Metabolites Produced by the Oral Commensal Bacterium Corynebacterium durum Extend the Lifespan of Caenorhabditis elegans via SIR-2.1 Overexpression.

Human microbiota is heavily involved in host health, including the aging process. Based on the hypothesis that the human microbiota manipulates host aging via the production of chemical messengers, lifespan-extending activities of the metabolites produced by the oral commensal bacterium Corynebacterium durum and derivatives thereof were evaluated using the model organism Caenorhabditis elegans. Chemical investigation of the acetone extract of a C. durum culture led to the identification of monoamines and N-acetyl monoamines as major metabolites. Phenethylamine and N-acetylphenethylamine induced a potent and dose-dependent increase of the C. elegans lifespan, up to 21.6% and 19.9%, respectively. A mechanistic study revealed that the induction of SIR-2.1, a highly conserved protein associated with the regulation of lifespan, was responsible for the observed increased longevity.

Anti-Hyperuricemic, Anti-Inflammatory and Analgesic Effects of Siegesbeckia orientalis L. Resulting from the Fraction with High Phenolic Content.

BACKGROUND: The medicinal plant Siegesbeckia orientalis L. has been commonly used for the treatment of acute arthritis, rheumatism, and gout in Vietnam. However, pharmacological research of this plant associated with gout has not been reported. Anti-hyperuricemic and anti-inflammatory effects were evaluated and observed for the crude ethanol extract (CEE) of S. orientalis. Retention of these biological properties was found in a n-butanol-soluble fraction (BuOH fr.) of the extract, and therefore further biological and chemical investigations were undertaken on the BuOH fr. to support the medical relevance of this plant. METHODS: The aerial part of S. orientalis was obtained in the mountainous region of Vietnam. The crude ethanol extract (CEE) and its BuOH fr. were prepared from the plant materials. Anti-hyperuricemic activities of the CEE and BuOH fr. were tested in vivo using the model oxonate-induced hyperuricemia rats through determination of serum uric acid levels and inhibitory effects on xanthine oxidase (XO) in the rat liver. Anti-inflammatory activities of the BuOH fr. were also evaluated in vivo using carrageenan-induced paw edema and urate-induced synovitis in rats. Active components of the BuOH fr. were characterized by comparison of HPLC retention time (t R) and spectroscopic data (UV, 1H-NMR) with those of reference compounds. RESULTS: The CEE of S. orientalis displayed anti-hyperuricemic activity, and the BuOH fr. was found to be the most active portion of the extract. Further in vivo studies on this fraction showed 31.4% decrease of serum uric acid levels, 32.7% inhibition of xanthine oxidase (XO), 30.4% reduction of paw edema volume, symptomatic relief in urate-induced synovitis and significant analgesic effect at the dose of 120 mg/kg, as compared to the corresponding values of the control groups. Chemical analysis of the BuOH fr. revealed high phenolic content, identified as caffeic acid analogues and flavonones. CONCLUSIONS: This study suggested that anti-hyperuricemic and anti-inflammatory mechanism of S. orientalis is related to XO inhibitory effect of the phenolic components. Our findings support the use of this plant as the treatment of gout and other inflammatory diseases.

Disseminins and Spiciferone Analogues: Polyketide-Derived Metabolites from a Fungicolous Isolate of Pestalotiopsis disseminata.

Seven new polyketide metabolites (disseminins A-E, 1-5, and spiciferones D and E, 7 and 8) were obtained from cultures of a fungicolous isolate of Pestalotiopsis disseminata (NRRL 62562), together with a related compound (6) previously known only as a semisynthetic product. Structures were determined mainly by analysis of HRMS and NMR data. Biogenetically related compounds 1 and 2 possess uncommon bis-tetrahydrofuran and dioxabicyclo[3.2.1]octane ring systems, respectively. X-ray crystallographic analysis of the p-bromobenzoate derivative of 1 confirmed the structure and enabled assignment of its absolute configuration.

Cytotoxic activity of rearranged drimane meroterpenoids against colon cancer cells via down-regulation of ß-catenin expression.

