Peipei Guan

Jiangrines A-F and jiangolide from an actinobacterium, Jiangella gansuensis.

Seven new compounds, including five pyrrol-2-aldehyde derivatives, jiangrines A-E (1-5), one indolizine derivative, jiangrine F (7), and one glycolipid, jiangolide (8), along with a known compound, pyrrolezanthine (6), were isolated from the fermentation broth of Jiangella gansuensis, an actinobacterium assigned to a novel family, Jiangellaceae, and a novel order, Jiangellales. The structures were elucidated by detailed spectroscopic analysis and through chemical methods. Compounds 1, 2, 3/4, 5, 6, and 8 demonstrated inhibitory effects on lipopolysaccharide-induced NO production in RAW 264.7 macrophage cells, with IC50 values of 97.8, 60.7, 30.1, 54.9, 58.8, and 61.4 μM, respectively.

Bafilomycin C1 exert antifungal effect through disturbing sterol biosynthesis in Candida albicans

In a previous study on discovering new antimicrobial agents from microbial sources, nine bafilomycins were isolated from the fermentation broth of Streptomyces albolongus. Among them, bafilomycin C1 (Baf C1) showed strong antifungal activity against Candida albicans, with MIC value of 1.56 μg/mL. The aim of this study was to evaluate the action mechanism of Baf C1 against C. albicans. Quantitative PCR analysis revealed that ergosterol biosynthesis-related genes of C. albicans ACS1, HMG1, IDI1, ERG1, ERG2, ERG6, ERG7, ERG8, ERG9, ERG12, ERG13, ERG20, ERG24, ERG251, ERG252, ERG26, ERG27, and ERG28 were all down-regulated (Log2fold change < −1) after Baf C1(4 μg/mL) exposure. Moreover, the expression of MET6 gene, encoded methionine synthase, was also down-regulated (2.7-fold). It is corresponding with the quantitative PCR result, the content of ergosterol has dropped about 41% compared with the control. Transmission electron microscope examination also revealed that the Baf C1 strongly destroyed the cell membrane of C. albicans. In addition, the content of farnesol was significantly increased, about 2.1-fold compared with the control. The results indicated Baf C1 caused aberrations in sterol biosynthesis, leaded to the lack of ergosterol of the fungal membrane.

Effect of borrelidin on hepatocellular carcinoma cells in vitro and in vivo

Hepatocellular carcinoma (HCC) is the most common type of liver cancer with high prevalence and mortality. Borrelidin, produced by several actinomycete bacteria of Streptomycin sp. exhibited diversiform activities including anti-bacterial, anti-viral, anti-angiogenic, and anti-tumor. However, the effect of borrelidin on HCC cells has not been characterized. The present study demonstrated borrelidin exhibited great potential to inhibit the growth of HCC cells, HepG2 and SMMC7721 in vitro. Western blot and real-time qPCR analysis revealed that borrelidin decreased the expressions of cyclin D1, cyclin D3, cyclin E1, CDK2, CDK4, and CDK6 and increased the expression of p21, thereby inducing G0/G1 cell cycle arrest. Moreover, borrelidin down-regulated expression of Bcl-2, up-regulated expression of Bax and increased cleavages of caspase-9 and caspase-3 to activate caspase-dependent apoptosis in HCC cells. Borrelidin inhibited migration and invasion through suppressing the expression of MMP-2 and MMP-9 in HCC cells. Further investigation indicated that the anti-tumor effect of borrelidin was mediated by MAPKs signaling pathway. In addition, an in vivo experiment revealed that borrelidin suppressed tumor growth in SMMC7721 xenograft model mice with few side effects. Cell cycle arrest and induced apoptosis were also observed in tumor tissues of model mice treated with borrelidin.

