ABSTRACT
This study was aimed to assay the antibacterial activity of compounds from Rabdosia rubescens. Disc dif-fusion (K-B method) was used to screen the in vitro antibacterial activity. All kinds of chromatography were used to isolate the chemical constituent and structure was identified by MS and NMR spectroscopy. The results showed that six compounds were isolated and identified as oridonin (1), rosmarinic acid (2), caffeic acid (3), salicylic acid (4), ferulic acid (5), vanillic acid (6). Oridonin had activity against Staphylococcus aureus (SA), Methcillin-resistant Staphylococcus aureus (MRSA), β-lactamase positive Staphylococcus aureus (ESBLs-SA), and showed the highest ac-tivity (MIC is 3.125, 6.25 and 6.25 μg·disc-1, respectively), but was still weaker than that of berberine as positive control (MIC is 0.156 μg·disc-1). Ferulic acid had activity against SA and MRSA (MIC is 50 and 50 μg·disc-1, re-spectively). Salicylic acid had only activity against SA (MIC 50 μg·disc-1). It was concluded that oridonin, ferulic acid and salicylic acid were the main antibacterial activity compounds from R. rubescens.
ABSTRACT
OBJECTIVE: To study the antimicrobial activity and antibacterial mechanisms of cryptotanshinone against SA, MRSA and ESBLS-SA. METHODS: MIC value was determined by disc diffusion method. IC50 value was determined by liquid culture. The antibacterial mechanisms of cryptotanshinone were investigated by determining the changes in electric conductivity, concentration of AKP, protein content, and the changes of protein electrophoretic bands in SDS-PAGE. RESULTS: The antibacterial rings, MIC and IC50 values showed that the antimicrobial activity against SA was better than that against MRSA and ESBLs-SA. Treated with cryptotanshinone, the electric conductivity, concentration of AKP, and protein content were increased, and protein bands in SDS-PAGE were changed obviously. CONCLUSION: Cryptotanshinone significantly inhibits SA, MRSA and ESBLs-SA and can damage the structures of cell wall and cell membrane, which results in the increase of permeability of cell membrane and release of cell components. Cryptotanshinone can influence the synthesis of bacteria protein, destroy the protein or reject the anabolism or expression of the protein, and finally leads to the loss of normal physiological function of bacterium.