Biotransformation of Some Steroids by Aspergillus Candidus

Abstract

pathogen for humans. 4 Steroid biotransformations by A. candidus have not been described in the literature. In this work, dehydroepiandrosterone 1, progesterone 2 and pregnenolone 3 were incubated with A. candidus MRC 200634 for 5 days.Incubation of dehydroepiandrosterone 1 with A. candidus MRC 200634 for 5 days afforded six metabolites (Table 1). The first metabolite was identified as 3β,17β-dihydroxyandrost-5-ene 4 (Fig. 1). The metabolite had a new resonance (1H, t, J = 8.5 Hz) at δ H 3.65 ppm in its 1 H NMR spectrum and showed an upfield shift (Δ 0.11 ppm) for the 18-methyl resonance of the starting material, suggesting the presence of a 17β-hydroxy group. The 13 C NMR spectrum of the metabolite lacked the C-17 resonance of 1 at δ C 221.30 ppm and had a new carbon atom resonance at δ C 81.87 ppm (Table 2), which were in accordance with the reduction at C-17.The second metabolite was identified as 6β,17βdihydroxyandrost-4-en-3-one 5. The metabolite showed characteristic resonances at δ H 4.34 ppm 5 (1H, bs) and δ C 72.56 ppm 6 , suggesting the presence of a 6β-hydroxy group. The 1 H NMR spectrum of the metabolite lacked the 3-H resonance of starting material at δ H 3.46 ppm (1H, tt, J = 5.0 and 12.0 Hz) and the double bond resonance of 1 at δ H 5.35 ppm (1H, d, J = 5.0 Hz) had an important downfield shift to δ H 5.82 ppm (∆ 0.47 ppm), suggesting that the 5-en-3β-hydroxy moiety of 1 was converted into the 4-en-3-keto moiety. The 1 H NMR spectrum of the metabolite demonstrated a significant downfield shift (∆ 0.37 ppm) for the 19-methyl group, further suggesting the presence of the 4-en-3-keto moiety. The metabolite had a new resonance (1H, t, J = 8.5 Hz) at δ H 3.65 ppm in its 1 H NMR spectrum and showed an upfield shift (Δ 0.05 ppm) for the

The Biotransformation of Some Steroids by Aspergillus Sydowii MRC 200653

“…Incubation of pregnenolone 4 with A. sydowii MRC 200653 for 5 days yielded the same five metabolites (Fig. 1), which were identified by comparison of their 1 H and 13 C NMR spectra with those of the previously isolated metabolites from the incubation of progesterone 3 with the same fungus.…”

“…In a recent work, incubations of progesterone 3 and pregnenolone 4 with Aspergillus candidus also yielded 15β-hydroxypregn-4-en-3,20-dione 11, 11α-hydroxypregn-4en-3,20-dione 12, 11α,15β-dihydroxypregn-4-en-3,20-dione 13 and the 14α-hydroxy derivative of progesterone 3. 13 The yields from the incubation of progesterone 3 with A. candidus were higher than those from the incubation of pregnenolone 4 with the same fungus.…”

“…The metabolite had characteristic resonances at δ H 3.63 ppm (1H, m) and δ C 71.27 ppm, suggesting the presence of a 7β-hydroxy group. 8 The 13 C NMR spectrum of the metabolite showed a downfield shift for C-6 (∆ 9.88 ppm) and a γ-gauche upfield shift for C-5 (∆ 3.25), in accord with the presence of a 7β-hydroxy group. The metabolite showed other new resonances at δ H 4.46 ppm (1H, m) and δ C 73.69 ppm, which were typical of a 15β-hydroxy group.…”

“…The metabolite had characteristic resonances at δ H 4.13 ppm (1H, dt, J = 4 and 10 Hz) and δ C 72.51 ppm, indicating the presence a 15α-hydroxy group. 7 The 13 C NMR spectrum of the metabolite showed downfield shifts for C-14 (∆ 8.44 ppm) and C-16 (∆ 12.94 ppm) and there was a γ-gauche upfield shift for C-17 (∆ 1.98 ppm) confirming the presence of a 15α-hydroxy group.…”

“…The metabolite showed a typical resonance (1H, bs) at δ H 3.96 ppm and a downfield shift (∆ 0.28 ppm) for the 6-H resonance of 2, suggesting the presence of a 7α-hydroxy group. 7 The 13 C NMR spectrum of the metabolite showed downfield shifts for C-6 (∆ 2.53 ppm) and C-8 (∆ 5.93 ppm) and γ-gauche upfield shifts for C-9 (∆ 8.41 ppm) and C-14 (∆ 6.92 ppm), revealing the presence of a 7α-hydroxy group.…”