Dihydrotanshinone I-Induced CYP1 Enzyme Inhibition and Alteration of Estradiol Metabolism.

Dihydrotanshinone I (DHTI) is a pharmacologically active component occurring in the roots of the herbal medicine Salvia miltiorrhiza Bunge. This study investigated DHTI-induced inhibition of CYP1A1, CYP1A2, and CYP1B1 with the aim to determine the potential effects of DHTI on the bioactivation of estradiol (E2), possibly related to preventive/therapeutic strategy for E2-associated breast cancer. Ethoxyresorufin as a specific substrate for CYP1s was incubated with human recombinant CYP1A1, CYP1A2, or CYP1B1 in the presence of DHTI at various concentrations. Enzymatic inhibition and kinetic behaviors were examined by monitoring the formation of the corresponding product. Molecular docking was further conducted to define the interactions between DHTI and the three CYP1s. The same method and procedure were employed to examine the DHTI-induced alteration of E2 metabolism. DHTI showed significant inhibition of ethoxyresorufin O-deethylation activity catalyzed by CYP1A1, CYP1A2 and CYP1B1 in a concentration-dependent manner (IC50 = 0.56, 0.44, and 0.11 µM, respectively). Kinetic analysis showed that DHTI acted as a competitive type of inhibitor of CYP1A1 and CYP1B1, whereas it noncompetitively inhibited CYP1A2. The observed enzyme inhibition was independent of NADPH and time. Molecular docking analysis revealed hydrogen bonding interactions between DHTI and Asp-326 of CYP1B1. Moreover, DHTI displayed preferential activity to inhibit 4-hydroxylation of E2 (a genotoxic pathway) mediated by CYP1B1. Exposure to DHTI could reduce the risk of genotoxicity induced by E2. SIGNIFICANCE STATEMENT: CYP1A1, CYP1A2, and CYP1B1 enzymes are involved in the conversion of estradiol (E2) into 2-hydroxyestradiol (2-OHE2) and 4-hydroxyestradiol (4-OHE2) through oxidation. 2-OHE2 is negatively correlated with breast cancer risk, and 4-OHE2 may be a significant initiator and promoter of breast cancer. The present study revealed that dihydrotanshinone I (DHTI) competitively inhibits CYP1A1/CYP1B1 and noncompetitively inhibits CYP1A2. DHTI exhibits a preference for inhibiting the genotoxicity associated with E2 4-hydroxylation pathway mediated by CYP1B1, potentially reducing the risk of 4-OHE2-induced genotoxicity.

On-chip multi-trap optical tweezers based on a guided wave-driven metalens.

Optical tweezer arrays (OTAs) have emerged as a powerful tool for quantum simulation, quantum computation, and quantum many-body physics. Conventional OTAs require bulky and costly optical components to generate multiple optical traps, such as spatial light modulators (SLMs). An integrated way to achieve on-chip OTAs is a sought-after goal for compact optical manipulation. In this Letter, we have numerically demonstrated compact on-chip multi-trap optical tweezers based on a guided wave-driven metalens. The presented on-chip optical tweezers are capable of capturing multiple polystyrene nanospheres in parallel. Moreover, we proposed an analytical design method to generate customized focal points from the integrated photonics chip into free space. Different trapping patterns are demonstrated to validate our proposed off-chip emission scheme. Our approach offers a promising solution to realize on-chip optical tweezers and provides a prospective way to realize elaborate emission control of guided waves into free-space beams.

Cytokinetic engineering enhances the secretory production of recombinant human lysozyme in Komagataella phaffii.

BACKGROUND: Human lysozyme (hLYZ) is a natural antibacterial protein with broad applications in food and pharmaceutical industries. Recombinant production of hLYZ in Komagataella phaffii (K. phaffii) has attracted considerable attention, but there are very limited strategies for its hyper-production in yeast. RESULTS: Here through Atmospheric and Room Temperature Plasma (ARTP)-based mutagenesis and transcriptomic analysis, the expression of two genes MYO1 and IQG1 encoding the cytokinesis core proteins was identified downregulated along with higher hLYZ production. Deletion of either gene caused severe cytokinesis defects, but significantly enhanced hLYZ production. The highest hLYZ yield of 1,052,444 ± 23,667 U/mL bioactivity and 4.12 ± 0.11 g/L total protein concentration were obtained after high-density fed-batch fermentation in the Δmyo1 mutant, representing the best production of hLYZ in yeast. Furthermore, O-linked mannose glycans were characterized on this recombinant hLYZ. CONCLUSIONS: Our work suggests that cytokinesis-based morphology engineering is an effective way to enhance the production of hLYZ in K. phaffii.

