Characterization and purification via nucleic acid aptamers of a novel esterase from the metagenome of paper mill wastewater sediments.

A new esterase gene est906 was identified from paper mill wastewater sediments via a function-based metagenomic approach. The gene encoded a protein of 331 amino acids, that shared 86% homology with known esterases. Based on the results of multiple sequence alignment and phylogenetic analysis, it was confirmed that Est906 contained a characteristic hexapeptide motif (G-F-S-M-G-G), which classified it as a lipolytic enzyme family V protein. Est906 displayed the highest hydrolysis activity to ρ-nitrophenyl caproate (C6), and its optimal temperature and pH were 54 °C and 9.5, respectively. Additionally, this enzyme had good stability under strong alkaline conditions (pH 10.0-11.0) in addition to moderate heat resistance and good tolerance against several metal ions and organic solvents. Furthermore, a specific nucleic acid aptamer (Apt1) bound to Est906 was obtained after five rounds of magnetic bead SELEX screening. Apt1 displayed high specific recognition and capture ability to Est906. In conclusion, this study not only identified a new esterase of family V with potential industrial application by metagenomic technology but also provided a new method to purify recombinant esterases via nucleic acid aptamers, which will facilitate the isolation and purification of target proteins in the future.

A Novel Multifunctional Compound Camellikaempferoside B Decreases Aß Production, Interferes with Aß Aggregation, and Prohibits Aß-Mediated Neurotoxicity and Neuroinflammation.

Accumulating evidence suggested that soluble oligomeric ß-amyloid protein (Aß) exerts diverse roles in neuronal cell death, neuroinflammation, oxidative stress, and the eventual dementia associated with Alzheimer's disease (AD). Developing an agent with multiple properties may be a reasonable strategy for the treatment of AD. In this study, we isolated a novel multifunctional compound named camellikaempferoside B (YCF-2) from Fuzhuan brick tea. YCF-2 consists of kaempferol backbone, p-coumaric acid (p-CA) group, and a novel structure of rhamnopyranosyl group at the C-4' position, possessing the properties of both kaempferol and p-CA. YCF-2 significantly inhibited Aß production by decreasing ß-secretase activity. Moreover, YCF-2 suppressed Aß42 fibrillation and facilitated nontoxic oligomer formation by binding to Aß42 oligomers and by blocking the conformational transition to ß-sheet. Furthermore, YCF-2 ameliorated Aß-induced neuronal cell death, ROS production, inflammatory factor release, and microglia activation by blocking the NF-κB signaling pathway in microglia. These findings indicated that YCF-2 with a novel lead structure has potential applications for drug development for AD treatment.

A new anti-proliferative acylated flavonol glycoside from Fuzhuan brick-tea.

Fuzhuan brick-tea (FBT) is unique for a fungal fermentation stage in its manufacture process and is classified in dark tea. A new acylated flavonol glycoside, kaempferol 3-O-[E-p-coumaroyl-(→2)][α-l-arabinopyranosyl-(1→3)][α-l-rhamnopyranosyl(1→6)]-ß-d-glucopyranoside, which was trivially named as camellikaempferoside A (1), was isolated from FBT along with camelliquercetiside C (2). Their structures were unambiguously elucidated by combination of spectroscopic and chemical methods. Compound 1 showed anti-proliferative activity against MCF-7 and MDA-MB-231 cells with IC50 values of 7.83 and 19.16 µM, respectively.