Anti-Inflammatory Activities and Liver Protection of Alisol F and 25-Anhydroalisol F through the Inhibition of MAPK, STAT3, and NF-κB Activation In Vitro and In Vivo

Alisol F and 25-anhydroalisol F isolated from Alisma orientale, were proved to exhibit anti-inflammatory potential in our previous work. In the current study, the anti-inflammatory effects and action mechanisms of alisol F and 25-anhydroalisol F were investigated in vitro. Moreover, the pharmacological effects of alisol F in lipopolysaccharide (LPS)/d-galactosamine (d-gal)-induced acute liver-injured mice were evaluated. The results demonstrated that alisol F and 25-anhydroalisol F could suppress LPS-induced production of nitric oxide (NO), interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and interleukin-1β (IL-1β), as well as inhibit the mRNA and protein levels of inducible nitric oxide (iNOS) and cyclooxygenase-2 (COX-2). In addition, we investigated the role of alisol F and 25-anhydroalisol F in mediating mitogen-activated protein kinases (MAPKs), signal transducers, and activators of transcription 3 (STAT3) and nuclear factor κB (NF-κB) pathways involved in the inflammation process of LPS-stimulated RAW 264.7 cells. The phosphorylation of ERK, JNK, p38, and STAT3, and the NF-κB signaling pathway, were obviously suppressed in alisol F and 25-anhydroalisol F treated cells. Results obtained from in vitro experiments suggested alisol F obviously improved liver pathological injury by inhibiting the production of TNF-α, IL-1β, and IL-6, and significantly decreasing the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in LPS/d-gal-induced mice. Furthermore, the reduction of phosphorylation of ERK and JNK, as well as suppression of the NF-κB signaling pathway, were also observed in liver tissues of the alisol F-treated mice model. Alisol F and 25-anhydroalisol F may serve as potential leads for development of anti-inflammatory agents for acute liver failure treatment.

Anti-Inflammatory Effects, SAR, and Action Mechanism of Monoterpenoids from Radix Paeoniae Alba on LPS-Stimulated RAW 264.7 Cells

Nine monoterpenoids from Radix Paeoniae Alba, including paeoniflorin derivatives, paeoniflorin (PF), 4-O-methylpaeoniflorin (MPF), 4-O-methylbenzoylpaeoniflorin (MBPF); paeonidanin derivatives, paeonidanin (PD), paeonidanin A (PDA), albiflorin derivatives, albiflorin (AF), benzoylalbiflorin (BAF), galloylalbiflorin (GAF), and debenzoylalbiflorin (DAF), were obtained in our previous phytochemistry investigations. Their anti-inflammatory effects were determined in the present study. The expression and production of pro-inflammatory cytokines in lipopolysaccharides (LPS)-stimulated RAW 264.7 cells were measured using an Elisa assay and nitric oxide (NO) release was determined using the Griess method. The results demonstrated that the most of the monoterpenoids suppressed the LPS-induced production of NO, interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α). The anti-inflammatory activities of these monoterpenoids were closely related to their structural characteristics. Paeoniflorins and paeonidanins presented stronger anti-inflammatory activities than those of albiflorin derivatives. Furthermore, the action mechanisms of MBPF, having a strong anti-inflammatory effect, were investigated using quantitative reverse transcription polymerase chain reaction (RT-PCR) and Western blot methods. The results indicated that MBPF could down-regulate the mRNA and protein expression level of inducible nitric oxide synthase (iNOS) in LPS-stimulated RAW 264.7 cells. The mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K)/AKT and nuclear factor κB (NF-κB) signaling pathways are involved in mediating the role of MBPF in suppressing the expression and production of pro-inflammatory cytokines in RAW 264.7 cells.

Bafilomycin C1 induces G0/G1 cell-cycle arrest and mitochondrial-mediated apoptosis in human hepatocellular cancer SMMC7721 cells

