Biotransformation Of Triptolide And Triptonide By Plant Cell Suspension Cultures And Microbes

Triptolide and triptonide, diterpenoid triepoxide, are the major active constituents of Tripterygium wilfordii Hook. f. Previous studies showed that triptolide is effective in the treatment of autoimmune diseases and have potent antileukemic and antitumor activities, and triptonide has effective anti-inflammatory and antifertility activities. As the biologically active agents, the application of triptolide and triptonide were limited due to their strong toxicity. To find more effective compounds with less toxicity, scientists have been searching for the approach to modify the structures of triptolide and triptonide by efficient methods.Biotransformation is now becoming a useful tool for structural modifications of bioactive natural products. It is a kind of chemical reaction of structure modification by enzymes of plant cell suspension cultures and microorganisms, which modifies the structures of specific substrates. It has such advantages over chemical synthesis as high stereo- and regio-selectivity, as well as mild reaction conditions, lower cost, less by-product and pollution. Some reactions which can't be fulfilled in chemical approach are facile process by biotransformation. Biotransformation is often used to modify natural products to obtain the novel leading compounds and predict mammalian metabolism in vitro. This paper presents the biotransformation of two bioactive natural products including triptolide 1a and triptonide 2a were carried out for the first time. The biotransformation products were obtained and identified by employing spectroscopic methods.Catharanthus roseus and Platycodon grandiflorwn cell suspension cultures were used to biotransform triptolide 1a, from which triptriolide 1b was identified, Cunninghamella blakesleana (AS 3.970) was selected from 31 strains of microorganisms to transform la, from which seven products were isolated and characterized as 5ct-hydroxytriptolide Ic, 19a-hydroxytriptolide 1d-a, 19p-hydroxytriptolide 1d-a, tripdiolide 1e, 16-hydroxytriptolideIf, triptolidenol Ig and 1 -hydroxytriptolide Ih. Products 1c, 1d-a, 1d-b and Ih are newcompounds.Triptonide 2a was converted by Platycodon grandiflorum cell suspension cultures, which resulted in ten transformed products, including triptolide la, tripdiolide le, 12,13-dihydroxytripotonide 2b, 5a-hydroxytripotonide 2c, 2-hydroxytripotonide 2d, 12,13-dihydroxytripotonide 2e, 12,13-epidihydroxytripotonide 2f, 12,13-tripotonide 2g, epitripotolide-14-O- D-glucoside 2h and 17-hydroxytripotonide 2i, among which products 2b, 2c, 2e, 2f, 2h and 2i are new compounds. Microbial biotransformation of triptonide 2a by Aspergillus niger AS 3.739 was investigated and four products including 17-hydroxytriptonide 2i, 16-hydroxytriptonide 2j, 5-hydroxytripotonide 2c and triptolide la were obtained. Product 2j is a new product.In vitro antitumor activity assay showed that products Ic, le, If, Ig, Ih, 2c, 2d, 2i, 2j and 2g possessed cytotoxic activity to several tumor cell lines including BGC823, HeLa, HL-60, KB and MCF-7, while compounds Ib, Id, 2b, 2f and 2h had no effect on some of these cell lines. In vitro immunosuppressive activity test showed that product Ic has remarkable suppressive activity on the lien lymphocytes proliferation after induced by Con A, while it has no toxic on normal lien lymphocytes at the same dose of 1X10-7 g/mL.