Aogacillins A and B Produced by Simplicillium sp. FKI-5985: New Circumventors of Arbekacin Resistance in MRSA

Sinulariapeptide F, a new peptide from culture broth of marine-derived fungus Simplicillium sp. SCSIO 41222

One new compound named sinulariapeptide F (1) together with one known butyrolactone (2) and seven known peptides (3-9) were isolated from the fungus Simplicillium sp. SCSIO 41222. Their structures and absolute configurations were established using HRESIMS, NMR spectroscopy (1H, 13C, HSQC, HMBC) and marfey's method. All of these compounds were assessed their inhibitory activity of acetylcholinesterase (AChE) and pancreatic lipase (PL). Compounds 4 and 6 were selected to test for the inhibitory activity against programmed cell death-1 (PD-1)/ programmed cell death-ligand 1 (PD-L1). The results indicated that compound 4 displayed potent inhibition activity against PD-1/ PD-L1 with an IC50 value of 0.656 μM. Furthermore, the docking analysis demonstrated the interactions between 4 and proteins, suggesting PD-L1 to be a probable target for compound 4.

Toward the stereochemical assignment of euvesperins A and B: total synthesis of the possible structures of the natural products

The possible structures of euvesperins A and B were synthesized. The results of our synthesis suggest that euvesperin A may be a mixture of the (2R,3R,4S,7S) and (2S,3S,4R,7S) isomers and euvesperin B may be a mixture of the (2R,3S,4S,7S) and (2S,3R,4R,7S) isomers in consideration of their putative biosynthetic pathways.

Total Synthesis of Penicyclone A Using a Double Grignard Reaction

We describe the first total synthesis of penicyclone A, a novel deep-sea fungus-derived polyketide, and a reevaluation of its antimicrobial activity. The synthesis of this unique spirolactone was achieved in 10 steps starting from a known d-ribose derivative. The key steps include a double Grignard reaction for the diastereoselective construction of the chiral tertiary alcohol intermediate, tandem oxidation/cyclization, and photooxygenation, followed by an oxidative rearrangement to introduce the enone functionality.

The genus Simplicillium and Emericellopsis: A review of phytochemistry and pharmacology

The demand for novel and improved medicine from biological sources to cater to the biopharmaceutical sector has increased significantly in recent years. Among the vast and miscellaneous microbial diversity, fungi provide a prolific source of structurally unique and biologically active secondary metabolites. Natural products obtained from fungi have reformed the era of biomedicine, providing effective drugs that have diverse healing potential. In this review, we focus on the isolation, chemical structure, and bioactivity of biomolecules that have been identified and studied for the first time. Further, we also explain in substantial detail that how the vast uninvestigated Emericellopsis and Simplicillium species may serve as a potential treasure trove of chemically diverse compounds.

Entomopathogenic Potential of Simplicillium lanosoniveum Native Strain in Suppressing Invasive Whitefly, Aleurodicusrugioperculatus Martin (Hemiptera: Aleyrodidae), Infesting Coconut

In 2016, infestation of an exotic polyphagous pest, the rugose spiraling whitefly (RSW), Aleurodicus rugioperculatus Martin (Hemiptera: Aleyrodidae), was documented on coconut for the first time in India. Instantaneously, RSW has garnered wide attention owing to its damage severity and rapid spread across the coconut-growing regions of the country. Hence, an attempt was made to devise a sustainable integrated pest management (IPM) module using biological control agents as a mainstay component. The present study documented the identification and characterization of a potential entomopathogenic fungal isolate for the management of RSW. An entomopathogenic fungus isolated from nymphal cadavers of RSW was identified as Simplicillium lanosoniveum based on morphological and phylogenetic analyses. A gradient of five conidial concentrations (1 × 10⁴, 1 × 10⁵, 1 × 10⁶, 1 × 10⁷ and 1 × 10⁸ conidia/mL) of the S.lanosoniveum were tested against eggs, first instars, second to third instars and pupae of RSW. Results revealed that S.lanosoniveum is highly virulent to all developmental stages of RSW by causing mortality rates of 95.20%, 87.33%, 85.38% and 72.85%, in eggs, initial, middle and later instar nymphs of RSW, respectively, at the highest tested concentration (1 × 10⁸ conidia/mL) at seven days after exposure. The LC₅₀ and LT₅₀ values of S.lanosoniveum were 4.72 × 10⁴, 4.94 × 10⁴, 5.11 × 10⁵, 5.92 × 10⁵ conidia/mL and 4.27, 4.86, 4.56, 5.89 days against eggs, initial, middle and later instar nymphs of RSW, respectively. Further, preliminary field trials with S.lanosoniveum strain at 1 × 10⁸ conidia/mL exhibited a significant reduction in the egg and nymphal population by 57.8% and 56.3%, respectively. This report thus demonstrated that the newly isolated S.lanosoniveum is an effective pathogen at suppressing all the developmental stages of RSW. This is the first record of S.lanosoniveum infecting RSW, and it has a great potential to be developed as a mycoinsecticide.