Colorectal cancer has emerged as a major cause of death in Western countries. Down-regulation of ß-catenin expression has been considered a promising approach for cytotoxic drug formulation. Eight 4,9-friedodrimane-type sesquiterpenoids (1-8) were acquired using the oxidative potential of Verongula rigida on bioactive metabolites from two Smenospongia sponges. Compounds 3 and 4 contain a 2,2-dimethylbenzo[d]oxazol-6(2H)-one moiety as their substituted heterocyclic residues, which is unprecedented in such types of meroterpenoids. Gauge-invariant atomic orbital NMR chemical shift calculations were employed to investigate stereochemical details with support of the application of advanced statistics such as CP3 and DP4. Compounds 2 and 8 and the mixture of 3 and 4 suppressed ß-catenin response transcription (CRT) via degrading ß-catenin and exhibited cytotoxic activity on colon cancer cells, implying that their anti-CRT potential is, at least in part, one of their underlying antineoplastic mechanisms.

Activation of p53 with ilimaquinone and ethylsmenoquinone, marine sponge metabolites, induces apoptosis and autophagy in colon cancer cells.

The tumor suppressor, p53, plays an essential role in the cellular response to stress through regulating the expression of genes involved in cell cycle arrest, apoptosis and autophagy. Here, we used a cell-based reporter system for the detection of p53 response transcription to identify the marine sponge metabolites, ilimaquinone and ethylsmenoquinone, as activators of the p53 pathway. We demonstrated that ilimaquinone and ethylsmenoquinone efficiently stabilize the p53 protein through promotion of p53 phosphorylation at Ser15 in both HCT116 and RKO colon cancer cells. Moreover, both compounds upregulate the expression of p21WAF1/CIP1, a p53-dependent gene, and suppress proliferation of colon cancer cells. In addition, ilimaquinone and ethylsmenoquinone induced G2/M cell cycle arrest and increased caspase-3 cleavage and the population of cells that positively stained with Annexin V-FITC, both of which are typical biochemical markers of apoptosis. Furthermore, autophagy was elicited by both compounds, as indicated by microtubule-associated protein 1 light chain 3 (LC3) puncta formations and LC3-II turnover in HCT116 cells. Our findings suggest that ilimaquinone and ethylsmenoquinone exert their anti-cancer activity by activation of the p53 pathway and may have significant potential as chemo-preventive and therapeutic agents for human colon cancer.

Ilimaquinone and ethylsmenoquinone, marine sponge metabolites, suppress the proliferation of multiple myeloma cells by down-regulating the level of ß-catenin.

Deregulation of Wnt/ß-catenin signaling promotes the development of a broad range of human cancers, including multiple myeloma, and is thus a potential target for the development of therapeutics for this disease. Here, we used a cell-based reporter system to demonstrate that ilimaquinone and ethylsmenoquinone (formerly smenorthoquinone), sesquiterpene-quinones from a marine sponge, inhibited ß-catenin response transcription induced with Wnt3a-conditioned medium, by down-regulating the level of intracellular ß-catenin. Pharmacological inhibition of glycogen synthase kinase-3ß did not abolish the ilimaquinone and ethylsmenoquinone-mediated ß-catenin down-regulation. Degradation of ß-catenin was consistently found in RPMI-8226 multiple myeloma cells after ilimaquinone and ethylsmenoquinone treatment. Ilimaquinone and ethylsmenoquinone repressed the expression of cyclin D1, c-myc, and axin-2, which are ß-catenin/T-cell factor-dependent genes, and inhibited the proliferation of multiple myeloma cells. In addition, ilimaquinone and ethylsmenoquinone significantly induced G0/G1 cell cycle arrest and apoptosis in RPMI-8266 cells. These findings suggest that ilimaquinone and ethylsmenoquinone exert their anti-cancer activity by blocking the Wnt/ß-catenin pathway and have significant potential as therapies for multiple myeloma.

Quercetin and its derivatives from lotus (Nelumbo nucifera) seedpod extract combat radioresistance by suppressing ACSL4.

