Diterpenoids and Their Glycosides from the Stems of Tinospora crispa with Beta-Cell Protective Activity.

Seven previously undescribed diterpenoids, tinocrisposides A-D (1-4) and borapetic acids A (5), B (6), and C (7), together with 16 known compounds, were isolated from the stem of Tinospora crispa (Menispermaceae). The structures of the new isolates were elucidated by spectroscopic and chemical methods. The ß-cell protective effect of the tested compounds was examined on insulin-secreting BRIN-BD11 cells under dexamethasone treatment. Diterpene glycosides 12, 14-16, and 18 presented a substantial protective effect on BRIN-BD11 cells treated with dexamethasone in a dose-dependent manner. Compounds 4 and 17 with two sugar moieties exhibited clear protective effects on ß-cells.

Protective Effects of Pear Extract on Skin from In Vitro and In Vivo UVA-Induced Damage.

The ancient Chinese medical book "Compendium of Materia Medica" records that pears can relieve symptoms of respiratory-related diseases. Previous research has shown that pear Pyrus Pyrifolia (Burm.f.) Nakai has antioxidant and anti-inflammatory properties. However, the anti-inflammatory, antioxidant, and anti-photoaging protective effects of Pyrus pyrifolia (Burm.f.) Nakai seed components have not been studied. Ultraviolet light (UV) causes skin inflammation, damages the skin barrier, and is an important cause of skin photoaging. Therefore, UV light with a wavelength of 365 nm was used to irradiate HaCaT and mice. Western blot, real-time quantitative polymerase chain reaction, and fluorescence imaging system were used to explore its anti-UVA mechanism. Dialysis membrane and nuclear magnetic resonance were used for the chemical constituent analysis of pear seed water extract (PSWE). We found that PSWE can significantly reduce UVA-induced skin cell death and mitogen-activated protein kinase phosphorylation and can inhibit the mRNA expression of UVA-induced cytokines (including IL-1ß, IL-6, and TNF-α). In addition, PSWE can also reduce the generation of oxidative stress within skin cells. In vivo experimental studies found that PSWE pretreatment effectively reduced transepidermal water loss, inflammation, redness, and dryness in hairless mice. The molecular weight of the active part of pear water extract is approximately 384. Based on the above results, we first found that pear seeds can effectively inhibit oxidative stress and damage caused by UVA. It is a natural extract with antioxidant properties and anti-aging activity that protects skin cells and strengthens the skin barrier.

Structural insights into the substrate selectivity of α-oxoamine synthases from marine Vibrio sp. QWI-06.

Pyridoxal phosphate (PLP)-dependent α-oxoamine synthases are generally believed to be responsible for offloading and elongating polyketides or catalyzing the condensation of amino acids and acyl-CoA thioester substrates, such as serine into sphingolipids and cysteate into sulfonolipids. Previously, we discovered vitroprocines, which are tyrosine- and phenylalanine-polyketide derivatives, as potential new antibiotics from the genus Vibrio. Using bioinformatics analysis, we identified putative genes of PLP-dependent enzyme from marine Vibrio sp. QWI-06, implying a capability to produce amino-polyketide derivatives. One of these genes was cloned, and the recombinant protein, termed Vibrio sp. QWI-06 α-oxoamine synthases-1 (VsAOS1), was overexpressed for structural and biochemical characterization. The crystal structure of the dimeric VsAOS1 was determined at 1.8-Å resolution in the presence of L-glycine. The electron density map indicated a glycine molecule occupying the pyridoxal binding site in one monomer, suggesting a snapshot of the initiation process upon the loading of amino acid substrate. In mass spectrometry analysis, VsAOS1 strictly acted to condense L-glycine with C12 or C16 acyl-CoA, including unsaturated acyl analog. Furthermore, a single residue replacement of VsAOS1 (G243S) allowed the enzyme to generate sphingoid derivative when L-serine and lauroyl-CoA were used as substrates. Our data elucidate the mechanism of substrate binding and selectivity by the VsAOS1 and provide a thorough understanding of the molecular basis for the amino acid preference of AOS members.