Design and simulation of an extreme ultraviolet metalens based on the Pancharatnam-Berry phase.

Extreme ultraviolet (EUV) radiation plays a key role in the fields of material science, attosecond metrology, and lithography. However, the reflective optical components typically used in EUV systems contribute to their bulky size, weight, and increased costs for fabrication. In this paper, we theoretically investigate transmissive metalens designs capable of focusing the EUV light based on the Pancharatnam-Berry phase. The designed metalens is composed of nanoscale elliptical holes, which can guide and manipulate EUV light due to the higher refractive index of the vacuum holes compared to that of the surrounding material. We designed an EUV metalens with a diameter of 10 µm, which supports a focal length of 24 µm and a numerical aperture of up to 0.2. It can focus 55-nm EUV incident light to a diffraction-limited spot, and the focusing efficiency is calculated to be as high as about 7% over a broad EUV frequency range (50-65 nm). This study reveals the possibility of applying a dielectric metalens in the EUV region without a transmissive optical material.

Advances in mesenchymal stem cells therapy for tendinopathies.

Tendinopathies are chronic diseases of an unknown etiology and associated with inflammation. Mesenchymal stem cells (MSCs) have emerged as a viable therapeutic option to combat the pathological progression of tendinopathies, not only because of their potential for multidirectional differentiation and self-renewal, but also their excellent immunomodulatory properties. The immunomodulatory effects of MSCs are increasingly being recognized as playing a crucial role in the treatment of tendinopathies, with MSCs being pivotal in regulating the inflammatory microenvironment by modulating the immune response, ultimately contributing to improved tissue repair. This review will discuss the current knowledge regarding the application of MSCs in tendinopathy treatments through the modulation of the immune response.

Effects of xenobiotics on CYP1 enzyme-mediated biotransformation and bioactivation of estradiol.

Endogenous estradiol (E2) exerts diverse physiological and pharmacological activities, commonly used for hormone replacement therapy. However, prolonged and excessive exposure to E2 potentially increases estrogenic cancer risk. Reportedly, CYP1 enzyme-mediated biotransformation of E2 is largely concerned with its balance between detoxification and carcinogenic pathways. Among the three key CYP1 enzymes (CYP1A1, CYP1A2, and CYP1B1), CYP1A1 and CYP1A2 mainly catalyze the formation of nontoxic 2-hydroxyestradiol (2-OH-E2), while CYP1B1 specifically catalyzes the formation of genotoxic 4-hydroxyestradiol (4-OH-E2). 4-OH-E2 can be further metabolized to electrophilic quinone intermediates accompanied by the generation of reactive oxygen species (ROS), triggering DNA damage. Since abnormal alterations in CYP1 activities can greatly affect the bioactivation process of E2, regulatory effects of xenobiotics on CYP1s are essential for E2-associated cancer development. To date, thousands of natural and synthetic compounds have been found to show potential inhibition and/or induction actions on the three CYP1 members. Generally, these chemicals share similar planar polycyclic skeletons, the structural motifs and substituent groups of which are important for their inhibitory/inductive efficiency and selectivity toward CYP1 enzymes. This review comprehensively summarizes these known inhibitors and/or inductors of E2-metabolizing CYP1s based on chemical categories and discusses their structure-activity relationships, which would contribute to better understanding of the correlation between xenobiotic-regulated CYP1 activities and estrogenic cancer susceptibility.

Absorption enhancement in GaAs based quantum dot solar cells using double-sided nanopyramid arrays.

Quantum dot solar cells (QDSCs) are regarded as one of the most efficient devices due to their intermediate band structures. A suitable light-trapping (LT) strategy matching the absorption spectrum is important to improve the photocurrent conversion efficiency of QDSCs. In this paper, we have proposed a design of the periodically patterned top and bottom dielectric nanopyramid arrays for highly efficient light trapping in GaAs-based QDSCs. The dielectric nanopyramid arrays significantly improve the light absorption of QDSCs in the longer wavelength between 0.8 µm and 1.2 µm. In addition, this LT structure ensures a completely flat window layer and back surface field layer while passivating these semiconductor surfaces. For the optimized double-sided structure, the short-circuit current generated by QDSC is 34.32m A/c m 2, where the photocurrent from the quantum dots (QDs) is 5.17m A/c m 2. Compared to the photocurrent of the QDSC without an LT structure, the photocurrent of the double-sided structure is increased by 84%. The QD photocurrent of the double-sided structure is increased by 570% compared to that of the QDSC without the LT structure.

