Antimalarial 20-membered macrolides from Streptomyces sp. BCC33756

Two new natural products, samroiyotmycins A (1) and B (2), along with two naturally new novclobiocin 101 (3) and 4-hydroxy-3-(3-methylbut-2-enyl)benzamide (5), and five known substances including neoantimycin, clorobiocin (4), 29-O-methylabierixin, daidzein, and 1-(3-indolyl)-2,3-dihydroxypropan-1-one have been isolated from Streptomyces sp. BCC33756. Their chemical structures were determined based on NMR spectral information and the relative stereochemistry of compound 1 was determined by X-ray crystallographic data. Both samroiyotmycins A and B exhibited antimalarial activity against Plasmodium falciparum K1—multi-drug resistant strain, with IC₅₀ values of 3.65 and 3.16 μg/mL, respectively. Compound 1 was inactive against both cancerous (MCF-7, KB) and non-cancerous (Vero) cells, while compound 2 displayed cytotoxicity against Vero cell with IC₅₀ value of 29.57 μg/mL.     

Hamigeromycins C-G, 14-membered macrolides from the fungus Hamigera avellanea BCC 17816

Five new 14-membered macrolides, hamigeromycins C-G, together with the previously described compounds, hamigeromycin A and 89-250904-F1 (radicicol analog A), were isolated from the fungus Hamigera avellanea BCC 17816. Hamigeromycins A, C, D, and E are stereoisomers differing from one another in the absolute configurations of the 4′,5′-diol moiety. Hamigeromycins F and G are unusual 5′-keto-analogs, and they are 6′-epimers to each other. The structures and the stereochemistry of the new compounds were deduced by analyses of the NMR spectroscopic and mass spectrometry data in combination with chemical means.     

Pyridone alkaloids from the scale-insect pathogenic fungus Hypocrella discoidea BCC 71382

Hypocrellutins A–C (1–3), 2- and 4-pyridone alkaloids, were isolated from cultures of the scale-insect pathogenic fungus Hypocrella discoidea BCC 71382. The structures were elucidated on the basis of NMR spectroscopic and mass spectrometry data. The absolute configuration of hypocrellutin B (2) was determined by ECD calculation. Their plausibly biosynthetic pathways are proposed. All isolated compounds were inactive in the antifungal, antimalarial, antitubercular, and cytotoxic activity assays.     

Effect of Heat Treatment Temperature on Surface Topography and Hydrophobicity of Polydimethylsiloxane/Titanium Oxide Hybrid Films

Hydrophobic thin films of polydimethylsiloxane (PDMS) - titamium (hydrous) oxide hybrid material were deposited on glass substrate by dip coating from the precursor containing hydroxyl-terminated PDMS and titanium tetraisopropoxide (TIP), as well as small amounts of water and ethyl acetoacetate. Film's hydrophobicity was evaluated by performing contact angle measurement, while surface topography was analyzed by using an atomic force microscope (AFM). Effects of heat treatment temperature and TIP:PDMS ratio on film's hydrophobicity are described.     

Seco‐Tremulanes from Cultures of the Basidiomycete Flavodon flavus BCC 17421

A new seco‐tremulane, 11,12‐epoxy‐5,6‐secotremula‐1,6(13)‐dien‐5,12‐olide ( 1 ), was isolated together with the known compounds, conocenolides A ( 2 ) and B ( 3 ), tremulenediol A ( 4 ), tremulenolide A ( 5 ), and two lanostane triterpenoids, trametenolic acid B ( 6 ), and pinicolic acid A ( 7 ), from cultures of the basidiomycete Flavodon flavus BCC 17421. Interconversion of conocenolides A/B was demonstrated. Compound 1 exhibited weak cytotoxic activities, whereas tremulenediol A showed antiplasmodial activity (IC₅₀ 8.6 μg/ml). Pinicolic acid A exhibited activity against herpes simplex virus type‐1 (IC₅₀ 15 μg/ml) as well as cytotoxic activities.     