Radioresistance poses a significant obstacle in cancer treatment. Lotus seedpod extract (LSE) has demonstrated anticancer effects in various cancer cells. However, its potential against radioresistant tumors remains unclear. In this study, we aimed to investigate the effect of LSE on radioresistant breast cancer cells, explore the underlying mechanism, and identify the major constituents responsible for its cytotoxic effect. LSE, extracted using 70% ethanol, exhibited selective cytotoxic effects against radioresistant breast cancer cells compared with their parental cells. Chemical analysis identified quercetin and its derivatives, hyperoside and miquelianin, as the major constituents responsible for these selective effects. Notably, quercetin displayed the most potent cytotoxicity against radioresistant breast cancer cells compared with hyperoside and miquelianin. Further investigation revealed that these compounds inhibited the activation of DNA repair systems, leading to the accumulation of DNA damage and the induction of apoptosis. Importantly, they efficiently suppressed the expression of ACSL4, a factor previously associated with radioresistance. In an in vivo study, quercetin exhibited a significant suppression of tumor growth in radioresistant tumor-bearing mice. Taken together, our findings highlight the potential of LSE and its major constituents, quercetin and its derivatives, in overcoming radioresistance in breast cancer. This study provides compelling evidence to support the use of LSE as a medicinal source for the future adjunctive therapy to combat radioresistance in breast cancers.

Oxidative tryptamine dimers from Corynebacterium durum directly target survivin to induce AIF-mediated apoptosis in cancer cells.

Accumulating evidence indicates that microbial communities in the human body crucially affect health through the production of chemical messengers. However, the relationship between human microbiota and cancer has been underexplored. As a result of a biochemical investigation of the commensal oral microbe, Corynebacterium durum, we identified the non-enzymatic transformation of tryptamine into an anticancer compound, durumamide A (1). The structure of 1 was determined using LC-MS and NMR data analysis as bis(indolyl)glyoxylamide, which was confirmed using one-pot synthesis and X-ray crystallographic analysis, suggesting that 1 is an oxidative dimer of tryptamine. Compound 1 displayed cytotoxic activity against various cancer cell lines with IC50 values ranging from 25 to 35 µM. A drug affinity responsive target stability assay revealed that survivin is the direct target protein responsible for the anticancer effect of 1, which subsequently induces apoptosis-inducing factor (AIF)-mediated apoptosis. Inspired by the chemical structure and bioactivity of 1, a new derivative, durumamide B (2), was synthesized using another indole-based neurotransmitter, serotonin. The anticancer properties of 2 were similar to those of 1; however, it was less active. These findings reinforce the notion of human microbiota-host interplay by showing that 1 is naturally produced from the human microbial metabolite, tryptamine, which protects the host against cancer.

Phenylacetic acid, an anti-vaginitis metabolite produced by the vaginal symbiotic bacterium Chryseobacterium gleum.

The human microbiome contains genetic information that regulates metabolic processes in response to host health and disease. While acidic vaginal pH is maintained in normal conditions, the pH level increases in infectious vaginitis. We propose that this change in the vaginal environment triggers the biosynthesis of anti-vaginitis metabolites. Gene expression levels of Chryseobacterium gleum, a vaginal symbiotic bacterium, were found to be affected by pH changes. The distinctive difference in the metabolic profiles between two C. gleum cultures incubated under acidic and neutral pH conditions was suggested to be an anti-vaginitis molecule, which was identified as phenylacetic acid (PAA) by spectroscopic data analysis. The antimicrobial activity of PAA was evaluated in vitro, showing greater toxicity toward Gardnerella vaginalis and Candida albicans, two major vaginal pathogens, relative to commensal Lactobacillus spp. The activation of myeloperoxidase, prostaglandin E2, and nuclear factor-κB, and the expression of cyclooxygenase-2 were reduced by an intravaginal administration of PAA in the vaginitis mouse model. In addition, PAA displayed the downregulation of mast cell activation. Therefore, PAA was suggested to be a messenger molecule that mediates interactions between the human microbiome and vaginal health.

A novel natural phenyl alkene with cytotoxic activity.

A novel phenyl alkene (1) was isolated from a mixture of three Florida sponges, Smenospongia aurea, Smenospongia cerebriformis, and Verongula rigida. Unlike terpenoids or amino acid derivatives, which are commonly known classes of secondary metabolites from these genera, the chemical structure of 1 showed an unprecedented linear phenyl alkene skeleton. Through comprehensive analyses of NMR and MS data, the gross structure of 1 was determined to be (E)-10-benzyl-5,7-dimethylundeca-1,5,10-trien-4-ol. The absolute configuration at C-4 was established as R by a modified Mosher's method. Based on the relative configuration between C-4 and C-7, the absolute configuration at C-7 was assigned as S. Compound 1 showed in vitro cytotoxic activity against HL-60 human leukemia cancer cells with an IC50 value of 8.1 µM. Molecular docking study suggests that the structure of compound 1 matches the pharmacophore of eribulin required to display cytotoxic activity through the inhibition of microtubule activity.