Sclareol attenuates liver fibrosis through SENP1-mediated VEGFR2 SUMOylation and inhibition of downstream STAT3 signaling.

Liver fibrosis is a key global health care burden. Sclareol, isolated from Salvia sclarea, possesses various biological activities. Its effect on liver fibrosis remains unknown. This study was proposed to evaluate the antifibrotic activity of sclareol (SCL) and explore its underlying mechanisms. Stimulated hepatic stellate cells served as an in vitro liver fibrosis model. The expression of fibrotic markers was assessed by western blot and real-time PCR. Two classical animal models, bile duct-ligated rats and carbon tetrachloride-treated mice, were utilized for the in vivo experiments. The liver function and fibrosis degree were determined by serum biochemical and histopathological analyses. VEGFR2 SUMOylation was analyzed using coimmunoprecipitation assay. Our results indicated that SCL treatment restricted the profibrotic propensity of activated HSCs. In fibrotic rodents, SCL administration alleviated hepatic injury and reduced collagen accumulation. Mechanistic studies indicated that SCL downregulated the protein level of SENP1 and enhanced VEGFR2 SUMOylation in LX-2 cells, which affected its intracellular trafficking. Blockade of the interaction between VEGFR2 and STAT3 was observed, resulting in the suppression of downstream STAT3 phosphorylation. Our findings demonstrated that SCL has therapeutic efficacy against liver fibrosis through mediating VEGFR2 SUMOylation, suggesting that SCL may be a potential candidate compound for its treatment.

Coordination of Polyketide Release and Multiple Detoxification Pathways for Tolerable Production of Fungal Mycotoxins.

Efficient biosynthesis of microbial bioactive natural products (NPs) is beneficial for the survival of producers, while self-protection is necessary to avoid self-harm resulting from over-accumulation of NPs. The underlying mechanisms for the effective but tolerable production of bioactive NPs are not well understood. Herein, in the biosynthesis of two fungal polyketide mycotoxins aurovertin E (1) and asteltoxin, we show that the cyclases in the gene clusters promote the release of the polyketide backbone, and reveal that a signal peptide is crucial for their subcellular localization and full activity. Meanwhile, the fungus adopts enzymatic acetylation as the major detoxification pathway of 1. If intermediates are over-produced, the non-enzymatic shunt pathways work as salvage pathways to avoid excessive accumulation of the toxic metabolites for self-protection. These findings provided new insight into the interplay of efficient backbone release and multiple detoxification strategies for the production of fungal bioactive NPs.

LncRNA MEG3 induces endothelial differentiation of mouse derived adipose-derived stem cells by targeting MiR-145-5p/KLF4.

BACKGROUND: The present study aimed to investigate the mechanisms through which long non-coding RNA (lncRNA) maternally expressed 3 (MEG3) affected the endothelial differentiation of mouse derived adipose-derived stem cells (ADSCs). MATERIALS AND METHODS: ADSCs were isolated and identified by specific surface marker detection. The effects of lncRNA MEG3 on endothelial differentiation of ADSCs were also detected via quantitative PCR, western blotting, immunofluorescence and Matrigel angiogenesis assays. In addition, using target gene prediction tools and luciferase reporter assays, the downstream target gene was demonstrated. RESULTS: LncRNA MEG3 targeted and reduced the expression levels of microRNA-145-5p (miR-145-5p), which upregulated the expression levels of Krüppel like factor 4 (KLF4), promoting endothelial differentiation of ADSCs. CONCLUSION: LncRNA MEG3 induced endothelial differentiation of ADSCs by targeting miR-145-5p/KLF4, which may provide novel insights to illustrate the mechanism of endothelial differentiation of ADSCs.

Dehydromevalonolactone ameliorates liver fibrosis and inflammation by repressing activation of NLRP3 inflammasome.

