The influence of β-cyclodextrin on the kinetics of progesterone transformation byRhizopus nigricans

Hydroxylation of Progesterone and Its Derivatives by the Entomopathogenic Strain Isaria farinosa KCh KW1.1

Progesterone biotransformation is worth studying because of the high industrial value of its derivatives. This study investigated the catalytic ability of the entomopathogenic filamentous fungus strain Isaria farinosa KCh KW1.1 to transform progesterone derivatives: 11α-hydroxyprogesterone, 17α-hydroxyprogesterone, 16α,17α-epoxyprogesterone and pregnenolone. In the culture of Isaria farinosa KCh KW1.1, 11α-hydroxyprogesterone was effectively transformed into only one product: 6β,11α-dihydroxyprogesterone. Transformation of 17α-hydroxyprogesterone gave three hydroxy derivatives: 6β,17α-dihydroxyprogesterone, 12β,17α-dihydroxyprogesterone and 6β,12β,17α-trihydroxyprogesterone. Two products: 6β-hydroxy-16α,17α-epoxyprogesterone and 6β,11α-dihydroxy-16α,17α-epoxyprogesterone, were obtained from the 16α,17α-epoxyprogesterone transformation. We isolated two compounds from the biotransformation medium with pregnenolone: 11α-hydroxy-7-oxopregnenolone and 5α,6α-epoxy-3β,11α-dihydroxypregnan-7,20-dione. In this study, we observed only mono- and dihydroxy derivatives of the tested substrates, and the number of obtained products for each biotransformation did not exceed three.

Production of 4-androstene-3,17-dione and 1,4-androstadiene-3,17-dione from rice germ and wheat germ extracts by Mycobacterium sp

OBJECTIVE

To study the biotransformation of phytosterol and phytosterol-containing rice germ and wheat germ ethanolic extracts to produce 4-androstene-3,17-dione (AD) and 1,4-androstadiene-3,17-dione (ADD) by Mycobacterium sp. DSM 2966 using phytosterol to hydroxypropyl-β-cyclodextrin (2:1, 1:1 and 1:2 mol/mol) and 2 % (w/v) Tween 80 as solubilizing agents.

RESULTS

A maximum yield of 180 ± 27 mg AD l(-1) and 31 ± 11.4 mg ADD l(-1) with a total conversion of 65 % (day 12) was obtained using 1 g phytosterol l(-1) and hydroxypropyl-β-cyclodextrin (2 : 1 mol/mol) with 2 % (w/v) Tween 80 in the fermentation medium. The most appropriate conditions for rice germ extract and wheat germ extract which gave the maximum conversion of 22 and 43 % (day 14) were obtained by using 2 % (w/v) Tween 80.

CONCLUSIONS

Phytosterol and wheat germ are effective sources for AD and ADD production while rice germ required further development. Hydroxypropyl-β-cyclodextrin (2 :1 mol/mol) and/or 2 % (w/v) Tween 80 in the biotransformation process could improve AD and ADD yields, depending on substrates and biotransformation conditions.

Optimization of biotransformation from phytosterol to androstenedione by a mutant Mycobacterium neoaurum ZJUVN-08

Biotransformation of phytosterol (PS) by a newly isolated mutant Mycobacterium neoaurum ZJUVN-08 to produce androstenedione has been investigated in this paper. The parameters of the biotransformation process were optimized using fractional factorial design and response surface methodology. Androstenedione was the sole product in the fermentation broth catalyzed by the mutant M. neoaurum ZJUVN-08 strain. Results showed that molar ratio of hydroxypropyl-β-cyclodextrin (HP-β-CD) to PS and substrate concentrations were the two most significant factors affecting androstenedione production. By analyzing the statistical model of three-dimensional surface plot, the optimal process conditions were observed at 0.1 g/L inducer, pH 7.0, molar ratio of HP-β-CD to PS 1.92:1, 8.98 g/L PS, and at 120 h of incubation time. Under these conditions, the maximum androstenedione yield was 5.96 g/L and nearly the same with the non-optimized (5.99 g/L), while the maximum PS conversion rate was 94.69% which increased by 10.66% compared with the non-optimized (84.03%). The predicted optimum conditions from the mathematical model were in agreement with the verification experimental results. It is considered that response surface methodology was a powerful and efficient method to optimize the parameters of PS biotransformation process.

Influence of hydroxypropyl-β-cyclodextrin on phytosterol biotransformation by different strains of Mycobacterium neoaurum

Cyclodextrins (CDs) can improve productivity in the biotransformation of steroids by increasing conversion rate, conversion ratio, or substrate concentration. However, little is known of the proportion of products formed by multi-catabolic enzymes, e.g., via sterol side chain cleavage. Using three strains with different androst-1,4-diene-3,17-dione (ADD) to androst-4-ene-3,17-dione (AD) ratios, Mycobacterium neoaurum TCCC 11028 (MNR), M. neoaurum TCCC 11028 M1 (MNR M1), and M. neoaurum TCCC 11028 M3 (MNR M3), we found that hydroxypropyl-β-cyclodextrin (HP-β-CD) can appreciably increase the ratio of ADD to AD, the reaction rate, and the molar conversion. In the presence of HP-β-CD, conversion of 0.5 g/L of phytosterol (PS) was 2.4, 2.4, and 2.3 times higher in the MNR, MNR M1, and MNR M3 systems, respectively, than in the controls. The ADD proportion increased by 38.4, 61.5, and 5.9 % compared with the control experiment, which resulted in a strong shift in the ADD/AD ratio in the ADD direction. Our results imply that the three PS-biotransforming strains cause efficient side chain degradation of PS, and the increased conversion of PS when using HP-β-CD may be associated with the higher PS concentration in each case. A similar solubilizing effect may not induce a prominent influence on the ADD/AD ratio. However, the different activities of the Δ1-dehydrogenase of PS-biotransforming strains result in different incremental percentage yields of ADD and ADD/AD ratio in the presence of HP-β-CD.

