Cytotoxicity and molecular docking analysis of racemolactone I, a new sesquiterpene lactone isolated from Inula racemosa

Abstract

Context: Traditionally, Inula racemosa Hook. f. (Asteraceae) has been reported to be effective in cancer treatment which motivated the authors to explore the plant for novel anticancer compounds. Objective: To isolate and characterize new cytotoxic phytoconstituents from I. racemosa roots. Materials and methods: The column chromatography of I. racemosa ethyl acetate extract furnished a novel sesquiterpene lactone whose structure was established by NMR (1D/2D), ES-MS and its cytotoxic properties were assessed on HeLa, MDAMB-231, and A549 cell lines using MTT and LDH (lactate dehydrogenase) assays. Further, morphological changes were analyzed by flow cytometry, mitochondrial membrane potential, AO-EtBr dual staining, and comet assay. Molecular docking and simulation were performed using Glide and Desmond softwares, respectively, to validate the mechanism of action. Results: The isolated compound was identified as racemolactone I (compound 1). Amongst the cell lines tested, considerable changes were observed in HeLa cells. Compound 1 (IC 50 ¼ 0.9 mg/mL) significantly decreased cell viability (82%) concomitantly with high LDH release (76%) at 15 mg/mL. Diverse morphological alterations along with significant increase (9.23%) in apoptotic cells and decrease in viable cells were observed. AO-EtBr dual staining also confirmed the presence of 20% apoptotic cells. A gradual decrease in mitochondrial membrane potential was observed. HeLa cells showed significantly increased comet tail length (48.4 mm), indicating broken DNA strands. In silico studies exhibited that compound 1 binds to the active site of Polo-like kinase-1 and forms a stable complex. Conclusions: Racemolactone I was identified as potential anticancer agent, which can further be confirmed by in vivo investigations.

Antiproliferative and cell cycle arrest potentials of 3-O-acetyl-11-keto-β-boswellic acid against MCF-7 cells in vitro

“…Boswellia serrata is a medicinal plant known for its potential health characteristics in different parts of the world mostly in Asia. Due to its pharmacological activities such as anti-inflammatory, antiasthma and antidiarrheal, much interest was recently focused on B. serrata natural metabolites as novel and effective anticancer agents [ 7 , 30 ]. AKBA, as a pentacyclic triterpenic acid, is considered as the most important natural constituent of B. serrata with promising therapeutic activity as a tumour antiproliferative agent [ 27 ].…”

“…After incubation, cells were treated with AKBA ( IC 50 concentration, ~ 100 µg mL −1 ) and allowed the cells to incubate for another 24 h. After that, the cells were rinsed twice with PBS to remove the medium and an aliquot of 100 µL of dual fluorescent dye (equal volume of AO and EtBr, 10 µg mL −1 ) was added to each well and then visualizing the cells under a fluorescence inverted microscope. Identification criteria were concentrated green areas of chromatin condensation in the nucleus considered early apoptosis, green intact nuclei considered viable cells and dense orange areas of chromatin condensation and intact nuclei considered late apoptosis [ 7 ].…”

Research progress on antitumor mechanisms and molecular targets of Inula sesquiterpene lactones

“…The residues that racemolactone I interacted with PLK-1 were mainly Leucine 59, Glycine 60, Lysine 61, Glycine 62, etc. [ 102 , 103 ].…”

Phytochemical Diversity in Relation to Cytogenetic Variability inInula racemosaHook.f., an Endangered Medicinal Plant of Himalayas

“…[10] Regarding the chemical investigation, there exists some literature on the species. [17,[20][21][22][23][24] However, these studies do not give any information about the actual quantification of the vital secondary metabolites of the species. To quantify and scrutinize the diversity in the concentration of major bioactive ingredients of populations/cytotypes of this species obtained from different localities of Kashmir ranging from 2000 to 3500 m altitude, a contemporary study was undertaken.…”

“…Regarding the chemical investigation, there exists some literature on the species [17,20‐24] . However, these studies do not give any information about the actual quantification of the vital secondary metabolites of the species.…”