Deciphering colchicine like actions of clerodin in terms of microtubule destabilization based mitotic abnormalities, G2/M-phase arrest, and plant polyploidy

Clerodin (C24H34O7), a clerodane diterpenoid, is a bitter principle of Clerodendrum viscosum. The present study aimed to decipher colchicine-like actions of clerodin in terms of microtubule destabilization based mitotic abnormalities, G2-M arrest, and plant polyploidy. Purified clerodin showed increased metaphase frequency in Human Peripheral Blood Lymphocytes (HPBLs), Human Embryonic Kidney cells (HEK-293), and Allium cepa root apical meristem cells. Both squashed slide of the onion root tip and flow cytometric analysis of radish protoplast revealed a significantly increased frequency of polyploid cells. Flow cytometric analysis showed an increase in frequencies of G2-M in MCF-7 cells from 6.10 to 16.25% after clerodin (200g/mL) treatment for 24 h. Confocal microscopy imaging of tubulin in clerodin-treated MCF-7 cells revealed microtubule destabilization. Molecular docking and LIGPLOT analysis indicate that clerodin interact in the colchicine binding site, including, single hydrogen bond with Asn 101 of -tubulin. In summary, our experimental data revealed that clerodin has metaphase arresting, microtubule destabilization, and polyploidy inducing ability similar to colchicine. Molecular docking analysis revealed for the first time that clerodin and colchicine interact at the common site of tubulin residue indicating a common mechanism of action. The results also indicate similar cytotoxic potentialities of both clerodin and colchicine even though they belong to different chemical groups. Thus, clerodin may be used in place of colchicine as a plant polyploidy inducing agent in plant breeding programs in Agriculture.