Cytotoxic constituents of Amanita subjunquillea

Anti-Inflammatory Ergosteroid Derivatives from the Coral-Associated Fungi Penicillium oxalicum HL-44

To obtain the optimal fermentation condition for more abundant secondary metabolites, Potato Dextrose Agar (PDA) medium was chosen for the scale-up fermentation of the fungus Penicillium oxalicum HL-44 associated with the soft coral Sinularia gaweli. The EtOAc extract of the fungi HL-44 was subjected to repeated column chromatography (CC) on silica gel and Sephadex LH-20 and semipreparative RP-HPLC to afford a new ergostane-type sterol ester (1) together with fifteen derivatives (2-16). Their structures were determined with spectroscopic analyses and comparisons with reported data. The anti-inflammatory activity of the tested isolates was assessed by evaluating the expression of pro-inflammatory factors Tnfα and Ifnb1 in Raw264.7 cells stimulated with LPS or DMXAA. Compounds 2, 9, and 14 exhibited significant inhibition of Ifnb1 expression, while compounds 2, 4, and 5 showed strong inhibition of Tnfα expression in LPS-stimulated cells. In DMXAA-stimulated cells, compounds 1, 5, and 7 effectively suppressed Ifnb1 expression, whereas compounds 7, 8, and 11 demonstrated the most potent inhibition of Tnfα expression. These findings suggest that the tested compounds may exert their anti-inflammatory effects by modulating the cGAS-STING pathway. This study provides valuable insight into the chemical diversity of ergosteroid derivatives and their potential as anti-inflammatory agents.

Non-peptide secondary metabolites from poisonous mushrooms: overview of chemistry, bioactivity, and biosynthesis

Covering: up to June 2021A wide variety of mushrooms have traditionally been recognized as edible fungi with high nutritional value and low calories, and abundantly produce structurally diverse and bioactive secondary metabolites. However, accidental ingestion of poisonous mushrooms can result in serious illnesses and even death. Chemically, mushroom poisoning is associated with secondary metabolites produced in poisonous mushrooms, causing specific toxicity. However, many poisonous mushrooms have not been fully investigated for their secondary metabolites, and the secondary metabolites of poisonous mushrooms have not been systematically summarized for details such as chemical composition and biosynthetic mechanisms. The isolation and identification of secondary metabolites from poisonous mushrooms have great research value since these compounds could be lethal toxins that contribute to the toxicity of mushrooms or could provide lead compounds with remarkable biological activities that can promote advances in other related disciplines, such as biochemistry and pharmacology. In this review, we summarize the structures and biological activities of secondary metabolites identified from poisonous mushrooms and provide an overview of the current information on these metabolites, focusing on their chemistry, bioactivity, and biosynthesis.

Chemical constituents from the barks of Melia azedarach and their PTP1B inhibitory activity

One new long-chain ester derivative of trans-ferulic acid 1 and one natural tirucallane-type triterpenoid 2, together with forty known compounds (3-42), were isolated from the barks of Melia azedarach. Their structures were established on the basis of spectroscopic data interpretation. Compounds 7, 9, 10, 12, 13 showed significant inhibitory activities against PTP1B with IC₅₀ values of 13.82 ± 1.29 μM, 13.29 ± 2.26 μM, 20.27 ± 0.52 μM, 24.36 ± 1.25 μM, 15.23 ± 0.6 μM, respectively.

Bioactivity of compounds secreted by symbiont bacteria of Nudibranchs from Indonesia