Bafilomycin C1, which was isolated from Streptomyces albolongus in our previous work, exhibited strong cytotoxicity against several cancer cell lines. This study aimed to evaluate its antitumor effect on human hepatocellular cancer SMMC7721 cells and the underlying mechanism in vitro and in vivo. MTT assay revealed that bafilomycin C1 retarded SMMC7721 cell growth and proliferation. Western blot and real-time qPCR analysis revealed that bafilomycin C1 caused partial G0/G1 phase cell-cycle arrest, downregulated the expression of cyclin D3, cyclin E1, CDK2, CDK4, and CDK6 and upregulated the expression of p21. Moreover, bafilomycin C1 caused mitochondrial membrane dysfunction through oxidative stress. Furthermore, bafilomycin C1 decreased the expression of Bcl-2; increased the expression of Bax, p53, and P-p53; and increased cleavage of caspase-9 and caspase-3, thereby inducing the intrinsic caspase-dependent apoptotic pathway. In vivo experiments in mice suggested that bafilomycin C1 suppressed tumor growth with few side effects. Cell-cycle arrest and induced apoptosis in tumor tissues in a mouse model treated with bafilomycin C1 were demonstrated by histological analyses, western blot and TUNEL. These findings indicate that bafilomycin C1 may be a promising candidate for hepatic cellular cancer therapy.

Heronamides G–L, polyene macrolactams from Streptomyces niveus

Six new polyene macrolactams, heronamides G–L (1–6), one new polyenoic acid derivative, niveamide B (10), together with four known compounds, BE-14106-6 (7), BE-14106 (8), GT32-B (9), and niveamide (11), were isolated from the fermentation broth of Streptomyces niveus. Their planar structures were elucidated by detailed analysis of spectroscopic data. The absolute configurations of compounds 1–6 were determined by calculated ECD spectra and analysis of the possible biosynthetic pathways. Compounds 1–6 and 8–11 did not exhibit any significant antimicrobial activities, cytotoxicities, or inhibitory effects on lipopolysaccharide-induced NO production in BV2 microglial cells.

Total synthesis of (±)-(1β,4β,4aβ,8aα)-4,8a-dimethyl-octahydro-naphthalene-1,4a(2H)-diol

The first total synthesis of (±)-(1β,4β,4aβ,8aα)-4,8a-dimethylocta-hydronaphthalene-1,4a(2H)-diol (1), a degraded sesquiterpene isolated from a fermentation broth of Streptomyces albolongus, has been achieved via three different synthetic approaches (13–15 steps) starting from racemic Wieland–Miescher ketone (2). The configuration of hydroxyl groups at C-1 and C-4a in 1 was availably managed using the Mitsunobu reaction and stereo- and regioselective epoxidation. Moreover, the syntheses of configuration isomers 12, 17, 45 and 54 were also described in the present study.

Actinofuranones D-I from a Lichen-Associated Actinomycetes, Streptomyces gramineus, and Their Anti-Inflammatory Effects

Six new metabolites, actinofuranones D-I (compounds 1–6), were isolated together with three known compounds—JBIR-108 (7), E-975 (8), and E-492 (9)—from a fermentation broth of Streptomyces gramineus derived from the lichen Leptogium trichophorum. The structures of the new compounds 1–6 were established using comprehensive NMR spectroscopic data analysis, as well as UV, IR, and MS data. The anti-inflammatory activity of these isolated compounds were evaluated by examining their ability to inhibit nitric oxide (NO) production in LPS-stimulated RAW 264.7 macrophage cells. Compounds 4, 5, 8, and 9 attenuated the production of NO due to the suppression of the expression of nitric oxide synthase (iNOS) in LPS-induced RAW 264.7 cells. Moreover, 4, 5, 8, and 9 also inhibited LPS-induced release of proinflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor α (TNF-α).

Violacin A, a new chromanone produced by Streptomyces violaceoruber and its anti-inflammatory activity

A new chromanone derivative, named violacin A (1), was isolated from the fermentation broth of Streptomyces violaceoruber as a potential anti-inflammatory compound. The structure of violacin A was established using comprehensive NMR spectroscopic data analysis together with UV, IR, and MS data. The anti-inflammatory effects and action mechanisms of violacin A were investigated in vitro. The results demonstrated that violacin A attenuated the production of NO, IL-1β, IL-6, and TNF-α as well as inhibited the expression of iNOS in LPS-induced RAW 264.7 cells. Additionally, Western blot and qRT-PCR results revealed that 1 down-regulated pro-inflammatory cytokines expression correlated with the suppression of NF-κB signaling pathway.