Liver fibrosis is an important process in chronic liver disease and is strongly related to poor prognosis. Dehydromevalonolactone (C8) is a natural product isolated from a fungus of Fusarium sp. CPCC 401218, and its pharmacological activity has never been reported before. In this study, the potential of C8 as an anti-hepatic fibrosis agent was investigated. In human hepatic stellate cell (HSC) line LX-2, C8 suppressed the increased expression of COL1A1 and α-SMA induced by TGFß1, which indicated that C8 could repress the activation of HSCs. In bile duct ligated rats, C8 administration (100 mg/kg, i.p.) markedly attenuated liver injury, fibrosis, and inflammation, and suppressed the expression of the macrophage surface marker F4/80. In terms of mechanism, C8 treatment blocked the activation of the NLRP3 inflammasome, which was stimulated by LPS and nigericin in bone marrow-derived macrophages (BMDMs) and companied by the release of active IL-1ß. In addition, the activation of LX-2 cells induced by IL-1ß released from BMDMs was also inhibited after C8 administration, which indicated that C8 repressed HSCs activation by inhibiting the activation of NLRP3 inflammasome in macrophages. Furthermore, C8 exhibited the effects of anti-fibrosis and inhibiting the expression of NLRP3 inflammasome in non-alcoholic steatohepatitis (NASH) mice. Finally, C8 can be commendably absorbed in vivo and was safe for mice at the concentration of 1000 mg/kg (p.o.). In summary, our study reveals that C8 ameliorates HSCs activation and liver fibrosis in cholestasis rats and NASH mice by inhibiting NLRP3 inflammasome in macrophages, and C8 might be a safe and effective candidate for the treatment of liver fibrosis.

Rab32 GTPase, as a direct target of miR-30b/c, controls the intracellular survival of Burkholderia pseudomallei by regulating phagosome maturation.

Burkholderia pseudomallei is a gram-negative, facultative intracellular bacterium, which causes a disease known as melioidosis. Professional phagocytes represent a crucial first line of innate defense against invading pathogens. Uptake of pathogens by these cells involves the formation of a phagosome that matures by fusing with early and late endocytic vesicles, resulting in killing of ingested microbes. Host Rab GTPases are central regulators of vesicular trafficking following pathogen phagocytosis. However, it is unclear how Rab GTPases interact with B. pseudomallei to regulate the transport and maturation of bacterial-containing phagosomes. Here, we showed that the host Rab32 plays an important role in mediating antimicrobial activity by promoting phagosome maturation at an early phase of infection with B. pseudomallei. And we demonstrated that the expression level of Rab32 is increased through the downregulation of the synthesis of miR-30b/30c in B. pseudomallei infected macrophages. Subsequently, we showed that B. pseudomallei resides temporarily in Rab32-positive compartments with late endocytic features. And Rab32 enhances phagosome acidification and promotes the fusion of B. pseudomallei-containing phagosomes with lysosomes to activate cathepsin D, resulting in restricted intracellular growth of B. pseudomallei. Additionally, Rab32 mediates phagosome maturation depending on its guanosine triphosphate/guanosine diphosphate (GTP/GDP) binding state. Finally, we report the previously unrecognized role of miR-30b/30c in regulating B. pseudomallei-containing phagosome maturation by targeting Rab32 in macrophages. Altogether, we provide a novel insight into the host immune-regulated cellular pathway against B. pseudomallei infection is partially dependent on Rab32 trafficking pathway, which regulates phagosome maturation and enhances the killing of this bacterium in macrophages.

MicroRNA-146a inhibits autophagy to maintain the intracellular survival of Burkholderia pseudomallei by targeting LIPA.

Burkholderia pseudomallei is the etiological agent of melioidosis, which is an emerging infectious disease endemic to many tropical regions. Autophagy is an intrinsic cellular process that degrades cytoplasmic components and plays an important role in protecting the host against pathogens. Like many intracellular pathogens, B. pseudomallei can evade the autophagy-dependent cellular clearance. However, the underlying mechanism remains unclear. In this study, we applied a combination of multiple assays to monitor autophagy processes and found that B. pseudomallei induced an incomplete autophagic flux and eliminate autophagy clearance in macrophages by blocking autophagosome-lysosome fusion. Based on a high-throughput microarray screening, we found that LIPA (lysosomal acid LIPAse A) was downregulated during B. pseudomallei infection. MiR-146a was then identified to be specifically upregulated upon infection with B. pseudomallei and further regulated LIPA expression by interacting with 3'UTR of LIPA. Furthermore, overexpression of miR-146a contributed to the defect of autophagic flux caused by B. pseudomallei and was beneficial for the survival of B. pseudomallei in macrophages. Therefore, our findings suggest that miR-146a inhibits autophagy via posttranscriptional suppression of LIPA expression to maintain B. pseudomallei survival in macrophages.