The aims of this work are to isolate bacterial symbionts from nudibranchs and subsequently to determine anti-Methicillin resistant Staphylococcus aureus (MRSA), cytotoxicity and anti-Herpes simplex virus type 1 (HSV-1) activities of bio compounds. A total of 15 species of nudibranchs were collected from Karimunjawa and five species from Bali, respectively. A total of 245 bacteria isolates were obtained. The anti-MRSA activity screening activity indicated two active bacteria. Ethyl acetate extracts from supernatants, indicating extracelullar compounds, showed an inhibition zone against MRSA at concentrations of 500–1,000 µg/ml. DNA sequence analysis showed that the strain KJB-07 from Phyllidia coelestis was closely related to Pseudoalteromonas rubra, whereas the strain NP31-01 isolated from Phyllidia varicosa was closely related to Virgibacillus salarius. The extract of Pseudoalteromonas rubra was cytotoxic to Vero cells at a concentration of 75 µg/ml. The extract of V. salarius presented no cytotoxicity at concentrations of 5–1,000 µg/ml. No anti HSV-1 was observed for both isolated bacteria. This is the first study describing research on anti-MRSA, cytotoxicity and anti HSV-1 activity of bacterial symbionts from the viscera of nudibranch. Compounds produced by Pseudoalteromonas rubra and V. salarius, had potential anti-MRSA activity. However, only extracts from Pseudoalteromonas rubra showed cytotoxic effects on Vero cells. Three compounds were identified by LC/MS after purification from culture supernatant.

Lanostane triterpenoids and ergostane-type steroids from the cultured mycelia of Ganoderma capense

Two new lanostane triterpenoids (1 and 2), two new ergostane-type steroids (3 and 4) together with two known lanostane triterpenoids (5 and 6) and one known steroid (7) were isolated from the cultured mycelia of Ganoderma capense (CGMCC 5.71). Their structures were determined on the basis of extensive spectroscopic (HRESIMS, 1D NMR, 2D NMR) data analyses. Compound 1 exhibited moderate cytotoxic activity against the human cancer cell line NCI-H1650 with an IC₅₀ value of 22.3 μM, and 7 displayed cytotoxic activity against the human cancer cell line HCT116 with an IC₅₀ value of 17.4 μM. In addition, compounds 2, 3, 5, and 6 displayed weak anti-HIV activity with IC₅₀ values of 23.5, 46.7, 21.6, and 30.1 μM, respectively.

Structural Diversity and Biological Activities of Fungal Cyclic Peptides, Excluding Cyclodipeptides

Cyclic peptides are cyclic compounds formed mainly by the amide bonds between either proteinogenic or non-proteinogenic amino acids. This review highlights the occurrence, structures and biological activities of fungal cyclic peptides (excluding cyclodipeptides, and peptides containing ester bonds in the core ring) reported until August 2017. About 293 cyclic peptides belonging to the groups of cyclic tri-, tetra-, penta-, hexa-, hepta-, octa-, nona-, deca-, undeca-, dodeca-, tetradeca-, and octadecapeptides as well as cyclic peptides containing ether bonds in the core ring have been isolated from fungi. They were mainly isolated from the genera Aspergillus, Penicillium, Fusarium, Acremonium and Amanita. Some of them were screened to have antimicrobial, antiviral, cytotoxic, phytotoxic, insecticidal, nematicidal, immunosuppressive and enzyme-inhibitory activities to show their potential applications. Some fungal cyclic peptides such as the echinocandins, pneumocandins and cyclosporin A have been developed as pharmaceuticals.

A new antiviral pregnane from a gorgonian-derived Cladosporium sp. fungus

A new pregnane, 3α-hydroxy-7-ene-6,20-dione (1), and five known steroids (2-6), along with one known steroidal glycoside (7) were obtained from the fungus Cladosporium sp. WZ-2008-0042 cultured from a gorgonian Dichotella gemmacea collected from the South China Sea. The structure and absolute configuration of the new compound (1) were elucidated by comprehensive spectroscopic data and X-ray diffraction data. The compound has a rare configuration of 3α-OH that is different from most of pregnanes. All of the isolated compounds were evaluated for their antiviral activities against respiratory syncytial virus (RSV). Among them, 1 exhibited potential antiviral activity with the IC₅₀ value of 0.12 mM.

