Identification of compounds with anti-proliferative activity from the wood of Ficus elastica Roxb. ex Hornem. aerial roots

The natural products fromplants still remain an important source of pharmaceuticals. In the current study, methanolicwood extracts of Ficus elastica Roxb. ex Hornem. (Moraceae) aerial roots were screened for anti-cancer activity. Using bioassay-guided fractionation, three new compounds, elasticamide (1), elastiquinone (2) and ficusoside B (3), together with four known compounds, were isolated. The structures of the new compounds were established by means of extensive spectroscopic analyses (1D and 2D NMR, HR-ESI-MS, as well as IR and UV) and by comparison of their spectroscopic data with those reported for structurally related molecules. The isolated compounds were afterwards evaluated for their anti-proliferative effect on six human cancer cell lines (U373n and Hs683 glioblastoma, MCF7 and A549 NSCLC carcinoma, and B16F10 and SK-MEL-28 melanoma) using colorimetric MTT assay. Most notably, elastiquinone (2) showed cytotoxic activity with IC₅₀ = 14 μM against B16F10 melanoma cells, whereas the peracetylated form of ficusoside B (3a) displayed the lowest IC₅₀ value (11 μM) against U373n gliomacell lines. Elasticamide (1) and ficusoside B (3) exhibited aweak cytotoxicity with IC₅₀ values ≥88 μM. The results of this investigation demonstrate that the wood of F. elastica aerial roots might be a potential source for identifying new compounds with potent anti-proliferative activity.