Rotenoids and isoflavones from the leaf and pod extracts of Millettia brandisiana Kurz

Phytochemical investigations of the leaf and pod extracts of Millettia brandisiana Kurz led to the isolation and identification of four previously undescribed rotenoids, (-)-(6aS,12aS)-millettiabrandisins A-C and (-)-(6aS,12aS)-6-deoxyclitoriacetal, two previously undescribed isoflavones, millettiabrandisins D and E, and 20 known compounds. The structures of previously undescribed compounds were determined on the basis of NMR and MS data. The absolute configurations of (-)-(6aS,12aS)-millettiabrandisins A-C were determined from the comparison of their experimental and calculated ECD spectra. (-)-(6aR,12aR)-12a-Hydroxy-α-toxicarol was also confirmed by X-ray crystallographic data. Some isolated compounds were evaluated for their cytotoxicity against three cancer cell lines, including lung cancer (A549), colorectal cancer (SW480), and leukemic cells (K562). Of these, α-toxicarol displayed the best cytotoxicity against lung cancer (A549) and leukemic cells (K562) with the IC50 values of 104.4 and 67.5 μM, respectively. 6″,6″-Dimethylchromene-[2″,3″:7,8]-flavone showed the highest cytotoxicity against colorectal cancer (SW480) with an IC50 value of 97.2 μM.

Brandisianones F and G from Millettia brandisiana Kurz and their cytotoxicity

A new flavanone and a new chalcone, brandisianones F and G, were purified from the roots of Millettia brandisiana Kurz, moreover, sixteen known compounds were found. The chemical structures of all isolated compounds were identified using spectroscopic methods including 1D-NMR, 2D-NMR, MS, IR and CD data. Chalcone 15 exhibited the most cytotoxic activity against liver cancer, HepG2, and cholangiocarcinoma, KKU-M156, cell lines with IC₅₀ values of 1.74 ± 0.91 and 1.95 ± 0.95 µg/mL, respectively. Chalcones 2, 14, 16 and 18 as well as flavones 5, 6 and 12 showed moderate cytotoxicity with IC₅₀ values ranging from 5.39 to 14.00 µg/mL.

Diverse flavonoids from the roots of Millettia brandisiana

The phytochemical investigation for the constituents of the roots of Millettia brandisiana, using bioassay guided fractionation, resulted in the isolation of five previously undescribed (namely brandisianones A-E) and twenty-six known flavonoids. Their chemical structures were determined using a combination of NMR, MS, IR, optical rotation and CD analysis, as well as comparison with the literature data. The crude extract as well as the isolated compounds were evaluated in various biological assays for their cytotoxicity against a panel of human cancer cell lines, potential inhibitory activity against aromatase, and antioxidant property using the oxygen radical absorbance capacity (ORAC) with an aim to search for leads and develop them to drug candidates in our drug discovery effort, we identified three bioactive flavonoids from M. brandisiana which could be further developed into a potential chemopreventive (antiaromatase) agent against breast cancer.