Fungal biotransformation of diuretic and antihypertensive drug spironolactone with Gibberella fujikuroi, Curvularia lunata, Fusarium lini, and Aspergillus alliaceus

Effects of Impeller Geometry on the 11α-Hydroxylation of Canrenone in Rushton Turbine-Stirred Tanks

The 11α-hydroxylation of canrenone can be catalyzed by Aspergillus ochraceus in bioreactors, where the geometry of the impeller greatly influences the biotransformation. In this study, the effects of the blade number and impeller diameter of a Rushton turbine on the 11α-hydroxylation of canrenone were considered. The results of fermentation experiments using a 50 mm four-blade impeller showed that 3.40% and 11.43% increases in the conversion ratio were achieved by increasing the blade number and impeller diameter, respectively. However, with an impeller diameter of 60 mm, the conversion ratio with a six-blade impeller was 14.42% lower than that with a four-blade impeller. Data from cold model experiments with a large-diameter six-blade impeller indicated that the serious leakage of inclusions and a 22.08% enzyme activity retention led to a low conversion ratio. Numerical simulations suggested that there was good gas distribution and high fluid flow velocity when the fluid was stirred by large-diameter impellers, resulting in a high dissolved oxygen content and good bulk circulation, which positively affected hyphal growth and metabolism. However, a large-diameter six-blade impeller created overly high shear compared to a large-diameter four-blade impeller, thereby decreasing the conversion ratio. The average shear rates of the former and latter cases were 43.25 s^-1 and 35.31 s^-1, respectively. We therefore concluded that appropriate shear should be applied in the 11α-hydroxylation of canrenone. Overall, this study provides basic data for the scaled-up production of 11α-hydroxycanrenone.

Fungal mediated biotransformation of melengestrol acetate, and T-cell proliferation inhibitory activity of biotransformed compounds

Glomerella fusaroide, and Rhizopus stolonifer were effectively able to transform the steroidal hormone melengestrol acetate (MGA) (1) into four (4) new metabolites, 17α-acetoxy-11α-hydroxy-6-methyl-16-methylenepregna-4,6-diene-3,20-dione (2), 17α-acetoxy-11α-hydroxy-6-methyl-16-methylenepregna-1,4,6-triene-3,20-dione (3), 17α-acetoxy-6,7α-epoxy-6β-methyl-16-methylenepregna-4,6-diene-3,20-dione (4), and 17α-acetoxy-11β,15β-dihydroxy-6-methyl-16-methylenepregna-4,6-diene-3,20-dione (5). All these compounds were structurally characterized by different spectroscopic techniques. The objective of the current study was to assess the anti-inflammatory potential of melengestrol acetate (1), and its metabolites 2-5. The metabolites and the substrate were assessed for their inhibitory effects on proliferation of T-cells in vitro. The substrate (IC₅₀ = 2.77 ± 0.08 µM) and its metabolites 2 (IC₅₀ = 2.78 ± 0.07 µM), 4 (IC₅₀ = 2.74 ± 0.1 µM), and 5 (IC₅₀ = < 2 µM) exhibited potent T- cell proliferation inhibitory activities, while compound 3 (IC₅₀ = 29.9 ± 0.09 µM) showed a moderate activity in comparison to the standard prednisolone (IC₅₀ = 9.73 ± 0.08 µM). All the metabolites were found to be non-toxic against 3T3 normal cell line. This study thus identifies some potent compounds active against T-cell proliferation. Their anti-inflammatory potential, therefore, deserves to be further investigated.

Biotransformation of androst-4-ene-3,17-dione and nandrolone decanoate by genera of Aspergillus and Fusarium

The ability of five fungal species belonging to two genera of Aspergillus and Fusarium has been examined in the microbial transformation of androst-4-ene-3, 17-dione (AD). Furthermore, the biotransformation of nandrolone decanoate (2) by F. fujikuroi has been studied. AD (1) was converted by cultures of Aspergillus sp. PTCC 5266 to form 11α-hydroxy-AD (3) as the only product, with a yield of 86% in 3 days. Moreover, two hydroxylated metabolites 11α-hydroxy-AD (3, 65%) and 7β-hydroxy-AD (4; 18%) were isolated in biotransformation of AD by A. nidulans. On the other hand, it was metabolized by F. oxysporum to produce 14α-hydroxy-AD (5; 38%) and testosterone (6; 12%). Microbial transformation of AD by F. solani led to the production of 11α-hydroxy-AD (3; 54%) and testosterone (6; 14%). AD was reduced at the 17-position by F. fujikuroi to produce testosterone in the yield of 42%. Finally, nandrolone decanoate was transformed by F. fujikuroi via hydrolysis and oxidation at the 17-position to produce two metabolites namely 17β-hydroxyestr-4-en-3-one (7, 25.4%) and estr-4-en-3,17-dione (8, 33%), respectively. The all metabolites were purified and subsequently identified based on their spectra data analysis and comparing them to the literature data.