| Reference | [1]. Chen, C., Ye, Y., Wang, R., Zhang, Y., Wu, C., Debnath, S.C., Ma, Z., Wang, J. and Wu, M., 2018.<br />
Streptomyces nigra sp. nov. is a novel actinobacterium isolated from mangrove soil and exerts a potent antitumor activity in vitro.<br />
Abstract: A new bacterial strain, designated 452T, was isolated from the rhizosphere soil of the mangrove Avicennia marina in China. As determined, its cell wall peptidoglycan contained LL-diaminopimelic acid; MK-9(H8) and MK-9(H6) were the major isoprenoid quinones; and iso-C16:0 (31.3%), anteiso-C15:0 (16.9%), and iso-C15:0 (12.5%) were the major cellular fatty acids (>10.0%). Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain 452T formed a distinct lineage in the clade of the genus Streptomyces, and was closely related to S. coerulescens DSM 40146T (99.6% sequence identity), S. bellus DSM 40185T (99.5%), and S. coeruleorubidus DSM 41172T (99.3%). The DNA-DNA relatedness between strain 452T and these type strains ranged between 29.3 and 42.3%. Based on the phenotypic, chemotaxonomic, and phylogenetic features, the strain 452T is considered to represent a novel species of the genus Streptomyces, for which the name Streptomyces nigra sp. nov. is proposed. The type strain is 452T (=KCTC 39960T = MCCC 1K03346T). Further, strain 452T extracts exhibited a pronounced antitumor activity against human cancer cell lines A549, HCT-116, and HepG2, but not against normal human colon cells CCD-18Co. Active substances in the fermentation broth of strain 452T were isolated by bioassay-guided analysis, and then purified using a macroporous resin, silica gel, sephadex LX-20 column, and semi-preparative high-performance liquid chromatography (HPLC). Eight proline-containing diketopiperazines, namely, cyclo(Pro-Ala), cyclo(Pro-Gly), cyclo(Pro-Phe), cyclo(Pro-Met), cyclo(Pro-Val), cyclo(Pro-Leu), cyclo(Pro-Tyr), and cyclo(L-Leu-trans-4-hydroxy-L-Pro), were identified by electrospray ionization mass spectrometry (MS) and nuclear magnetic resonance (NMR). The compounds displayed different levels of cytotoxicity. The highest cytotoxicity was exhibited by cyclo(Pro-Ala) and cyclo(Pro-Met) against A549 cells, and cyclo(Phe-Pro) and cyclo(Pro-Ala) against HCT-116 cells, with average IC50 values equal to 18.5, 27.3, 32.3, and 47.6 μg/mL, respectively. The diversity of diketopiperazines and other chemicals produced by 452T was further investigated using gas chromatography (GC)-MS and liquid chromatography (LC)-MS. The analysis revealed 16 types of metabolites with antitumor activity and 16 other types of diketopiperazines. Hence, extracts of the newly identified strain may be used a starting material for the development of antitumor agents.<br />
Frontiers in microbiology, 9, p.1587.<br />
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[2]. Wang, X., Lin, M., Xu, D., Lai, D. and Zhou, L., 2017.<br />
Structural diversity and biological activities of fungal cyclic peptides, excluding cyclodipeptides.<br />
Abstract: Cyclic peptides are cyclic compounds formed mainly by the amide bonds between either proteinogenic or non-proteinogenic amino acids. This review highlights the occurrence, structures and biological activities of fungal cyclic peptides (excluding cyclodipeptides, and peptides containing ester bonds in the core ring) reported until August 2017. About 293 cyclic peptides belonging to the groups of cyclic tri-, tetra-, penta-, hexa-, hepta-, octa-, nona-, deca-, undeca-, dodeca-, tetradeca-, and octadecapeptides as well as cyclic peptides containing ether bonds in the core ring have been isolated from fungi. They were mainly isolated from the genera Aspergillus, Penicillium, Fusarium, Acremonium and Amanita. Some of them were screened to have antimicrobial, antiviral, cytotoxic, phytotoxic, insecticidal, nematicidal, immunosuppressive and enzyme-inhibitory activities to show their potential applications. Some fungal cyclic peptides such as the echinocandins, pneumocandins and cyclosporin A have been developed as pharmaceuticals<br />
Molecules, 22(12), p.2069.<br />
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[3]. Elkhateeb, W.A., Kolaibe, A.G.A., Elkhateeb, A. and Daba, G.M., 2021.<br />
Allergen, pathogen, or biotechnological tool? The dematiaceous fungi Alternaria what’s for it and what’s on it?.<br />
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[4]. Eram, D., Arthikala, M.K., Melappa, G. and Santoyo, G., 2018.<br />
Alternaria species: endophytic fungi as alternative sources of bioactive compounds.<br />
Abstract: Fungal endophytes are a rich source of functional metabolites. In particular, the different species of the genus Alternaria stand out for their arsenal of metabolites, which have roles as antimicrobial molecules, antioxidants; as well as activities against HIV or cancer or diabetes. This review will highlight on selected aspects of the fungal endophytes of Alternaria species: their widespread distribution, and the role of their metabolites with pharmaceutical or agronomical importance. The family plants associated with Alternaria species, their bioactive compounds and biological activity to date are examined.<br />
Italian Journal of Mycology, 47, pp.40-54.
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