A 7-dimethylallyl tryptophan synthase from a fungal Neosartorya sp.: Biochemical characterization and structural insight into the regioselective prenylation

A putative 7-dimethylallyl tryptophan synthase (DMATS) gene from a fungal Neosartorya sp. was cloned and overexpressed as a soluble His₆-fusion protein in Escherichia coli. The enzyme was found to catalyze the prenylation of l-tryptophan at the C7 position of the indole moiety in the presence of dimethylallyl diphosphate; thus, it functions as a 7-DMATS. In this study, we describe the biochemical characterization of 7-DMATS from Neosartorya sp., referred to as 7-DMATS^Neo, and the structural basis of the regioselective prenylation of l-tryptophan at the C7 position by comparison of the three-dimensional structural models of 7-DMATS^Neo with FgaPT2 (4-DMATS) from Aspergillus fumigatus.     

4,21-Secovincanol,a Novel Immunosuppressive Monoterpenoid Indole Alkaloid from Kopsia Hainanensis

4,21-Secovincanol ( 1 ), a novel C-21/N-4 cleavage monoterpenoid indole alkaloid, along with four analogs ( 2 – 5 ), were obtained from the aerial parts of Kopsia hainanensis. Structurally, compound 1 might be a derivative of epivincanol ( 2 ) via C-21/N-4 cleavage. Their structures were confirmed by means of comprehensive spectroscopic data analysis and comparison with the reported data. All isolates significantly inhibited Con A-stimulated mice splenocytes proliferation at 10–40 μM in a dose-dependent manner in vitro. Especially, compound 3 exhibited potent activities comparable to positive control (Dexamethasone, DXM).     

Synthesis and Biological Activity of N-Acyl O-Indolylalkyl Ethanolamines

The plant-growth regulators, indole-3-carboxylic acids, were introduced into N-acyl ethanolamines, and a series of N-acyl O-indolylalkyl ethanolamines were prepared. Their biological activities to regulate rape hypocotyl elongation, cucumber cotyledon expansion and common wheat coleoptile growth were tested. The results indicate that the title compounds inhibited rape hypocotyl elongation, especially the indole-3-propionic acid derivatives, whose bioactivity was better than that of indole-3-acetic acid.     

内生型解淀粉芽孢杆菌YTB1407对甘薯根系的促生作用及其调控机理

本实验室从西洋参根中分离筛选获得兼具生防和促生效果的内生型解淀粉芽孢杆菌YTB1407.为调查其应用潜力,以甘薯为材料,以无菌水灌根处理(CK)为对照,采用不同浓度YTB1407菌悬液灌根盆栽甘薯植株,通过对甘薯生长前期3个主要生育时间点YTB1407在植株内的内生定殖检测和根系表型效应比较,筛选菌悬液灌根的最适处理浓度.对根系内源生长素吲哚乙酸(IAA)、细胞分裂素玉米素核苷(ZR)、反式玉米素核糖核苷(t-ZR)的含量和吲哚乙酸氧化酶类中的吲哚乙酸氧化酶(IAAO)、过氧化物酶(POD)和多酚氧化酶(PPO)的活性进行分析.结果表明: YTB1407促进了甘薯生长前期根系统的定殖、不定根幼根的伸长生长及侧根的发生,提高了根系活力;在甘薯生长后期形成了更大的吸收根系生物量和更低的地上部和总根系生物量比.其中OD₆₀₀值为0.50的菌悬液处理(T_0.50)促生效应显著,在甘薯茎叶封垄期的单株块根鲜质量和有效薯块数量最高.YTB1407通过提高ZR、t-ZR含量,降低IAAO活性、提高PPO活性和IAA含量以及(t-ZR+ZR)/IAA,促进块根分化建成初期甘薯不定根幼根向块根的分化;通过降低IAAO、PPO活性和提高IAA含量,降低(t-ZR+ZR)/IAA,促进块根分化建成后期甘薯分化根向块根的建成.     

16-epi-19-S-vindolinine,an indoline alkaloid from Catharanthus roseus

Studies on the alkaloids of Catharanthus roseus have resulted in the isolation of a new alkaloid, to which the structure of 16-epi-19-S-vindolinine has been assigned.     

Nitrogen metabolism in cultures of Tabernaemontana divaricata

A cell suspension culture from Tabernaemontana divaricata was fed with ¹⁵N-labelled ammonium or nitrate. The incorporation of label in free amino acids, protein amino acids and indole alkaloids was determined. Ammonium was found to be used more extensively than nitrate in the biosynthesis of these compounds. For tryptamine considerably lower labelling percentages were found than for the indole alkaloid O-acetylvallesamine and the amino acids. This indicates a vacuolar pool of tryptamine, formed at the beginning of the culture-period and not available for further alkaloid biosynthesis.