Structural basis for inhibition of 17β-hydroxysteroid dehydrogenases by phytoestrogens: The case of fungal 17β-HSDcl

Expression, Purification, and Bioinformatic Prediction of Mycobacterium tuberculosis Rv0439c as a Potential NADP+-Retinol Dehydrogenase

Although the genome of Mycobacterium tuberculosis (Mtb) H37Rv, the causative agent of tuberculosis, has been repeatedly annotated and updated, a range of proteins from this human pathogen have unknown functions. Mtb Rv0439c, a member of the short-chain dehydrogenase/reductases superfamily, has yet to be cloned and characterized, and its function remains unclear. In this work, we present for the first time the optimized expression and purification of this enzyme, as well as bioinformatic analysis to unveil its potential coenzyme and substrate. Optimized expression in Escherichia coli yielded soluble Rv0439c, while certain tag fusions resulted in insolubility. Sequence and docking analyses strongly suggested that Rv0439c has a clear preference for NADP+, with Arg53 being a key residue that confers coenzyme specificity. Furthermore, functional prediction using CLEAN and DEEPre servers suggested that this protein is a potential NADP+-retinol dehydrogenase (EC No. 1.1.1.300) in retinol metabolism, and this was supported by a BLASTp search and docking studies. Collectively, our findings provide a solid basis for future functional characterization and structural studies of Rv0439c, which will contribute to enhanced understanding of Mtb biology.

Naringenin-Zinc Oxide Nanocomposites Amalgamated Polymeric Gel Augmented Drug Delivery and Attenuated Experimental Cutaneous Candidiasis in Balb/c Mice: In Vitro and In Vivo Studies

Naringenin (NRG) inhibits the fungal 17β-hydroxysteroid dehydrogenase accountable for ergosterol synthesis in Candida albicans (C. albicans), a causative agent for cutaneous candidiasis. In present research, NRG was complexed with ZnO nanomaterial (NRG-Zn2+) to synthesize NRG-Zn2+ nanocomposites. The particle size and ζ-potential of NRG-Zn2+ nanocomposites were respectively estimated to be 180.33 ± 1.22-nm and - 3.92 ± 0.35-mV. In silico data predicted the greater affinity of NRG-Zn2+ nanocomposite for 14α-demethylase and ceramide in comparison to NRG alone. Later, NRG-Zn2+ nanocomposites solution was transformed in to naringenin-zinc oxide nanocomposites loaded chitosan gel (NRG-Zn-CS-Gel) with viscosity and firmness of 854806.7 ± 52386.43 cP and 698.27 ± 10.35 g, respectively. The ex-vivo skin permeation demonstrated 70.49 ± 5.22% skin retention, significantly greater (P < 0.05) than 44.48 ± 3.06% of naringenin loaded chitosan gel (NRG-CS-Gel) and 31.24 ± 3.28% of naringenin solution (NRG Solution). NRG-Zn-CS-Gel demonstrated 6.71 ± 0.84% permeation of NRG with a flux value of 0.046 ± 0.01-µg/cm2/h. The MIC50 of NRG-Zn-CS-Gel against C. albicans was estimated to be 0.156-µg/mL with FICI (fractional inhibitory concentration index) of 0.018 that consequently exhibited synergistic efficacy. Further, NRG-Zn-CS-Gel demonstrated superior antifungal efficacy in C. albicans induced cutaneous candidiasis infection in Balb/c mice. The fungal burden in NRG-Zn-CS-Gel treated group was 109 ± 25 CFU/mL, significantly lower (P < 0.05) than positive control (2260 ± 446 CFU/mL), naringenin loaded chitosan gel (NRG-CS-Gel; 928 ± 127 CFU/mL) and chitosan gel (CS-Gel; 2116 ± 186 CFU/mL) treated mice. Further, histopathology examination and cytokine profiling of TNF-α, IL-1β and IL-10 revealed the healing of skin and inflammation associated with cutaneous candidiasis infection. In conclusion, NRG-Zn-CS-Gel may be a potential candidate for translating in to a clinical viable topical nanotherapeutic.

