Microbial biotransformation of bioactive and clinically useful steroids and some salient features of steroids and biotransformation

A Dehydrogenative Diels-Alder/Aromatization Sequence to Access 6/6/6/6/5 Pentacyclic Steroids: Their Anti-inflammatory Activities

6/6/6/6/5 Pentacyclic steroids represent an emerging class of architecturally unique and biologically promising steroids. Herein, we developed a DDQ-mediated dehydrogenative Diels-Alder/aromatization cascade reaction between ergosterol derivatives and dienophiles inspired by plausible biosynthetic pathways, which enabled straightforward access to various 6/6/6/6/5 pentacyclic steroids in 24-66% yields. This work offers significant advantages in assembling 6/6/6/6/5 pentacyclic steroids such as the use of inexpensive starting materials, mild reaction conditions, and simple operations. Furthermore, the anti-inflammatory investigations of these steroids on LPS-stimulated RAW264.7 cells led to the discovery of four steroids (i.e., 2h, 4f, 5b, and 5f) as potent anti-inflammatory agents with minimal side effects. This work not only achieves a rapid and biomimetic approach to the unique pentacyclic steroids but also unveils their therapeutic potential in anti-inflammation therapy.

Untargeted metabolomics unravels the effects of ginkgolide B-producing Lactiplantibacillus plantarum and co-induced fermentation of ginkgo kernel juice and their underlying vascular endothelial cell protection activity

The objective of this study was to investigate the fermentation mechanism of ginkgo kernel juice (GKJ) under unfermented (Group A), Ginkgolide B (GB)-producing Lactiplantibacillus plantarum fermented (Group B), and co-induced fermented (Group C) conditions. The conditions were optimized and further evaluated for their vascular endothelial cell protective effects in vitro. The co-induced fermented GKJ group extensively promoted GB and total phenol contents, reaching 109.94 and 599.57 μg/mL, respectively. While pH declined from 5.90 to 3.42 during fermentation, the highest total viable count (8.85 log CFU/mL) was detected at 16 h in the L. plantarum group. The co-induced group recorded the highest total phenol contents (594.05 μg/mL) and markedly induced the survival rate, reactive oxygen species formation, and lactate dehydrogenase assay cytotoxicity of H2O2-induced human umbilical vein endothelial cells. An untargeted metabolomics analysis identified 2633 metabolites in the groups. The principal component and orthogonal partial least squares discriminant score plots showed a clear metabolite distinction among the fermentation groups. From the Kyoto Encyclopedia of Genes and Genomes analysis, 309 differential accumulated metabolites (DAMs) were up-regulated and 604 were down-regulated in the A vs. B group, while 702 downregulated and 304 upregulated DAMs were exhibited in the B vs. C group. These DAMs were primarily lipids and lipid-like molecules, organic acids and their derivatives, organoheterocyclic compounds, organic oxygen compounds, benzenoids, phenylpropanoids and polyketides, and unclassified compounds at the superclass level. Overall, the results indicated that L. plantarum and co-induced fermentation improved the cell protection efficacy of GKJ, showing excellent potential for drug delivery applications.

Functional characterization and unraveling the structural determinants of novel steroid hydroxylase CYP154C7 from Streptomyces sp. PAMC26508

This study characterized cytochrome P450 enzyme CYP154C7 from Streptomyces sp. PAMC26508, emphasizing its capability to hydroxylate steroids, especially at the 16α-position. The enzymatic assay of CYP154C7 demonstrated effective conversion across a pH range of 7.2-7.6, with optimal activity at 30 °C in the Pdx/PdR plus NADH system. Kinetic analysis on most converted steroids (androstenedione and adrenosterone) was performed which shows a greater affinity for androstenedione (K m , 11.06 ± 1.903 μM; V max, 0.0062 ± 0.0002 sec-1) compared to adrenosterone (K m , 34.50 ± 6.2 μM; V max, 0.0119 ± 0.0007 sec-1). A whole-cell system in Escherichia coli, overexpressing recombinant CYP154C7, achieved substantial conversion for steroids, indicating that CYP154C7 can also be used as a potential whole-cell biocatalyst. To gain structural insights, homology models of CYP154C7 and its homologs were constructed using CYP154C5 (PDB ID: 6TO2), refined, validated, and used for docking studies. Comparative docking analysis suggests that lysine (K236) in the active site and tyrosine (Y197) in the substrate access channel of CYP154C7 are crucial for substrate selectivity and catalytic efficiency. This study suggests that CYP154C7 could be a promising candidate for developing modified steroids, providing valuable insights for protein engineering to design commercially useful CYP steroid hydroxylases with diverse substrate specificities.

Modification of B-Nor Steroids Mediated by Filamentous Fungus Fusarium culmorum: Focus on 15α-Hydroxylase Activity

