BackgroundClinical use of chemotherapeutic drug, cisplatin is limited by its toxicity and drug resistance. Therefore, efforts continue for the discovery of novel combination therapies with cisplatin, to increase efficacy and reduce its toxicity. Here, we screened 16 medicinal plant extracts from Northeast part of India and found that leaf extract of Zanthoxylumarmatum DC. (ZALE) induced cytotoxicity as well as an effect on the increasing of the efficiency of chemotherapeutic drugs (cisplatin, mitomycin C and camptothecin). This work shows detail molecular mechanism of anti-cancer activity of ZALE and its potential for combined treatment regimens to enhance the apoptotic response of chemotherapeutic drugs.ResultsZALE induced cytotoxicity, nuclear blebbing and DNA fragmentation in HeLA cells suggesting apoptosis induction in human cervical cell line. However, the apoptosis induced was independent of caspase 3 activation and poly ADP ribose polymerase (PARP) cleavage. Further, ZALE activated Mitogen-activated protein kinases (MAPK) pathway as revealed by increased phosphorylation of extracellular-signal-regulated kinases (ERK), p38 and c-Jun N-terminal kinase (JNK). Inhibition of ERK activation but not p38 or JNK completely blocked the ZALE induced apoptosis suggesting an ERK dependent apoptosis. Moreover, ZALE generated DNA double strand breaks as suggested by the induction γH2AX foci formation. Interestingly, pretreatment of certain cancer cell lines with ZALE, sensitized the cancer cells to cisplatin and other chemotherapeutic drugs. Enhanced caspase activation was observed in the synergistic interaction among chemotherapeutic drugs and ZALE.ConclusionPurification and identification of the bio-active molecules from the ZALE or as a complementary treatment for a sequential treatment of ZALE with chemotherapeutic drugs might be a new challenger to open a new therapeutic window for the novel anti-cancer treatment.Electronic supplementary materialThe online version of this article (doi:10.1186/s40659-015-0037-4) contains supplementary material, which is available to authorized users.

The leaf crude extract of Oroxylum indicum (L.) Kurz induces genomic DNA fragmentation, comet formation, and the inhibition of cell proliferation in the prostate cancer cell line PC3, as assessed by agarose gel electrophoresis, comet assay and MTT assay, respectively. The bioactive compound was purified through bioassay-guided fractionation using preparative HPLC and MTT assay. The light brown and water-soluble compound was characterized using 1H and 13C nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR), and electrospray ionization (ESI) mass spectrometry. The compound was identified as a glycosylated hydroquinone derivative, 2-[p-(2-Carboxyhydrazino)phenoxy]-6-(hydroxymethyl) tetrahy-dro-2H-pyran-3,4,5-triol (molecular formula, C13H18N2O8; molecular mass = 330). The identified phytocompound has not been reported earlier elsewhere. Therefore, the common name of the novel anticancer phytocompound isolated from Oroxylum indicum in this current study is oroxyquinone. The half-maximal inhibitory concentration (IC50) of oroxyquinone on PC3 cells was 58.9 µM (95% CI = 54.5 to 63.7 µM). Treatment of PC3 cells with oroxyquinone induced genomic DNA fragmentation and chromatin condensation, increased in the annexin-V positive cells, arrested the cell cycle at S phases, and inhibited the cell migration; as assessed by comet assay, DAPI staining, flow cytometry and a wound healing assay, respectively. On the investigation of the molecular mechanism of the induction of apoptosis, the results indicated that oroxyquinone induced caspase-3 and PARP independent apoptosis but through the p38 pathway and the localization of AIF into the nucleus. The present study identifies a novel anticancer molecule and provides scientific evidence supporting the therapeutic potency of Oroxylum indicum for ethnomedicinal uses.

The use of cisplatin as a chemotherapeutic drug is impeded by the development of drug resistance. Combination therapies of a chemosensitizer for cisplatin have been studied, but with little success, and the search for an effective combination therapy is continuing. Our earlier reports have shown that Zanthoxylum armatum DC. extract enhances the apoptotic effect of cisplatin in cancer cell lines. In this study, we purified and identified the bioactive phytocompound through bio-assay-guided purification, using column chromatography and HPLC. Chemical characterization using NMR and mass spectrometry revealed the compound as planispine A, with molecular structure C25H30O6 and molecular weight, 426.16 g/mol. Planispine A was found to inhibit cancer cell proliferation in a dose-dependent manner and to sensitize the cancer cells to cisplatin-augmented apoptotic cell death, in a caspase-dependent manner. A combination of planispine A and cisplatin induced S-phase cell cycle arrest, and reduced the expression of survival proteins such as cyclin D1. Interestingly, planispine A inhibits the Fanconi anemia pathway, as shown by reduced FANCD2 foci formation and FANCD2 monoubiquitination, which revealed the molecular mechanism of chemo-sensitization of cancer cells to cisplatin. Evaluation of this combination therapy in cisplatin-resistant tumors may lead to more efficient cisplatin treatment.