Estrogenic activities of flavonoids in Thai medicinal plant Dalbergia parviflora

In a search for new phytoestrogens from Thai medicinal plants, an extract of the heartwood of Dalbergia parviflora (Leguminosae) was investigated, and thirteen new compounds, khrinones A, B, C, D, E, isodarparvinol A, B, dalparvin, dalparvin A, B, dalparvinol C, neokhrinol A and (3S)-sativanone, along with 55 known compounds, have been isolated and characterized.¹ Isolates were evaluated for their cell proliferation stimulatory activity against the MCF-7 and T47D human breast cancer cell lines, and isoflavones such as genistein, biochanin A, tectorigenin, and 2′-methoxyformononetin stimulated the proliferation of both cells, and concentrations of lower than 1µM of these compounds showed equivalent activity to 10 pM of estradiol (E2). The new isoflavanone also showed activity against both cell types, although it was less active than that of the corresponding isoflavone (2′-methoxy-formononetin). On the other hand, none of the isolates showed any significant effects on human breast cancer BT20 cell proliferation, and these results indicated that the stimulative activity of these compounds was not general to any cell proliferations. We also examined the steroidogenesis activity of some flavonoids using H295R human adrenocortical carcinoma cells. One ompound showed 200 folds of E2 production compared to genistein with LC-MS analysis whereas its activity was 1/200 to that of genistein in E-screen assay. These results show us that some constituents are able to act as estrogenic substances by modulating various cytochrome P450 enzymes involved in steroidogenesis.

References: 1. Umehara, K. et al. (2009)J. Nat. Prod. 72:2163–2168, (2008) Phytochemistry 69:546–552.