Antiproliferative Potential of Gloriosine: A Lead for Anticancer Drug Development

Isolation of a new cytotoxic colchinoid from Gloriosa superba roots

A new colchinoid compound, identified as N-deacetyl-N-formylcornigerine (1), named glorigerine was isolated from the roots of Gloriosa superba, along with two known compounds. The structures of isolated compounds were elucidated by 1 D and 2 D NMR and HRMS experiments. Glorigerine (1) differed from cornigerine (6) by the presence of an N-formyl group instead of the N-acetyl group. Glorigerine (1) was found to have moderate cytotoxicity when tested against four human cancer cell lines.

Indole derivatives targeting colchicine binding site as potential anticancer agents

Microtubules are appealing as intracellular targets for anticancer activity due to their importance in cell division. Three important binding sites are present on the tubulin protein: taxane, vinca, and colchicine binding sites (CBS). Many USFDA-approved drugs such as paclitaxel, ixabepilone, vinblastine, and combretastatin act by altering the dynamics of the microtubules. Additionally, a large number of compounds have been synthesized by medicinal chemists around the globe that target different tubulin binding sites. Although CBS inhibitors have proved their cytotoxic potential, no CBS-targeting drug had been able to reach the market. Several studies have reported design, synthesis, and biological evaluation of indole derivatives as potential anticancer agents. These compounds have been shown to inhibit cancer cell proliferation, induce apoptosis, and disrupt microtubule formation. Moreover, the binding affinity of these compounds to the CBS has been demonstrated using molecular docking studies and competitive binding assays. The present work has reviewed indole derivatives as potential colchicine-binding site inhibitors. The structure-activity relationship studies have revealed the crucial pharmacophoric features required for the potent and selective binding of indole derivatives to the CBS. The development of these compounds with improved efficacy and reduced toxicity could potentially lead to the development of novel and effective cancer therapies.

Mangiferin from Enicostemma littorale Blume with in silico and in vitro anti-inflammatory potential

The bioassay-guided fractionation of the extract of aerial parts of Enicostemma littorale resulted in two fractions 3 and 4 with moderate and potent antioxidant activity, respectively. The purification of fraction 3 gave swertiamarin (1), while the LCMS profile of fraction 4 unveiled the presence of another constituent along with swertiamarin. The extensive purification of fraction 4 led to the unusual isolation of mangiferin (2) from E. littorale. The uncommon isolation of mangiferin from E. littorale motivated us to conduct its in silico and in vitro screening as an anti-inflammatory agent. Both studies have proved mangiferin to be a promising anti-inflammatory molecule with a binding energy of -9.17 kcal/mol against Cyclooxygenase-2 protein and IC50 of 146.07 nanomolar. This study is the first report of the isolation of mangiferin, a xanthone glycoside from E. littorale.Communicated by Ramaswamy H. Sarma.

Docking experiments suggest that gloriosine has microtubule-targeting properties similar to colchicine

Gloriosine, the predominant metabolite of Gloriosa superba L., shares chemical properties with colchicine. We analyze the microtubule-binding affinity of gloriosine at the colchicine binding site (CBS) using an in silico-in vivo approach. The In silico docking of gloriosine showed a binding score of (-) 7.5 kcal/Mol towards β-tubulin at CBS and was validated by overlapping the coupling pose of the docked ligand with co-crystallized colchicine. 2D plots (Ligplot +) showed > 85% overlap between gloriosine and colchicine. The ADMET profile of gloriosine was in accordance with Lipinski's rule of five. Gloriosine belongs to class II toxicity with anLD₅₀ value of 6 mg/kg. In vivo and transmission electron microscopy studies revealed that gloriosine induces abnormalities in cell division such as condensed chromosomes in C-metaphase and enlarged nucleus with increased nuclear material. Gloriosine treated cells exhibited mitotic index of about 14% compared to control of 24% and high anti-proliferative activity i.e. 63.94% cell viability at a low concentration (0.0004 mg/ml). We conclude that gloriosine has a strong affinity for β-tubulin at CBS and thus can be used as a colchicine alternative in cytology and other clinical conditions.