An efficient Agrobacterium tumefaciens-mediated transformation method for Simplicillium subtropicum (Hypocreales: Cordycipitaceae)

Filamentous fungi are the organisms of choice for most industrial biotechnology. Some species can produce a variety of secondary metabolites and enzymes of commercial interest, and the production of valuable molecules has been enhanced through different molecular tools. Methods for genetic manipulation and transformation have been essential for the optimization of these organisms. The genus Simplicillium has attracted increased attention given several potential biotechnological applications. The Simplicillium genus harbors several entomopathogenic species and some isolates have been explored for bioremediation of heavy metal contaminants. Furthermore, the myriad of secondary metabolites isolated from Simplicillium spp. render these organisms as ideal targets for deep exploration and further biotechnological mining possibilities. However, the lack of molecular tools hampered the exploration of this genus. Thus, an Agrobacterium tumefaciens-mediated transformation method was established for Simplicillium subtropicum, employing the far-red fluorescent protein TURBOFP635/Katushka, as a visual marker, and the selection marker SUR gene, that confers resistance to chlorimuron ethyl. Notably, one round of transformation using the established method yielded almost 400 chlorimuron resistant isolates. Furthermore, these transformants displayed mitotic stability for, at least, five generations. We anticipate that this method can be useful for deep molecular exploration and improvement of strains in the Simplicillium genus.

Taxonomic and phylogenetic characterizations reveal four new species of Simplicillium (Cordycipitaceae, Hypocreales) from Guizhou, China

Simplicillium species are commonly found from soil, seawater, rock surface, decayed wood, air and as symbiotic, endophytic, entomopathogenic and mycoparasitic fungi. Minority insect-associated species was reported. Simplicillium coccinellidae, S. hymenopterorum, S. neolepidopterorum and S. scarabaeoidea were introduced as the newly insect-associated species. The phylogenetic analyses of two combined datasets (LSU + RPB1 + TEF and SSU + ITS + LSU) revealed that S. coccinellidae and S. hymenopterorum were both nested in an independent clade. S. neolepidopterorum and S. scarabaeoidea have a close relationship with S. formicidae and S. lepidopterorum, respectively. S. neolepidopterorum can be easily distinguished from S. formicidae by ellipsoidal to cylindrical, solitary conidia which occasionally gather in short imbricate chains. S. scarabaeoidea could be easily distinguished from S. lepodopterorum by having longer phialides and larger conidia. Based on the morphological and phylogenetic conclusion, we determine the four newly generated isolates as new species of Simplicillium and a new combination is proposed in the genus Leptobacillium.

Simplicilones A and B Isolated from the Endophytic Fungus Simplicillium subtropicum SPC3

Two new tetracyclic polyketides with a spirocenter, simplicilones A (1) and B (2) were isolated from the broth-culture of the endophytic fungus Simplicilliumsubtropicum (SPC3) in the course of our screening for new bioactive secondary metabolites. This endophytoic fungus is naturally harboured in the fresh bark of the Cameroonian medicinal plant Duguetia staudtii (Engl. and Diels) Chatrou. The planar structures of the simplicilones were elucidated by MS and 1D as well as 2D NMR spectroscopic techniques. The relative configuration was assigned by NOESY experiments in conjunction with coupling constants; subsequently, the absolute configurations were assigned by the modified Mosher’s method. The compounds showed weak cytotoxic effects against the cell line KB3.1 (in vitro cytotoxicity (IC₅₀) = 25 µg/mL for 1, 29 µg/mL for 2), but were inactive against the tested Gram-positive and Gram-negative bacteria as well as fungi.