Lanostane triterpenoids from the mushroom Naematoloma fasciculare

In our continuing search for structurally interesting and bioactive metabolites from Korean wild mushrooms, bioassay-guided fractionation and a chemical investigation of the MeOH extracts of the fruiting bodies of the mushroom Naematoloma fasciculare resulted in the isolation of four new lanostane triterpenoids (1-4), together with 11 known compounds (5-15). The structures of 1-5 were determined by a combination of 1D and 2D NMR and HRMS. The absolute configuration of the 3-hydroxy-3-methylglutaryl group as a side chain in 1 and 2 was determined by the alkaline methanolysis method. The full NMR data assignment of the known compound fasciculol G (5) is reported for the first time. Compounds 1-15 were tested for their antiproliferative activities against four human cancer cell lines (A549, SK-OV-3, SK-MEL-2, and HCT-15) and evaluated for their inhibitory effects on nitric oxide production in a lipopolysaccharide-activated murine microglial cell line.

Lactarane sesquiterpenoids from Lactarius subvellereus and their cytotoxicity

Subvellerolactones B (1), D (2), and E (3), structurally unusual lactarane sesquiterpenoids, were isolated from the fruiting bodies of Lactarius subvellereus together with four known lactarane sesquiterpenes (4-7). The chemical structures and stereochemistries of compounds 1-3 were determined on the basis of spectroscopic analyses, including 1D and 2D NMR experiments and a convenient Mosher ester procedure. Subvellerolactone B (1) exhibited cytotoxicity against the A549, SK-MEL-2, and HCT-15 cell lines with IC50 values of 26.5, 18.3, and 14.2 microM, respectively, and subvellerolactones D (2) and E (3) showed cytotoxicity against the A549 and HCT-15 cell lines (IC50 (2): 25.1 and 17.8 microM, and IC50 (3): 19.6 and 28.7 microM, respectively).

Oxysterols from free radical chain oxidation of 7-dehydrocholesterol: product and mechanistic studies

Free radical chain oxidation of highly oxidizable 7-dehydrocholesterol (7-DHC), initiated by 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), was carried out at 37 degrees C in benzene for 24 h. Fifteen oxysterols derived from 7-DHC were isolated and characterized with 1D and 2D NMR spectroscopy and mass spectrometry. A mechanism that involves abstraction of hydrogen atoms at C-9 and/or C-14 is proposed to account for the formation of all of the oxysterols and the reaction progress profile. In either the H-9 or H-14 mechanism, a pentadienyl radical intermediate is formed after abstraction of H-9 or H-14 by a peroxyl radical. This step is followed by the well-precedented transformations observed in peroxidation reactions of polyunsaturated fatty acids such as oxygen addition, peroxyl radical 5-exo cyclization, and S(H)i carbon radical attack on the peroxide bond. The mechanism for peroxidation of 7-DHC also accounts for the formation of numerous oxysterol natural products isolated from fungal species, marine sponges, and cactaceous species. In a cell viability test, the oxysterol mixture from 7-DHC peroxidation was found to be cytotoxic to Neuro2a neuroblastoma cells in the micromolar concentration range. We propose that the high reactivity of 7-DHC and the oxysterols generated from its peroxidation may play important roles in the pathogenesis of Smith-Lemli-Opitz syndrome, X-linked dominant chondrodysplasia punctata, and cerebrotendinous xanthomatosis, all of these being metabolic disorders characterized by an elevated level of 7-DHC.

Synthesis of Aib-containing cyclopeptides via the ‘azirine/oxazolone method’

The cyclic pentapeptide cyclo[Gly-Phe(2Me)-Aib-Aib-Gly], containing three α,α-disubstituted α-amino acids, was prepared by cyclization of H-Gly-Phe(2Me)-Aib-Aib-Gly-OH with diphenyl phosporazidate (DPPA) in 60% yield. The synthesis of the linear precursor was performed by using the ‘azirine/oxazolone method’, in which the α,α-disubstituted α-amino acids were introduced by coupling of the corresponding amino or peptide acid with a 2,2-disubstituted 3-amino-2H-azirine. Whereas the cyclization of an analogous hexapeptide afforded the cyclopeptide in 42% yield, the corresponding tetrapeptide yielded a 1:2 mixture of the monomeric and dimeric cyclopeptide. In the case of the tripeptide H-Gly-Phe(2Me)-Aib-OH, the cyclization with DPPA led to the dimeric cyclohexapeptide exclusively.