A new fusicoccane diterpene and a new polyene from the plant endophytic fungus Talaromyces pinophilus and their antimicrobial activities.

A new fusicoccane diterpene, pinophicin A (1), and a new polyene, pinophol A (2), were isolated from the plant endophytic fungus Talaromyces pinophilus obtained from the aerial parts of Salvia miltiorrhiza. The structures and relative configurations of 1-2 were determined by the analysis of extensive spectroscopic data, chemical method, and comparison with known compounds. Compound 2 exhibited weak antibacterial activity against Bacterium paratyphosum B with an MIC value of 50 µg/mL.

Study of the activity of Punica granatum-mediated silver nanoparticles against Candida albicans and Candida glabrata, alone or in combination with azoles or polyenes.

The continuous emergence of Candida strains resistant to currently used antifungals demands the development of new alternatives that could reduce the burden of candidiasis. In this work silver nanoparticles synthesized using a green route are efficiently used, alone or in combination with fluconazole, amphotericin B or nystatine, to inhibit growth of C. albicans and C. glabrata oral clinical strains, including in strains showing resistance to fluconazole. A potent inhibitory effect over biofilm formation prompted by the two Candida species was also observed, including in mature biofilm cells. These results foster the use of phytotherapeutics as effective treatments in oral candidiasis.

Screening of Natural Lead Molecules Against Putative Molecular Targets of Drug-resistant Cryptococcus spp: An Insight from Computer-aided Molecular Design.

Cryptococcosis is one of the major invasive fungal infections distributed worldwide with high mortality rate. C. neoformans and C. gattii are the major organisms that cause various types of infections. Anti-fungal resistances exhibited by the mentioned species of Cryptococcus threaten their effective prevention and treatment. There is limited information available on human to human transmission of the pathogen and virulent factors that are responsible for Cryptococcus mediated infections. Hence, there is high scope for understanding the mechanism, probable drug targets and scope of developing natural therapeutic agents that possess high relevance to pharmaceutical biotechnology and medicinal chemistry. The proposed review illustrates the role of computer-aided virtual screening for the screening of probable drug targets and identification of natural lead candidates as therapeutic remedies. The review initially focuses on the current perspectives on cryptococcosis, major metabolic pathways responsible for the pathogenesis, conventional therapies and associated drug resistance, challenges and scope of structure-based drug discovery. The review further illustrates various approaches for the prediction of unknown drug targets, molecular modeling works, screening of natural compounds by computational virtual screening with ideal drug likeliness and pharmacokinetic features, application of molecular docking studies and simulation. Thus, the present review probably provides AN insight into the role of medicinal chemistry and computational drug discovery to combat Cryptococcus infections and thereby open a new paradigm for the development of novel natural therapeutic against various drug targets for cryptococcal infections.

A new method based on supercritical fluid extraction for polyacetylenes and polyenes from Echinacea pallida (Nutt.) Nutt. roots.

The genus Echinacea (Asteraceae) includes species traditionally used in phytotherapy. Among them, Echinacea pallida (Nutt.) Nutt. root extracts are characterized by a representative antiproliferative activity, due to the presence of acetylenic compounds. In this study, supercritical fluid extraction (SFE) was applied and compared with conventional Soxhlet extraction (SE) in order to obtain a bioactive extract highly rich in polyacetylenes and polyenes from E. pallida roots. The composition of the extracts was monitored by means of HPLC-UV/DAD and HPLC-ESI-MSn by using an Ascentis Express C18 column (150mm×3.0mm I.D., 2.7µm, Supelco, Bellefonte, PA, USA) with a mobile phase composed of (A) water and (B) acetonitrile, under gradient elution. By keeping SFE time at the threshold of 1h (15min static and 45min dynamic for 1 cycle) with the oven temperature set at 40-45°C and 90bar of pressure, an overall extraction yield of 1.18-1.21% (w/w) was obtained, with a high selectivity for not oxidized lipophilic compounds. The biological activity of the extracts was evaluated against human non-small lung A549 and breast carcinoma MCF-7 cancer cell lines. The cytotoxic effect of the SFE extract was more pronounced towards the MCF-7 than the A549 cancer cells, with IC50 values ranging from 21.01±2.89 to 31.11±2.l4µg/mL; cell viability was affected mainly between 24 and 48h of exposure. The results show the possibility of a new "green" approach to obtain extracts highly rich in genuine polyacetylenes and polyenes from E. pallida roots. The bioactivity evaluation confirmed the cytotoxicity of E. pallida extracts against the considered cancer cell lines, especially against MCF-7 cells, thus suggesting to represent a valuable tool for applicative purposes in cancer prevention.