The metabolic activities of microorganisms to modify the chemical structures of organic compounds are an effective tool for the production of high-value steroidal drugs or active pharmaceutical ingredients (APIs). The integration of biotransformation into the synthesis of APIs can greatly reduce the number of reaction steps and achieve higher process efficiency, thus enabling their greener production. The current research efforts are focused on either the optimization of existing processes or identification of new potentially useful bioconversions. This study aimed to assess the catalytic abilities of the filamentous fungus Fusarium culmorum AM 282 to transform B-nor analogues (5(6→7)abeo compounds) of steroid hormones: androstenedione (AD), dehydroepiandrosterone (DHEA) and its acetate. Our previous studies have demonstrated that this strain is an active hydroxylating catalyst for many steroidal compounds with diverse structures. The results presented in this work showed that the hydroxylation of B-nor steroids occurred with the regio- and stereoselectivity typical of this strain in relation to the corresponding natural hormones of the standard 6:6 A/B series. After the transformations of B-nor-DHEA and its acetate, 15α-hydroxy-B-nor-DHEA was obtained as the sole product of the reaction, while the transformation of the AD analogue resulted in a mixture of its 15α- and 6α-hydroxy derivatives. A detailed analysis of the transformation course indicated that all the obtained hydroxy derivatives could be the result of the activity of the same enzyme. The presented results may provide a basis for research aimed at understanding the molecular nature of cytochrome P-450 monooxygenase from F. culmorum AM 282 with its ability for 15α-hydroxylation of steroidal compounds. An analysis of the pharmacokinetic and pharmacodynamic properties of the obtained metabolites with cheminformatics tools suggests their potential biological activity.

Recent developments in the enzymatic modifications of steroid scaffolds

Steroids are an important family of bioactive compounds. Steroid drugs are renowned for their multifaceted pharmacological activities and are the second-largest category in the global pharmaceutical market. Recent developments in biocatalysis and biosynthesis have led to the increased use of enzymes to enhance the selectivity, efficiency, and sustainability for diverse modifications of steroids. This review discusses the advancements achieved over the past five years in the enzymatic modifications of steroid scaffolds, focusing on enzymatic hydroxylation, reduction, dehydrogenation, cascade reactions, and other modifications for future research on the synthesis of novel steroid compounds and related drugs, and new therapeutic possibilities.

Metabolism of natural and synthetic bioactive compounds in Cunninghamella fungi and their applications in drug discovery

Investigation of xenobiotic metabolism is a key step for drug discovery. Since the in vivo investigations may be associated with harmful effects attributed to production of toxic metabolites, it is deemed necessary to predict their structure especially at the preliminary clinical studies. Furthermore, the application of microorganisms that are capable of metabolizing drugs mimic human metabolism and consequently may predict possible metabolites. The genus Cunninghamella has been proven to be a potential candidate, which mimics xenobiotic metabolism occurring inside the human body, including phase I and II metabolic reactions. Moreover, biotransformation with Cunninghamella showed chemical diversity, where a lot of products were detected in relation to the initial substrates after being modified by oxidation, hydroxylation, and conjugation reactions. Some of these products are more bioactive than the parent compounds. The current review presents a comprehensive literature overview regarding the Cunninghamella organisms as biocatalysts, which simulate mammalian metabolism of natural secondary and synthetic compounds.

Improved 2α-Hydroxylation Efficiency of Steroids by CYP154C2 Using Structure-Guided Rational Design

Cytochrome P450 enzymes are promising biocatalysts for industrial use because they catalyze site-selective C-H oxidation and have diverse catalytic reactions and a broad substrate range. In this study, the 2α-hydroxylation activity of CYP154C2 from Streptomyces avermitilis MA-4680T toward androstenedione (ASD) was identified by an in vitro conversion assay. The testosterone (TES)-bound structure of CYP154C2 was solved at 1.42 Å, and this structure was used to design eight mutants, including single, double, and triple mutants, to improve the conversion efficiency. Mutants L88F/M191F and M191F/V285L were found to enhance the conversion rates significantly (i.e., 8.9-fold and 7.4-fold for TES, 46.5-fold and 19.5-fold for ASD, respectively) compared with the wild-type (WT) enzyme while retaining high 2α-position selectivity. The substrate binding affinity of the L88F/M191F mutant toward TES and ASD was enhanced compared with that of WT CYP154C2, supporting the measured increase in the conversion efficiencies. Moreover, the total turnover number and kcat/Km of the L88F/M191F and M191F/V285L mutants increased significantly. Interestingly, all mutants containing L88F generated 16α-hydroxylation products, suggesting that L88 in CYP154C2 plays a vital role in substrate selectivity and that the amino acid corresponding to L88 in the 154C subfamily affects the orientation of steroid binding and substrate selectivity. IMPORTANCE Hydroxylated derivatives of steroids play essential roles in medicine. Cytochrome P450 enzymes selectively hydroxylate methyne groups on steroids, which can dramatically change their polarity, biological activity and toxicity. There is a paucity of reports on the 2α-hydroxylation of steroids, and documented 2α-hydroxylate P450s show extremely low conversion efficiency and/or low regio- and stereoselectivity. This study conducted crystal structure analysis and structure-guided rational engineering of CYP154C2 and efficiently enhanced the conversion efficiency of TES and ASD with high regio- and stereoselectivity. Our results provide an effective strategy and theoretical basis for the 2α-hydroxylation of steroids, and the structure-guided rational design of P450s should facilitate P450 applications in the biosynthesis of steroid drugs.