Inhibition of fatty acid synthase by ginkgolic acids from the leaves of Ginkgo biloba and their cytotoxic activity.

Fatty acid synthase (FAS) has been proposed to be a new drug target for the development of anticancer agents because of the significant difference in expression of FAS between normal and tumour cells. Since a n-hexane-soluble extract from Ginkgo biloba was demonstrated to inhibit FAS activity in our preliminary test, we isolated active compounds from the n-hexane-soluble extract and evaluated their cytotoxic activity in human cancer cells. Three ginkgolic acids 1-3 isolated from the n-hexane-soluble extract inhibited the enzyme with IC(50) values 17.1, 9.2 and 10.5 µM, respectively, and they showed cytotoxic activity against MCF-7 (human breast adenocarcinoma), A549 (human lung adenocarcinoma) and HL-60 (human leukaemia) cells. Our findings suggest that alkylphenol derivatives might be a new type of FAS inhibitor with cytotoxic activity.

Asterosaponins isolated from the starfish Asterias amurensis.

Three new asterosaponins 1-3 and four known saponins 4-7 have been isolated from the starfish Asterias amurensis LÜTKEN. By means of high magnetic field 1D- and 2D-NMR ((1)H-(1)H correlation spectroscopy (COSY), total correlation spectroscopy (TOCSY), heteronuclear multiple quantum coherence (HMQC), heteronuclear single quantum coherence (HSQC), heteronuclear multiple bond correlation (HMBC), and nuclear Overhauser effect spectroscopy (NOESY)) and MS analyses, the chemical structures of new compounds were determined to be 6α-O-[ß-D-fucopyranosyl-(1→2)-ß-D-galactopyranosyl-(1→4)-[ß-D-quinovopyranosyl-(1→2)]-ß-D-quinovopyranosyl-(1→3)-ß-D-galactopyranosyl]-5α-chol-9(11)-en-23-one-3ß-yl sodium sulfate (1), 6α-O-[ß-D-fucopyranosyl-(1→2)-ß-D-galactopyranosyl-(1→4)-[ß-D-quinovopyranosyl-(1→2)]-ß-D-quinovopyranosyl-(1→3)-ß-D-galactopyranosyl]-5α-cholesta-9(11),24-dien-23-one-3ß-yl sodium sulfate (2), and 6α-O-[ß-D-fucopyranosyl-(1→2)-ß-D-galactopyranosyl-(1→4)-[ß-D-quinovopyranosyl-(1→2)]-ß-D-quinovopyranosyl-(1→3)-ß-D-galactopyranosyl]-5α-cholest-9(11)-en-23-one-3ß-yl sodium sulfate (3). In addition, the NMR data for known saponins 4-7 were completely assigned by extensive 2D-NMR analysis without chemical degradation.

Oleanane triterpenoids from Rubia philippinensis and their inhibitory effect on 20-HETE synthesis.

A new oleanane triterpenoid (2) was isolated from the roots of Rubia philippinensis. The structure of 2 was determined by analysis of HRMS and NMR data and identified as a rubiprasin analogue, 16ß-hydroxyrubiprasin B. Four related known compounds were also encountered which include rubiprasin B (1), maslinic acid (3), 4-epi-hederagenin (4) and oleanolic acid (5). The compounds 3-5 displayed moderate inhibitory activity against the synthesis of the eicosanoid 20-HETE.

