Regioselective bioconversion of colchicine and thiocolchicine into their corresponding 3-demethyl derivatives

Anticancer Secondary Metabolites: From Ethnopharmacology and Identification in Native Complexes to Biotechnological Studies in Species of Genus Astragalus L. and Gloriosa L

Some of the most effective anticancer compounds are still derived from plants since the chemical synthesis of chiral molecules is not economically efficient. Rapid discovery of lead compounds with pronounced biological activity is essential for the successful development of novel drug candidates. This work aims to present the chemical diversity of antitumor bioactive compounds and biotechnological approaches as alternative production and sustainable plant biodiversity conservation. Astragalus spp., (Fabaceae) and Gloriosa spp. (Liliaceae) are selected as research objects within this review because they are known for their anticancer activity, because they represent two of the largest families respectively in dicots and monocots, and also because many of the medicinally important plants are rare and endangered. We summarized the ethnobotanical data concerning their anticancer application, highlighted the diversity of their secondary metabolites possessing anticancer properties such as saponins, flavonoids, and alkaloids, and revealed the potential of the in vitro cultures as an alternative way of their production. Since the natural supply is limited, it is important to explore the possibility of employing plant cell or organ in vitro cultures for the biotechnological production of these compounds as an alternative.

Biotransformation to Produce the Anticancer Compound Colchicoside Using Cell Suspension Cultures of Astragalus vesicarius Plant Species

This paper discusses the biotechnological process affected by means of plant suspension cultures, for production of colchicoside, the 3- O-glucosyl derivative of 3- O-demethylcolchicine. Colchicoside can be considered as an antitumoural prodrug which is activated after oral administration and may have more beneficial effects and a better toxicity profile (because of a slow-release effect) than colchicine. We have developed a green and efficient biotechnological method using colchicine, as a precursor, derived from its natural source G. superba seeds. Plant suspension cultures of Astragalus vesicarius were used to design a practical biotechnological platform to replace a methyl group at C-3 regiospecifically by a glycosyl moiety in colchicine. Using different concentrations of a colchicine-rich extract, the maximum enzymatic potential of Astragalus vesicarius suspension cells was achieved. According to quantitative HPLC-UV analysis, levels of 9.35 μmol/g DW colchicoside were achieved. This is the first report of region-specific glycosylation at C-3 of the aromatic ring A of the colchicine using plant suspension cultures.

Microbial Catalyzed Regio-Selective Demethylation of Colchicine by Streptomyces griseus ATCC 13273

Colchicinoids and their derivatives are of great importance in pharmaceutical applications, and colchicine is usually used as the first choice for the treatment of gout. To expand the structural diversities and clinical application of colchicinoids, many attempts have been established for the derivatives with better activity or less toxicity. Herein, in this paper, we report a direct microbial transformation of colchicine into 2-O-demethyl-colchicine (M1) and 3-O-demethl-colchicine (M2) by Streptomyces griseus ATCC 13273. It is noteworthy that when DMF was used as co-solvent, the yield of M1 and M2 could reach up to 51 and 31%, respectively. All the structures of the metabolites were elucidated unambiguously by ESI-MS, ¹H-NMR, ¹³C-NMR, and 2D-NMR spectroscopy.

Constrained azeotropic optimization of extraction system components for the safe and efficient recovery of a desired metabolite (e.g., 3-demethylated colchicine)

Constrained azeotropic optimization of extraction system components for the safe and efficient recovery of a desired metabolite (e.g., 3-DMC) using artificial learning and evolutionary optimization techniques.

Biotransformation of colchicinoids into their corresponding 3-O-glucosyl derivatives by selected strains of Bacillus megaterium

Natural colchicinoids and their semisynthetic derivatives are important active ingredients for pharmaceutical applications. Thiocolchicoside (3-demethoxy-3-glucosyloxythiocolchicine) is used in several countries as standard therapy for the treatment of diseases of the muscle-skeletal system, due to its potent antiinflammatory and myorelaxant properties. Manufacturing of thiocolchicoside requires a key step, the regioselective demethylation and glucosylation of chemically derivative thiocolchicine. High selectivity and efficiency of this transformation cannot be achieved in a satisfactory way with a chemical approach. In particular, the chemical demethylation, a part from requiring toxic and aggressive reagents, generates a complex mixture of products with no industrial usefulness. We report herein an efficient, direct and green biotransformation of thiocolchicine into thiocolchicoside, performed by a specific strain of Bacillus megaterium. The same process, with minor modifications, can be used to convert the by-product 3-O-demethyl-thiocolchicine into thiocolchicoside. In addition, we describe the B. megaterium strain selection process and the best conditions for this effective double biotransformation. The final product has a pharmaceutical quality, and the process has been industrialised.