Structural and stereochemical studies of five new pregnane steroids from the stem bark of Toona ciliata var. pubescens

Five new pregnane steroids, toonasterones A (1), B (2), (Z)-aglawone (3), (Z)-toonasterone C (4), and (E)-toonasterone C (5), were isolated from the stem bark of Toona ciliata var. pubescens. Their structures were elucidated by means of detailed spectroscopic (IR, MS, and 2D NMR) analysis, and the stereochemistry of 1 was secured by X-ray diffraction analysis. (Z)-aglawone (3) exhibited moderate inhibitory activity of protein tyrosine phosphatase 1B (PTP1B), a potential drug target for treatment of type-II diabetes and obesity, with an IC50 value of 1.12 μg/mL.

Research highlights
► Five new pregnane steroids were isolated from Toona ciliata var. pubescens.
► The isolates were evaluated for the inhibitory activity of PTP1B.
► (Z)-Aglawone (3) exhibited moderate inhibitory activity of PTP1B with an IC50 value of 1.12 μg/mL.