Loop pathways are responsible for tuning the accumulation of C19- and C22-sterol intermediates in the mycobacterial phytosterol degradation pathway

4-Androstene-3,17-dione (4-AD) and 22-hydroxy-23,24-bisnorchol-4-ene-3-one (BA) are the most important and representative C19- and C22-steroidal materials. The optimalization of sterol production with mycobacterial phytosterol conversion has been investigated for decades. One of the major challenges is that current industrial mycobacterial strains accumulate unignorable impurities analogous to desired sterol intermediates, significantly hampering product extractions and refinements. Previously, we identified Mycobacterium neoaurum HGMS2 as an efficient 4-AD-producing strain (Wang et al. in Microb Cell Fact. 19:187, 2020). Recently, we have genetically modified the HGMS2 strain to remove its major impurities including ADD and 9OH-AD (Li et al. in Microb Cell Fact. 20:158, 2021). Unexpectedly, the modified mutants started to significantly accumulate BA compared with the HGMS2 strain. In this work, while we attempted to block BA occurrence during 4-AD accumulation in HGMS2 mutants, we identified a few loop pathways that regulated metabolic flux switching between 4-AD and BA accumulations and found that both the 4-AD and BA pathways shared a 9,10-secosteroidial route. One of the key enzymes in the loop pathways was Hsd4A1, which played an important role in determining 4-AD accumulation. The inactivation of the hsd4A1 gene significantly blocked the 4-AD metabolic pathway so that the phytosterol degradation pathway flowed to the BA metabolic pathway, suggesting that the BA metabolic pathway is a complementary pathway to the 4-AD pathway. Thus, knocking out the hsd4A1 gene essentially made the HGMS2 mutant (HGMS2^Δhsd4A1) start to efficiently accumulate BA. After further knocking out the endogenous kstd and ksh genes, an HGMS2^Δhsd4A1 mutant, HGMS2^{Δhsd4A1/Δkstd1}, enhanced the phytosterol conversion rate to BA in 1.2-fold compared with the HGMS2^Δhsd4A1 mutant in pilot-scale fermentation. The final BA yield increased to 38.3 g/L starting with 80 g/L of phytosterols. Furthermore, we knocked in exogenous active kstd or ksh genes to HGMS2^{Δhsd4A1/Δ kstd1} to construct DBA- and 9OH-BA-producing strains. The resultant DBA- and 9OH-BA-producing strains, HGMS2^{Δhsd4A1/kstd2} and HGMS2^{Δkstd1/Δhsd4A1/kshA1B1}, efficiently converted phytosterols to DBA- and 9OH-BA with the rates of 42.5% and 40.3%, respectively, and their final yields reached 34.2 and 37.3 g/L, respectively, starting with 80 g/L phytosterols. Overall, our study not only provides efficient strains for the industrial production of BA, DBA and 9OH-BA but also provides insights into the metabolic engineering of the HGMS2 strain to produce other important steroidal compounds.

The traditional uses, phytochemistry and pharmacology of Abrus precatorius L.: A comprehensive review

ETHNOPHARMACOLOGICAL RELEVANCE

Abrus precatorius L. (AP) is a folk medicine with a long-term medicinal history worldwide, which is extensively applied to various ailments, such as bronchitis, jaundice, hepatitis, contraception, tumor, abortion, malaria, etc. Meanwhile, its leaves are also served as tea in China, and its roots are employed as a substitute for Glycyrrhiza uralensis or as a raw material for the extraction of glycyrrhizin in India. Thus, AP is considered to be a plant with dual values of medicine and economy as well as its chemical composition and biological activity, which are of growing interest to the scientific community.

AIM OF REVIEW

In the review, the traditional application, botany, chemical constituents, pharmacological activities, and toxicity are comprehensively and systematically summarized.

MATERIALS AND METHODS

An extensive database retrieval was conducted to gather the specific information about AP from 1871 to 2022 using online bibliographic databases Web of Science, PubMed, SciFinder, Google Scholar, CNKI, and Baidu Scholar. The search terms comprise the keywords "Abrus precatorius", "phytochemistry", "pharmacological activity", "toxicity" and "traditional application" as a combination.

RESULTS

To date, AP is traditionally used to treat various diseases, including sore throat, cough, bronchitis, jaundice, hepatitis, abdominal pain, contraception, tumor, abortion, malaria, and so on. More than 166 chemical compounds have been identified from AP, which primarily cover flavonoids, phenolics, terpenoids, steroids, alkaloids, organic acids, esters, proteins, polysaccharides, and so on. A wide range of in vitro and in vivo pharmacological functions of AP have been reported, such as antitumor, antimicrobial, insecticidal, antiprotozoal, antiparasitic, anti-inflammatory, antioxidant, immunomodulatory, antifertility, antidiabetic, other pharmacological activities. The crushed seeds in powder or paste form were comparatively toxic to humans and animals by oral administration. Interestingly, the methanolic extracts were non-toxic to adult Wistar albino rats at various doses (200 and 400 mg/kg) daily.

CONCLUSIONS

The review focuses on the traditional application, botany, phytochemistry, pharmacological activities, and toxicity of AP, which offers a valuable context for researchers on the current research status and a reference for further research and applications of this medicinal plant.

Development of a High-Titer Culture Medium for the Production of Cholesterol by Engineered Saccharomyces cerevisiae and Its Fed-Batch Cultivation Strategy

Steroids are a class of compounds with cyclopentane polyhydrophenanthrene as the parent nucleus, and they usually have unique biological and pharmacological activities. Most of the biosynthesis of steroids is completed by a series of enzymatic reactions starting from cholesterol. Synthetic biology can be used to synthesize cholesterol in engineered microorganisms, but the production of cholesterol is too low to further produce other high-value steroids from cholesterol as the raw material and precursor. In this work, combinational strategies were established to increase the production of cholesterol in engineered Saccharomyces cerevisiae RH6829. The basic medium for high cholesterol production was selected by screening 8 kinds of culture media. Single-factor optimization of the carbon and nitrogen sources of the culture medium, and the addition of calcium ions, zinc ions and citric acid, further increased the cholesterol production to 192.53 mg/l. In the 5-L bioreactor, through the establishment of strategies for glucose and citric acid feeding and dissolved oxygen regulation, the cholesterol production was further increased to 339.87 mg/l, which was 734% higher than that in the original medium. This is the highest titer of cholesterol produced by microorganisms currently reported. The fermentation program has also been conducted in a 50-L bioreactor to prove its stability and feasibility.

