Four new fatty acid derivatives from Diaporthe sp. T24, an endophytic fungus isolated from Ligularia fischer.

The endophytic fungus Diaporthe sp. is known to contain many secondary metabolites, but fatty acid derivatives have rarely been found. In this study, four new fatty acid derivatives (1-4), together with four known compounds (5-8), were isolated from Diaporthe sp., which was obtained from the stem of Ligularia fischeri. The absolute configurations of the new compounds 1-4 were deduced based on spectroscopic technique and J-based coupling constant analysis. Moreover, compound 1 exhibited cytotoxic activities against HCT-8 and MCF-7 cancer cells, and compounds 3 and 4 showed modest selectivity for HCT-8 cells by MTT assay.

Theoretical studies on the effect of a bithiophene bridge with different substituent groups (R = H, CH3, OCH3 and CN) in donor-π-acceptor copolymers for organic solar cell applications.

An effective way to enhance the efficiency of bulk heterojunction (BHJ) solar cells is to insert suitable bridges (π) between donor units (D) and acceptor units (A) in D-π-A copolymers. This work is devoted to uncovering how the characteristics of a HT (the substituent groups via head- to-tail (HT) connection) bithiophene bridge with different substituent groups (R = H, CH3, OCH3 and CN) affect the ground state structure, electronic, optical and charge transport properties of D-π-A copolymers for improving the photovoltaic performance. Based on the D-π-A copolymer PPBzT(2)-CEHß (P1) with a HT bridge of 3,4'-diethylhexyl-2,2'-bithiophene (π1), we designed six new copolymers (P2-P6') by introducing six kinds of HT bridges. From the calculated results, the introduction of different substituent groups into the bithiophene-bridge can markedly affect the HOMO and LUMO levels, band gaps, light-absorbing efficiency and hole transport ability of the copolymers. In particular, the copolymer P6 combining the cyano and methoxyl groups into the bridge has remarkable electronic and optical properties and hole transport ability among all the copolymers P1-P6', and it can be a candidate for donor materials of organic solar cells. We hope that the present results could provide a theoretical guidance for designing efficient donors in organic solar cells.

SWATH label-free proteomics analyses revealed the roles of oxidative stress and antioxidant defensing system in sclerotia formation of Polyporus umbellatus.

Understanding the initiation and maturing mechanisms is important for rational manipulating sclerotia differentiation and growth from hypha of Polyporus umbellatus. Proteomes in P. umbellatus sclerotia and hyphae at initial, developmental and mature phases were studied. 1391 proteins were identified by nano-liquid chromatograph-mass spectrometry (LC-MS) in Data Dependant Acquisition mode, and 1234 proteins were quantified successfully by Sequential Window Acquisition of all THeoretical fragment ion spectra-MS (SWATH-MS) technology. There were 347 differentially expressed proteins (DEPs) in sclerotia at initial phase compared with those in hypha, and the DEP profiles were dynamically changing with sclerotia growth. Oxidative stress (OS) in sclerotia at initial phase was indicated by the repressed proteins of respiratory chain, tricarboxylic acid cycle and the activation of glycolysis/gluconeogenesis pathways were determined based on DEPs. The impact of glycolysis/gluconeogenesis on sclerotium induction was further verified by glycerol addition assays, in which 5% glycerol significantly increased sclerotial differentiation rate and biomass. It can be speculated that OS played essential roles in triggering sclerotia differentiation from hypha of P. umbellatus, whereas antioxidant activity associated with glycolysis is critical for sclerotia growth. These findings reveal a mechanism for sclerotial differentiation in P. umbellatus, which may also be applicable for other fungi.

Oxalic acid and sclerotial differentiation of Polyporus umbellatus.

The present investigation aimed to uncover the effects of exogenous oxalic acid during the sclerotial formation of Polyporus umbellatus, with an emphasis on determining the content of the endogenic oxalic acid in the fungus. To this end, the oxalic acid content of the vegetative mycelia, sclerotia, culture mediums and sclerotial exudate were measured using High Performance Liquid Chromatography (HPLC). Furthermore, the lipid peroxidation was estimated by detecting thiobarbituric bituric acid reactive substances (TBARS). The results showed that the exogenous oxalic acid caused a delay in sclerotial differentiation (of up to 9 or more days), suppressed the sclerotial biomass and decreased the lipid peroxidation significantly in a concentration-dependent manner. Oxalic acid was found at very low levels in the mycelia and the maltose medium, whereas it was found at high levels in the mycelia and sucrose medium. After sclerotial differentiation, oxalic acid accumulated at high levels in both the sclerotia and the sclerotial exudate. Oxalic acid was therefore found to inhibit P. umbellatus sclerotial formation.