A potent tumoricidal co-drug ‘Bet-CA’ - an ester derivative of betulinic acid and dichloroacetate selectively and synergistically kills cancer cells

Abstract

Selective targeting of cancer cells employing multiple combinations as co-drug holds promise for new generation therapeutics. Betulinic acid (BA), a plant secondary metabolite kills cancer cells and Dichloroacetate (DCA) is capable of reversing the Warburg phenotype by inhibiting pyruvate dehydrogenase kinase (PDK). Here, we report synthesis, characterization and tumoricidal potential of a co-drug Bet-CA, where a DCA molecule has been appended on C-3 hydroxyl group of BA to generate an ester derivative for increased solubility and subsequent cleavage by internal esterase(s) to release one unit each of BA and DCA. In vitro studies revealed pronounced synergistic cytotoxicity of Bet-CA against a broad spectrum of cancer cells and it selectively killed them when co-cultured with human fibroblasts. Bet-CA treatment increased reactive oxygen species (ROS) production, significantly altered mitochondrial membrane potential gradient (ΔΨm); followed by the release of cytochrome c (Cyt c) which prompted cells to undergo mitochondria mediated apoptosis. In vivo experimentation expectedly exhibited tumor inhibitory potential of Bet-CA and clinically achievable doses did not produce any apparent toxicity. Taken together, results suggestively raise an important corollary hypothesis stating that Bet-CA selectively and synergistically combats cancer without producing toxic manifestations and emerges to be the prospect for the new generation therapeutics.

Therapeutic applications of dichloroacetate and the role of glutathione transferase zeta-1

“…In most of the studied tumor cell lines, mitaplatin had comparable cell-killing potency to cisplatin, however, unlike cisplatin, mitaplatin did not kill normal cells (Dhar & Lippard, 2009) Recently a formulation of mitaplatin as a nanoparticle encapsulation was found to have improved bioavailability characteristics and to be effective in animal models (Johnstone, et al, 2013). Another example of a DCA co-drug is Bet-CA, an ester of the alcoholic hydroxy group of betulinic acid and the carboxylate of DCA (Saha, et al, 2015). Betulinic acid is a natural product with anticancer activity (Fulda & Kroemer, 2009).…”

“…Betulinic acid is a natural product with anticancer activity (Fulda & Kroemer, 2009). Bet-CA was reported to be more potent than either drug alone or a mixture of betulinic acid and DCA in several cancer cell lines, but was non-toxic to normal cells (Saha, et al, 2015). So far, no clinical data have been reported for either of the co-drugs.…”

Restoration of mitochondria function as a target for cancer therapy

“…DCA in combination with 5-fluorouracil synergistically inhibited cell proliferation and induced apoptosis in colorectal cancer in vitro [97]. Recently, a co-drug, Bet-CA, an ester derivative of betulinic acid and DCA, has shown promising anticancer effects against a variety of cell types, and also reduced melanoma tumor growth and pulmonary metastasis [98]. DCA sensitizes metformin cytotoxicity by reprogramming glucose metabolism in cancer cells leading to apoptosis induction [73] under high glucose conditions.…”

New Pharmacological Opportunities for Betulinic Acid

“…It was also more potent than the effect of betulinic acid + dichloroacetic acid combined as well as the effect observed in non-tumoral cells (WI-38 and 3T3 fibroblasts). In vivo, the results of the test compound on pulmonary metastases were positive, since both the number and, more importantly, the size of the nodules were notably reduced [73].…”