(-)-ß-Homoarginine anhydride, a new antioxidant and tyrosinase inhibitor, and further active components from Trichosanthes truncata.

One new amino acid derivative, (-)-ß-homoarginine anhydride 1, as well as nine known compounds were isolated from Trichosanthes truncata. The structures of the isolates were elucidated by spectroscopic methods. Among them, compounds 5 and 11 could notably dose-dependently inhibit ROS productions in HaCaT keratinocyte cells without cytotoxicity in the concentration range of 0.2-20 µM. In cell-free mushroom tyrosinase assay, compounds 1-5, 10 and 11 had more potential anti-tyrosinase activities with IC50 values of 106.9-255.6 µM than arbutin that were similar to predicted values of binding affinity calculated by molecule docking. The most active 2 had hydrogen bonds (Ser77, Glu309, Phe454) and electrostatic charges (Glu309, Glu248) interactions with mushroom tyrosinase, respectively. Our data manifested that T. truncata and its components are potentially to be developed as anti-aging and whitening agents for skin disorders.

Prevalence and Persistence of Listeria monocytogenes in Ready-to-Eat Tilapia Sashimi Processing Plants.

A 2-year study was performed at two ready-to-eat tilapia sashimi processing plants (A and B) to identify possible routes of contamination with Listeria monocytogenes during processing. Samples were collected from the aquaculture environments, transportation tanks, processing plants, and final products. Seventy-nine L. monocytogenes isolates were found in the processing environments and final products; 3.96% (50 of 1,264 samples) and 3.86% (29 of 752 samples) of the samples from plants A and B, respectively, were positive for L. monocytogenes . No L. monocytogenes was detected in the aquaculture environments or transportation tanks. The predominant L. monocytogenes serotypes were 1/2b (55.70%) and 4b (37.97%); serotypes 3b and 4e were detected at much lower percentages. At both plants, most processing sections were contaminated with L. monocytogenes before the start of processing, which indicated that the cleaning and sanitizing methods did not achieve adequate pathogen removal. Eleven seropulsotypes were revealed by pulsed-field gel electrophoresis and serotyping. Analysis of seropulsotype distribution revealed that the contamination was disseminated by the processing work; the same seropulsotypes were repeatedly found along the work flow line and in the final products. Specific seropulsotypes were persistently found during different sampling periods, which suggests that the sanitation procedures or equipment used at these plants were inadequate. Plant staff should improve the sanitation procedures and equipment to reduce the risk of L. monocytogenes cross-contamination and ensure the safety of ready-to-eat tilapia products.