Disulfide bridge-targeted metabolome mining unravels an antiparkinsonian peptide

Peptides are a particular molecule class with inherent attributes of some small-molecule drugs and macromolecular biologics, thereby inspiring continuous searches for peptides with therapeutic and/or agrochemical potentials. However, the success rate is decreasing, presumably because many interesting but less-abundant peptides are so scarce or labile that they are likely 'overlooked' during the characterization effort. Here, we present the biochemical characterization and druggability improvement of an unprecedented minor fungal RiPP (ribosomally synthesized and post-translationally modified peptide), named acalitide, by taking the relevant advantages of metabolomics approach and disulfide-bridged substructure which is more frequently imprinted in the marketed peptide drug molecules. Acalitide is biosynthetically unique in the macrotricyclization via two disulfide bridges and a protease (AcaB)-catalyzed lactamization of AcaA, an unprecedented precursor peptide. Such a biosynthetic logic was successfully re-edited for its sample supply renewal to facilitate the identification of the in vitro and in vivo antiparkinsonian efficacy of acalitide which was further confirmed safe and rendered brain-targetable by the liposome encapsulation strategy. Taken together, the work updates the mining strategy and biosynthetic complexity of RiPPs to unravel an antiparkinsonian drug candidate valuable for combating Parkinson's disease that is globally prevailing in an alarming manner.

Cytotoxic and antibacterial polyketide-indole hybrids synthesized from indole-3-carbinol by

Two skeletally undescribed polyketide-indole hybrids (PIHs), named indolchromins A and B, were generated from indole-3-carbinol (I3C) in the fungal culture (). The indolchromin structures were elucidated mainly by their 1D and 2D NMR spectra with the former confirmed by the single-crystal X-ray crystallographic analysis. Each indolchromin alkaloid was chirally separated into four isomers, whose absolute configurations were assigned by comparing the recorded circular dichroism (CD) spectra with the electronic CD (ECD) curves computed for all optional stereoisomers. Furthermore, the indolchromin construction pathways in fungal culture were clarified through enzyme inhibition, precursor feeding experiment, and energy calculation. The cascade reactions, including decarboxylative Claisen condensation catalyzed by 8-amino-7-oxononanoate synthase (AONS), C()-H activation, double bond migration, and Michael addition, all undergone compatibly during the fungal cultivation. In an MIC range of 1.3-8.6 μmol/L, (2,4)- and (2,4)-indolchromin A and (2,4)-indolchromin B are inhibitory against , , sp., , and . (2,4)-Indolchromin A and (2,4)-indolchromin B were cytotoxic against the human breast cancer cell line MDA-MB-231 with IC values of 27.9 and 131.2 nmol/L, respectively, with the former additionally active against another human breast cancer cell line MCF-7 (IC 94.4 nmol/L).

Assessment of the Cytotoxic and Apoptotic Effects of Chaetominine in a Human Leukemia Cell Line

Chaetominine is a quinazoline alkaloid originating from the endophytic fungus Aspergillus fumigatus CY018. In this study, we showed evidence that chaetominine has cytotoxic and apoptotic effects on human leukemia K562 cells and investigated the pathway involved in chaetominine-induced apoptosis in detail. Chaetominine inhibited K562 cell growth, with an IC50 value of 35 nM, but showed little inhibitory effect on the growth of human peripheral blood mononuclear cells. The high apoptosis rates, morphological apoptotic features, and DNA fragmentation caused by chaetominine indicated that the cytotoxicity was partially caused by its pro-apoptotic effect. Under chaetominine treatment, the Bax/Bcl-2 ratio was upregulated (from 0.3 to 8), which was followed by a decrease in mitochondrial membrane potential, release of cytochrome c from mitochondria into the cytosol, and stimulation of Apaf-1. Furthermore, activation of caspase-9 and caspase-3, which are the main executers of the apoptotic process, was observed. These results demonstrated that chaetominine induced cell apoptosis via the mitochondrial pathway. Chaetominine inhibited K562 cell growth and induced apoptotic cell death through the intrinsic pathway, which suggests that chaetominine might be a promising therapeutic for leukemia.

Chemical constituents of basidiomycete Hydnum repandum / 中草药

Objective To study the chemical constituents of the fruiting bodies of Hydnum repandum.Methods Separation and purification were performed on silica gel, Sephadex LH-20 and ODS CC. Their sturctures were established by 2D-NMR (1H-1HCOSY, HMQC, HMBC, and NOESY), MS, HR-MS spectra, and ORD data. Results Eleven compounds were obtained and identified as sarcodonin A ( Ⅰ ),scabronine B (Ⅱ), 3β-hydroxy-5α, 8α-epidioxyergosta-6, 22-dien (Ⅲ), (22E, 24R)-ergosta-7, 22-diene3β, 5α, 6β- triol (Ⅳ), (22E, 24R)-ergosta-7, 22-diene-3β-ol (Ⅴ), benzoic acid (Ⅵ), 4-hydroxylbenzaldehyde (Ⅶ), 4-monopropanoylbenzenediol (Ⅷ), ethyl-β-D-glucopyranoside (Ⅸ), thioacetic anhydride ( Ⅹ ), (2S, 2'R, 3S, 4R)-2-(2-hydroxyoctadecanoylamino) docosane-1, 3, 4-triol (Ⅺ). Conclusion All of the compounds are isolated from this fungus for the first time.

Purification of fibrinolytic enzyme from Perinereis aibuhitensis / 中草药

Object To extract and purify a novel fibrinolytic enzyme from Perinereis aibuhitensis Grube Methods The enzyme was precipitated from the extract by ammonium sulfate, dialyzed, chromatographed on Sephadex G 100 column, and then purified by polyacrylamide gel electrophoresis Its fibrinolytic activity was assessed with fibrin plate method Results The purified enzyme showed an isoelectric point (PI) around 4 5 as tested by gel isoelectric focusing It consisted of two polypeptide chains with molecular weights around 33 000 u and 14 400 u, respectively Conclusion This was a novel fibrinolytic enzyme discovered from P aibuhitensis for the first time

Methodology for quick finding of leading compounds based on botanical metabonomic concept of determination for mixture by 1H-NMR / 中草药

Objective To set up a methodology for quick finding of important leading compounds from complex plant samples. Methods A mixture fraction was determined by 1H-NMR techniques to find any evidence, further isolation of the fraction guided with this evidence was carried out. Results Based on the botanical metabonomic concept, a novel valuable sesquiterpene compound has been quickly isolated from the aerial part of Carpesium lipskyi. Conclusion The efficiency for finding of leading compounds could be improved if the isolation is based on metabonomics under the guidence of the new method of botanical mixture determination by 1H-NMR.

RAPD Analysis of germplasm resource in Artemisia annua / 中草药

Objective To analyze the genetic diversity of higher artemisinin-yielding Artemisia annua. Methods With the chemical investigation of artemisinin contents, RAPD analyses of selected plants from ten various habitats in China were carried out using arbitrary primers. Results The RAPD data clearly indicated the genetic diversity level in A. annua was relatively high with 53.6% polymorphic sites. UPGMA Analyses of RAPD and phytochemical trait data showed that the wide phytochemical diversity was included within the genetic diversity being present in at least four geographical regions. ConclusionArtemisinin has obvious inherited differentiation that further support the prospects for selection and breeding of superior artemisinin containing lines.