Antimicrobial Metabolites of Caucasian Medicinal Plants as Alternatives to Antibiotics

This review explores the potential of antimicrobial metabolites derived from Caucasian medicinal plants as alternatives to conventional antibiotics. With the rise of antibiotic resistance posing a global health threat, there is a pressing need to investigate alternative sources of antimicrobial agents. Caucasian medicinal plants have traditionally been used for their therapeutic properties, and recent research has highlighted their potential as sources of antimicrobial compounds. Representatives of 15 families of Caucasian medicinal plant extracts (24 species) have been explored for their efficacy against these pathogens. The effect of these plants on Gram-positive and Gram-negative bacteria and fungi is discussed in this paper. By harnessing the bioactive metabolites present in these plants, this study aims to contribute to the development of new antimicrobial treatments that can effectively combat bacterial infections while minimizing the risk of resistance emergence. Herein we discuss the following classes of bioactive compounds exhibiting antimicrobial activity: phenolic compounds, flavonoids, tannins, terpenes, saponins, alkaloids, and sulfur-containing compounds of Allium species. The review discusses the pharmacological properties of selected Caucasian medicinal plants, the extraction and characterization of these antimicrobial metabolites, the mechanisms of action of antibacterial and antifungal plant compounds, and their potential applications in clinical settings. Additionally, challenges and future directions in the research of antimicrobial metabolites from Caucasian medicinal plants are addressed.

Naringenin-Capped Silver Nanoparticles Amalgamated Gel for the Treatment of Cutaneous Candidiasis

The current research was aimed to synthesize a phytomolecule, naringenin (NRG)-mediated silver nanoparticles (NRG-SNPs) to study their antifungal potential against Candida albicans (C. albicans) and Candida glabrata (C. glabrata). The NRG-SNPs were synthesized by using NRG as a reducing agent. The synthesis of NRG-SNPs was confirmed by a color change and surface plasmon resonance (SPR) peak at 425 nm. Furthermore, the NRG-SNPs were analyzed for size, PDI, and zeta potential, which were found to be 35 ± 0.21 nm, 0.19 ± 0.03, and 17.73 ± 0.92 mV, respectively. In silico results demonstrated that NRG had a strong affinity towards the sterol 14α-demethylase. The docking with ceramide revealed the skin permeation efficiency of the NRG-SNPs. Next, the NRG-SNPs were loaded into the topical dermal dosage form (NRG-SNPs-TDDF) by formulating a gel using Carbopol Ultrez 10 NF. The MIC₅₀ of NRG solution and TSC-SNPs against C. albicans was found to be 50 µg/mL and 4.8 µg/mL, respectively, significantly (P < 0.05) higher than 0.3625 µg/mL of NRG-SNPs-TDDF. Correspondingly, MIC₅₀ results were calculated against C. glabrata and the results of NRG, TSC-SNPs, NRG-SNPs-TDDF, and miconazole nitrate were found to be 50 µg/mL, 9.6 µg/mL, 0.3625 µg/mL, and 3-µg/mL, respectively. Interestingly, MIC₅₀ of NRG-SNPs-TDDF was significantly (P < 0.05) lower than MIC₅₀ of miconazole nitrate against C. glabrata. The FICI (fractional inhibitory concentration index) value against both the C. albicans and C. glabrata was found to be 0.016 and 0.011, respectively, which indicated the synergistic antifungal activity of NRG-SNPs-TDDF. Thus, NRG-SNPs-TDDF warrants further in depth in vivo study under a set of stringent parameters for translating in to a clinically viable antifungal product.

Antimicrobial Activity of Quercetin: An Approach to Its Mechanistic Principle

Quercetin, an essential plant flavonoid, possesses a variety of pharmacological activities. Extensive literature investigates its antimicrobial activity and possible mechanism of action. Quercetin has been shown to inhibit the growth of different Gram-positive and Gram-negative bacteria as well as fungi and viruses. The mechanism of its antimicrobial action includes cell membrane damage, change of membrane permeability, inhibition of synthesis of nucleic acids and proteins, reduction of expression of virulence factors, mitochondrial dysfunction, and preventing biofilm formation. Quercetin has also been shown to inhibit the growth of various drug-resistant microorganisms, thereby suggesting its use as a potent antimicrobial agent against drug-resistant strains. Furthermore, certain structural modifications of quercetin have sometimes been shown to enhance its antimicrobial activity compared to that of the parent molecule. In this review, we have summarized the antimicrobial activity of quercetin with a special focus on its mechanistic principle. Therefore, this review will provide further insights into the scientific understanding of quercetin’s mechanism of action, and the implications for its use as a clinically relevant antimicrobial agent.

