Total Phenolic Content and Antioxidative Activity in Seasoning Protein Hydrolysate as Affected by Pasteurization and Storage

Protein hydrolysate prepared from fish and shrimp by-products were used to prepare a seasoning protein hydrolysate （SPH）. The effects of pasteurization and storage on total phenolic content （TPC）, DPPH radical scavenging activity, reducing power, and color of the SPH were investigated. Pasteurization at 90 ℃ for 10 minutes led to a reduction of TPC and DPPH radical scavenging activity and an increase of reducing power of solid fraction of SPH by about 30%, 99%, and 100%, respectively. Consequently it increased TPC DPPH radical scavenging activity, and reducing power of the liquid phase by about 32%, 600%, and 100%, respectively. Storage at 28, 35, or 45 ℃ for 12 weeks altered color values and increased brownness intensity （OD420）. The storage led to an apparent increase of the TPC and antioxidative activity of the product. The results indicate the possibility of producing healthy appetizers from protein hydrolysate prepared from by-products of the seafood industry.

Teasaponin induces reactive oxygen species-mediated mitochondrial dysfunction in Candida albicans

Candida albicans is the most prevalent commensal fungus and readily causes invasive fungal infection in immunocompromised individuals. Teasaponin(TS), a natural product generally regarded as safe, has been reported to inhibit filamentation of C. albicans. This study found that TS could exert moderate fungicidal activity against C. albicans, and the mode of action was further explored. The minimum fungicidal concentration(MFC) was determined by the broth microdilution method. The colony counting method was used to determine the time-killing curve of TS against C. albicans in every 2 h. The effect of TS on the content of intracellular reactive oxygen species(ROS) in C. albicans was analyzed by 2′,7′-dichlorofluorescin diacetate(DCFH-DA) staining, and the mitochondrial membrane potential(mtΔψ) was determined by rhodamine123(RH123) staining. An ATP assay kit was utilized to determine the intracellular ATP levels after TS treatment. Results showed that TS-induced ROS accumulation and mitochondrial dysfunction contributed to the death of C. albicans cells. Further research demonstrated that VC could reinforce the fungicidal ability of TS. On the contrary, VE could antagonize the function of TS against C. albicans, which might guide the clinical application of TS. The results preliminarily elucidated the potential mechanisms of TS against C. albicans and might provide a potential option for the treatment of clinical Candida.

Graphene oxide-Fe_3O_4 nanocomposites as high-performance antifungal agents against Plasmopara viticola

Plasmopam viticola, a causal agent of grapevine downy mildew, is a widely distributed pathogen, which can cause destructive disease in field-grown grapevines. Although fungicides are used to treat the disease, fungicide-resistant strains have been emerging. In this study, we developed graphene oxide （GO）-Fe3O4 nanocomposites, which could effectively repress the germination of sporangia and inhibit the development of downy mildew. 50 μg mL^-1 GO-Fe3O4 showed excellent protective and fungiddal activities. 250 μg mL^-1 GO-Fe3O4 on grapevine leaves in the field could significantly decrease the severity of downy mildew, suggesting its potent curative effect. Moreover, GO-Fe3O4 had no significant toxic effects on grapevine plants even at the concentration twice that of the highest dosage （1000 μg mL^-1） used in this study. Our work suggested that GO-Fe3O4 would offer an important opportunity to develop new approach for controlling plant diseases.