Larvicidal activity of Blumea eriantha essential oil and its components against six mosquito species, including Zika virus vectors: the promising potential of (4E,6Z)-allo-ocimene, carvotanacetone and dodecyl acetate.

The effective and environmentally sustainable control of mosquitoes is a challenge of essential importance. This is due to the fact that some invasive mosquitoes, with special reference to the Aedes genus, are particularly difficult to control, due to their high ecological plasticity. Moreover, the indiscriminate overuse of synthetic insecticides resulted in undesirable effects on human health and non-target organisms, as well as resistance development in targeted vectors. Here, the leaf essential oil (EO) extracted from a scarcely studied plant of ethno-medicinal interest, Blumea eriantha (Asteraceae), was tested on the larvae of six mosquitoes, including Zika virus vectors. The B. eriantha EO was analyzed by GC and GC-MS. The B. eriantha EO showed high toxicity against 3rd instar larvae of six important mosquito species: Anopheles stephensi (LC50=41.61 µg/ml), Aedes aegypti (LC50=44.82 µg/ml), Culex quinquefasciatus (LC50 =48.92 µg/ml), Anopheles subpictus (LC50=51.21 µg/ml), Ae. albopictus (LC50=56.33 µg/ml) and Culex tritaeniorhynchus (LC50=61.33 µg/ml). The major components found in B. eriantha EO were (4E,6Z)-allo-ocimene (12.8%), carvotanacetone (10.6%), and dodecyl acetate (8.9%). Interestingly, two of the main EO components, (4E,6Z)-allo-ocimene and carvotanacetone, achieved LC50 lower than 10 µg/ml on all tested mosquito species. The acute toxicity of B. eriantha EO and its major constituents on four aquatic predators of mosquito larval instars was limited, with LC50 ranging from 519 to 11.431 µg/ml. Overall, the larvicidal activity of (4E,6Z)-allo-ocimene and carvotanacetone far exceed most of the LC50 calculated in current literature on mosquito botanical larvicides, allowing us to propose both of them as potentially alternatives for developing eco-friendly mosquito control tools.

Cryptic antifungal compounds active by synergism with polyene antibiotics.

The majority of antifungal compounds reported so far target the cell wall or cell membrane of fungi, suggesting that other types of antibiotics cannot exert their activity because they cannot penetrate into the cells. Therefore, if the permeability of the cell membrane could be enhanced, many antibiotics might be found to have antifungal activity. We here used the polyene antibiotic nystatin, which binds to ergosterol and forms pores at the cell membrane, to enhance the cellular permeability. In the presence of nystatin, many culture extracts from entomopathogenic fungi displayed antifungal activity. Among all the active extracts, two active components were purified and identified as helvolic acid and terramide A. Because the minimum inhibitory concentration of either compound was reduced four-fold in the presence of nystatin, it can be concluded that this screening method is useful for detecting novel antifungal activity.

Prolidase-dependent mechanism of (Z)-8,9-epoxyheptadeca-1,11,14-triene-induced inhibition of collagen biosynthesis in cultured human skin fibroblasts.

