Yabin Yang

Antimicrobial metabolites from a novel halophilic actinomycete Nocardiopsis terrae YIM 90022

A quinoline alkaloid 1 and five known compounds (2–6) were isolated from a novel halophilic actinomycete Nocardiopsis terrae YIM 90022, and their structures were determined by spectroscopic studies as 4-oxo-1,4-dihydroquinoline-3-carboxamide (1), p-hydroxybenzoic acid (2), N-acetyl-anthranilic acid (3), indoly-3-carboxylic acid (4), cyclo(Trp-Gly) (5) and cyclo(Leu-Ala) (6). Compound 1 was isolated from natural resources for the first time. Compounds 1 and 3 showed antimicrobial activities against some plant pathogens.

Metabolites of Streptomyces sp., an endophytic actinomycete from Alpinia oxyphylla.

Four known compounds had been isolated from the Streptomyces sp. YIM66017, and their structures were elucidated by spectral analysis as 2,6-dimethoxy terephthalic acid (1), yangjinhualine A (2), α-hydroxyacetovanillone (3) and cyclo(Gly-Trp) (4). Compound 1 was isolated from natural resources for the first time, and compounds 2–4 were isolated from streptomycetes for the first time. The 2,2-diphenyl-1-picrylhydrazyl radical-scavenging activity assays showed that 1 showed higher activity than rutin with IC50 of 4.61 μg/mL and 2 showed the activity with IC50 of 57.12 μg/mL.

A new cyclic tetrapeptide from an endophytic Streptomyces sp. YIM67005.

One new cyclic tetrapeptide, cyclo(l-Tyr-l-Pro-l-Phe-trans-4-hydroxy-l-Pro) (1), together with two known cyclodipeptides, cyclo(l-Phe-trans-4-hydroxy-l-Pro) (2) and cyclo(l-Val-l-Tyr) (3), were isolated from the fermentation broth of Streptomyces sp. YIM67005 associated with Inula cappa DC. The planar structure of compound 1 was determined on the basis of spectroscopic techniques, while the absolute configurations of the amino acid residues were determined by the application of the advanced Marfey method. The cytotoxicity and antimicrobial activity of compound 1 were investigated.

Antimicrobial and antioxidant activities of a new benzamide from endophytic Streptomyces sp. YIM 67086

A new benzamide (1) and four known compounds (2–5) were isolated from endophytic Streptomyces YIM67086, and their structures were determined as 2-amino-3,4-dihydroxy-5-methoxybenzamide (1), 4-hydroxy-3-methoxybenzoic acid (2), phenylacetic acid (3), N-acetyltyramine (4) and p-hydroxytruxinic acid (5). Compound 5 was first found in the microorganism. The antimicrobial activities of compounds 1–5 and antioxidant activity of compound 1 were investigated.

Koningiopisins A-H, Polyketides with Synergistic Antifungal Activities from the Endophytic Fungus Trichoderma koningiopsis.

Eight new fungal polyketides named koningiopisins A-H (1-8) and four previously known polyketides (9-12) were isolated from the endophytic fungus Trichoderma koningiopsis YIM PH 30002. Their structures were elucidated using extensive spectral data interpretation, and their antifungal and synergistic activities were also evaluated. Koningiopisin C (3) exhibited in vitro antifungal activity against the phytopathogenic fungus Plectosphaerella cucumerina with an MIC of 16 µg/mL. Although the antifungal activities of single compounds were not obvious, a mixture of six compounds (4-9) exhibited potent synergistic antifungal activity against P. cucumerina with an MIC of 16 µg/mL, and the antifungal activity of the mixture of any two compounds with a 1:1 ratio was better than that observed from the individual compound. The synergistic biological activity of the metabolites in YIM PH 30002 demonstrates the significant ecological function of the endophyte for its host plant, and provides additional insight into the search for and development of agents for biological control.