An ethnopharmacological review on the therapeutical properties of flavonoids and their mechanisms of actions: A comprehensive review based on up to date knowledge

Flavonoids -a class of low molecular weight secondary metabolites- are ubiquitous and cornucopia throughout the plant kingdom. Structurally, the main structure consists of C6-C3-C6 rings with different substitution patterns so that many sub-classes are obtained, for example: flavonols, flavonolignans, flavonoid glycosides, flavans, anthocyanidins, aurones, anthocyanidins, flavones, neoflavonoids, chalcones, isoflavones, flavones and flavanones. Flavonoids are evaluated to have drug like nature since they possess different therapeutic activities, and can act as cardioprotective, antiviral, antidiabetic, anti-inflammatory, antibacterial, anticancer, and also work against Alzheimer's disease and others. However, information on the relationship between their structure and biological activity is scarce. Therefore, the present review tries to summarize all the therapeutic activities of flavonoids, their mechanisms of action and the structure activity relationship.

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Latest updated ethnopharmacological review of the therapeutic effects of flavonoids.

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Flavonoids are attracting attention because of their therapeutic properties.

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Flavonoids are valuable candidates for drug development against many dangerous diseases.

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This overview summarizes the most important therapeutic effect and mechanism of action of flavonoids.

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General knowledge about the structure activity relationship of flavonoids is summarized.

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Substitution of chemical groups in the structure of flavonoids can significantly change their biological and chemical properties.

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The chemical properties of the basic flavonoid structure should be considered in a drug-based structural program.

Influence of synthetic isoflavones on selected urinary steroid biomarkers: Relevance to doping control

In this work we have investigated the influence of the intake of two synthetic isoflavones, methoxyisoflavone and ipriflavone, on the urinary concentration of endogenous steroids, and on their relative ratios, of doping relevance. Specifically, the concentrations of testosterone (T), epitestosterone (E), androsterone (A), etiocholanolone (Etio), 5α-androstan-3α,17α-diol (5αAdiol), 5β-androstan-3α,17α-diol (5βAdiol), and the ratios T/E, A/T, A/Etio, 5αAdiol/5βAdiol, 5αAdiol/E, were considered, in the framework of the Steroidal Module of the Athlete Biological Passport (ABP). The above set of parameters were complemented by the urinary levels of luteinizing hormone (total LH) and the ratio between T and LH (T/total LH), to assess the possible effects on the biosynthesis of the mentioned steroids. Five healthy Caucasian male volunteers were selected for the study. Urine samples were collected before and during the administration of (i) methoxyisoflavone (Methoxyisoflavone, MyProtein) and (ii) ipriflavone (Osteofix ®, Chiesi Farmaceutici). For the analysis of the urinary steroid profile, after enzymatic hydrolysis with β-glucuronidase from Escherichia Coli (E. Coli) and liquid-liquid extraction with tert-buthylmethyl ether, all samples were analyzed by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS), while for the determination of total LH all urine samples were directly analyzed by a chemiluminescent immunometric assay technique (Siemens Immulite 2000 LH). Our results show that the administration of either methoxyisoflavone or ipriflavone causes an alteration of the urinary concentrations and concentration ratios of the investigated steroids, in the range 55-80% from the baseline values. Furthermore, an oversecretion of LH after the daily intake of methoxyisoflavone or ipriflavone was also recorded in all volunteers, corresponding to an increase in the biosynthesis and excretion of T and some of its metabolites. These changes trigger a disregulation in the pattern of urinary excretion of the steroids included in the Steroidal Module of the ABP, which makes more difficult the interpretation of the longitudinal steroid profile based on the definition of individual normality ranges for each athlete. Our data are also consistent with previous evidence regarding the in vitro effects of natural and synthetic isoflavones, suggesting that their monitoring in doping control routine analysis would be very beneficial for the result management activities.