The effects of polyolefinic compound from roots of Cirsium palustre, (Z)-8,9-epoxyheptadeca-1,11,14-triene (EHT) on collagen biosynthesis, prolidase activity, expression of insulin-like growth factor receptor (IGF-IR), ß1 integrin, MAP kinases (pERK1/2), the transcription factors such as nuclear factor kappa B (NF-κB) and hypoxia-inducible factor-1α (HIF-1α) were evaluated in human dermal fibroblasts treated with micromolar concentrations (40-200 µM) for 24 h. It was found that EHT-dependent inhibition of collagen biosynthesis was accompanied by parallel inhibition in prolidase activity. Since IGF-I is the most potent regulator of both processes and prolidase is regulated by ß1 integrin signalling, the effect of EHT on IGF-IR and ß1 integrin receptor expressions were evaluated. Exposure of the cells to EHT contributed to distinct increase in IGF-IR and slight increase in ß1 integrin receptor expressions. It was accompanied by decrease in expression of pERK1/2, HIF-1α and NF-κB. EHT-dependent inhibition of collagen biosynthesis results from inhibition of prolidase activity, the enzyme involved in collagen biosynthesis.

Genome-Directed Lead Discovery: Biosynthesis, Structure Elucidation, and Biological Evaluation of Two Families of Polyene Macrolactams against Trypanosoma brucei.

Marine natural products are an important source of lead compounds against many pathogenic targets. Herein, we report the discovery of lobosamides A-C from a marine actinobacterium, Micromonospora sp., representing three new members of a small but growing family of bacterially produced polyene macrolactams. The lobosamides display growth inhibitory activity against the protozoan parasite Trypanosoma brucei (lobosamide A IC50 = 0.8 µM), the causative agent of human African trypanosomiasis (HAT). The biosynthetic gene cluster of the lobosamides was sequenced and suggests a conserved cluster organization among the 26-membered macrolactams. While determination of the relative and absolute configurations of many members of this family is lacking, the absolute configurations of the lobosamides were deduced using a combination of chemical modification, detailed spectroscopic analysis, and bioinformatics. We implemented a "molecules-to-genes-to-molecules" approach to determine the prevalence of similar clusters in other bacteria, which led to the discovery of two additional macrolactams, mirilactams A and B from Actinosynnema mirum. These additional analogs have allowed us to identify specific structure-activity relationships that contribute to the antitrypanosomal activity of this class. This approach illustrates the power of combining chemical analysis and genomics in the discovery and characterization of natural products as new lead compounds for neglected disease targets.

Synthetic studies of enacyloxins: a series of antibiotics isolated from Frateuria sp. W-315: C1'-C8' and C9'-C15' fragments.

Synthetic studies of enacyloxins (ENXs), a series of yellow-colored, polyene-polyol antibiotics produced by Frateuria sp. W-315, are described. The C1'-C8' polyene fragments were prepared using successive Wittig reactions. The C9'-C15' and C10'-C15' fragments were constructed from (S)-isopropylideneglyceraldehyde using Yamaguchi's nucleophilic substitution reaction of acetylide to epoxide, and/or Marshall's allenylindium mediated reaction as the key steps.

Isolation of a new broad spectrum antifungal polyene from Streptomyces sp. MTCC 5680.

UNLABELLED: A new polyene macrolide antibiotic PN00053 was isolated from the fermentation broth of Streptomyces sp. wild-type strain MTCC-5680. The producer strain was isolated from fertile mountain soil of Naldehra region, Himachal Pradesh, India. The compound PN00053 was purified through various steps of chromatographic techniques and bio-activity guided fractionation followed by its characterization using physiochemical properties, spectral data ((1) H-NMR, (13) C-NMR, HMBC, HSQC, and COSY) and MS analysis. PN00053 exhibited broad spectrum in vitro antifungal activity against strains of Aspergillus fumigatus (HMR), A. fumigatus ATCC 16424, Candida albicans (I.V.), C. albicans ATCC 14503, C. krusei GO6, C. glabrata HO4, Cryptococcus neoformans, Trichophyton sp. as well as fluconazole resistant strains C. krusei GO3 and C. glabrata HO5. It did not inhibit growth of gram positive and gram-negative bacteria, displaying its specificity against fungi. SIGNIFICANCE AND IMPACT OF THE STUDY: PN00053 is a novel polyene macrolide isolated from a wild strain of Streptomyces sp. PM0727240 (MTCC5680), an isolate from the mountainous rocky regions of Himachal Pradesh, India. The compound is a new derivative of the antibiotic Roflamycoin [32, 33-didehydroroflamycoin (DDHR)]. It displayed broad spectrum antifungal activity against yeast and filamentous fungi. However, it did not show any antibacterial activity. The in vitro study revealed that PN00053 has better potency as compared to clinical gold standard fluconazole. The development of pathogenic resistance against the polyenes has been seldom reported. Hence, we envisage PN00053 could be a potential antifungal lead.