Betamethasone Dipropionate Derivatization, Biotransformation, Molecular Docking, and ADME Analysis as Glucocorticoid Receptor

Betamethasone is an important glucocorticoids (GCs), frequently used to cure allergies (such as asthma and angioedema), Crohn's disease, skin diseases (such as dermatitis and psoriasis), systemic lupus erythematosus, rheumatic disorders, and leukemia. Present investigation deals to find potential agonist of glucocorticoid receptors after biotransformation of betamethasone dipropionate (1) and to carry out the molecular docking and ADME analyses. Biotransformation of 1 was carried out with Launaea capitata (dandy) roots and Musa acuminate (banana) leaves. M. acuminate furnished low-cost value-added products such as Sananone dipropionate (2) in 5% yields. Further, biocatalysis of Sananone dipropionate (2) with M. acuminate gave Sananone propionate (3) and Sananone (4) in 12% and 7% yields, respectively. However, Sananone (4) was obtained in 37% yields from Launaea capitata. Compound 5 was obtained in 11% yield after β-elimination of propionic acid at C-17 during oxidation of compound 1. The structure elucidation of new compounds 2-5 was accomplished through combined use of X-ray diffraction and NMR (1D and 2D) studies. In addition to this, molecular docking and ADME analyses of all transformed products of 1 were also done. Compounds 1-5 showed -12.53 to -10.11 kcal/mol potential binding affinity with glucocorticoid receptor (GR) and good ADME profile. Moreover, all the compounds showed good oral bioavailability with the octanol/water partition coefficient in the range of 2.23 to 3.65, which indicated that compounds 1-5 were in significant agreement with the given criteria to be considered as drug-like.

Identification of a fungal cytochrome P450 with steroid two-step ordered selective hydroxylation characteristics in Colletotrichum lini

Microbial hydroxylation reaction has greatly enriched the number of steroids and created many meaningful new compounds. The dihydroxylation of dehydroepiandrosterone (DHEA) by filamentous fungi produces an important product 3β,7α,15α-trihydroxy-5-androstene-17-one (7α,15α-diOH-DHEA), which can be used as a key intermediate for the synthesis of contraceptive drospirenone. The introduction of microbial hydroxylation reaction reduces the traditional chemical synthesis process by 4 steps and greatly improves the productivity and economic efficiency. Colletotrichum lini is an industrial strain producing 7α,15α-diOH-DHEA, but the related cytochrome P450 that plays hydroxylation effect has not yet been discovered. In this work, a combination of quantitative proteomics, qRT-PCR, and functional expression in Pichia pastoris was used to identify highly induced steroid hydroxylase from Colletotrichum lini ST-1. A novel fungal cytochrome P450 monooxygenase CYP68JX was identified. The biotransformation in recombinant yeast confirmed that the cytochrome P450 has steroid C7α and C15α hydroxylase activities. The hydroxylation of DHEA by CYP68JX is an ordered reaction, proceeding from the C7 to the C15 site of the steroidal nucleus. The cloning and identification of the CYP68JX gene provide useful information for deepening the understanding regarding the structural basis of its regional and stereoselectivity.

Recent advances in chemical synthesis, biocatalysis, and biological evaluation of diosgenin derivatives - A review

Extracting organic compounds from plants and developing derivatives are essential methods for drug discovery. Diosgenin, extracted from Dioscoreaceae plants, is a type of spirostan steroid with various biological effects, including anti-inflammation, neuro-protection, and apoptosis-induction. Many researchers committed their work to the chemical semi-synthesis of diosgenin derivatives to improve diosgenin's therapeutic bioavailability and expand its range of applications in disease treatment and prevention. Biotransformation, a mild whole-cell biocatalysis method, also made crucial contributions to the structural diversity of diosgenin analogs in recent years. Although the structural modification of diosgenin has made significant progress, it lacks a comprehensive review. Here, we review the chemical modification and biotransformation of diosgenin along with the biological evaluation of diosgenin derivatives to provide a reference for the structural modification strategy and pharmaceutical application of diosgenin derivatives.

Metabolomics-Guided Analysis of the Biocatalytic Conversion of Sclareol to Ambradiol by Hyphozyma roseoniger

The biocatalytic conversion of sclareol to ambradiol, a valuable component in the fragrance industry, using whole-cell biotransformation by the dimorphic yeast Hyphozyma roseoniger, was investigated using metabolomics tools. An integrated approach was used to identify and quantify the participating intermediates in this bioconversion using both nuclear magnetic resonance (NMR) spectroscopy and liquid chromatography coupled to mass spectrometry (LC–MS). This study entailed growth stage-dependent analysis of H. roseoniger suspensions grown in batch culture over a 14-day period, beginning with a three-day induction period using 20 mg/200 mL sclareol, followed by a further 1 g/200 mL sclareol dose to enable ambradiol production. The progress of the bioconversion and the resulting dynamic changes to the metabolome were monitored using NMR analysis and semi-targeted LC–MS metabolomics. This outlined the molecular conversions occurring within the matrix and no novel intermediates participating in the sclareol to ambradiol conversion could be identified. This study presents new findings about the transformative capabilities of H. roseoniger as a whole cell biocatalyst, highlighting its potential utility in similar applications.