Pantoprazole ameliorates liver fibrosis and suppresses hepatic stellate cell activation in bile duct ligation rats by promoting YAP degradation.

Liver fibrosis is one of the most severe pathologic consequences of chronic liver diseases, and effective therapeutic strategies are urgently needed. Proton pump inhibitors (PPIs) are H+/K+-ATPase inhibitors and currently used to treat acid-related diseases such as gastric ulcers, which have shown other therapeutic effects in addition to inhibiting acid secretion. However, few studies have focused on PPIs from the perspective of inhibiting hepatic fibrosis. In the present study, we investigated the effects of pantoprazole (PPZ), a PPI, against liver fibrosis in a bile duct ligation (BDL) rat model, human hepatic stellate cell (HSC) line LX-2 and mouse primary HSCs (pHSCs), and explored the potential mechanisms underlying the effects of PPZ in vitro and in vivo. In BDL rats, administration of PPZ (150 mg· kg-1· d-1, i.p. for 14 d) significantly attenuated liver histopathological injury, collagen accumulation, and inflammatory responses, and suppressed fibrogenesis-associated gene expression including Col1a1, Acta2, Tgfß1, and Mmp-2. In LX-2 cells and mouse pHSCs, PPZ (100-300 µM) dose-dependently suppressed the levels of fibrogenic markers. We conducted transcriptome analysis and subsequent validation in PPZ-treated LX-2 cells, and revealed that PPZ inhibited the expression of Yes-associated protein (YAP) and its downstream targets such as CTGF, ID1, survivin, CYR61, and GLI2. Using YAP overexpression and silencing, we demonstrated that PPZ downregulated hepatic fibrogenic gene expression via YAP. Furthermore, we showed that PPZ promoted the proteasome-dependent degradation and ubiquitination of YAP, thus inhibiting HSC activation. Additionally, we showed that PPZ destabilized YAP by disrupting the interaction between a deubiquitinating enzyme OTUB2 and YAP, and subsequently blocked the progression of hepatic fibrosis.

Genomic and transcriptomic survey of an endophytic fungus Calcarisporium arbuscula NRRL 3705 and potential overview of its secondary metabolites.

BACKGROUND: Secondary metabolites as natural products from endophytic fungi are important sources of pharmaceuticals. However, there is currently little understanding of endophytic fungi at the omics levels about their potential in secondary metabolites. Calcarisporium arbuscula, an endophytic fungus from the fruit bodies of Russulaceae, produces a variety of secondary metabolites with anti-cancer, anti-nematode and antibiotic activities. A comprehensive survey of the genome and transcriptome of this endophytic fungus will help to understand its capacity to biosynthesize secondary metabolites and will lay the foundation for the development of this precious resource. RESULTS: In this study, we reported the high-quality genome sequence of C. arbuscula NRRL 3705 based on Single Molecule Real-Time sequencing technology. The genome of this fungus is over 45 Mb in size, larger than other typical filamentous fungi, and comprises 10,001 predicted genes, encoding at least 762 secretory-proteins, 386 carbohydrate-active enzymes and 177 P450 enzymes. 398 virulence factors and 228 genes related to pathogen-host interactions were also predicted in this fungus. Moreover, 65 secondary metabolite biosynthetic gene clusters were revealed, including the gene cluster for the mycotoxin aurovertins. In addition, several gene clusters were predicted to produce mycotoxins, including aflatoxin, alternariol, destruxin, citrinin and isoflavipucine. Notably, two independent gene clusters were shown that are potentially involved in the biosynthesis of alternariol. Furthermore, RNA-Seq assays showed that only expression of the aurovertin gene cluster is much stronger than expression of the housekeeping genes under laboratory conditions, consistent with the observation that aurovertins are the predominant metabolites. Gene expression of the remaining 64 gene clusters for compound backbone biosynthesis was all lower than expression of the housekeeping genes, which partially explained poor production of other secondary metabolites in this fungus. CONCLUSIONS: Our omics data, along with bioinformatics analysis, indicated that C. arbuscula NRRL 3705 contains a large number of biosynthetic gene clusters and has a huge potential to produce a profound number of secondary metabolites. This work also provides the basis for development of endophytic fungi as a new resource of natural products with promising biological activities.

