Natural products are an important source of antibacterial agents. Canthin-6-one alkaloids have displayed potential antibacterial activity based on our previous work. In order to improve the activity, twenty-two new 3-N-benzylated 10-methoxy canthin-6-ones were designed and synthesized through quaternization reaction. The in vitro antibacterial activity against three bacteria was evaluated by double dilution method. Four compounds (6f, 6i, 6p and 6t) displayed 2-fold superiority (minimum inhibitory concentration (MIC) = 3.91 µg/mL) against agricultural pathogenic bacteria R. solanacearum and P. syringae than agrochemical propineb. Moreover, the structure–activity relationships (SARs) were also carefully summarized in order to guide the development of antibacterial canthin-6-one agents.

In this study, an extracellular metalloprotease from Pseudoalteromonas sp. H2 was purified and identified. The EH2 maintained more than 80% activity over a wide pH range of 5-10 and the stability was also nearly independent of pH. More than 65% of activity was detected in a wide temperature of 20-70℃. The high stability of the protease in presence of different surfactants and oxidizing agent was also observed. Moreover, we also investigated the antioxidant activities of the hydrolysates generated from porcine and salmon skins collagen by EH2. The results show that salmon skins collagen hydrolysates demonstrated higher DPPH (42.88%±1.85) and hydroxyl radical (61.83%±3.05) scavenging activity compared to those produced with porcine skins collagen. For oxygen radical absorbance capacity, the hydrolysates from porcine skins collagen had higher efficiency (7.72±0.13 μmol·TE/μmol). Even 1 nM mixed peptides can effectively reduce the levels of intracellular ROS. And the two type of substrates exerted the best antioxidant activity when hydrolyzed for 3 hours. Hydrolysis time and type of substrate exerted important effect on the antioxidant property of hydrolysates. This study may have implications for the potential application of marine protease in biocatalysis industry. In addition, the hydrolyzed peptides from meat waste containing beneficial collagen by protease have good antioxidant activity indicating it may be a potential additive in the food processing industry and cosmetics industry.

Increasing rates of infection by antibiotic resistant bacteria have led to a resurgence of interest in bacteriophage (phage) therapy. Several phage therapy studies in animals and humans have been completed over the last two decades. We conducted a systematic review of safety and toxicity data associated with phage therapy in both animals and humans reported in English-language publications from 2008 – 2021. Overall, 69 publications met our eligibility criteria including 20 animal studies, 35 clinical case reports or case series, and 14 clinical trials. After summarizing safety and toxicity data from these publications, we discuss potential approaches to optimizing safety and toxicity monitoring with the therapeutic use of phage moving forward. In our systematic review of the literature, we found few, but no serious, adverse events associated with phage therapy. Comprehensive and standardized reporting of potential toxicities associated with phage therapy has generally been lacking in the published literature. Structured safety and tolerability endpoints are necessary when phages are administered as anti-infective therapeutics.