Structure-antifungal activity relationships of polyene antibiotics of the amphotericin B group.

A comprehensive comparative analysis of the structure-antifungal activity relationships for the series of biosynthetically engineered nystatin analogues and their novel semisynthetic derivatives, as well as amphotericin B (AMB) and its semisynthetic derivatives, was performed. The data obtained revealed the significant influence of the structure of the C-7 to C-10 polyol region on the antifungal activity of these polyene antibiotics. Comparison of positions of hydroxyl groups in the antibiotics and in vitro antifungal activity data showed that the most active are the compounds in which hydroxyl groups are in positions C-8 and C-9 or positions C-7 and C-10. Antibiotics with OH groups at both C-7 and C-9 had the lowest activity. The replacement of the C-16 carboxyl with methyl group did not significantly affect the in vitro antifungal activity of antibiotics without modifications at the amino group of mycosamine. In contrast, the activity of the N-modified derivatives was modulated both by the presence of CH3 or COOH group in the position C-16 and by the structure of the modifying substituent. The most active compounds were tested in vivo to determine the maximum tolerated doses and antifungal activity on the model of candidosis sepsis in leukopenic mice (cyclophosphamide-induced). Study of our library of semisynthetic polyene antibiotics led to the discovery of compounds, namely, N-(L-lysyl)-BSG005 (compound 3n) and, especially, L-glutamate of 2-(N,N-dimethylamino)ethyl amide of S44HP (compound 2j), with high antifungal activity that were comparable in in vitro and in vivo tests to AMB and that have better toxicological properties.

Bauer ketones 23 and 24 from Echinacea paradoxa var. paradoxa inhibit lipopolysaccharide-induced nitric oxide, prostaglandin E2 and cytokines in RAW264.7 mouse macrophages.

Among the nine Echinacea species, E. purpurea, E. angustifolia and E. pallida, have been widely used to treat the common cold, flu and other infections. In this study, ethanol extracts of these three Echinacea species and E. paradoxa, including its typical variety, E. paradoxa var. paradoxa, were screened in lipopolysaccharide (LPS)-stimulated macrophage cells to assess potential anti-inflammatory activity. E. paradoxa var. paradoxa, rich in polyenes/polyacetylenes, was an especially efficient inhibitor of LPS-induced production of nitric oxide (NO), prostaglandin E2 (PGE2), interleukin-1 beta (IL-1ß) and interleukin-6 (IL-6) by 46%, 32%, 53% and 26%, respectively, when tested at 20 µg/ml in comparison to DMSO control. By bioactivity-guided fractionation, pentadeca-8Z-ene-11, 13-diyn-2-one (Bauer ketone 23) and pentadeca-8Z, 13Z-dien-11-yn-2-one (Bauer ketone 24) from E. paradoxa var. paradoxa were found primarily responsible for inhibitory effects on NO and PGE2 production. Moreover, Bauer ketone 24 was the major contributor to inhibition of inflammatory cytokine production in LPS-induced mouse macrophage cells. These results provide a rationale for exploring the medicinal effects of the Bauer ketone-rich taxon, E. paradoxa var. paradoxa, and confirm the anti-inflammatory properties of Bauer ketones 23 and 24.