Structural deformation in pathogenic bacteria cells caused by marine fungal metabolites: An in vitro investigation

Over the past 50 years, fungal natural products have revolutionized medicine, yielding drugs which have enormous therapeutic potential. The aim of this study was to investigate the probable effect of marine fungal natural products on various skin pathogens. Initially, seventy natural extracts obtained from 35 different marine fungal strains were analysed by the agar well diffusion and broth micro dilution assay for their antibacterial action against six human skin pathogens. The minimum inhibitory effects of all active fungal methanolic extracts on targeted pathogens were observed between 90 and 99% at the concentration of 1 mg/mL. The highest activity was recorded by fungal strains belonging to genera Penicillium, Emericellopsis and Simplicillium. Thereafter, possible effects on target bacterial cells were studied by scanning electron microscopy which show significant destruction and structural deformation in the bacterial cell wall. The results of the present study provided good evidence that the studied marine fungi can be a potential source of natural antibacterial agents against skin bacterial pathogens.

Fungi: outstanding source of novel chemical scaffolds

A large number of remarkable studies on the secondary metabolites of fungi have been conducted in recent years. This review gives an overview of one hundred and sixty-seven molecules with novel skeletons and their bioactivities that have been reported in seventy-nine articles published from 2013 to 2017. Our statistical data showed that endophytic fungi and marine-derived fungi are the major sources of novel bioactive secondary metabolites.

The genus Simplicillium

Simplicillium species have a wide host range and an extensive distribution. Some species are associated with rusts, as well as other plant pathogenic fungi and play an important role in biological control. In this study, two specimens of Simplicillium were collected from Chiang Mai Province, Thailand. Simplicilliumformicae sp. nov. was isolated from an infected ant and S.lanosoniveum from Ophiocordycepsunilateralis which is a new host record. Species were initially identified using ITS gene sequences and confirmed using morphology coupled with phylogenetic analyses of a combined nrLSU, nrSSU, TEF and RPB1 dataset. Simplicilliumformicae differs from other species in the genus by the presence of flask-shaped synnemata and phialides with intercalary nodes. Simplicilliumlanosoniveum resembles other collections of the species by its completely solitary, tapering phialides and globose to ellipsoidal conidia which adhere in a slimly head. A key to species of Simplicillium is also provided.

Three novel insect-associated species of Simplicillium (Cordycipitaceae, Hypocreales) from Southwest China

In this paper, we introduce three new species of Simplicillium, viz. S. cicadellidae, S. formicidae and S. lepidopterorum, which were isolated from an infected leafhopper, ant and carpenterworm, respectively. Morphological comparisons and phylogenetic analyses based on multigene datasets (LSU+RPB1+RPB2+TEF and ITS+LSU) support the establishment of the three new species. Simplicillium cicadellidae was distinguished from other species in morphological characteristics by having smaller phialides and ellipsoidal conidia, and lacking octahedral crystals. The reverse of colonies were yellowish (#FFBF00), especially in the middle, and radially sulcate. Simplicillium formicidae was morphologically distinguished from other by having longer phialides and filiform to fusoid conidia, and by lacking octahedral crystals. Simplicillium lepidopterorum was morphologically distinguished from other species by having smaller, ellipsoidal to fusiform conidia, and by lacking octahedral crystals. The reverse of the colony was pale white. The three new species are likely to be nourished by plant to animal (especially insect) nutrients based on the evolutionary pattern of the Hypocreales, and they are described herein as being clearly distinct from other species in Simplicillium.

