Biotransformation of contraceptive drug desogestrel with Cunninghamella elegans, and anti-inflammatory activity of its metabolites

Abstract

Biotransformation of an orally active contraceptive drug, desogestrel (1), with Cunninghamella elegans yielded a new metabolite, 13β-ethyl-11-methylene-18,19-dinor-17α-pregn-4-en-20-yn-17β-ol-3,6-dione (2), along with five known metabolites, i.e., 13β-ethyl-11-methylene-18,19-dinor-17α-pregn-4-en-20-yn-3β,6β,17β-triol (3), 13β-ethyl-11-methylene-18,19-dinor-17α-pregn-4-en-20-yn-6β,17β-diol-3-one (4), 13β-ethyl-11-methylene-18,19-dinor-17α-pregn-4-en-20-yn-17β-ol-3-one (5), 13β-ethyl-11-epoxy-18,19-dinor-17α-pregn-4-en-20-yn-17β-ol-3-one (6), and 13β-ethyl-11-methylene-18,19-dinor-17α-pregn-4-en-20-yn-10β,17β-diol-3-one (7). The structure of new metabolite 2 was elucidated by using 1H-, 13C-, and 2D-NMR, EI-, and HREI-MS, IR, and UV spectroscopic data. Compounds 1–7 were evaluated for anti-inflammatory activities, i.e., inhibition of T-cell proliferation, and pro-inflammatory cytokine (TNF-α). Compounds 1 (IC50 = 1.12 ± 0.03 µg/mL), 2 (IC50 = 1.15 ± 0.05 µg/mL), 3 (IC50 = 1.15 ± 0.05 µg/mL), 4 (IC50 = 1.40 ± 0.03 µg/mL), 5 (IC50 = 1.78 ± 0.08 µg/mL), and 6 (IC50 = 1.36 ± 0.07 µg/mL) were identified as potent inhibitors of T-cells proliferation, in comparison to the standard drug, prednisolone (IC50 = 3.51 ± 0.03 µg/mL). Compound 7 (IC50 = 6.18 ± 0.04 µg/mL) showed a good activity. In addition, substrate 1 (IC50 ≤ 1 µg/mL), and its metabolites 2 (IC50 = 4.1 ± 0.60 µg/mL), and 6 (IC50 = 6.8 ± 0.8 µg/mL) also showed a potent inhibition of pro-inflammatory cytokine (TNF-α) production, as compared to the standards drug, pentoxifilline (IC50 = 94.8 ± 2.1 µg/mL). Whereas compounds 3 (IC50 = 57.9 ± 7.6 µg/mL), and 5 (IC50 = 27.2 ± 6.8 µg/mL) showed a moderate inhibition of TNF-α production, while compounds 4 and 7 showed no inhibition. Compounds 1–7 were found to be non-cytotoxic to 3T3 normal cell line (mouse fibroblast).