Antimicrotubular effect of calvatic acid and of some related compounds

Natural Compounds as Modulators of Cell Cycle Arrest: Application for Anticancer Chemotherapies

Natural compounds from various plants, microorganisms and marine species play an important role in the discovery novel components that can be successfully used in numerous biomedical applications, including anticancer therapeutics. Since uncontrolled and rapid cell division is a hallmark of cancer, unraveling the molecular mechanisms underlying mitosis is key to understanding how various natural compounds might function as inhibitors of cell cycle progression. A number of natural compounds that inhibit the cell cycle arrest have proven effective for killing cancer cells in vitro, in vivo and in clinical settings. Significant advances that have been recently made in the understanding of molecular mechanisms underlying the cell cycle regulation using the chemotherapeutic agents is of great importance for improving the efficacy of targeted therapeutics and overcoming resistance to anticancer drugs, especially of natural origin, which inhibit the activities of cyclins and cyclin-dependent kinases, as well as other proteins and enzymes involved in proper regulation of cell cycle leading to controlled cell proliferation.

Natural products containing a nitrogen-nitrogen bond

As of early 2013, over 200 natural products are known to contain a nitrogen-nitrogen (N-N) bond. This report categorizes these compounds by structural class and details their isolation and biological activity.

Allicin inhibits cell polarization, migration and division via its direct effect on microtubules

Allicin (diallyl thiosulfinate) is a major biologically active component of garlic that is known to inhibit cell proliferation and induce apoptosis. The effects of allicin are attributed to its ability to react with thiol groups. However, the mechanism underlying the cytostatic activity of allicin, as well as the identity of the relevant subcellular targets, are not known. In the present study, we found that the effects of allicin on cell polarization, migration, and mitosis are similar to the effects of microtubule-depolymerizing drugs such as nocodazole. Moreover, treatment of cultured fibroblasts with micromolar doses of allicin results in microtubule depolymerization in cells within minutes of its application, without disrupting the actin cytoskeleton or inducing direct cytotoxic effects. Furthermore, allicin blocks the polymerization of pure tubulin in vitro in a concentration-dependent manner, suggesting that it acts directly on tubulin dimers. Sulfhydryl (SH)-reducing reagents such as 2-mercaptoethanol and dithiothreitol abolish the effect of allicin on microtubule polymerization. Thus, allicin is a potent microtubule-disrupting reagent interfering with tubulin polymerization by reaction with tubulin SH groups.

Tubulin as a target for anticancer drugs: agents which interact with the mitotic spindle

Tubulin is the biochemical target for several clinically used anticancer drugs, including paclitaxel and the vinca alkaloids vincristine and vinblastine. This review describes both the natural and synthetic agents which are known to interact with tubulin. Syntheses of the more complex agents are referenced and the potential clinical use of the compounds is discussed. This review describes the biochemistry of tubulin, microtubules, and the mitotic spindle. The agents are discussed in relation to the type of binding site on the protein with which they interact. These are the colchicine, vinca alkaloid, rhizoxin/maytansine, and tubulin sulfhydryl binding sites. Also included are the agents which either bind at other sites or unknown sites on tubulin. The literature is reviewed up to October 1997.