New steroidal anti-inflammatory antedrugs: methyl 21-desoxy-21-chloro-11beta,17alpha-dihydroxy-3,20-dioxo-1, 4-pregnadiene-16alpha-carboxylate, methyl 21-desoxy-21-chloro-11beta-hydroxy-3,20-dioxo-1, 4-pregnadiene-16alpha-carboxylate, and their 9alpha-fluoro derivatives*

Synthesis and crystal structures of D-annulated pentacyclic steroids: looking within and beyond AR signalling in prostate cancer

Carbocyclic steroids D-annulated at 16α and 17α positions with a 5-membered ring E are easily accessible via the interrupted Nazarov cyclization. Three steroid series have been structurally studied: chlorine-containing D-annulated...

Biotransformation of progesterone and testosterone enanthate by Circinella muscae

In this study, the biotransformation of progesterone (1) and testosterone enanthate (5) using the whole cells of Circinella muscae was investigated for the first time. Microbial transformation of 1 with C. muscae afforded three known metabolites including 9α-hydroxyprogesterone (2), 14α-hydroxyprogesterone (3) and 6β,14α dihydroxyprogesterone (4) after 6 days of incubation at 26 °C. The biotransformation of 5 with C. muscae yielded a new metabolite; 8β,14α-dihydroxytestosterone (8), in addition to two known metabolites; 6β-hydroxytestosterone (6), and 9α-hydroxytestosterone (7). The structure of the metabolites were established on the basis of spectroscopic data.

Biotransformation of cholesterol and 16,17-alpha epoxypregnenolone by novel Cladosporium sp. strain IS547

Nowadays, there are a few steroid drugs or intermediates that have been obtained via the transformation of microorganisms, and many strains of transformed steroids have not been found yet. Therefore, it is very significant to screen for the strains that have the abilities to transform steroids to produce valuable products. This study has focused on the screen and identification of strains, the structural identification of converted products, and the optimization of transformation conditions, as well as the establishment of transformation systems. A soil microbiota was screened for strain involved in the biotransformation of steroids. A new isolate IS547 is capable of converting a variety of steroids (such as cholesterol, ergosterol, hydrocortisone, progesterone, pregnenolone, and 16,17-alpha-epoxypregnenolone). Based on the 18S rDNA gene sequence comparison, the isolate IS547 has been demonstrated to be very closely related to Cladosporium sp. genus. Present paper is the first report regarding the microbial transformation by Cladosporium sp. to produce active intermediates, which include 7-hydroxy cholesterol, 20-droxyl-16α,17α-epoxypregna-4-dien-3-one, 7-ketocholesterol, and 7-droxyl-16α,17α-epoxypregna-4-dien-3,20-dione. Under the optimum conditions, the yields of product 3 and product 4 were 20.58 and 17.42%, respectively, higher than that prior to the optimization. The transformation rate increased significantly under the optimum fermentation conditions. This study describes an efficient, rapid, and inexpensive biotransformation system for the production of active pharmaceutical intermediates.

Biological transformations of steroidal compounds: a review

Microbial transformation is an important tool for structural modification of organic compounds, especially natural products with complex structures like steroids. It can be used to synthesize chemical structures that are difficult to obtain by ordinary methods and as a model of mammalian metabolism due to similarity between mammalian and microbial enzyme systems. During recent years research has been focused on the structural modifications of bioactive steroids by using various microorganisms, in order to obtain biologically potent compounds with diverse structures. Steroidal compounds are responsible for important biological functions in the cells and manifest a variety of activities. This article covers the microbial transformation of sterols, steroidal hormones and some new types of steroids known as bufadienolides. Emphasis has placed on reporting metabolites that may be of general interest and on the practical aspects of work in the field of microbial transformations. The review covers the literature from 1994 to 2011.

Chirality effect of C-20 on metabolism of methyl 11beta,17alpha,20-trihydroxy-3-oxo-1,4-pregnadien-21-oate derivatives