Shortening Synthetic Routes to Small Molecule Active Pharmaceutical Ingredients Employing Biocatalytic Methods

Biocatalysis, using enzymes for organic synthesis, has emerged as powerful tool for the synthesis of active pharmaceutical ingredients (APIs). The first industrial biocatalytic processes launched in the first half of the last century exploited whole-cell microorganisms where the specific enzyme at work was not known. In the meantime, novel molecular biology methods, such as efficient gene sequencing and synthesis, triggered breakthroughs in directed evolution for the rapid development of process-stable enzymes with broad substrate scope and good selectivities tailored for specific substrates. To date, enzymes are employed to enable shorter, more efficient, and more sustainable alternative routes toward (established) small molecule APIs, and are additionally used to perform standard reactions in API synthesis more efficiently. Herein, large-scale synthetic routes containing biocatalytic key steps toward >130 APIs of approved drugs and drug candidates are compared with the corresponding chemical protocols (if available) regarding the steps, reaction conditions, and scale. The review is structured according to the functional group formed in the reaction.

Solitumergosterol A, a unique 6/6/6/6/5 steroid from the deep-sea-derived Penicillium solitum MCCC 3A00215

A unique C30 steroid, solitumergosterol A (1), was isolated from the deep-sea-derived fungus Penicillium solitum MCCC 3A00215. The planar structure and relative configuration of 1 were established mainly on the basis of extensive analysis of its 1D and 2D NMR as well as HRESIMS data, while its absolute configuration was clarified by comparison of the experimental and theoretical ECD spectra. Noteworthily, 1 is a Diels-Alder adduct of a heterogeneous steroid bearing a 6/6/6/6/5 pentacyclic carbon skeleton. Solitumergosterol A (1) exhibited weak in vitro anti-tumor activity against MB231 cells by a RXRα-dependent mechanism.

NOD1 in the interplay between microbiota and gastrointestinal immune adaptations

Nucleotide-binding oligomerization domain 1 (NOD1), a pattern recognition receptor (PRR) that detects bacterial peptidoglycan fragments and other danger signals, has been linked to inflammatory pathologies. NOD1, which is expressed by immune and non-immune cells, is activated after recognizing microbe-associated molecular patterns (MAMPs). This recognition triggers host defense responses and both immune memory and tolerance can also be achieved during these processes. Since the gut microbiota is currently considered a master regulator of human physiology central in health and disease and the intestine metabolizes a wide range of nutrients, drugs and hormones, it is a fact that dysbiosis can alter tissues and organs homeostasis. These systemic alterations occur in response to gastrointestinal immune adaptations that are not yet fully understood. Even if previous evidence confirms the connection between the microbiota, the immune system and metabolic disorders, much remains to be discovered about the contribution of NOD1 to low-grade inflammatory pathologies such as obesity, diabetes and cardiovascular diseases. This review compiles the most recent findings in this area, while providing a dynamic and practical framework with future approaches for research and clinical applications on targeting NOD1. This knowledge can help to rate the consequences of the disease and to stratify the patients for therapeutic interventions.

Enzymatic Characterization and Comparison of Two Steroid Hydroxylases CYP154C3-1 and CYP154C3-2 from Streptomyces Species

Bacterial cytochrome P450 (CYP) enzymes are responsible for the hydroxylation of diverse endogenous substances with a heme molecule used as a cofactor. This study characterized two CYP154C3 proteins from Streptomyces sp. W2061 (CYP154C3-1) and Streptomyces sp. KCCM40643 (CYP154C3-2). The enzymatic activity assays of both CYPs conducted using heterologous redox partners' putidaredoxin and putidaredoxin reductase showed substrate flexibility with different steroids and exhibited interesting product formation patterns. The enzymatic characterization revealed good activity over a pH range of 7.0 to 7.8 and the optimal temperature range for activity was 30 to 37°C. The major product was the C16-hydroxylated product and the kinetic profiles and patterns of the generated hydroxylated products differed between the two enzymes. Both enzymes showed a higher affinity toward progesterone, with CYP154C3-1 demonstrating slightly higher activity than CYP154C3-2 for most of the substrates. Oxidizing agents (diacetoxyiodo) benzene (PIDA) and hydrogen peroxide (H₂O₂) were also utilized to actively support the redox reactions, with optimum conversion achieved at concentrations of 3 mM and 65 mM, respectively. The oxidizing agents affected the product distribution, influencing the type and selectivity of the CYP-catalyzed reaction. Additionally, CYP154C3s also catalyzed the C-C bond cleavage of steroids. Therefore, CYP154C3s may be a good candidate for the production of modified steroids for various biological uses.

Biotransformation of Cortisone with Rhodococcus rhodnii: Synthesis of New Steroids

Cortisone is a steroid widely used as an anti-inflammatory drug able to suppress the immune system, thus reducing inflammation and attendant pain and swelling at the site of an injury. Due to its numerous side effects, especially in prolonged and high-dose therapies, the development of the pharmaceutical industry is currently aimed at finding new compounds with similar activities but with minor or no side effects. Biotransformations are an important methodology towards more sustainable industrial processes, according to the principles of "green chemistry". In this work, the biotransformation of cortisone with Rhodococcus rhodnii DSM 43960 to give two new steroids, i.e., 1,9β,17,21-tetrahydoxy-4-methyl-19-nor-9β-pregna-1,3,5(10)-trien-11,20-dione and 1,9β,17,20β,21-pentahydoxy-4-methyl-19-nor-9β-pregna-1,3,5(10)-trien-11-one, is reported. These new steroids have been fully characterized.

