Galloyl, caffeoyl and hexahydroxydiphenoyl esters of dihydrochalcone glucosides from Balanophora tobiracola.

Seven galloyl, caffeoyl and (S)-hexahydroxydiphenoyl (HHDP) esters of dihydrochalcone glucosides were isolated from Balanophora tobiracola; based on spectroscopic and chemical evidence, their structures were determined to be 6''-O-galloyl-, 3'',4''-di-O-galloyl-, 4'',6''-di-O-galloyl-, 4'',6''-O-(S)-HHDP-, 3''-O-galloyl-4'',6''-O-(S)-HHDP-, 3''-O-caffeoyl-4'',6''-O-(S)-HHDP-3-hydroxyphloretin 4'-O-beta-D-glucosides and 3''-O-galloyl-4'',6''-O-(S)-HHDP-phloretin 4'-O-beta-D-glucoside, respectively. By contrast, these compounds were not found in the taxonomically related B. japonica. The 3''-galloyl-4'',6''-HHDP esters of the dihydrochalcone glucosides showed strong inhibitory activities against alpha-glucosidase. Four known compounds were also isolated namely, (+/-)-eriodictyol 7-O-beta-D-glucoside, 1-O-caffeoyl-3-O-galloyl-beta-D-glucose, phloretin 4'-O-beta-D-glucoside, and 3-hydroxyphloretin 4'-O-beta-D-glucoside.