3-Oxyanthranilic acid derivatives from Actinomadura sp. BCC27169

Eight new compounds including 9′-[2-amino-3-(4″-O-methyl-α-rhamnopyranosyloxy) phenyl]nonanoic acid (1), 9′-[2-amino-3-(4″-O-methyl-α-ribopyranosyloxy)phenyl] nonanoic acid (2), 11′-[2-amino-3-(4″-O-methyl-α-rhamnopyranosyloxy)phenyl]undecanoic acid (3), 11′-[2-amino-3-(4″-O-methyl-α-ribopyranosyloxy)phenyl]undecanoic acid (4), 8-(4′-O-methyl-α-rhamnopyranosyloxy)-3,4-dihydroquinolin-2(1H)-one (5), 8-(4′-O-methyl-α-ribopyranosyloxy)-3,4-dihydroquinolin-2(1H)-one (6), 8-(4′-O-methyl-α-rhamnopyranosyloxy)-2-methyquinoline (7), and 8-(4′-O-methyl-α-ribopyranosyloxy)-2-methylquinoline (8) were isolated from Actinomadura sp. BCC27169. The chemical structures of these compounds were determined based on NMR and high-resolution mass spectroscopy. The absolute configurations of these monosaccharides were revealed by the hydrolysis of compounds 7 and 8. Compounds 3 and 8 exhibited antitubercular activity at MIC 50 μg/mL. Only compound 3 showed cytotoxicity against KB cell at IC₅₀ 18.63 μg/mL, while other isolated compounds were inactive at tested maximum concentration (50 μg/mL).     

Novel cyclopropyl diketones and 14-membered macrolides from the soil fungus Hamigera avellanea BCC 17816

Two novel cyclopropyl diketones, hamavellone A (1) and B (2), and two new 14-membered nonaketide macrolactones, hamigeromycin A (3) and B (4), together with six known compounds, 89-250904-F1 (radicicol analogue A, 5), pseurotin A (6), emodin (7), ω-hydroxyemodin (8), and emodin bianthrones (9 and 10) were isolated from the soil fungus Hamigera avellanea BCC 17816. The structures of the new compounds were defined by analysis of NMR and MS data. The absolute stereochemistry of 3 was addressed by chemical correlation to 5. Hamavellone B (2) exhibited antimalarial activity with an IC₅₀ of 5.2 μg/mL, whereas it also showed comparable cytotoxicity.     

Cytotoxic tropolones from the fungus Nemania sp. BCC 30850

Twelve new compounds, including nine tropolones, nemanolones A?I (1–9), three 7-isochromenones, nemanecins A?C (10–12), and a new naturally isolated 4-isochromanone (13), along with two known compounds, 7,8-dihydroxy-3-methyl isochroman-4-one (XJP), and chaetoquadrin F, were isolated from culture broth of the fungus Nemania sp. BCC 30850. Structures of these compounds were elucidated by NMR and MS spectroscopic analyses. Nemanolones exhibited cytotoxic activities and two of them, compounds 1 and 2, also showed antibacterial activity against Bacillus cereus and antifungal activity against Candida albicans.     

Visible-light-sensitive N-doped TiO<Subscript>2</Subscript> photocatalysts prepared by a mechanochemical method: effect of a nitrogen source

Nitrogen-doped titanium dioxide (N-doped TiO₂) photocatalysts were prepared by a mechanochemical method by using a high-speed ball milling of P25 TiO₂ with nitrogen sources such as ammonia solution, hexamine, and urea. Visible-light absorption was determined from the onset of diffused reflectance spectrum. The photocatalytic activity of the N-doped TiO₂ was evaluated through the removal of methylene blue (MB) under visible-light irradiation. The effects of nitrogen precursors used during the mechanochemical synthesis on the catalysts’ properties, such as the effective particle size, surface area, and photocatalytic activity, were extensively investigated.     

Torrubiellutins A-C, from insect pathogenic fungus Torrubiella luteorostrata BCC 12904

Investigation of the insect pathogenic fungus Torrubiella luteorostrata led to the isolation of three new macrocyclic torrubiellutins A-C (1-3) and the known pyrone diterpene 4. Structures were elucidated by spectroscopic data including 1D, 2D NMR, and MS spectral data. The absolute stereochemistry was determined by chemical means using Mosher reactions and Marfey's reagent, together with NOESY spectral data. Torrubiellutin C showed biological activities against KB, MCF-7, NCI-H187, and Vero cell lines with IC₅₀ varying from 0.78 to 4.36 μg/mL, while compound 4 exhibited antimalaria and anti-inflammatory activity with IC₅₀ values of 3.49 and 1.21 μg/mL, respectively.