Antimicrobial properties of unusual eremophilanes from the endophytic Diaporthe sp. BCC69512.

Six undescribed infrequent eremophilane derivatives including diaportheremopholins A - F and its previously undescribed side chain (E)-2-methyloct-2-enoic acid, together with three known compounds (testacein, xestodecalactones B and C), were isolated from the endophytic fungus Diaporthe sp. BCC69512. The chemical structures were determined based on NMR spectroscopic information in conjunction with the evidence from NOESY spectrum, Mosher's application, and chemical reactions for corroborating the absolute configurations. The isolated compounds were evaluated for biological properties such as antimalarial, anti-TB, anti-phytopathogenic fungal, antibacterial activities and for cytotoxicity against malignant (MCF-7 and NCI-H187) and non-malignant (Vero) cells. Diaportheremopholins B (2) and E (5) possessed broad antimicrobial activity against Mycobacterium tuberculosis, Bacillus cereus, Alternaria brassicicola and Colletotrichum acutatum with MICs in a range of 25.0-50.0 µg/mL. Testacein (7) exhibited strong anti-A. brassicicola and anti-C. acutatum activities with equal MIC values of 3.13 µg/mL. Moreover, diaportheremopholin F (6) and compound 8 displayed antitubercular activity with equal MIC values of 50.0 µg/mL. All tested compounds were non-cytotoxic against MCF-7, NCI-H187, and Vero cells, except those compounds 2 and 5-7 exhibited weak cytotoxicity against both malignant and non-malignant cells with IC50 values in a range of 15.5-115.5 µM.

Abyssomicin derivatives from the rhizosphere soil actinomycete Microbispora rhizosphaerae sp. nov. TBRC6028.

Three undescribed abyssomicin derivatives, including microbimisin, abyssomicins Z1, and Z2, were isolated from the soil actinomycete Microbispora rhizosphaerae sp. nov. TBRC6028. Chemical structures were determined by NMR spectroscopic data (1H, 13C, COSY, HSQC, HMBC, and NOESY spectra) and the absolute configurations were verified by single-crystal X-ray diffraction analyses together with the ECD spectral data. Microbimisin and abyssomicin Z1 exhibited weak antibacterial activity against Bacillus cereus with MIC values of 25.0 and 50.0 µg/mL without cytotoxicity against MCF-7 and Vero cells at the concentration of 50 µg/mL.

Chromone derivatives, R- and S- taeniolin, from the marine-derived fungus Taeniolella sp. BCC31839.

Two unknown enantiomeric compounds, named (R)- and (S)-taeniolin, along with six known compounds, were isolated from the marine-associated fungus Taeniolella sp. BCC31839. Chemical structures were determined by NMR spectroscopic techniques, and the absolute configurations were confirmed by Mosher application together with CD spectral analyses. Both were inactive for antimicrobial activity against multidrug-resistant malaria parasite (Plasmodium falciparum) and bacteria (Mycobacerium tuberculosis and Bacillus cereus) at maximum tested concentration.

Antibacterial, antitubercular, antimalarial and cytotoxic substances from the endophytic Streptomyces sp. TBRC7642.

Eight previously undescribed naturally-occurring compounds, including abyssomycins Y - Z, methyl aeruginoate, desferri-ferrithocin-4-hydroxyphenethylester, streptomethiocins A - B, furaquinocin I, and streptolactone, along with eleven known compounds were isolated from the endophytic Streptomyces sp. TBRC7642. The chemical structures were determined based on spectroscopic means including 1D, 2D NMR spectroscopy and mass spectrometry. The absolute configurations were assigned by relying on CD spectra and their optical rotations. In addition, the isolated compounds were evaluated for biological activity, such as antimalarial, antitubercular, antibacterial (both Gram-positive and Gram-negative bacteria), as well as for cytotoxicity against MCF-7, NCI-H187, and Vero cells.

Antimicrobial drimane - phthalide derivatives from Hypoxylon fendleri BCC32408.

Fourteen new compounds including thirteen drimane - phthalide derivatives (fendlerals A - C, fendlerins A - D, fendlerols A - B, fendleric acids A - C, fendlerinine G) and one terphenyl derivative (fendleryl E) along with eight known compounds, fendlerinine A, rickenyls C - D, fendleryls C - D, atromentin, tetramethyl atromentin, and (±)-microsphaerophthalide F, were isolated from the wood fungus Hypoxylon fendleri BCC32408. Compared with the prior work, the results indicated the agitation effect on the production of bioactive drimane - phthalides. The chemical structures were determined based upon spectroscopic analyses and the absolute configurations were verified by comparison of the ECD spectral data with the calculated ECD spectra of the related compounds. Compounds 1-3 exhibited antimicrobial activity against Plasmodium falciparum (IC50 4.15-4.39 µM), Colletotrichum capsici (MIC 6.25-12.5 µg/mL), and Bacillus cereus (MIC 1.56-3.13 µg/mL). All tested compounds displayed broad cytotoxicity against cancerous (MCF-7, KB, and NCI-H187) and non-cancerous (Vero) cells.

Terphenyl derivatives and drimane - Phathalide/isoindolinones from Hypoxylon fendleri BCC32408.

The genus Hypoxylon, a member of the family Xylariaceae, has been known to produce significant secondary metabolites in terms of chemical diversity. Moreover, the compounds isolated can also be used as chemotaxonomic characters for differentiation among the two sections, which are sect. Annulata and sect. Hypoxylon. In our continuing chemical screening programme for novel compounds, the crude extracts of H. fendleri BCC32408 gave significant chemical profiles in HPLC analyses. Thus, the chemical investigation of these crude extracts was then carried out. The investigation led to the isolation of ten previously undescribed compounds including three terphenylquinones (fendleryls A - C), one terphenyl (fendleryl D), and six novel drimane - phthalide-type lactone/isoindolinones derivatives (fendlerinines A - F) along with seven known compounds (2-O-methylatromentin, rickenyl E, atromentin, rickenyls C - D, (+)-ramulosin, and O-hydroxyphenyl acetic acid). The chemical structures were determined on the basis of spectroscopic analyses, including 1D, 2D NMR and high-resolution mass spectrometry, as well as chemical transformations. In addition, these isolated compounds were assessed for antimicrobial activity including antimalarial (against Plasmodium falciparum, K-1 strain), antifungal (against Candida albicans), antibacterial (against Bacillus cereus) activities. Cytotoxicity against both cancerous (KB, MCF-7, NCI-H187) and non-cancerous (Vero) cells of these compounds were also evaluated.

Antimycobacterial substances from Phaeosphaeria sp BCC8292.

Eleven substances including naphthalenones, naphthoquinones, unsymmetrical naphthoquinone dimers and a chlorinated diphenyl ether, three of which are new, have been isolated from the fungus Phaeosphaeria sp. The absolute stereochemistry of naphthalenones has been determined by the Mosher and exciton chirality methods. The biological activity of these compounds against Mycobacterium tuberculosis and cytotoxicity against KB, BCA, NCI-H 187 and Vero cell lines were evaluated.

Depsidones from the endophytic fungus BCC 8616.

Three new depsidones (1-3) have been isolated from the endophytic fungus BCC 8616 and their structures analyzed on the basis of spectroscopic data interpretation. Compound 1 exhibited weak cytotoxic activity against breast and epidermoid carcinoma cell lines.