Andrographolide (AGP) is the main bioactive constituent isolated from the traditional medicinal, Andrographis paniculata which contributes towards its various biological activities, including anticancer property. In this study, a series of new AGP derivatives were semi-synthesised and screened against the NCI in vitro 60 cell lines. From the screening results, we had identified SRS07 as the most potent AGP derivative, against breast and colon cancer cell lines. Subsequently, SRS07 was tested for its capability to induce cell cycle arrest and apoptosis in MCF-7 and HCT116 cancer cells. SRS07 effectively induced G1 cell cycle arrest in both cell lines and ultimately apoptosis by inducing DNA fragmentation in HCT116 cells. The apoptotic cell death induced by SRS07 was confirmed via FITC Annexin-V double staining. Western blot analysis of SRS07-treated HCT116 cells revealed that the compound induced apoptosis be activating caspase 8 which in turn cleaved Bid to t-Bid to initiate cell death cascade. Prediction of the possible mode of action of SRS07 by utilising NCI COMPARE analysis failed to reveal a distinct mechanism category. Hence, it is speculated that SRS07 possesses novel mechanism of action. In conclusion, SRS07 demonstrated superior in vitro anticancer profiles and emerged as a potential lead anticancer candidate.
Limited tumor penetrability of anti-cancer drugs is recognized as one of the major factors that lead to poor anti-tumor activity. SRJ09 (3,19-(2-bromobenzylidene) andrographolide) has been identified as a lead anti-cancer agent for colon cancer. Recently, this compound was shown by us to be a mutant K-Ras binder. In this present study, the penetrability of SRJ09 through the DLD-1 colon cancer multicell layer (MCL) was evaluated. The amount of SRJ09 that penetrated through the MCL was quantitated by utilizing high performance liquid chromatography (HPLC). Histopathological staining was used to visualize the morphology of MCL. A chemosensitivity assay was performed to assess the anti-cancer activity of SRJ09 in DLD-1 cells. SRJ09 was able to penetrate through DLD-1 MCL and is inversely proportional with the MCL thickness. The flow rates for SRJ09 through MCL were 0.90 ± 0.20 μM/min/cm(2) and 0.56 ± 0.06 μM/min/cm(2) for days 1 and 5, respectively, which are better than doxorubicin. Histopathological examination revealed that the integrity of the DLD-1 MCL was retained and no visible damage was inflicted on the cell membrane, confirming the penetration of SRJ09 was by diffusion. Short term exposure (1 h) in DLD-1 cells demonstrated SRJ09 had IC50 of 41 μM which was approximately 4-folds lower than andrographolide, the parent compound of SRJ09. In conclusion, SRJ09 successfully penetrated through DLD-1 MCL by diffusion and emerged as a potential candidate to be developed as a clinically viable anti-colon cancer drug.