Placoisoflavones A and B, two new cytotoxic isoflavonoids from Placolobium vietnamense N.D.Khôi & Yakovlev.

Two previously unreported isoflavonoids, placoisoflavones A and B (1 and 2), along with five known compounds, calopogonium isoflavone B (3), jamaicin (4), 6-methoxycalopogonium isoflavone A (5), vestitol (6), and caviunin (7) have been isolated from the stems of Placolobium vietnamense N.D.Khôi & Yakovlev. The structures of all isolated compounds were fully characterized using spectroscopic data and comparison with the previous literature. The cytotoxicity of all isolated compounds was evaluated against HepG2 cell line, and compound 1 showed the most potent cytotoxicity with an IC50 value of 8.0 µM.

New Benzil and Isoflavone Derivatives with Cytotoxic and NO Production Inhibitory Activities from Placolobium vietnamense.

The phytochemical investigation of Placolobium vietnamense stems led to the isolation of a new isoflavone derivative (1) and three new benzil derivatives (2-4), together with four known pyranoisoflavones (5-8). The structures of all isolated compounds were determined on the basis of extensive spectroscopic analyses, including NMR and HRMS spectral data, as well as comparison of their spectroscopic data with those reported in the literature. The cytotoxicity of all isolated compounds was assessed against the human liver hepatocellular carcinoma (Hep G2) cell line, and compound 1 displayed the most significant cytotoxicity with an IC50 value of 8.0 µM. Furthermore, all isolated compounds were also tested for their inhibitory activity against NO production in RAW 264.7 macrophages. Of these, compound 1 exhibited the strongest inhibitory efficacy against the LPS-induced NO production with the IC50 value of 13.7 µM.

Bougainvinones NP, three new flavonoids from Bougainvillea spectabilis.

In an effort to identify natural bioactive compounds, three new flavonoids (1-3) and six known compounds (4-9) were isolated from the stem bark of Bougainvillea spectabilis. The structures of these compounds were accomplished using comprehensive spectroscopic methods, including 1D and 2D NMR spectra with references to the literatures, as well as high-resolution mass spectrometric analysis. Their cytotoxicity against KB and HeLa S-3 cell lines was also evaluated.