Cryptotanshinone (CT), a major tanshinone of medicinal plant Salvia miltiorrhiza Bunge, demonstrated effective in vitro antibacterial activity against all oral bacteria tested in this experiment. The antibacterial act...Cryptotanshinone (CT), a major tanshinone of medicinal plant Salvia miltiorrhiza Bunge, demonstrated effective in vitro antibacterial activity against all oral bacteria tested in this experiment. The antibacterial activities of CT against oral bacteria were assessed using the checkerboard and time-kill methods to evaluate the synergistic effects of treatment with ampicillin or gentamicin. The CT was determined against oral pathogenic bacteria with MIC and MBC values ranging from 0.5 to 16 and 1 to 64 μg/mL;for am- picillin from 0.0313 to 16 and 0.125 to 32 μg/mL;for gentamicin from 2 to 256 and 4 to 512 μg/mL respectively. The range of MIC50 and MIC90 were 0.0625 - 8 μg/mL and 1 - 64 μg/mL, respectively. The combination effects of CT with antibiotics were synergistic (FIC index < 0.5) against tested oral bacteria except additive, Streptococcus sobrinus, S. criceti, and Actinobacillus actinomycetemcomitans (FIC index < 0.75 - 1.0). The MBCs were shown reducing ≥4 - 8-fold, indicating a synergistic effect as defined by a FBCI of ≤0.5. Furthermore, a time-kill study showed that the growth of the tested bacteria was completely attenuated after 3 - 6 h of treatment with the 1/2 MIC of CT, regardless of whether it was administered alone or with ampicillin or gentamicin. The results suggest that CT could be employed as a natural antibacterial agent against cariogenic and periodontopathogenic bac- teria.展开更多
OBJECTIVE To evaluate the synergistic effect of rosmarinic acid(RA)with antibiotics against Staphylococcus aureus(S.aureus)and MRSA and to identify the possible mechanism of action responsible for synergism if any.MET...OBJECTIVE To evaluate the synergistic effect of rosmarinic acid(RA)with antibiotics against Staphylococcus aureus(S.aureus)and MRSA and to identify the possible mechanism of action responsible for synergism if any.METHODS The antibacterial activity of Rosmarinic acid was studied for its zone of inhibition by agar well diffusion and MIC determination by liquid broth dilution technique against MRSA and VRSA.The synergistic effect of RA with antibiotics like amoxicillin,ofloxacin and vancomycin was evaluated by Broth checker board method and further confirmed with time kill kinetic studies.Microbial Surface Components Recognizing Adhesive Matrix Molecules(MSCRAMMs)were isolated by protein precipitation technique and its expression was studied by SDS PAGE.Further RA was evaluated for its beta lactamase inhibition property.RESULTS Rosmarinic acid exhibited antibacterial activity against S.aureus and MRSAby showing a MIC value of 0.8mg·mL-1 against S.aureus and 10mg·mL-1 against MRSA.Rosmarinic acid at 1/4X MIC value reduced the MIC of vancomycin,amoxicillin and ofloxacin by 1/4 times against S.aureus.But against MRSA,vancomycin was found to be synergistic.All the synergistic combinations have shown FIC value of 0.5.In order to measure the kinetics of the anti-bacterial activity,the bacterial growth rate with RA,antibiotics and synergistic combinations against S.aureus and MRSA was studied.It is observed that the synergistic combinations showed better time kill kinetics as compared to RA and antibiotics.Further RA could able to destruct the cell surface proteins MSCRAMMs which was studied by SDS PAGE.RA was also found to showβlactamase inhibiting property.CONCLUSION It is concluded that RA possess antibacterial activity but at a very higher concentration(in mg/mL)against S.aureus and MRSA.However it shows synergism with antibiotics and could able to reduce the MIC of antibiotics.Thus RA could be developed as an adjuvant for antibiotics against S.aureus and MRSA caused infections.Further studies are needed to identify the mechanism for its synergism with antibiotics.展开更多
文摘Cryptotanshinone (CT), a major tanshinone of medicinal plant Salvia miltiorrhiza Bunge, demonstrated effective in vitro antibacterial activity against all oral bacteria tested in this experiment. The antibacterial activities of CT against oral bacteria were assessed using the checkerboard and time-kill methods to evaluate the synergistic effects of treatment with ampicillin or gentamicin. The CT was determined against oral pathogenic bacteria with MIC and MBC values ranging from 0.5 to 16 and 1 to 64 μg/mL;for am- picillin from 0.0313 to 16 and 0.125 to 32 μg/mL;for gentamicin from 2 to 256 and 4 to 512 μg/mL respectively. The range of MIC50 and MIC90 were 0.0625 - 8 μg/mL and 1 - 64 μg/mL, respectively. The combination effects of CT with antibiotics were synergistic (FIC index < 0.5) against tested oral bacteria except additive, Streptococcus sobrinus, S. criceti, and Actinobacillus actinomycetemcomitans (FIC index < 0.75 - 1.0). The MBCs were shown reducing ≥4 - 8-fold, indicating a synergistic effect as defined by a FBCI of ≤0.5. Furthermore, a time-kill study showed that the growth of the tested bacteria was completely attenuated after 3 - 6 h of treatment with the 1/2 MIC of CT, regardless of whether it was administered alone or with ampicillin or gentamicin. The results suggest that CT could be employed as a natural antibacterial agent against cariogenic and periodontopathogenic bac- teria.
基金The project supported by TEQIP PhaseⅡgrant under Anna University BIT campus,Tiruchirappalli-620024,Tamilnadu,India
文摘OBJECTIVE To evaluate the synergistic effect of rosmarinic acid(RA)with antibiotics against Staphylococcus aureus(S.aureus)and MRSA and to identify the possible mechanism of action responsible for synergism if any.METHODS The antibacterial activity of Rosmarinic acid was studied for its zone of inhibition by agar well diffusion and MIC determination by liquid broth dilution technique against MRSA and VRSA.The synergistic effect of RA with antibiotics like amoxicillin,ofloxacin and vancomycin was evaluated by Broth checker board method and further confirmed with time kill kinetic studies.Microbial Surface Components Recognizing Adhesive Matrix Molecules(MSCRAMMs)were isolated by protein precipitation technique and its expression was studied by SDS PAGE.Further RA was evaluated for its beta lactamase inhibition property.RESULTS Rosmarinic acid exhibited antibacterial activity against S.aureus and MRSAby showing a MIC value of 0.8mg·mL-1 against S.aureus and 10mg·mL-1 against MRSA.Rosmarinic acid at 1/4X MIC value reduced the MIC of vancomycin,amoxicillin and ofloxacin by 1/4 times against S.aureus.But against MRSA,vancomycin was found to be synergistic.All the synergistic combinations have shown FIC value of 0.5.In order to measure the kinetics of the anti-bacterial activity,the bacterial growth rate with RA,antibiotics and synergistic combinations against S.aureus and MRSA was studied.It is observed that the synergistic combinations showed better time kill kinetics as compared to RA and antibiotics.Further RA could able to destruct the cell surface proteins MSCRAMMs which was studied by SDS PAGE.RA was also found to showβlactamase inhibiting property.CONCLUSION It is concluded that RA possess antibacterial activity but at a very higher concentration(in mg/mL)against S.aureus and MRSA.However it shows synergism with antibiotics and could able to reduce the MIC of antibiotics.Thus RA could be developed as an adjuvant for antibiotics against S.aureus and MRSA caused infections.Further studies are needed to identify the mechanism for its synergism with antibiotics.
