Chemical Constituents of Rabdosia Species and Their Antimicrobial and Antioxidant Activities in Extending Meat Shelf...

Food spoilage causes significant economic losses and poses severe risks to public health. Therefore, the development of effective antimicrobial agents, preservatives, and food additives is urgently required. The seedlings and tender leaves of Rabdosia species (locally called Xiang Cha Cai) are well-known vegetables in East Asia and have the effects of eliminating heat and dampness. In this study, we conducted a comprehensive analysis of 104 fractions from 13 Rabdosia species, isolating and characterizing seven bioactive constituents (SZ-05, BY-05, XY-01, XY-04, YH-02, GM-02, and XZ-05) and evaluating their antimicrobial activities. Through a bioactivity-guided principal component analysis (PCA), three bioactive compounds-oridonin, lasiokaurin, and abietic acid-were identified and characterized by examining the relationships between chemical compositions and their bioactivity. The antimicrobial minimum inhibitory concentrations (MIC) of the studied bioactive fractions and compounds ranged from 16 to 128 µg/mL. A synergistic effect (ε̃<-0.5; fractional inhibitory concentration index ≤0.5) was observed between oridonin and vitexin against vancomycin-resistant Enterococcus. The oridonin-vitexin combination removed the biofilm and caused changes in the surface structure of the bacteria. In addition, the bioactive Rabdosia irrorata fraction of 40% ethanol rinse macroporous resin (GM-02) exhibited both antioxidant and antimicrobial properties, which contributed to prolonging the shelf life of ready-to-eat food. Experimental results demonstrate that GM-02 has the potential to serve as a natural, non-toxic, and environmentally safe antimicrobial agent and food preservative. These findings may effectively help reduce the incidence of foodborne diseases and improve the stability of food storage.