Mitochondria and fungal pathogenesis: drug tolerance, virulence, and potential for antifungal therapy.

Recently, mitochondria have been identified as important contributors to the virulence and drug tolerance of human fungal pathogens. In different scenarios, either hypo- or hypervirulence can result from changes in mitochondrial function. Similarly, specific mitochondrial mutations lead to either sensitivity or resistance to antifungal drugs. Here, we provide a synthesis of this emerging field, proposing that mitochondrial function in membrane lipid homeostasis is the common denominator underlying the observed effects of mitochondria in drug tolerance (both sensitivity and resistance). We discuss how the contrasting effects of mitochondrial dysfunction on fungal drug tolerance and virulence could be explained and the potential for targeting mitochondrial factors for future antifungal drug development.

Commercial mouthwashes are more effective than azole antifungals against Candida albicans biofilms in vitro.

OBJECTIVE: The aim of this study was to evaluate and compare the activity of prescription and over-the-counter antimicrobial compounds against planktonic and biofilm forms of Candida albicans isolated from cases of oral candidiasis in vitro. STUDY DESIGN: The efficacy of azoles, polyenes, an echinocandin, and 4 over-the-counter mouthwashes were tested against C. albicans-derived planktonic and biofilm cells. RESULTS: Planktonic cells were shown to be highly sensitive to all of the antifungal agents tested. Sessile cells were highly resistant to azoles (≥128 mg/L) but equally sensitive to caspofungin and short treatments with Corsodyl, Listerine, and Oraldene. CONCLUSIONS: Although C. albicans is sensitive to azole antifungal agents in planktonic form, it is highly resistant within the biofilm. The good efficacy of the over-the-counter mouthwashes against candidal biofilms in vitro suggests that clinical trials should now be designed to establish their role in the clinical management of oral candidal infections.

Design, synthesis and biological evaluation of simplified analogues of the RNA polymerase inhibitor etnangien.

Novel simplified analogues of the potent RNA polymerase inhibitor etnangien were obtained by total synthesis and evaluated for antibacterial activity against Gram-positive bacteria and one Gram-negative bacterium.

The responses of HT22 cells to the blockade of mitochondrial complexes and potential protective effect of selenium supplementation.

Mitochondria are the major reactive oxygen species (ROS)--generating sites in mammalian cells. Blockade of complexes in the electron transport chain (ETC) increases the leakage of single electrons to O(2) and therefore increases ROS levels. Complexes I and III have been reported to be the major ROS-generating sites in mitochondria. In this study, using mouse hippocampal HT22 cells as in vitro model, we monitored the change of intracellular ROS level in response to the blockade of ETC at different complex, and measured changes of gene expression of antioxidant enzymes and phase II enzymes, also evaluated potential protective effect of selenium (Se) supplementation to the cells under this oxidative stress. In summary, our results showed that complex I was the major ROS-generating site in HT22 cells. Complex I blockade upregulated the mRNA levels of glutamylcysteine synthetase heavy and light chains, glutathione-S-transferases omega1 and alpha 2, hemoxygenase 1, thioredoxin reductase 1, and selenoprotein H. Unexpectedly, the expression of the enzymes that directly scavenge ROS decreased, including superoxide dismutases 1 and 2, glutathione peroxidase 1, and catalase. Se supplementation increased glutathione levels and glutathione peroxidase activity, indicating a potential protective role in oxidative stress caused by ETC blockade.

Efficacy of a skin-protection powder for use as a dressing for intractable ulcers.