Chaga mushroom extract induces autophagy via the AMPK-mTOR signaling pathway in breast cancer cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Chaga mushrooms (Inonotus obliquus) are commonly used in traditional treatments in Eastern Europe and Asia due to their diverse pharmacological effects, including anti-tumor and immunologic effects. Thus, many cancer patients take Chaga mushrooms as a complementary medicine, even during chemotherapy or radiotherapy. However, few studies have investigated the effects or molecular targets of Chaga mushrooms in breast cancer. AIM OF THE STUDY: Herein, we examined the anticancer effects of Chaga mushrooms in different types of breast cancer cell lines, and explored the underlying molecular mechanism to better understand their effects and benefits. MATERIALS AND METHODS: Chaga mushroom extract (CME) was prepared by extracting Chaga mushrooms with 70% ethanol. The cytotoxic effects of CME were assessed by MTT assay and protein expressions were evaluated by western blotting. To evaluate in vivo anti-tumor effects of CME, CME (2 g/kg) was orally administered to 4T1 tumor-bearing BALB/c mice every other day over 30 days (15 administrations), and tumor sizes were measured. Silica gel column chromatography was used to fractionate CME, and major constituents responsible for cytotoxic effects of CME were identified by 1H/13C-NMR and LC-MS. RESULTS: CME inhibited the proliferation of 4T1 mouse breast cancer cells in a dose and time-dependent manner. The expression of LC3 and phosphorylation of AMPK were increased by CME, while the phosphorylation of mTOR, S6, and S6K1 were suppressed, suggesting that CME induced autophagy by activating AMPK and inhibiting mTOR signaling pathways. Consistent with its observed cytotoxic effect in vitro, CME effectively suppressed tumor growth in 4T1 tumor-bearing BALB/c mice. In addition, inotodiol and trametenolic acid were identified as the major constituents responsible for the cytotoxic effects of CME on breast cancer cells. Moreover, inotodiol and trametenolic acid-enriched fractions both exhibited cytotoxic effects regardless of breast cancer cell subtypes and did not interfere with the cytotoxic effects of conventional drugs. CONCLUSIONS: Taken together, Chaga mushroom extract induced autophagy by activating AMPK and inhibiting the mTOR signaling pathway. Our data suggest Chaga mushrooms may be a beneficial complementary medicine for breast cancer patients.

Protein tyrosine phosphatase 1B inhibitory activity of 24-norursane triterpenes isolated from Weigela subsessilis.

During the screening effort to discover new types of protein tyrosine phosphatase 1B (PTP1B) inhibitors, it was found that a MeOH extract of the leaves and stems of Weigela subsessilis (Caprifoliaceae) inhibited the enzyme activity. By means of an in vitro bioassay-guided fractionation on the MeOH extract, two 24-norursane triterpenes, ilekudinol A (1) and ilekudinol B (2), were isolated as active metabolites. Compounds 1 and 2 inhibited PTP1B with IC(50) values of 29.1 ± 2.8 and 5.3 ± 0.5 µM, respectively. Kinetic studies suggest that both 1 and 2 are non-competitive inhibitors of PTP1B. The findings indicate that the free carboxyl group at C-28 in this type of triterpenes plays a critical role in the inhibition of PTP1B.

Correction to: Lifespan-extending property of 6-shogaol from Zingiber officinale Roscoe in Caenorhabditis elegans.

The author would like to include conflict of interest statement of the online published article. The correct conflict of interest statement should read as: The authors declare no conflict of interest.

Lifespan-extending property of 6-shogaol from Zingiber officinale Roscoe in Caenorhabditis elegans.

Aging is a key risk factor for many diseases, understanding the mechanism of which is becoming more important for drug development given the fast-growing aging population. In the course of our continued efforts to discover anti-aging natural products, the active constituent 6-shogaol was isolated from Zingiber officinale Roscoe. The chemical structure of 6-shogaol was identified by comparison of its NMR data with literature values. The lifespan-extending effect of 6-shogaol was observed in a dose-dependent manner in Caenorhabditis elegans that has been widely used as a model organism for human aging studies. Mechanism of such action was investigated using C. elegans models, suggesting that 6-shogaol is capable of increasing stress tolerances via enzyme induction. The proposed mechanism was further supported by observation of the increase in SOD and HSP expressions upon treatment with 6-shogaol in transgenic strains of C. elegans which contain GFP-based reporters. In addition, the mechanism was elaborated by confirming that the effect observed for 6-shogaol is independent from other aging-related factors that are known to affect the aging process of C. elegans.

Chromomycin A2 potently inhibits glucose-stimulated insulin secretion from pancreatic ß cells.