The antifungal metabolites obtained from the rhizospheric Aspergillus sp. YIM PH30001 against pathogenic fungi of Panax notoginseng

Eight anthraquinones (1–8), three xanthones (11–13) and two phenols (9–10) were isolated from Aspergillus sp. associated with Panax notoginseng, and their structures were determined as ziganein-1-methyl ether (1), 8-O-methylchrysophanol (2), averythrin (3), averufin (4), 8-O-methyl averufin (5), versicolorin B (6), averantin (7), methyl-averantin (8), arugosin C (9), diorcinol (10), sterigmatocystin (11), demethylsterigmatocystin (12) and dihydrosterigmatocystin (13) by spectroscopic analyses. Compounds 1, 2 and 5 were the novel isolates from genus Aspergillus. Compounds 3, 6 and 7 exhibited antifungal activity against Fusariumsolani, pathogenic fungus of P. notoginseng, with minimum inhibitory concentrations (MICs) of 16–32 μg/mL, and compounds 1, 3, 4, 7 and 9 showed antibacterial activity against Bacillussubtilis with MICs of 64–128 μg/mL, 16–32 μg/mL, 8–16 μg/mL, 16–32 μg/mL and 64–128 μg/mL, respectively. The metabolites showed the potential value in the research of antifungal agents, especially in searching for a biocontrol of diseases of P. notoginseng. The preliminary structure–activity relationships have been discussed for some of the compounds.

A new natural nucleotide and other antibacterial metabolites from an endophytic Nocardia sp.

Nine compounds were isolated from Nocardia sp. YIM 64630, and their structures were elucidated as 5′-O-acetyl-2′-deoxyuridine (1), 22E,24R-5α,6α-epoxyergosta-8(14),22-diene-3β,7α-diol (2), 22E,24R-5α,6α-epoxyergosta-8,22-diene-3β,7α-diol (3), 22E,24R-ergosta-7,22-diene-3β,5α,6β-triol (4), 5α,8α-epidioxyergosta-6,22-dien-3β-ol (5), 4′,5,6-trihydroxy-7-methoxyisoflavone (6), 2,4,4′-trihydroxy-deoxybenzoin (7), methyl [4-hydroxyphenyl]acetate (8) and daidzein by extensive spectroscopic analyses. Compound 1 was isolated from natural resources for the first time. The antimicrobial and antioxidant activities of compounds 1–8 were investigated.

A new daidzein derivative from endophytic Streptomyces sp. YIM 65408

A new daidzein derivative, 1″-O-methyl-8-hydroxymethyl-daidzein (1) was isolated from Streptomyces sp. YIM 65408 in soybean powder containing medium. The structure was elucidated on the basis of extensive 1D and 2D NMR as well as HR-ESI-MS spectroscopic analyses. The radical-scavenging activity and cytotoxicity of compound 1 were also investigated, and 1 was found to be more active than daidzein in the 2,2-diphenyl-1-picrylhydrazyl method with IC50 at 0.60 mmol/L, but no cytotoxicity of 1 against HL-60, SMMC-7721, A-549, MCF-7 and SW480 cell lines was shown. The possible biosynthesis pathway from daidzein (2) to compound 1 was proposed.

Cyclodipeptides from the Secondary Metabolites of Two Novel Actinomycetes

Abstract Aim To investigate the secondary metabolites of two novel actinomycetes in order to find new compounds or effective components. Methods Compounds were isolated on silica gel column. The structures were elucidated on the basis of spectral data. Results Four cyclodipeptides were isolated from the fermentation broth of Sphaerisporangium album, and their structures were determined as cyclo (L-Pro-L-Asn) ( 1 ), cyclo (L-Pro-L-Ser) ( 2 ), cyclo (L-Pro-L-Ala) ( 3 ), and cyclo (L-Pro-L-Thr) ( 4 ). Three cyclodipeptides were isolated from the fermentation broth of Kribbella yunnanensis, and their structures were determined as cyclo (L-Pro-L-Ser) ( 2 ), cyclo (L-Pro-L-Thr) ( 4 ), and cyclo-di- N δ -acetyl-L-ornithyl ( 5 ). Conclusion 5 was a new natural compound. The full assignments of 1 H and 13 C NMR chemical shifts for 1 and 5 were obtained by 2D NMR firstly. All compounds were isolated from these two actinomycetes for the first time. When tested against tumor cell line panel (k563), 1 displayed cytotoxicity.

New megastigmane glycoside and alkaloids from Streptomyces sp. YIM 63342

New sesquiterpene glycoside, cyclodipeptide and piperidine derivative were isolated from Streptomyces sp. YIM 63342. On the basis of spectral data, their structures were determined as 3R, 5R, 6S, 7E, 9R-megastigman-7-en-3,5,6,9-tetrol-9-O-β-D-apiofuranosyl-(1   2)-β-D-glucopyranoside (1), cyclo (L-Pro-L-OMet) (2) and (R)-(E, E)-2-(l,3-pentadienyl) piperidine (3), together with three known compounds as N-acetyltyramine (4), lycoperodine-1 (5), cyclo(L-Pro-L-Tyr)(6).