OBJECTIVE: Stomahesive skin-protection powder has been reported to be useful as a skin-care and skin-barrier product for the management of stomas. This study aimed to evaluate its efficacy, in terms of wound healing, moisture retention and pain management, as an alternative to conventional dressing materials. Both clinical and animal studies were undertaken. METHOD: The efficacy of the Stomahesive powder was tested by measuring the thickness of granulation tissue formed in a total skin defect in a db/db mouse model. We then compared the healing process using either the skin-protection powder or a conventional film dressing material. In the clinical study 17 patients with various intractable ulcers were treated with Stomahesive powder, and healing was evaluated. RESULTS: In the mouse model, granulation tissue in the wounds treated with the powder was 2.86 times thicker than that of the wounds treated with the film dressing. In the clinical study, 16 out of 17 wounds healed completely. CONCLUSION: The Stomahesive powder could be an effective treatment modality for contact ulceration, superficial ulcers with complex contours and morphology, and superficial ulcers contaminated by liquid faeces or vaginal discharge that have not responded to conventional dressings. DECLARATION OF INTEREST: None.

Evaluation of the antioxidant activity of new carotenoid-like compounds by electron paramagnetic resonance.

The antioxidant activity of a novel series of derivatives with a carotenoid-like structure was studied. These derivatives have recently been isolated chemically as a result of studies on the pigments present in a particular species of birds, namely parrots. These novel derivatives, which are also called parrodienes, have been proved to possess interesting biological properties that differ from those that carotenoids are known to have. The objective of this study was to demonstrate the ability of these novel compounds to inhibit the formation of reactive oxygen species, especially their ability to block the formation of hydroxyl radicals, which are among the most reactive products of oxygen reactions and which produce the greatest damage to cells and tissues. The technique used to assess this antioxidant capacity of parrodienes was electron paramagnetic resonance, which allows direct assessment of inhibition of hydroxyl radical formation (.OH). The results show that these derivatives, especially octatriene, are able to exert evident antioxidant activity, thus confirming that their antioxidant properties are important for their biological activity.

Stem cell factor augments Fc epsilon RI-mediated TNF-alpha production and stimulates MAP kinases via a different pathway in MC/9 mast cells.

Mast cells express the receptor tyrosine kinase kit/stem cell factor receptor (SCFR) which is encoded by the proto-oncogene c-kit. Ligation of SCFR induces its dimerization and activation of its intrinsic tyrosine kinase activity leading to activation of Raf-1, phospholipases, phosphatidylinositol 3-kinase, and extracellular signal-regulated kinases. However, little is known about the downstream signals initiated by SCFR ligation except for activation of extracellular signal-regulated kinases. The murine mast cell line, MC/9, synthesizes and secretes TNF-alpha following the aggregation of high affinity Fc receptors for IgE (Fc epsilonRI). Ligation of SCFR or Fc epsilonRI on MC/9 cells resulted in the activation of all three MAP kinase family members, extracellular signal-regulated kinases, c-Jun amino-terminal kinase (JNK), and p38. Stem cell factor (SCF)-induced activation of JNK and p38 was insensitive to wortmannin, cyclosporin A, and FK506 whereas activation of these kinases through Fc epsilonRI was sensitive to these drugs. Coligation of SCFR augmented Fc epsilonRI-mediated activation of MAP kinases, especially JNK activation, and SCF augmented Fc epsilonRI-mediated TNF-alpha production in MC/9 cells, although SCF alone did not induce TNF-alpha production. This augmentation by SCF was regulated at the level of transcription, at least in part, since the promoter activity of TNF-alpha was enhanced following addition of SCF. These results demonstrate that SCF can augment Fc epsilonRI-mediated JNK activation and cytokine gene transcription but via pathways that are regulated differently than the ones activated through Fc epsilonRI.

Antimycobacterial polyynes of Devil's Club (Oplopanax horridus), a North American native medicinal plant.

Two new (3 and 5), as well as three known (1, 2, and 4), polyynes were isolated from Devil's Club (Oplopanax horridus; Araliaceae), a medicinal plant of North America. The structures were established by 1H and 13C NMR. The absolute configurations of 2 and 5 were determined by application of Mosher's method. All the polyynes exhibited significant anti-Candida, antibacterial, and antimycobacterial activity, with an ability to kill Mycobacterium tuberculosis and isoniazid-resistant Mycobacterium avium at 10 micrograms/disk in a disk diffusion assay.