Simpotentin, a new potentiator of amphotericin B activity against Candida albicans, produced by Simplicillium minatense FKI-4981

Simpotentin, a new potentiator of amphotericin B activity against Candida albicans and Cryptococcus neoformans, was isolated from the culture broth of Simplicillium minatense FKI-4981 by Diaion HP-20 column chromatography, centrifugal partition chromatography, and preparative HPLC. The structure of simpotentin was elucidated by spectroscopic analyses including NMR and MS. The compound has a mannose core to which two medium-chain fatty acids are linked. Simpotentin was found to potentiate amphotericin B activity against C. albicans by the microdilution method.

Depsidones and an α-pyrone derivative from Simplicillium sp. PSU-H41, an endophytic fungus from Hevea brasiliensis leaf [corrected]

Nine previously undescribed depsidones (simplicildones A-I) and one previously undescribed α-pyrone (simplicilopyrone) were isolated from the endophytic fungus Simplicillium sp. PSU-H41 along with 11 known compounds. Their structures were established by extensive spectroscopic analysis. Simplicildone A and known botryorhodine C displayed weak antibacterial against Staphylococcus aureus with equal MIC values of 32 μg/mL. Additionally, botryorhodine C was active against methicillin-resistant S. aureus with the same MIC value. Simplicildone C exhibited weak antifungal activity against Cryptococcus neoformans with an MIC value of 32 μg/mL. In addition, simplicildones A and C and botryorhodine C were noncytotoxic against noncancerous Vero cells.

A new antibiotic produced by the cyanobacterium-symbiotic fungus Simplicillium lanosoniveum

The culture broth of the cyanobacterium-symbiotic fungus Simplicillium lanosoniveum var. Tianjinienss Q. L. Dong exhibited unanticipated antibacterial activities against the Gram-positive bacteria, particularly the pathogenic bacterium Staphylococcus aureus, indicating the secretion of antibiotic-like metabolite, for which the modified Sabouraud medium was the suitable medium. The antibiotic-like metabolite was separated with macroporous resins CT-12 (absorption) and 95% ethanol (desorption), purified by ion-exchange resins D301T and displayed a characteristic absorption peak at 228 nm, suggesting the presence of nitrogen. The negative biuret and ninhydrin tests confirmed the absence of -NH₂ and -COOH groups. Further, HPLC and mass spectrometry analyses showed that the retention time and molecular weight of the antibiotic-like metabolite were 4.1031 min and 163.0182 (Δ ± 2.3 ppm), respectively. Taking together, we speculated that the antibiotic-like metabolite was a new antibiotic structurally similar to alkaloid, which was the first one isolated from the species of Simplicillium genus.

Combination cellulose plate (non-agar solid support) and agar plate method improves isolation of fungi from soil

This is the first report describing the improved isolation of common filamentous fungi via a method combining cellulose plate and agar plate system. A cellulose plate is a porous plate made of nanofibrous crystaline cellulose. Isolating fungi from soils using these types of media separately resulted in the number of fungal colonies appearing on cellulose plates being lower than that on agar plates. However, the number of actual fungal species isolated using cellulose plates alone was more or less the same as that found using agar plates. Significantly, the diversity of isolates using a combination of the two media was greater than using each media individually. As a result, numerous new or rare fungal species with potential, including previously proposed new species, were isolated successfully in this way. All fungal colonies, including the Penicillium species, that appeared on the cellulose plate penetrated in potato dextrose were either white or yellow. Cultivation on cellulose plates with added copper ion overcomes the change in coloration, the colonies appearing as they do following cultivation on potato dextrose agar.

Isolation and biosynthesis of preussin B, a pyrrolidine alkaloid from Simplicillium lanosoniveum

A new pyrrolidine alkaloid, preussin B (1), was isolated from the culture extract of the fungus Simplicillium lanosoniveum TAMA 173 along with the known congener preussin (2). The structure and absolute configuration of 1 were determined by spectroscopic analysis and spectral comparison with 2. Feeding experiments with 13C-labeled precursors revealed that the pyrrolidine ring of 1 was assembled from acetate and l-phenylalanine by a PKS-NRPS hybrid biosynthetic pathway.

Vibronic spectra of organic electronic chromophores

Vibronic effects in organic electronic building blocks are presented.