Biotransformation of ginsenoside Rc to Rd by endophytic bacterium Bacillus sp. G9y isolated from Panax quinquefolius

To isolate endophytic bacterium with the ability to specifically convert ginsenoside Rc from Panax quinquefolius. An endophytic bacterium G9y was isolated from Panax quinquefolius and indentified as Bacillus sp. based on 16s rDNA gene sequence. Ginsenoside Rc was effectively converted to Rd by G9y, which was confirmed by thin-layer chromatography and high performance liquid chromatography (HPLC) analysis. The biotransformation conditions were further optimized as follows: inoculum amount 5%, converting temperature 45 °C, medium beef extract peptone broth at pH of 7, and the time of Rc addition was 4 h after bacterium G9y growth, under which ginsenoside Rc was completely converted to Rd by bacterium G9y within 25 h after inoculation. A strain of G9y with the ability to convert ginsenoside Rc into Rd was screened from endophytic bacteria isolated from P. quinquefolius. The results provide a new microbial resource for preparing ginsenoside Rd via biotransformation, and explore a pathway for Rc utilization, which has great potential application value.

Whole-genome and enzymatic analyses of an androstenedione-producing Mycobacterium strain with residual phytosterol-degrading pathways

Mycobacterium neoaurum strains can transform phytosterols to 4-androstene-3,17-dione (4-AD), a key intermediate for the synthesis of advanced steroidal medicines. In this work, we presented the complete genome sequence of the M. neoaurum strain HGMS2, which transforms β-sitosterol to 4-AD. Through genome annotation, a phytosterol-degrading pathway in HGMS2 was predicted and further shown to form a 9,10-secosteroid intermediate by five groups of enzymes. These five groups of enzymes included three cholesterol oxidases (ChoM; group 1: ChoM1, ChoM2 and Hsd), two monooxygenases (Mon; group 2: Mon164 and Mon197), a set of enzymes for side-chain degradation (group 3), one 3-ketosteroid-1,2-dehydrogenase (KstD; group 4: KstD211) and three 3-ketosteroid-9a-hydroxylases (Ksh; group 5: KshA226, KshA395 and KshB122). A gene cluster encoding Mon164, KstD211, KshA226, KshB122 and fatty acid β-oxidoreductases constituted one integrated metabolic pathway, while genes encoding other key enzymes were sporadically distributed. All key enzymes except those from group 3 were prepared as recombinant proteins and their activities were evaluated, and the proteins exhibited distinct activities compared with enzymes identified from other bacterial species. Importantly, we found that the KstD211 and KshA395 enzymes in the HGMS2 strain retained weak activities and caused the occurrence of two major impurities, i.e., 1,4-androstene-3,17-dione (ADD) and 9-hydroxyl-4-androstene-3,17-dione (9OH-AD) during β-sitosterol fermentation. The concurrence of these two 4-AD analogs not only lowered 4-AD production yield but also hampered 4-AD purification. HGMS2 has the least number of genes encoding KstD and Ksh enzymes compared with current industrial strains. Therefore, HGMS2 could be a potent strain by which the 4-AD production yield could be enhanced by disabling the KstD211 and KshA395 enzymes. Our work also provides new insight into the engineering of the HGMS2 strain to produce ADD and 9OH-AD for industrial application.

Bungsteroid A: One Unusual C34 Pentacyclic Steroid Analogue from Zanthoxylum bungeanum Maxim

Bungsteroid A (1), possessing an unreported carbon skeleton, was isolated from the pericarps of Zanthoxylum bungeanum Maxim. It represents the first carbon skeleton of a C₃₄ steroid analogue featuring a unique 6/6/6/6/5-fused pentacyclic skeleton, which has been determined by spectroscopic methods, quantum-chemical ¹³C NMR, ECD calculations, and calculations of optical rotations. Bungsteroid A showed the antiproliferative effects against HepG2, MCF-7, and HeLa cell lines with the IC₅₀ values of 56.3 ± 1.1, 64.2 ± 0.9, and 74.2 ± 1.3 μM, respectively.

Soluplus-Mediated Diosgenin Amorphous Solid Dispersion with High Solubility and High Stability: Development, Characterization and Oral Bioavailability

Background and Purpose

The traditional Chinese medicine, diosgenin (Dio), has attracted increasing attention because it possesses various therapeutic effects, including anti-tumor, anti-infective and anti-allergic properties. However, the commercial application of Dio is limited by its extremely low aqueous solubility and inferior bioavailability in vivo. Soluplus, a novel excipient, has great solubilization and capacity of crystallization inhibition. The purpose of this study was to prepare Soluplus-mediated Dio amorphous solid dispersions (ASDs) to improve its solubility, bioavailability and stability.

Methods

The crystallization inhibition studies were firstly carried out to select excipients using a solvent shift method. According to solubility and dissolution results, the preparation methods and the ratios of drug to excipient were further optimized. The interaction between Dio and Soluplus was characterized by differential scanning calorimetry (DSC), fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), powder X-ray diffraction (PXRD) and molecular docking. The pharmacokinetic study was conducted to explore the potential of Dio ASDs for oral administration. Furthermore, the long-term stability of Dio ASDs was also investigated.

