New Prenyl Flavanone and Diarylbutanol from Uvaria Siamensis Stem Bark and Their Α-Glucosidase Inhibitory Activity

One new prenyl flavanone (1), (2S)-8-prenyl-5,6-dihydroxy-7-methoxyflavanone, and one new diarylbutanol (2), (7 ' S)-3 '-hydroxy-linderagatin-A, were isolated from the stem bark of Uvaria siamensis (Annonaceae), along with five known compounds, eriodictyol (3), quercetin (4), paprazine (5), N-trans-caffeoyltyramine (6), and N-trans-feruloyltyramine (7). Their structures were determined through extensive spectroscopic analyses and comparison with the literature. The alpha-glucosidase inhibitory potential of 1-7 was evaluated. Compound 6 showed the highest inhibitory activity against alpha-glucosidase and exhibited superior potency compared to the positive control, with an IC50 value of 0.12 mu M.