Plant Flavonoids: Chemical Characteristics and Biological Activity

In recent years, more attention has been paid to natural sources of antioxidants. Flavonoids are natural substances synthesized in several parts of plants that exhibit a high antioxidant capacity. They are a large family, presenting several classes based on their basic structure. Flavonoids have the ability to control the accumulation of reactive oxygen species (ROS) via scavenger ROS when they are formed. Therefore, these antioxidant compounds have an important role in plant stress tolerance and a high relevance in human health, mainly due to their anti-inflammatory and antimicrobial properties. In addition, flavonoids have several applications in the food industry as preservatives, pigments, and antioxidants, as well as in other industries such as cosmetics and pharmaceuticals. However, flavonoids application for industrial purposes implies extraction processes with high purity and quality. Several methodologies have been developed aimed at increasing flavonoid extraction yield and being environmentally friendly. This review presents the most abundant natural flavonoids, their structure and chemical characteristics, extraction methods, and biological activity.

A Hybrid In Silico/In Vitro Target Fishing Study to Mine Novel Targets of Urolithin A and B: A Step Towards a Better Comprehension of Their Estrogenicity

SCOPE

Urolithin A and B are gut metabolites of ellagic acid and ellagitannins associated with many beneficial effects. Evidence in vitro pointed to their potential as estrogenic modulators. However, both molecular mechanisms and biological targets involved in such activity are still poorly characterized, preventing a comprehensive understanding of their bioactivity in living organisms. This study aimed at rationally identifying novel biological targets underlying the estrogenic-modulatory activity of urolithins.

METHODS AND RESULTS

The work relies on an in silico/in vitro target fishing study coupling molecular modeling with biochemical and cell-based assays. Estrogen sulfotransferase and 17β-hydroxysteroid dehydrogenase are identified as potentially subject to inhibition by the investigated urolithins. The inhibition of the latter undergoes experimental confirmation either in a cell-free or cell-based assay, validating computational outcomes.

CONCLUSIONS

The work describes target fishing as an effective tool to identify unexpected targets of food bioactives detailing the interaction at a molecular level. Specifically, it described, for the first time, 17β-hydroxysteroid dehydrogenase as a target of urolithins and highlighted the need of further investigations to widen the understanding of urolithins as estrogen modulators in living organisms.

Anti-Fungal Efficacy and Mechanisms of Flavonoids

The prevalence of fungal infections is growing at an alarming pace and the pathogenesis is still not clearly understood. Recurrence of these fungal diseases is often due to their evolutionary avoidance of antifungal resistance. The development of suitable novel antimicrobial agents for fungal diseases continues to be a major problem in the current clinical field. Hence, it is urgently necessary to develop surrogate agents that are more effective than conventional available drugs. Among the remarkable innovations from earlier investigations on natural-drugs, flavonoids are a group of plant-derived substances capable of promoting many valuable effects on humans. The identification of flavonoids with possible antifungal effects at small concentrations or in synergistic combinations could help to overcome this problem. A combination of flavonoids with available drugs is an excellent approach to reduce the side effects and toxicity. This review focuses on various naturally occurring flavonoids and their antifungal activities, modes of action, and synergetic use in combination with conventional drugs.

An investigation on the metabolic pathways of synthetic isoflavones by gas chromatography coupled to high accuracy mass spectrometry

RATIONALE

Isoflavones are a group of flavonoids that may be of interest in sport doping because they can be used by athletes in the recovery periods after the administration of anabolic steroids, with the aim of increasing the natural production of luteinizing hormone (LH) and, consequently, the biosynthesis of endogenous androgens.

METHODS

The in vivo metabolism of methoxyisoflavone (5-methyl-7-methoxyisoflavone) and ipriflavone (7-isopropoxyisoflavone), respectively present in a dietary supplement and in a pharmaceutical preparation, was investigated. The study was carried out by the analysis of urinary samples collected from male Caucasian subjects before, during and after the oral administration of methoxyisoflavone or ipriflavone. After enzymatic hydrolysis and liquid-liquid extraction, all urinary samples were analyzed by gas chromatography/quadrupole time-of-flight (qTOF MS system/qTOF) electron ionization mass spectrometry (EI-MS).

RESULTS

Eight metabolites of methoxyisoflavone and six metabolites of ipriflavone were isolated. The corresponding accurate mass spectra are specific for isoflavone structures and revealed also a retro-Diels-Alder fragmentation.

