A new steroid with potent antimicrobial activities and two new polyketides from Penicillium variabile EN-394, a fungus obtained from the marine red alga Rhodomela confervoides.

Three new compounds, including one steroid named penivariod A (1) and two polyketides penivarides A and B (2 and 3), as well as six known derivatives (4-9) were isolated from Penicillium variabile EN-394, a fungus afforded from the marine red alga Rhodomela confervoides. Their structures were elucidated by analysis of the HRESIMS, 1D and 2D NMR. The absolute stereochemistry was determined by X-ray crystallographic data, gauge-independent atomic orbital (GIAO) NMR shift calculation followed by DP4+ analysis combined with calculated electronic circular dichroism (ECD). Antimicrobial activities for the new compounds (1-3) were evaluated against human- and aquatic-pathogenic bacteria as well as plant pathogenic fungi. Compound 1 exhibited potent antimicrobial activity against most of the pathogenic strains, especially for Escherichia coli and Pseudomonas aeruginosa, with MIC values of 1.0 and 2.0 µg ml-1, respectively.

Sesquiterpene and Sorbicillinoid Glycosides from the Endophytic Fungus Trichoderma longibrachiatum EN-586 Derived from the Marine Red Alga Laurencia obtusa.

An unusual sesquiterpene glycoside trichoacorside A (1) and two novel sorbicillinoid glycosides sorbicillisides A (2) and B (3), together with a known compound sorbicillin (4), were isolated and identified from the culture extract of an endophytic fungus Trichoderma longibrachiatum EN-586, obtained from the marine red alga Laurencia obtusa. Trichoacorside A (1) is the first representative of a glucosamine-coupled acorane-type sesquiterpenoid. Their structures were elucidated based on detailed interpretation of NMR and mass spectroscopic data. The absolute configurations were determined by X-ray crystallographic analysis, chemical derivatization, and DP4+ probability analysis. The antimicrobial activities of compounds 1-4 against several human, aquatic, and plant pathogens were evaluated.

Talascortenes A-G, Highly Oxygenated Diterpenoid Acids from the Sea-Anemone-Derived Endozoic Fungus Talaromyces scorteus AS-242.

Eight new diterpenoid acids, namely, talascortenes A-G (1-7) and 5α,9ß-dihydroxyisocupressic acid (8), with four different carbon skeletons, were isolated and identified from the endozoic fungal strain Talaromyces scorteus AS-242 that was obtained from the inner fresh tissue of a deep sea Cerianthus sp. sea anemone. The structures of the new compounds were elucidated by detailed interpretation of NMR and mass spectrometric data. X-ray crystallographic analysis of compounds 1-5 and 7 confirmed their structures and absolute configurations. Compounds 1-8 showed inhibitory activities against several human, aquatic, and plant pathogens with MIC values ranging from 1 to 32 µg/mL.

Cladocladosin A, an unusual macrolide with bicyclo 5/9 ring system, and two thiomacrolides from the marine mangrove-derived endophytic fungus, Cladosporium cladosporioides MA-299.

A simple but previously undescribed macrolide with unprecedented bicyclo 5/9 ring system, namely, cladocladosin A (1), along with two new sulfur-containing macrolides, namely, thiocladospolides F and G (2 and 3), were characterized from the mangrove-derived endophytic fungus Cladosporium cladosporioides MA-299. The structures of these compounds were established on the basis of spectroscopic interpretation, and the absolute configurations of compounds 1-3 were determined by X-ray crystallographic analysis, Mosher's method, and by a biogenetic point of view. The possible biogenetic pathway for compounds 1-3 as well as their congeners thiocladospolides A-D and pandangolide 3 was proposed, providing a role in distinguishing the position of sulfur substitution in thiomacrolides. Compounds 1-3 were evaluated for antimicrobial activities against human-, aquatic-, and plant-pathogenic microbes.

Two New Neo-debromoaplysiatoxins-A Pair of Stereoisomers Exhibiting Potent Kv1.5 Ion Channel Inhibition Activities.

A pair of stereoisomers possessing novel structures with 6/6/5 fused-ring systems, neo-debromoaplysiatoxin E (1) and neo-debromoaplysiatoxin F (2), were isolated from the marine cyanobacterium Lyngbya sp. Their structures were elucidated using various spectroscopic techniques including high resolution electrospray ionization mass spectroscopy (HRESIMS) and nuclear magnetic resonance (NMR). The absolute stereochemistry was determined by calculated electronic circular dichroism (ECD) and gauge-independent atomic orbital (GIAO) NMR shift calculation followed by DP4+ analysis. Significantly, this is the first report on aplysiatoxin derivatives with different absolute configurations at C9-C12 (1: 9S, 10R, 11S, 12S; 2: 9R, 10S, 11R, 12R). Compounds 1 and 2 exhibited potent blocking activities against Kv1.5 with IC50 values of 1.22 ± 0.22 µM and 2.85 ± 0.29 µM, respectively.

Polyketides from the Mangrove-Derived Endophytic Fungus Cladosporium cladosporioides.

Five new polyketides, namely, 5R-hydroxyrecifeiolide (1), 5S-hydroxyrecifeiolide (2), ent-cladospolide F (3), cladospolide G (4), and cladospolide H (5), along with two known compounds (6 and 7), were isolated from the endophytic fungal strain Cladosporium cladosporioides MA-299 that was obtained from the leaves of the mangrove plant Bruguiera gymnorrhiza. The structures of these compounds were established by extensive analysis of 1D/2D NMR data, mass spectrometric data, ECDs and optical rotations, and modified Mosher's method. The structures of 3 and 6 were confirmed by single-crystal X-ray diffraction analysis and this is the first time for reporting the crystal structures of these two compounds. All of the isolated compounds were examined for antimicrobial activities against human and aquatic bacteria and plant pathogenic fungi as well as enzymatic inhibitory activities against acetylcholinesterase. Compounds 1-4, 6, and 7 exhibited antimicrobial activity against some of the tested strains with MIC values ranging from 1.0 to 64 µg/mL, while 3 exhibited enzymatic inhibitory activity against acetylcholinesterase with the IC50 value of 40.26 µM.

Thiocladospolides A-D, 12-Membered Macrolides from the Mangrove-Derived Endophytic Fungus Cladosporium cladosporioides MA-299 and Structure Revision of Pandangolide 3.

Four new 12-membered macrolides, thiocladospolides A-D (1-4), each possessing a sulfur substitution at C-2, along with the known congener pandangolide 3 (5) and the possible hydrolysis product seco-patulolide C (6), were isolated and identified from the culture extract of Cladosporium cladosporioides MA-299, an endophytic fungus obtained from the leaves of the mangrove plant Bruguiera gymnorrhiza. Their structures were established by interpretation of the NMR spectroscopic and mass spectrometric data. X-ray crystallographic analysis of compound 1, which represents the first crystal structure described for a sulfur-containing 12-membered macrolide, confirmed its structure and absolute configuration. The proposed sulfur side chain at C-3 in pandangolide 3 (5) was revised to be at C-2 by detailed analysis of the NMR data and by a comparison with data for thiocladospolide A (1). The structures for pandangolides 2 and 4 should also be considered for revisions. The isolated compounds were evaluated for the antimicrobial activities against aquatic bacteria and plant pathogens.