Taxiphyllin 6'-O-gallate, actinidioionoside 6'-O-gallate and myricetrin 2″-O-sulfate from the leaves of Syzygium samarangense and their biological activities.

Three new compounds were isolated from a MeOH extract of the leaves of Syzygium samarangense, one new cyanogenic glucoside, taxiphyllin 6'-O-gallate (1), one new megastigmane glucoside, actinidioionoside 6'-O-gallate (2), and one new sulfated flavonoid rhamnoside, myricetrin 2″-O-sulfate (3), together with 14 known compounds, lupeol (4), demethoxymatteucinol (5), cryptostrobin (6), betulinic acid (7), β-sitosterol glucoside (8), 2R-prunasin (9), myrciaphenone A (10), 1-feruloyl-β-D-glucopyranoside (11), (3S,5R,6R,7E,9S)-3,5,6,9-tetrahydroxymegastigman-7-ene (12), guaijaverin (13), myricetin 4'-methyl ether 3-O-α-L-rhamnopyranoside (14), myricetrin (15), gallic acid (16) and actinidioionoside (17). The structures of the new compounds were determined through a combination of spectroscopic, HPLC and chemical analyses.