Tyrosinase inhibitory activity of three new glycosides from Breynia fruticosa

Abstract Two new flavanone glycoside derivatives and one new sulfur-containing spiroacetal glycoside, (2 R , 3 R )-3-acetyl-7-methoxy-(−)-epicatechin 5- O -(6-isobutanoyl)- β - d -glucopyranoside ( 1 ), (2 R , 3 R )-3-acetyl-7-methoxy-(−)-epicatechin 5- O -[6-(2-methylbutanoyl)]- β - d -glucopyranoside ( 2 ) and 4-[(carboxymethyl)thio]-5′-hydroxy-phyllaemblic acid O - β - d -glucopyranosyl-(1 → 2)- β - d -glucopyranoside ester ( 3 ), along with twelve known flavonoids and one known sulfur-containing spiroacetal glycoside, were isolated from Breynia fruticosa . Their structures were elucidated by the use of extensive spectroscopic methods (UV, IR, HR-ESI-MS, 1D and 2D NMR, and CD). The in vitro inhibition of tyrosinase activity by all of these compounds was also evaluated, and we concluded that the flavanol-containing 5- O - and 7- O -sugar moieties possessed more potent effects than the other compounds examined herein.