 2-6 were isolated from this plant for the first time. Farther studies on the chemical constituents and pharmacological activities of P. hongkongensis will be carried out.

[Isolation and structure identification of chemical constituents from Polygala hongkongensis II].[Pubmed: 17639983]

To isolate and elucidate the constituents of herbs of Polygala hongkongensis.

Antioxidants and a new dihydroisocoumarins from Polygala hongkongensis Hemsl.[Pubmed: 17613814]

A new dihydroisocoumarins, 6-methoxy-8-hydroxy-3-(4-hydroxyphenyl)isochroman-1-one, named as hongkongenin (1), and seven known flavonoids were isolated from the methanol extract whole plant of Polygala hongkongensis Hemsl. Their structures were established on the basis of UV, IR, NMR, and MS spectral data. It is the first report of the occurrence of isocoumarins in Polygala, and the known compounds 2-8 were isolated from this plant for the first time. Flavonoids showed potent antioxidant activities in vitro against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, hydroxyl radicals, and reductive activity to Fe3+.