Microbial steroid transformations: current state and prospects

Studies of steroid modifications catalyzed by microbial whole cells represent a well-established research area in white biotechnology. Still, advances over the last decade in genetic and metabolic engineering, whole-cell biocatalysis in non-conventional media, and process monitoring raised research in this field to a new level. This review summarizes the data on microbial steroid conversion obtained since 2003. The key reactions of structural steroid functionalization by microorganisms are highlighted including sterol side-chain degradation, hydroxylation at various positions of the steroid core, and redox reactions. We also describe methods for enhancement of bioprocess productivity, selectivity of target reactions, and application of microbial transformations for production of valuable pharmaceutical ingredients and precursors. Challenges and prospects of whole-cell biocatalysis applications in steroid industry are discussed.

Effects of hydroxypropyl-β-cyclodextrin on cell growth, activity, and integrity of steroid-transforming Arthrobacter simplex and Mycobacterium sp

A comparative investigation was performed on the effects of hydroxypropyl-β-cyclodextrin (HP-β-CD) on the growth, biocatalytic activity, and cell integrity of Arthrobacter simplex TCCC 11037 (ASP) and Mycobacterium sp. NRRL B-3683 (MSP). The addition of HP-β-CD to ASP medium improved its cell wall permeability for lipophilic compounds but significantly inhibited its growth and biocatalytic activity. On the other hand, the addition of HP-β-CD to MSP broth had lesser effects. Atomic force microscopy scanning analysis revealed that HP-β-CD damaged the cell integrity in ASP, especially the outermost cell surface structure, but not in MSP, which remained intact, owing to the differences in their cell wall and cell membrane composition. Protein leaking and lipid content in ASP increased with increased HP-β-CD concentration, indicating possible alterations in ASP cell membrane features caused by HP-β-CD. These alterations may also explain the slow cell growth and decreased cell ΔΨm in ASP upon the addition of HP-β-CD.

The influence of host-guest inclusion complex formation on the biotransformation of cortisone acetate Delta(1)-dehydrogenation

An intensive and systematic investigation had been carried out on the Delta(1)-dehydrogenation of cortisone acetate (CA) to prednisone acetate (PA) by Arthrobacter simplex TCCC 11037 in the presence of native and modified beta-cyclodextrins (beta-CDs). The biotransformation was improved through the formation of the host-guest inclusion complex between CA and CDs in aqueous solution. The inclusion complexes of CDs with CA were investigated by means of phase solubility, 2D NMR spectroscopy and differential scanning calorimetry (DSC). The structural difference of CDs resulted in the stoichiometric differences between the complexes, the RM-beta-CD-CA, SBE-beta-CD-CA, HP-beta-CD-CA complexes were 1:1 whereas beta-CD-CA gave both 1:1 and 2:1 complexes, of which the 2:1 complex decreased the soluble CA concentration and inhibited the dissociation of beta-CD-CA in aqueous solution. The increase in solubility of CA was in the order of RM-beta-CD>SBE-beta-CD>HP-beta-CD>beta-CD. RM-beta-CD-CA, SBE-beta-CD-CA and HP-beta-CD-CA exhibited the higher biotransformation rate in comparison with native beta-CD. And the solubilization of CDs for CA in aqueous medium plays a key role in the biotransformation process. The article focuses on the various factors influencing the substrate water solubility, complex stability and biotransformation of CA through the addition of CDs in order to solve many problems associated with the process of drug delivery and biotransformation of different novel steroids.

Improvement of steroid biotransformation with hydroxypropyl-beta-cyclodextrin induced complexation

The inclusion complexes induced by cyclodextrins and its derivates have been shown previously to enhance the biotransformation of hydrophobic compounds. Using hydroxypropyl-beta-cyclodextrin (HP-beta-CD; 20% w/v), the water solubility of cortisone acetate increased from 0.039 to 7.382 g L(-1) at 32 degrees C. The solubilization effect of HP-beta-CD was far superior to dimethylformamide (DMF) and ethanol. The dissolution rate also significantly increased in the presence of HP-beta-CD. The enzymatic stability of Delta(1)-dehydrogenase from Arthrobacter simplex TCCC 11037 was not influenced by the increasing concentrations of HP-beta-CD contrary to the organic cosolvents which negatively influenced in the order DMF > ethanol. The activity inhibition effect caused by HP-beta-CD was not so conspicuous as ethanol and DMF. Inactivation constants of ethanol, DMF, and HP-beta-CD were 5.832, 4.541, and 1.216, respectively. The inactivation energy (E (a)) was in the order of HP-beta-CD (55.1 kJ mol(-1)) > ethanol (39.9 kJ mol(-1)) > DMF (37.1 kJ mol(-1)).