Results

Soluplus was preliminarily selected from various excipients because of its potential to improve solubility and stability. The optimized ASDs significantly improved the aqueous solubility of Dio due to its amorphization and the molecular interactions between Dio and Soluplus, as evidenced by dissolution test in vitro, DSC, FT-IR spectroscopy, SEM, PXRD and molecular docking technique. Furthermore, pharmacokinetic studies in rats revealed that the bioavailability of Dio from ASDs was improved about 5 times. In addition, Dio ASDs were stable when stored at 40°C and 75% humidity for 6 months.

Conclusion

These results indicated that Dio ASDs, with its high solubility, high bioavailability and high stability, would open a promising way in pharmaceutical applications.

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.

Fungal biocatalysts for labdane diterpene hydroxylation

Labdane diterpenes and their derivatives have shown remarkable biological activities and are useful as chiral building blocks for the synthesis of a variety of bioactive compounds. There is great interest in developing biocatalyst technology to achieve regio- and stereoselective hydroxylation of unactivated C-H bonds in complex natural products, since the functionalization of unactivated C-H bonds generally requires hard reaction conditions and highly reactive oxidizing agents, which are limited regarding the control of regio- and stereoselectivity. Filamentous fungi are efficient biocatalysts capable of catalyzing a wide variety of hydroxylation reactions, and the use of whole cell biocatalysts provides advantages regarding cofactor regeneration and is much less expensive. Therefore, the goal of this study was to select biocatalysts to develop biotransformation processes that can be scalable under mild reaction conditions for hydroxylation of a labdane diterpene, 3β-acetoxy-copalic acid, which contains the trans-decalin moiety and a side chain dienic system appropriate for the preparation of a variety of compounds. Biotransformation processes were carried out and five filamentous fungi were selected as capable of producing hydroxylated diterpenes at positions C-3, C-6, C-7 and C-18 of the trans-decalin moiety and C-13 of the side chain dienic system. Hydroxylation reactions occurred with regio- and stereoselectivity by using some fungi that produced only the 6α, 7α and 13α-hydroxyl derivatives. The chemical structures of the hydroxylated diterpenes were determined from spectrometric and spectroscopic data, and the relative stereochemistry of stereogenic centers was established from coupling constants, by NOE-diff experiments and/or by computational calculations.

Therapeutic significance of β-glucuronidase activity and its inhibitors: A review

The emergence of disease and dearth of effective pharmacological agents on most therapeutic fronts, constitutes a major threat to global public health and man's existence. Consequently, this has created an exigency in the search for new drugs with improved clinical utility or means of potentiating available ones. To this end, accumulating empirical evidence supports molecular target therapy as a plausible egress and, β-glucuronidase (βGLU) - a lysosomal acid hydrolase responsible for the catalytic deconjugation of β-d-glucuronides has emerged as a viable molecular target for several therapeutic applications. The enzyme's activity level in body fluids is also deemed a potential biomarker for the diagnosis of some pathological conditions. Moreover, due to its role in colon carcinogenesis and certain drug-induced dose-limiting toxicities, the development of potent inhibitors of βGLU in human intestinal microbiota has aroused increased attention over the years. Nevertheless, although our literature survey revealed both natural products and synthetic scaffolds as potential inhibitors of the enzyme, only few of these have found clinical utility, albeit with moderate to poor pharmacokinetic profile. Hence, in this review we present a compendium of exploits in the present millennium directed towards the inhibition of βGLU. The aim is to proffer a platform on which new scaffolds can be modelled for improved βGLU inhibitory potency and the development of new therapeutic agents in consequential.

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.

New Anti-inflammatory Triterpene Esters and Glycosides from Alstonia scholaris

BACKGROUND

Phytochemical studies on the ethanolic extract of aerial parts of Alstonia scholaris lead to the isolation of two new triterpenoid of the lanostanetype, lanosta 5ene,24-ethyl-3-O-β-D-glucopyranoside (1), lanosta,5ene,24-ethyl-3-O-β-D-glucopyranosideester (2) and new ursane type triterpenoidmethylester, 12-ursene-2,3,18,19-tetrol,28 acetate (nighascholarene) (3), together with seven known triterpenes, betuline, triterpene of the lupane type, alstoprenyol (4), 3β-hydroxy-28-β-acetoxy-5-olea triterpene (5),α-amyrin acetate (6), α-amyrin (7), lupeol acetate (8), 3β-hydroxy-24-nor-urs-4,12,28-triene triterpene (9) and ursolic acid (l0).

METHODOLOGY

The triterpenoid structures of these colorless compounds were deduced from the 1H and 13C-NMR data, and in particular from the application of two-dimensional 1H, 13C correlation experiments as well as by comparison with reported literature data.

CONCLUSION

This study deals with isolation and structural elucidation of natural new triterpenoidesters and glycosides with anti-inflammatory activity.