Modulators of insulin secretion could be used to treat diabetes and as tools to investigate ß cell regulatory pathways in order to increase our understanding of pancreatic islet function. Toward this goal, we previously used an insulin-linked luciferase that is cosecreted with insulin in MIN6 ß cells to perform a high-throughput screen of natural products for chronic effects on glucose-stimulated insulin secretion. In this study, using multiple phenotypic analyses, we found that one of the top natural product hits, chromomycin A2 (CMA2), potently inhibited insulin secretion by at least three potential mechanisms: disruption of Wnt signaling, interference of ß cell gene expression, and partial suppression of Ca2+ influx. Chronic treatment with CMA2 largely ablated glucose-stimulated insulin secretion even after washout, but it did not inhibit glucose-stimulated generation of ATP or Ca2+ influx. However, by using the KATP channel opener diazoxide, we uncovered defects in depolarization-induced Ca2+ influx that may contribute to the suppressed secretory response. Glucose-responsive ERK1/2 and S6 phosphorylation were also disrupted by chronic CMA2 treatment. By querying the FUSION bioinformatic database, we revealed that the phenotypic effects of CMA2 cluster with a number of Wnt-GSK3 pathway-related genes. Furthermore, CMA2 consistently decreased GSK3ß phosphorylation and suppressed activation of a ß-catenin activity reporter. CMA2 and a related compound, mithramycin, are known to have DNA interaction properties, possibly abrogating transcription factor binding to critical ß cell gene promoters. We observed that CMA2 but not mithramycin suppressed expression of PDX1 and UCN3. However, neither expression of INSI/II nor insulin content was affected by chronic CMA2. The mechanisms of CMA2-induced insulin secretion defects may involve components both proximal and distal to Ca2+ influx. Therefore, CMA2 is an example of a chemical that can simultaneously disrupt ß cell function through both noncytotoxic and cytotoxic mechanisms. Future therapeutic applications of CMA2 and similar aureolic acid analogues should consider their potential effects on pancreatic islet function.

Smenospongidine suppresses the proliferation of multiple myeloma cells by promoting CCAAT/enhancer-binding protein homologous protein-mediated ß-catenin degradation.

Abnormal up-regulation of ß-catenin expression is associated with the development and progression of multiple myeloma and is thus a potential therapeutic target. Here, we screened cell-based natural compounds and identified smenospongidine, a metabolite isolated from a marine sponge, as an antagonist of the Wnt/ß-catenin signaling pathway. Smenospongidine promoted the degradation of intracellular ß-catenin that accumulated via Wnt3a or 6-bromoindirubin-3'-oxime, an inhibitor of glycogen synthase kinase-3ß. Consistently, smenospongidine down-regulated ß-catenin expression and repressed the levels of ß-catenin/T cell factor-dependent genes such as axin2, c-myc, and cyclin D1 in RPMI-8226 multiple myeloma cells. Smenospongidine suppressed proliferation and significantly induced apoptosis in RPMI-8266 cells. In addition, smenospongidine-induced ß-catenin degradation was mediated by up-regulating CCAAT/enhancer-binding protein homologous protein (CHOP). These findings indicate that smenospongidine exerts its anti-proliferative activity by blocking the Wnt/ß-catenin signaling pathway and may be a potential chemotherapeutic agent against multiple myeloma.

Quinoxaline-, dopamine-, and amino acid-derived metabolites from the edible insect Protaetia brevitarsis seulensis.

Edible insects have been reported to produce metabolites showing various pharmacological activities, recently emerging as rich sources of health functional food. In particular, the larvae of Protaetia brevitarsis seulensis (Kolbe) have been used as traditional Korean medicines for treating diverse diseases, such as breast cancer, inflammatory disease, hepatic cancer, liver cirrhosis, and hepatitis. However, only few chemical investigations were reported on the insect larvae. Therefore, the aim of this study was to discover and identify biologically active chemical components of the larvae of P. brevitarsis seulensis. As a result, a quinoxaline-derived alkaloid (1) was isolated, which was not reported previously from natural sources. In addition, other related compounds (2, 4-10, 15, 16) were also encountered for the first time from the larvae. The structures of all the isolated compounds were established mainly by analysis of HRESIMS, NMR, and electronic circular dichroism data. Compound 5 exhibited inhibition of tyrosinase with IC50 value of 44.8 µM.