L‐methioninase production by Aspergillus flavipes under solid‐state fermentation

Solid‐state fermentation was carried out for the production of extra‐cellular L‐methioninase by Aspergillus flavipes (Bain and Sart.) using nine agro‐industrial residues, namely wheat bran, rice bran, wheat flour, coconut seeds, cotton seeds, ground nut cake, lentil hulls, soya beans and chicken feathers. Chicken feathers were selected as solid substrate for L‐methioninase production by A. flavipes. The maximum L‐methioninase productivity (71.0 U/mg protein) and growth (11 mg protein/ml) of A. flavipes was obtained using alkali pretreated chicken feathers of 50% initial moisture content as substrate supplemented with D‐glucose (1.0% w/v) and L‐methionine (0.2% w/v). External supplementation of the fermentation medium with various vitamin sources has no overinductive effect on L‐methioninase biosynthesis. The partially purified A. flavipes L‐methioninase preparation showed highest activity (181 U/ml) at pH 8.0 with stability over a pH range (pH 6–8) for 2 h. L‐methioninase activity was increased by preincubation of the enzyme for 2 h with Co²⁺, Mn²⁺, Cu²⁺ and Mg²⁺ and strongly inhibited by the presence of EDTA, NaN₃, Li²⁺, Cd²⁺, DMSO and 2‐mercaptoethanol. The enzyme preparation has a broad substrate spectrum showing a higher affinity to deaminate L‐glycine, N ‐acetylglucosamine and glutamic acid, in addition to their proteolytic activity against bovine serum albumin, casein, gelatin and keratin. The partially purified enzyme was found to be glyco‐metalloproteinic in nature as concluded from the analytical and spectroscopic profiles of the enzyme preparation. The demethiolating activity of the enzyme was also visualized chromogenially. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

海绵Aaptos sp.共附生真菌Aspergillus flavipes中aspochalasin类化合物及其生物活性

目的对海绵Aaptos sp.共附生真菌Aspergillus flavipes中的aspochalasin类化合物结构及其生物活性进行研究。方法利用硅胶柱层析、薄层色谱、Sephadex LH-20凝胶柱层析、中压液相色谱(MPLC)、高效液相色谱(HPLC)等分离手段对菌株发酵提取物进行分离和纯化;运用NMR、MS等现代波谱学方法,并结合相关文献数据比对,鉴定化合物的结构;通过活性筛选评价化合物活性。结果从真菌Aspergillus flavipes的次级代谢产物中获得了8个aspochalasin类化合物,分别为aspochalasin I(1)、aspochalasin D(2)、aspochalasin K(3)、aspergillin PZ(4)、trichalasin H(5)、aspochalasin H(6)、flavichalasine G(7)、aspochalasin E(8),其中化合物1表现出良好BEL-7402细胞毒活性,IC50为1.88μmol/L。     

2-Methyl-versiquinazoline C,a new fumiquinazoline-type alkaloid from the fungus Aspergillus flavipes PJ03-11

A new fumiquinazoline-type alkaloid 2-methyl-versiquinazoline C (1), together with six known compounds (2–7), was isolated from Aspergillus flavipes PJ03-11 using OSMAC method. Their structures were elucidated on the basis of extensive spectroscopic analysis, and the absolute configuration of compound 1 was determined by the experimental and calculated ECD data. In addition, the cytotoxic activities against three human cancer cell lines (HL-60, THP-1, and PC-3) were evaluated.