Bioactivity-directed fractionation of the n-butanol extract of fresh fruits of Randia siamensis led to the isolation of 4 new ginsenosides: pseudoginsenosides-RT2, -RT3, -RT4 and -RT5, together with 7 known compounds. Tyramine was found to be responsible for the hypertensive activity, whereas pseudoginsenosides-RT1 and -RP1 were responsible for the hypotensive activity. The structures were determined by spectroscopic and chemical methods.