Reversible and Irreversible Inhibition of Cytochrome P450 Enzymes by Methylophiopogonanone A.

Methylophiopogonanone A (MOA), an abundant homoisoflavonoid bearing a methylenedioxyphenyl moiety, is one of the major constituents in the Chinese herb Ophiopogon japonicas This work aims to assess the inhibitory potentials of MOA against cytochrome P450 enzymes and to decipher the molecular mechanisms for P450 inhibition by MOA. The results showed that MOA concentration-dependently inhibited CYP1A, 2C8, 2C9, 2C19, and 3A in human liver microsomes (HLMs) in a reversible way, with IC50 values varying from 1.06 to 3.43 µM. By contrast, MOA time-, concentration-, and NADPH-dependently inhibited CYP2D6 and CYP2E1, along with KI and kinact values of 207 µM and 0.07 minute-1 for CYP2D6, as well as 20.9 µM and 0.03 minutes-1 for CYP2E1. Further investigations demonstrated that a quinone metabolite of MOA could be trapped by glutathione in an HLM incubation system, and CYP2D6, 1A2, and 2E1 were the major contributors to catalyze the metabolic activation of MOA to the corresponding O-quinone intermediate. Additionally, the potential risks of herb-drug interactions triggered by MOA or MOA-related products were also predicted. Collectively, our findings verify that MOA is a reversible inhibitor of CYP1A, 2C8, 2C9, 2C19, and 3A but acts as an inactivator of CYP2D6 and CYP2E1. SIGNIFICANCE STATEMENT: Methylophiopogonanone A (MOA), an abundant homoisoflavonoid isolated from the Chinese herb Ophiopogon japonicas, is a reversible inhibitor of CYP1A, 2C8, 2C9, 2C19, and 3A but acts as an inactivator of CYP2D6 and CYP2E1. Further investigations demonstrated that a quinone metabolite of MOA could be trapped by glutathione in a human liver microsome incubation system, and CYP2D6, 1A2, and 2E1 were the major contributors to catalyze the metabolic activation of MOA to the corresponding O-quinone intermediate.

Comprehensive dissection of dispensable genomic regions in Streptomyces based on comparative analysis approach.

BACKGROUND: Large-scale genome reduction has been performed to significantly improve the performance of microbial chassis. Identification of the essential or dispensable genes is pivotal for genome reduction to avoid synthetic lethality. Here, taking Streptomyces as an example, we developed a combinatorial strategy for systematic identification of large and dispensable genomic regions in Streptomyces based on multi-omics approaches. RESULTS: Phylogenetic tree analysis revealed that the model strains including S. coelicolor A3(2), S. albus J1074 and S. avermitilis MA-4680 were preferred reference for comparative analysis of candidate genomes. Multiple genome alignment suggested that the Streptomyces genomes embodied highly conserved core region and variable sub-telomeric regions, and may present symmetric or asymmetric structure. Pan-genome and functional genome analyses showed that most conserved genes responsible for the fundamental functions of cell viability were concentrated in the core region and the vast majority of abundant genes were dispersed in the sub-telomeric regions. These results suggested that large-scale deletion can be performed in sub-telomeric regions to greatly streamline the Streptomyces genomes for developing versatile chassis. CONCLUSIONS: The integrative approach of comparative genomics, functional genomics and pan-genomics can not only be applied to perform a multi-tiered dissection for Streptomyces genomes, but also work as a universal method for systematic analysis of removable regions in other microbial hosts in order to generate more miscellaneous and versatile chassis with minimized genome for drug discovery.

Cytotoxic Diterpenoids from Caryopteris aureoglandulosa.

