ABSTRACT
Epigallocatechin gallate (EGCG) is the major polyphenolic compound of green tea. Polyphenolic compounds were extracted from the leaf of Camellia sinensis (Japanese green tea), and the minimum inhibitory concentration against canine oral bacteria was measured. Subsequently, we investigated the inhibitory effects of polyphenolic compounds and EGCG on the growth of canine oral bacteria. EGCG showed antimicrobial activity against a model bacterium, Streptococcus mutans. Our results indicate that EGCG can inhibit the growth and biofilm formation of S. mutans and that EGCG does not interact with streptococcal lipoteichoic acid (LTA). Furthermore, our findings suggest that EGCG interacts with other component(s) of the bacterial membrane aside from streptococcal LTA to inhibit biofilm formation and damage biofilms.
Subject(s)
Anti-Bacterial Agents/pharmacology , Camellia sinensis/chemistry , Catechin/pharmacology , Microbiota/drug effects , Mouth/microbiology , Plant Leaves/chemistry , Tea , Animals , Biofilms/drug effects , Catechin/analogs & derivatives , Dogs , Dose-Response Relationship, Drug , Microbial Sensitivity Tests , Streptococcus mutans/drug effects , Tea/chemistryABSTRACT
The cathelicidin family is one of the several families of antimicrobial peptides (AMPs). A bovine myeloid antimicrobial peptide (BMAP-28) belongs to this family. Recently, the emergence of drug-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) has become a big problem. AMPs are expected to be leading compounds of new antibiotics against drug-resistant bacteria. In this study, we focused on the activity of BMAP-28 against bacterial cell surfaces. First, we observed morphological change of MRSA caused by BMAP-28 using a scanning probe microscope. We also studied activities of BMAP-28 against adherence of S. aureus to fibronectin, collagen type I, collagen type IV. We confirmed whether BMAP-28 can bind to lipoteichoic acid (LTA) of S. aureus. BMAP-28 was indicated as damaging the cell surface of MRSA. In a particular range of concentrations, BMAP-28 promoted adherence of S. aureus against fibronectin and collagens. It was revealed that BMAP-28 and LTA of S. aureus bound with each other. Our study showed the potential of BMAP-28 which can damage MRSA and interact with LTA of S. aureus but promote its adherence in some concentrations. This study provides new points of which to take notice when we use AMPs as medicines.
Subject(s)
Bacterial Adhesion/drug effects , Methicillin-Resistant Staphylococcus aureus/drug effects , Proteins/pharmacology , Methicillin-Resistant Staphylococcus aureus/cytology , Microscopy, Electron, ScanningABSTRACT
A bovine myeloid antimicrobial peptide antimicrobial peptide (BMAP-28) is a member of the cathelicidin family and acts as a component of innate immunity. There are few reports of susceptibility difference of methicillin-resistant Staphylococcus aureus (MRSA) and susceptible strains (MSSA) against BMAP-28. This study aims to clarify how a few amino acid substitutions of BMAP-28 are related to its antimicrobial activity using four analog peptides of BMAP-28. We also compared cellular fatty acid components of MSSA and MRSA using gas chromatography. We found that a few amino acid substitutions of BMAP-28 do not change antimicrobial activity. It was also revealed that the percentage of cis-11-eicosenoic acid in total detected fatty acids of MRSA was significantly higher than that of MSSA. In addition, the percentage of palmitic acid in total detected fatty acids of MRSA tended to be lower than that of MSSA. Our results will provide new information to deal with the question of differences in bacterial susceptibility against BMAP-28.
Subject(s)
Anti-Bacterial Agents/pharmacology , Methicillin-Resistant Staphylococcus aureus/drug effects , Proteins/pharmacology , Staphylococcus aureus/drug effects , Amino Acid Substitution , Anti-Bacterial Agents/chemistry , Chromatography, Gas , Drug Resistance, Bacterial , Fatty Acids/metabolism , Fatty Acids, Monounsaturated/metabolism , Methicillin-Resistant Staphylococcus aureus/metabolism , Palmitic Acid/metabolism , Proteins/chemistry , Staphylococcus aureus/metabolism , Structure-Activity RelationshipABSTRACT
A bovine myeloid antimicrobial peptide (BMAP-28) is a member of the cathelicidin family which is included in the innate immune system of mammals. Recently, there have been many studies about antimicrobial peptides. This study aims to clarify whether BMAP-28 has bactericidal activity against methicillin-resistant Staphylococcus aureus (MRSA) and compares its activity against methicillin-susceptible S. aureus (MSSA) and MRSA. We found that the peptide was effective in killing MRSA (minimal inhibitory concentration (MIC) range; 5-20 µg/mL). It was also revealed that MSSA (MIC range; 1.25-20 µg/mL) had two levels of susceptibility to BMAP-28. We also examined the effect of BMAP-28 on bacterial shape to visually show its activity. After exposure to the peptide, both MSSA and MRSA cells showed the morphological changes on their surfaces. Our results indicate that BMAP-28 is a promising candidate for medicine against drug-resistant bacteria.
