Oceanalin B, a Hybrid α,ω-Bifunctionalized Sphingoid Tetrahydroisoquinoline β-Glycoside from the Marine Sponge Oceanapia sp.

Oceanalin B (1), an α,ω-bipolar natural product belonging to a rare family of sphingoid tetrahydoisoquinoline β-glycosides, was isolated from the EtOH extract of the lyophilized marine sponge Oceanapia sp. as the second member of the series after oceanalin A (2) from the same animal. The compounds are of particular interest due to their biogenetically unexpected structures as well as their biological activities. The structure and absolute stereochemistry of 1 as a α,ω-bifunctionalized sphingoid tetrahydroisoquinoline β-glycoside was elucidated using NMR, CD and MS spectral analysis and chemical degradation. Oceanalin B exhibited in vitro antifungal activity against Candidaglabrata with a MIC of 25 μg/mL.

Prospecting of anti-Candida bioactive in Origanum vulgare L. artisanal essential oil

Candida albicans is a yeast belonging to the normal microbiota of the human body, considered the most pathogenic species of the genus. It is the main microorganism related to candidiasis. Essential oils of Origanum vulgare have phenolic compounds, such as thymol and carvacrol, which have an effective antimycobacterial character at certain concentrations, but little is known about its biological activity in artisanal preparation. Thus, we evaluated the resistance of standard strains of opportunistic yeast C. albicans against in vitro antifungal activity of artisanal extract of O. vulgare. An inoculum of the challenger was subjected to different concentrations of the fungicidal agent in solidified Muller Hinton and broth followed by incubation at 35°C. The oil was prepared in a manner similar to a possible homemade procedure, and was further sterilized to ensure homogeneity of the indicator. The readings were performed in two days every 24 hours so that there were different possible moments of growth. The tests, which occurred in triplicate, showed that, under experimental conditions, the yeast was resistant to the essential oil compounds at all observed concentrations. Morphological variation was observed in both colonies and yeast cells. Based on analyzes, the artisanal essential oil is incorporated as a promising candidate for the development of antimycotics for clinical use, although in vivo tests are required.

Antifungal Activity of Extracts, Fractions, and Constituents from Coccoloba cowellii Leaves

Coccoloba cowellii Britton (Polygonaceae, order Caryophyllales) is an endemic and critically endangered plant species that only grows in the municipality of Camagüey, a province of Cuba. A preliminary investigation of its total methanolic extract led to the discovery of promising antifungal activity. In this study, a bioassay-guided fractionation allowed the isolation of quercetin and four methoxyflavonoids: 3-O-methylquercetin, myricetin 3,3′,4′-trimethyl ether, 6-methoxymyricetin 3,4′-dimethyl ether, and 6-methoxymyricetin 3,3′,4′-trimethyl ether. The leaf extract, fractions, and compounds were tested against various fungi and showed strong in vitro antifungal activity against Cryptococcus neoformans and various Candida spp. with no cytotoxicity (CC50 > 64.0 µg/mL) on MRC-5 SV2 cells, determined by a resazurin assay. A Candida albicans SC5314 antibiofilm assay indicated that the antifungal activity of C. cowellii extracts and constituents is mainly targeted to planktonic cells. The total methanolic extract showed higher and broader activity compared with the fractions and mixture of compounds.

A revision of malbranchea-like fungi from clinical specimens in the United States of America reveals unexpected novelty

ABSTRACTThe fungi of the order Onygenales can cause important human infections; however, their taxonomy and worldwide occurrence is still little known. We have studied and identified a representative number of clinical fungi belonging to that order from a reference laboratory in the USA. A total of 22 strains isolated from respiratory tract (40%) and human skin and nails (27.2%) showed a malbranchea-like morphology. Six genera were phenotypically and molecularly identified, i.e. Auxarthron/Malbranchea (68.2%), Arachnomyces (9.1%), Spiromastigoides (9.1%), and Currahmyces (4.5%), and two newly proposed genera (4.5% each). Based on the results of the phylogenetic study, we synonymized Auxarthron with Malbranchea, and erected two new genera: Pseudoarthropsis and Pseudomalbranchea. New species proposed are: Arachnomyces bostrychodes, A. graciliformis, Currahmyces sparsispora, Malbranchea gymnoascoides, M. multiseptata, M. stricta, Pseudoarthropsis crassispora, Pseudomalbranchea gemmata, and Spiromastigoides geomycoides, along with a new combination for Malbranchea gypsea. The echinocandins showed the highest in vitro antifungal activity against the studied isolates, followed by terbinafine and posaconazole; in contrast, amphotericin B, fluconazole, itraconazole and 5-fluorocytosine were less active or lacked in vitro activity against these fungi.

Latent Pathogenic Fungi in the Medicinal Plant Houttuynia cordata Thunb. Are Modulated by Secondary Metabolites and Colonizing Microbiota Originating from Soil

Latent pathogenic fungi (LPFs) affect plant growth, but some of them may stably colonize plants. LPFs were isolated from healthy Houttuynia cordata rhizomes to reveal this mechanism and identified as Ilyonectria liriodendri, an unidentified fungal sp., and Penicillium citrinum. Sterile H. cordata seedlings were cultivated in sterile or non-sterile soils and inoculated with the LPFs, followed by the plants’ analysis. The in vitro antifungal activity of H. cordata rhizome crude extracts on LPF were determined. The effect of inoculation of sterile seedlings by LPFs on the concentrations of rhizome phenolics was evaluated. The rates of in vitro growth inhibition amongst LPFs were determined. The LPFs had a strong negative effect on H. cordata in sterile soil; microbiota in non-sterile soil eliminated such influence. There was an interactive inhibition among LPFs; the secondary metabolites also regulated their colonization in H. cordata rhizomes. LPFs changed the accumulation of phenolics in H. cordata. The results provide that colonization of LPFs in rhizomes was regulated by the colonizing microbiota of H. cordata, the secondary metabolites in the H. cordata rhizomes, and the mutual inhibition and competition between the different latent pathogens.

Synthesis of Novel Thiazolyl Hydrazine Derivatives and Their Antifungal Activity

A series of novel thiazolyl hydrazine derivatives 3a–3o were synthesized and evaluated for their in vitro antifungal activity against six phytopathogenic strains, namely, Botryosphaeria dothidea (B. d.), Gibberella sanbinetti (G. s.), Fusarium oxysporum (F. o.), Thanatephorus cucumeris (T. c.), Sclerotinia sclerotiorum (S. s.), and Verticillium dahliae (V. d.), by the classical mycelial growth rate method. Biological assessment results showed that most of these target compounds showed good antifungal activity toward tested strains. Especially, compound 3l showed excellent antifungal activities against B. d. and G. s. with relatively lower EC50 values of 0.59 and 0.69 µg/mL, respectively, which were extremely superior to those of commercial fungicides fluopyram, boscalid, and hymexazol and were comparable to those of carbendazim. Given the excellent bioactivity of designed compounds, this kind of thiazolyl hydrazine framework can provide a suitable point for exploring highly efficient antifungal agents.