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Flavonols and proanthocyanidins are the major components that determine the black colouration of cucumber fruit spines and their synthesis is regulated by CsMYB60., Spine colour is an important fruit quality trait that influences the commercial value of cucumber (Cucumis sativus). However, little is known about the metabolites and the regulatory mechanisms of their biosynthesis in black spine varieties. In this study, we determined that the pigments of black spines are flavonoids, including flavonols and proanthocyanidins (PAs). We identified CsMYB60 as the best candidate for the previously identified B (Black spine) locus. Expression levels of CsMYB60 and the key genes involved in flavonoid biosynthesis were higher in black-spine inbred lines than that in white-spine lines at different developmental stages. The insertion of a Mutator-like element (CsMULE) in the second intron of CsMYB60 decreased its expression in a white-spine line. Transient overexpression assays indicated that CsMYB60 is a key regulatory gene and Cs4CL is a key structural gene in the pigmentation of black spines. In addition, the DNA methylation level in the CsMYB60 promoter was much lower in the black-spine line compared with white-spine line. The CsMULE insert may decrease the expression level of CsMYB60, causing hindered synthesis of flavonols and PAs in cucumber fruit spines.

Bioassay-guided fractionation of marine-derived fungi revealed that the EtOAc fraction from the fermentation broth of a mutated fungal strain Streptomyces nitrosporeus YBH10-5 had lipid-lowering effects in HepG2 cells. Chromatographic separation of the EtOAc fraction resulted in the isolation of 11 PKS-based derivatives, including a structurally unique meroterpenoid namely nitrosporeunol H (1). The structure of compound 1 was determined by the analysis of spectroscopic data. Further bioassay resulted in farnesylquinone (2) and its analogues to exert in vivo fat-reducing effects in C. elegans worm model. The underlying mode of action of compound 2 in the context of live worms was investigated, uncovering that compound 2 enhanced the mitochondrial &beta, oxidation rate and changed the transcriptional level of energy metabolism genes. Additional experiments revealed that compound 2 exerted its effects in C. elegans partially through repressing FAT-5, an isoform of stearoyl-CoA desaturase (SCD) which catalyzes the conversion of saturated fatty acids to monounsaturated fatty acids, thereafter leading to the modification of the fatty acid profile. Thus, compound 2 was suggested to be a promising lead for further optimization to treat obesity.

Chemical examination of an arctic actinomycete Streptomyces nitrosporeus resulted in the isolation of two new alkaloids named nitrosporeusines A (1) and B (2), an unprecedented skeleton containing benzenecarbothioc cyclopenta[c]pyrrole-1,3-dione. Their structures were determined through extensive spectroscopic analyses in association with X-ray single crystal diffraction. Both 1 and 2 exhibited inhibitory activities against the H1N1 virus in MDCK cells.

Prenylated indolocarbazoles have been reported neither from natural sources, nor by chemical synthetic approaches. In this Letter, we report a regiospecific prenylation of indolocarbazoles at the para- position of the indole N-atom by two recombinant enzymes from the dimethylallyltryptophan synthase (DMATS) superfamily, that is, 5-DMATS from Aspergillus clavatus and FgaPT2 from Aspergillus fumigatus .

Chemical examination of an arctic actinomycete Streptomyces nitrosporeus resulted in the isolation of two new alkaloids named nitrosporeusines A (1) and B (2), an unprecedented skeleton containing benzenecarbothioc cyclopenta[c]pyrrole-1,3-dione. Their structures were determined through extensive spectroscopic analyses in association with X-ray single crystal diffraction. Both 1 and 2 exhibited inhibitory activities against the H1N1 virus in MDCK cells.