Seven new (1-7) and 11 known diterpenoids were isolated and identified from Caryopteris aureoglandulosa. These diterpenoids were structurally determined by HRESIMS and NMR spectroscopic analyses, single-crystal X-ray diffraction, and ECD data. Structurally, aureoglandulosin A (1) is a highly oxygenated abietane diterpenoid with an unprecedented 7/6/6/5-ring system. Aureoglandulosins B (2) and C (3) represent naturally occurring new diterpenoids with an unusual 6/6/6/5-ring system. Additionally, the configurations of two known abietane diterpenoids 11 and 12 were determined by X-ray crystallographic data analysis for the first time. A plausible biosynthetic pathway for compounds 1-3 is proposed. The cytotoxicity of all isolates was evaluated, and compounds 1 and 11 exhibited significant cytotoxic activity against some cell lines with IC50 values in the range 1.6-8.2 µM.

The regulatory cascades of antibiotic production in Streptomyces.

Streptomyces is famous for its capability to produce the most abundant antibiotics in all kingdoms. All Streptomyces antibiotics are natural products, whose biosynthesis from the so-called gene clusters are elaborately regulated by pyramidal transcriptional regulatory cascades. In the past decades, scientists have striven to unveil the regulatory mechanisms involved in antibiotic production in Streptomyces. Here we mainly focus on three aspects of the regulation on antibiotic production. 1. The onset of antibiotic production triggered by hormones and their coupled receptors as regulators; 2. The cascades of global and pathway-specific regulators governing antibiotic production; 3. The feedback regulation of antibiotics and/or intermediates on the gene cluster expression for their coordinated production. This review will summarize how the antibiotic production is stringently regulated in Streptomyces based on the signaling, and lay a theoretical foundation for improvement of antibiotic production and potentially drug discovery.

Nitidine Chloride-Induced CYP1 Enzyme Inhibition and Alteration of Estradiol Metabolism.

The cytochrome P450 (P450) 1 family is an important phase I enzyme involved in carcinogen activation. Nitidine chloride (NC) is a pharmacologically active alkaloid with polyaromatic hydrocarbon found in the roots of Zanthoxylum nitidum (Roxb.) DC, a traditional medicinal herb widely used in China. We examined the inhibitory effects of NC on CYP1A1, 1B1, and 1A2. NC significantly inhibited CYP1A1- and 1B1-catalyzed ethoxyresorufin O-deethylation activity (IC50 = 0.28 ± 0.06 and 0.32 ± 0.02 µM, respectively) in a concentration-dependent manner, but only showed slight inhibition of CYP1A2 activity (IC50 > 50 µM). Kinetic analysis revealed that NC competitively inhibited CYP1B1 with a K i value of 0.47 ± 0.05 µM, whereas NC caused a mixed type of inhibition on CYP1A1 with K i and K I values of 0.14 ± 0.04 and 0.19 ± 0.09 µM, respectively. The observed enzyme inhibition neither required NADPH nor revealed time dependency. Molecular docking manifested the generation of strong hydrogen-bonding interactions of Ser116 in CYP1A1 and Ser127 in CYP1B1 with methoxy moiety of NC. Additionally, NC-induced alteration of estradiol (E2) metabolism was also investigated in the present study. Hydroxyestradiols, including 2-hydroxyestradiol [(2-OHE2) nontoxic] and 4-hydroxyestradiol [(4-OHE2) genotoxic] generated in recombinant enzyme incubation systems and cultured MCF-7 cells were analyzed, and NC was found to preferentially inhibit the nontoxic 2-hydroxylation activity of E2 mediated by CYP1A1. In conclusion, NC was a mixed type inhibitor of CYP1A1 and a competitive inhibitor of CYP1B1. The remarkable inhibition on E2 2-hydroxylation might increase the risk of 4-OHE2-induced genotoxicity. SIGNIFICANCE STATEMENT: CYP1 enzymes catalyze oxidative metabolism of a variety of compounds and are known to play a crucial role in the development of cancer. CYP1A1 and CYP1A2 are responsible for hydroxylation of estradiol (E2) at the C-2 position, resulting in the formation of 2-OHE2, which is proposed to be a detoxification pathway. However, CYP1B1-mediated hydroxylation of E2 at the C-4 position has been suggested to be a tumor initiator. The present study found that nitidine chloride is a mixed type inhibitor of CYP1A1 and a competitive inhibitor of CYP1B1. NC preferentially inhibited the nontoxic E2 2-hydroxylation pathway mediated by CYP1A1, which might increase the risk of 4-OHE2-induced genotoxicity and cause severe drug-drug interactions.