Potential Anti-Proliferative Natural Products from Bidens biternata (Lour.) Merr. & Sherff and Austrobuxus sanii (Beuzev. & C.T.White) Airy Shaw

Abstract

In this project, Bidens biternata (Lour.) Merr.& Sherff collected in Guangxi, China, and Austrobuxus swanii (Beuzev. & C.T.White) Airy Shaw from Queensland, Australia were chosen for NMR and MTS assay-guided chemical investigation. B. biternata, a traditional Chinese medicine (TCM), has been used to treat appendicitis, sore throat, diarrhea, dysentery, and stomach ache for hundreds of years. However, there are few of studies on the chemical constituents. Previous biological activity study indicated that the ethanol extract of B. biternata inhibited cell growth against several cancer cell lines. This warranted further research into the bioactive compounds from the TCM. The plant genus Austrobuxus belongs to one of the endemic taxa in Australia. A. swanii is a rare subtropical rainforest tree. There is also insufficient information of this species reported. A recent paper from our group reported four new picrotoxane terpenoids from A. swanii; the LC-MS analysis showed potential new picrotoxane terpenoids in the crude extract, which led to further chemical investigation of the plant species. Three phenyltriynes were isolated from the first biota, B. biternata, by using C18 flash column chromatography, diol silica gel chromatography and semi-preparative HPLC with the guidance of LC-MS and NMR data. One new picrotoxane terpenoid, austrabuxusin E, along with four know austrabuxusins (A-D) were isolated from the second biota, A. swanii by using solvent partitioning and several HPLC purification with the guidance of LC-MS and NMR data. The chemical structures of the pure compounds were elucidated by 1D and 2D NMR (COSY, HMBC, HSQC, ROSEY) and MS spectroscopic data. The anti-proliferative activity of the extracts and pure compounds were evaluated against Caco-2 and SKOV3 cell lines by the MTS assay.