Structure-based reconstruction of a Mycobacterium hypothetical protein into an active Δ5-3-ketosteroid isomerase

Protein engineering based on structure homology holds the potential to engineer steroid-transforming enzymes on demand. Based on the genome sequencing analysis of industrial Mycobacterium strain HGMS2 to produce 4-androstene-3,17-dione (4-AD), three hypothetical proteins were predicted as putative Δ⁵-3-ketosteroid isomerases (KSIs) to catalyze an intramolecular proton transfer involving the transformation of 5-androstene-3,17-dione (5-AD) into 4-AD, which were defined as mKSI228, mKSI291 and mKSI753. Activity assays indicated that mKSI228 and mKSI291 exhibited weak activity, as low as 0.7% and 1.5%, respectively, of a well-studied and highly active KSI from Pseudomonas putida KSI (pKSI), while mKSI753 had no activity similar to Mycobacterium tuberculosis KSI (mtKSI). Although the 3D structures of the putative mKSIs were homologous to pKSI, their amino acid sequences were significantly different from those of pKSI and tKSI. Thus, by use of these two KSIs as homology models, we were able to convert the low-active mKSI291 into a high-active active KSI by site-directed mutagenesis. On the other hand, an X-ray crystallographic structure of mKSI291 identified a water molecule in its active site. This unique water molecule might function as a bridge to connect Ser-OH, Tyr57-OH and C3O of the intermediate form a hydrogen-bonding network that was responsible for its weak activity, compared with that of mtKSI. Our results not only demonstrated the use of a protein engineering approach to understanding KSI catalytic mechanism, but also provided an example for engineering the catalytic active sites and gaining a functional enzyme based on homologous structures.

Timosaponin AIII, a steroidal saponin, exhibits anti-tumor effect on taxol-resistant cells in vitro and in vivo

Timosaponin AIII (TAIII), a steroidal saponin isolated from the rhizome of Anemarrhena asphodeloides, exerted cytotoxic effect in many cancer cell lines. However, the effect of TAIII on resistant tumor cancer cells was unclear. In this study, MTT assay showed that TAIII exhibited significant cytotoxicity against A549/Taxol and A2780/Taxol cells in vitro. Annexin V-FITC/PI staining revealed that TAIII induced apoptosis in A549/T and A2780/T cells. Furthermore, Western blot analysis demonstrated that TAIII inhibited the expressions of phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT), mammalian target of rapamycin (mTOR) as well as Ras, Raf, mitogen-activated protein kinase (MEPK), extracellular regulated protein kinases (ERK) in two taxol-resistant cancer cell lines. Besides, in vivo studies demonstrated that TAIII inhibited tumor growth in a nude mouse xenograft model. Additionally, TAIII (2.5 and 5 mg/kg) also down-regulated the protein expressions of PI3K/AKT/mTOR and Ras/Raf/MEK/ERK pathways in vivo. Taken together, these findings demonstrated that TAIII exhibited significant anti-tumor effect on taxol-resistant cells.

Synthesis, cytotoxic evaluation, and molecular docking studies of the semi-synthetic "triterpenoid-steroid" hybrids

Synthetic transformations of steroids for drug discovery and improvement of drug effectiveness have been an important part of modern medicinal chemistry and pharmaceutical sciences. Pentacyclic triterpenoids, being represented in the nature by various structures and biogenetically related to steroids, can largely expand the spectrum of biologically active steroidal agents via synthesis of the so-called "triterpenoid-steroid" hybrids. In the presented work, the nitrile anion cyclizations of 3,4-secolupane and 3,4-seco-oleanane nitriles and follow-up synthetic transformations of the cyclized products with formation of the gemm-dimethyl-free A ring "triterpenoid-steroid" hybrids were studied. Furthermore, the resulting cyclic compounds were modified at C3, C4, and/or C5 positions of ring A, as well as at C20, C28, and C30 positions of the isopropylidene moiety in the case of lupane triterpenoids. The cytotoxic effect of the synthesized compounds against seven cancer cell lines HEp-2, HCT 116, MS, RD TE32, A549, MCF7, and PC3 was evaluated. The in silico identification of potential anticancer protein targets with regard to the compounds, which were active at micromolar concentrations against tested cell lines, was carried out. The molecular docking studies showed that compound 19, which demonstrated most pronounced cytotoxicity (IC₅₀ 0.64-3.17 μM) against all tested cell lines, fits well the active sites of CDK6 and HER2/neu.

Timosaponin AIII: A novel potential anti-tumor compound from Anemarrhena asphodeloides

Timosaponin AIII, a major steroidal saponin found in Anemarrhena asphodeloides Bge., which has been widely used as anti-pyretic, anti-diabetic, anti-inflammatory, anti-platelet aggregator and anti-depressant agents in traditional Chinese medicine. Recent pharmacological study showed that timosaponin AIII had potent cytotoxicity, which was potential to be developed as an anticancer agent, however the molecular mechanism underlying the anticancer activity has not been fully elucidated. This review aims to give a systematic summary of the study of timosaponin AIII to reveal its anti-tumor activities by investigating invasion and migration, apoptosis, autophagy and reversing multi-drug resistance. Furthermore, we also make an overview of the mechanisms identified till now. These meaningful findings may provide novel insights on exploiting timosaponin AIII as a new anti-tumor agent.

The Antitumor Activities of Marsdenia tenacissima

Marsdenia tenacissima (MT), a traditional Chinese herbal medicine, has long been used for thousands of years to treat asthma, tracheitis, rheumatism, etc. An increasing number of recent studies have focused on the antitumor effects of MT. The effects of MT on cancer are the result of various activated signaling pathways and inhibiting factors and the high expression levels of regulatory proteins. MT can inhibit different cancer types including non-small cell lung cancer (NSCLC), malignant tumors, hepatic carcinoma, and so on. This article mainly focuses on the activities and mechanisms of MT. In addition, the efficacy and toxicity of MT are also discussed. Further studies of MT are required for improved medicinal utilization.

Microbiological Hydroxylations with Cephalosporium Aphidicola

The factors that affect the balance between biosynthetically patterned and xenobiotic transformations by the fungus Cephalosporium aphidicola involving terpenoid and steroidal substrates are reviewed. The potential role of the latter in the context of biodegradation is discussed.