Search

From the whole plant of Dendrobium senile , a new phenanthrene namely 2,5,7-trihydroxy-4-methoxyphenanthrene ( 1 ) was isolated, together with seven known compounds including moscatin ( 2 ), 2,5-dihydroxy-4,9-dimethoxyphenanthrene ( 3 ), moscatilin ( 4 ), aloifol I ( 5 ), 4,4',8,8'-tetramethoxy[1,1'-biphenanthrene]-2,2',7,7'-tetrol ( 6 ), 2,2',7,7'-tetrahydroxy-4,4'-dimethoxy-1,1'-biphenanthrene ( 7 ) and bleformin G ( 8 ). The structure of the new compound was elucidated by analysis of its spectroscopic data. Moscatin ( 2 ) and 2,5-dihydroxy-4,9-dimethoxyphenanthrene ( 3 ) showed appreciable pancreatic lipase inhibitory effects when compared with the positive control orlistat.

A new phenanthrene dimer, namely dendropalpebrone (1), was isolated from the whole plant of Dendrobium palpebre, along with nine known compounds (2-10). All of the isolates were evaluated for their hydroxyl radical scavenging effects using a deoxyribose assay. Dendroflorin (10) showed an appreciable activity, and therefore was selected for further studied in RAW264.7 cells. Compound 10 significantly decreased ROS in H 2 O 2 -stimulated RAW264.7 cells in a dose-dependent manner, and improved activity of SOD, GPx, and CAT enzymes.

Phytochemical investigation of the stem of Dendrobium capillipes resulted in the isolation of a new flavonol glycoside namely quercetin-3-O-α-L-rhamnopyranosyl-(1 → 2)-β-d-xylopyranoside, along with seven known phenolic compounds which included two flavonol glycosides and five bibenzyls. From the stem of Dendrobium secundum, a new compound named 5-hydroxy-3,4,3',4',5'-pentamethoxybibenzyl was characterized, together with two known bibenzyls and three glycosidic flavonoids. Some of the isolated bibenzyls showed cytotoxicity against KB, NCI-H187, and MCF-7 cancer cells, whereas all of the glycosidic flavonoids were devoid of activity.

A number of Dendrobium species (Orchidaceae) have been used as health foods. In Thailand, the tea prepared from the stems of Dendrobium draconis Rchb.f. (Orchidaceae) has been used as a blood tonic. Our phytochemical investigation of this plant led to the isolation of a new compound namely 5-methoxy-7-hydroxy-9,10-dihydro-1,4-phenanthrenequinone, along with four known stilbenoids including hircinol, gigantol, batatasin III, and 7-methoxy-9,10-dihydrophenanthrene-2,4,5-triol. The structures of these compounds were determined through extensive spectroscopic studies, including (1)H and (13)C NMR, DEPT, COSY, NOESY, HMQC, HMBC, ESI-MS, and HR-ESI-MS experiments. In the DPPH-free radical assay, these stilbene derivatives showed appreciable antioxidant activity.