CONCLUSIONS

When excreted in large amounts, the urinary metabolites of methoxyisoflavone and ipriflavone can be traced to potential confounding factors in doping analysis. As methoxyisoflavone and ipriflavone have been shown to inhibit the enzyme aromatase, thus interfering with the normal metabolic pathways of testosterone, the detection of their intake, by screening for the presence of their main metabolites in urine, might be helpful in routine doping control analysis.

Metabolic engineering of Rhodococcus ruber Chol-4: A cell factory for testosterone production

Rhodococcus ruber Chol-4 is a potent steroid degrader that has a great potential as a biotechnological tool. As proof of concept, this work presents testosterone production from 4-androstene-3,17-dione by tailoring innate catabolic enzymes of the steroid catabolism inside the strain. A R. ruber quadruple mutant was constructed in order to avoid the breakage of the steroid nucleus. At the same time, an inducible expression vector for this strain was developed. The 17-ketoreductase gene from the fungus Cochliobolus lunatus was cloned and overexpressed in this vector. The engineered strain was able to produce testosterone from 4-androstene-3,17-dione using glucose for cofactor regeneration with a molar conversion of 61%. It is important to note that 91% of the testosterone was secreted outside the cell after 3 days of cell biotransformation. The results support the idea that Rhodococcus ruber Chol-4 can be metabolically engineered and can be used for the production of steroid intermediates.

Hybrid in silico/in vitro target fishing to assign function to "orphan" compounds of food origin - The case of the fungal metabolite atromentin

Many small molecules of food origin may effect human health but lack an adequate description of their biological activity. To fill this knowledge gap, a first-line workflow is needed to assign putative functions, rank the endpoints for testing and guide wet-lab experiments. In this framework, the identification of potential biological targets can be used to probe the activity of orphan compounds using a so-called "target fishing" approach. Here, we present a proof of concept study using an in silico/in vitro target fishing approach on the fungal secondary metabolite atromentin. The procedure relies on a computational screening for activity identification coupled with experimental trials for dose-response characterization. Computational results identified estrogen receptors and 17-β-hydroxysteroid dehydrogenase as potential targets. Experiments confirmed a weak estrogenic activity, supporting the reliability of the procedure. Despite limited estrogenicity of atromentin, the proposed inhibition of 17-β-hydroxysteroid dehydrogenase should be considered as a source for endocrine disruptive effects.

The Impacts of Genistein and Daidzein on Estrogen Conjugations in Human Breast Cancer Cells: A Targeted Metabolomics Approach

The beneficial effect of dietary soy food intake, especially for women diagnosed with breast cancer, is controversial, as in vitro data has shown that the soy isoflavones genistein and daidzein may even stimulate the proliferation of estrogen-receptor alpha positive (ERα+) breast cancer cells at low concentrations. As genistein and daidzein are known to inhibit key enzymes in the steroid metabolism pathway, and thus may influence levels of active estrogens, we investigated the impacts of genistein and daidzein on the formation of estrogen metabolites, namely 17β-estradiol (E2), 17β-estradiol-3-(β-D-glucuronide) (E2-G), 17β-estradiol-3-sulfate (E2-S) and estrone-3-sulfate (E1-S) in estrogen-dependent ERα+ MCF-7 cells. We found that both isoflavones were potent inhibitors of E1 and E2 sulfation (85–95% inhibition at 10 μM), but impeded E2 glucuronidation to a lesser extent (55–60% inhibition at 10 μM). The stronger inhibition of E1 and E2 sulfation compared with E2 glucuronidation was more evident for genistein, as indicated by significantly lower inhibition constants for genistein [K_is: E2-S (0.32 μM) < E1-S (0.76 μM) < E2-G (6.01 μM)] when compared with those for daidzein [K_is: E2-S (0.48 μM) < E1-S (1.64 μM) < E2-G (7.31 μM)]. Concomitant with the suppression of E1 and E2 conjugation, we observed a minor but statistically significant increase in E2 concentration of approximately 20%. As the content of genistein and daidzein in soy food is relatively low, an increased risk of breast cancer development and progression in women may only be observed following consumption of high-dose isoflavone supplements. Further long-term human studies monitoring free estrogens and their conjugates are therefore highly warranted to evaluate the potential side effects of high-dose genistein and daidzein, especially in patients diagnosed with ERα+ breast cancer.