In the course of our chemical screening program, the novel acyl α‐L‐rhamnopyranosides (1‐6) were detected as metabolites from five different strains of Streptomycetes. The structures of all these compounds were elucidated by chemical and spectroscopic methods. The biosynthesis of 1 and 3 was established by feeding 13C‐labelled acetate, glycerol, and D‐glucose to Streptomyces griseoviridis (strain Tü 3634), and resulted in a complete labelling pattern of the 2,4‐dimethyl‐3‐furanylcarbonyl and benzoyl residues, as well as the rhamnose moiety. These results reveal biosynthetic pathways of general importance and give an insight into the generation of the hexose phosphates, from which deoxysugars are formed. The acyl rhamnosides are members of a novel family of microbial metabolites and are considered as rhamnoconjugates from Streptomycetes.

Background ADAMTS-13 activity can be regulated by its conformation, whereby interactions between the C-terminal CUB domains and the spacer domain maintain ADAMTS-13 in a closed conformation. ADAMTS-13 contains 10 N-linked glycans, with four sites present in theTSP2 through to CUB domains that may contribute to its conformation. Objectives/Methods We hypothesized that glycosylation contributes to ADAMTS-13 conformation and function. The proteolytic activity of glycan-modified ADAMTS-13 was assessed under static and shear stress conditions. Results Enzymatic removal of terminal silaic acid or entire N-linked glycan chains decreased activity against FRETS-VWF73 at pH 7.4 and against full-length von Willebrand factor (VWF) under shear stress. Using truncated ADAMTS-13, we demonstrated that this was attributable to loss of sialic acid from the glycans in the metalloprotease domain and an effect of N-linked glycosylation in the TSP2 through to CUB domains. Mutation of the N-linked glycan sites in the MDTCS domains reduced or abolished protein expression. However, the N707Q, N828Q, N1235Q and N1354Q (TSP2, TSP4, CUB1, and CUB2 domains, respectively) variants were expressed normally. Interestingly, the N707Q and N828Q variants showed reduced activity against FRETS-VWF73, but normal activity under flow conditions. In contrast, the N1235Q and N1354Q variants had enhanced activity against FRETS-VWF73 and VWF under shear stress. Immunoprecipitation experiments confirmed that loss of N-linked glycans in the CUB domains significantly reduced the interaction with the spacer domain and enhanced binding to the 6A6 anti-ADAMTS-13 antibody, which recognizes a cryptic epitope in the metalloprotease domain. Conclusions Together, these data demonstrate that the N-linked glycans of ADAMTS-13 play a crucial role in regulating ADAMTS-13 activity.

Substituted phenols can easily be recognized by using the chemical screening method, whereby they are found to be widely spread secondary metabolites of microorganisms. In the culture filtrate of Penicillium sp. (strain FH-A 6260) new phenols named waraterpols were detected by a striking purple coloration by using anisaldehyde/sulfuric acid. These secondary metabolites (1 to 3 and 6 to 8) exhibit a CIS-carbon skeleton and can be characterized as hydroxylated branched-chain sesquiterpenoids with a benzoide moiety. The minor compounds were 0-acetyl (2 and 3) and dehydrated derivatives (6 to 8) of the parent compound waraterpol (l), which was shown to be 6-[2-hydroxy-4-(hydroxymethyl)phenyl]-2-methylheptane-1,6-diol. Derivatization of 1 resulted in the quinone and hydroquinone compounds 10 and 5 as well as in the cyclic derivatives 11 and 12. The waraterpols exhibit distinct antibacterial and antifungal activities whereas an inhibition of HIV-1 in a MT-4 cell assay was found for 11.

Chemical screening with extracts of Actinomycetes strains resulted in the detection, isolation, and structural elucidation of two new heteroaromatic secondary metabolites, named ulupyrinone (1) and ulufuranol (2), from Streptomyces spina (strain FH-S 2144). The absolute configuration of ulufuranol (2) was determined by analysis of the CD spectra of its dibenzoate, 3, using the dibenzoate chirality rule.Our chemical screening routine, which has already been described in guided us to secondary metabolites produced by Streptomyces spina (strain FH-S 2144). This Actinomycetes strain was conspicuous because of two striking yellow and orange spots which were obtained after staining with anisaldehyde/sulfuric acid, following TLC analysis of XAD-16 eluates from a cultivation using an oatmeal medium. This paper deals with the isolation, structural elucidation, and physico-chemical properties of these new and unusual heteroaromatic metabolites. The names ulupyrinone (1) and ulufuranol (2) arise from both the structural features of the metabolites and the origin of the soil sample (Uluday, Turkey), from which the strain was isolatedL51.The producing strain has been classified by both morphological and chemotaxonomical-based m e t h o d~ [~,~] as an isolate of Streptomyces spina. For screening purposes its cultivation was carried out in 300-ml Erlenmeyer flasks using a culture medium containing oatmeal (medium B) or glycerol/casein peptone (medium C). In order to examine the secondary metabolite patternL2] of strain FH-S 2144, a standardized work-up procedure using an Amberlite XAD-16 adsorption, as well as a 1:50 concentration step, was applied to the culture Analysis of this concentrate by TLC using various solvent systems and staining reagents presented two substances that gave striking spots after staining with different reagents (see Table 1).In order to isolate the new metabolites detected by the chemical screening method, Streptomyces spina (strain FH-S 2144) was cultivated in a 10-1 fermentor using medium C at 30°C for 4 days. The detected metabolites were isolated from the culture filtrate by adsorption on Amberlite XAD-16 and elution with MeOH/H20 (4: 1). Column chromatography on silica gel yielded 3.2 mg/l of pure ulupyrinone (1)