Epimers at C-20 of methyl 11beta,17alpha,20-trihydroxy-3-oxo-1,4-pregnadien-21-oates, their 9alpha-fluoro analogs, their carbonate derivatives, and their acetonide derivatives were subjected to metabolism study in rat plasma and rat liver homogenate. These steroids were synthesized based on the antedrug concept. In rat plasma, the carboxy ester bonds of 20beta-triols and their acetonides were hydrolyzed with half-lives (T(1/2)) of between 5.7 and 7.7 min, while their corresponding alpha-epimers had longer half-lives of more than 2.5 h. A more profound difference was observed between the alpha- and beta-epimers of the carbonates, with the latter showing a T(1/2) less than 1 min (0.3 and 0.43 min for P20beta- and PF20beta-carbonate, respectively), while that of the former about 3 h (165 min for P20alpha-carbonate and 191 min for PF20alpha-carbonate). In rat liver homogenate, the triol and acetonide derivatives showed greater stability than they did in rat plasma, with T(1/2) for the beta-group in the range of 54-108 min, and T(1/2) for the alpha-group over 7 h. A significant difference in hydrolysis of the carbonate derivatives was also observed in rat liver homogenate. The half-lives of P20beta- and PF20beta-carbonate were 0.67 and 0.66 min, respectively, and the alpha-isomers showed the similar metabolic rate with other alpha-isomers. An esterase inhibitor effectively blocked the hydrolysis of the ester bond, indicating that this metabolism is an enzymatic reaction. Molecular modeling studies show that steric hindrance around the ester group of the alpha-epimers is much greater than that of their beta-counterparts, affording one explanation for the large difference in the metabolic hydrolysis rate; i.e. the carboxy ester bond of beta-isomer which is less hindered sterically than their counter alpha-isomers is hydrolyzed faster than that of alpha-isomers. In conclusion, this study confirms that chirality at C-20 had profound effects on metabolism and pharmacological profile of the steroid acid ester derivatives.

Prodrug and antedrug: two diametrical approaches in designing safer drugs

The prodrug and antedrug concepts, which were developed to overcome the physical and pharmacological shortcomings of various therapeutic classes of agents, employ diametrically different metabolic transformations. The prodrug undergoes a predictable metabolic activation prior to exhibiting its pharmacological effects in a target tissue while the antedrug undergoes metabolic deactivation in the systemic circulation upon leaving a target tissue. An increased therapeutic index is the aspiration for both approaches in designing as well as evaluation criteria. The recent research endeavors of prodrugs include the gene-directed and antibody-directed enzymatic activation of a molecule in a targeted tissue, organ specific delivery, improved bioavailabilities of nucleosides and cellular penetration of nucleotides. As for antedrugs, emphasis in research has been based upon the design and synthesis of systemically inactive molecule by incorporating a metabolically labile functional group into an active molecule.

New steroidal antiinflammatory antedrugs: Methyl 3,20-dioxo-9 alpha-fluoro-11 beta,17 alpha,21-trihydroxy-1,4-pregnadiene-16 alpha-carboxylate and its 21-O-acyl derivatives

In a continuing effort to increase local to systemic activity ratios of potent steroidal antiinflammatory antedrugs, a series of 21-O-acyl derivatives of methyl 3,20-dioxo-9 alpha-fluoro-11 beta,17 alpha,21-trihydroxy-1,4-pregnadiene-16 alpha-carboxylate, FP16CM, were synthesized. These derivatives were evaluated for antiinflammatory activity and their adverse effects in an acute and semi-chronic croton oil-induced ear edema bioassay. Following a single topical application in the croton oil-induced ear edema bioassay, treatment with all the compounds resulted in dose-dependent inhibition of edema. From these dose-response profiles, the following ID(50) values (nmol/ear resulting in a 50% reduction of edema) were calculated: prednisolone (Pred); 454, FP16CM; 255, 21-acetate (FP16CM-acetyl); 402, 21-propionate (FP16CM-propionyl); 474, 21-valerate (FP16CM-valeryl); 446 and 21-pivalate (FP16CM-pivalyl); 219 nmol. In a 5-day semi-chronic study at the equipotent doses, the novel steroidal antedrugs did not significantly alter body weight gain, thymus weights or plasma corticosterone levels unlike the parent compound Pred. The compounds were assessed for high-affinity glucocorticoid receptor binding and glucocorticoid-mediated inhibition of nitric oxide (NO) generation in an in vitro RAW 264.7 macrophage cell culture system. Binding affinities for cytosolic glucocorticoid receptors were Pred; 85, FP16CM-acetyl; 86, FP16CM-propionyl; 169, FP16CM-valeryl; 149, FP16CM-pivalyl; 126 nM, respectively. Concomitant potencies for inhibition of NO generation by macrophages stimulated with lipopolysaccharide were Pred; 159, FP16CM-acetyl; 377, FP16CM-propionyl; 405, FP16CM-valeryl; 344, FP16CM-pivalyl; 311 nM, respectively. Collectively, results of these investigations suggest that esterification of 21-OH with various anhydrides did not improve receptor binding, inhibition of NO generation and ear edema inhibition, however, serum corticosterone level and local over systemic activities (L/S) were markedly improved.