Binding and molecular dynamic studies of sesquiterpenes (2R-acetoxymethyl-1,3,3-trimethyl-4t-(3-methyl-2-buten-1-yl)-1t-cyclohexanol) derived from marine Streptomyces sp. VITJS8 as potential anticancer agent.

ABSTRACT

The main aim of the current study is to explore the bioactive potential of Streptomyces sp. VITJS8 isolated from the marine saltern. The cultural, biochemical, and morphological studies were performed to acquire the characteristic features of the potent isolate VITJS8. The 16Sr DNA sequencing was performed to investigate the phylogenetic relationship between the Streptomyces genera. The structure of the compound was elucidated by gas chromatography-mass spectrometry (GC-MS), infra-red (IR), and ultra-violet (UV) spectroscopic data analysis. The GC-MS showed the retention time at 22.39 with a single peak indicating the purity of the active compound, and the molecular formula was established as C14H9ONCl2 based on the peak at m/z 277 [M](+). Furthermore, separated by high-performance liquid chromatography (HPLC), their retention time (t r) 2.761 was observed with the absorption maxima at 310 nm. The active compound showed effective inhibitory potential against four clinical pathogens at 500 µg/mL. The antioxidant activity was found effective at the IC50 value of 500 µg/mL with 90 % inhibition. The 3-(4,5-dimethylthiazol-2-yl)-2,5-ditetrazolium bromide (MTT) assay revealed the cytotoxicity against HepG2 cells at IC50 of 250 µg/mL. The progression of apoptosis was evidenced by morphological changes by nuclear staining. The DNA fragmentation pattern was observed at 250 µg/mL concentration. Based on flow cytometric analysis, it was evident that the compound was effective in inhibiting the sub-G0/G1 phase of cell cycle. The in vitro findings were also supported by the binding mode molecular docking studies. The active compound revealed minimum binding energy of -7.84 and showed good affinity towards the active region of topoisomerase-2α that could be considered as a suitable inhibitor. Lastly, we performed 30 ns molecular dynamic simulation analysis using GROMACS to aid in better designing of anticancer drugs. Simulation result of root mean square deviation (RMSD) analysis showed that protein-ligand complex reaches equilibration state around 10 ns that illustrates the docked complex is stable. We propose the possible mechanism of sesquiterpenes to play a significant role in antitumor cascade. Hence, our studies open up a new facet for a potent drug as an anticancer agent.