Antimicrobial properties of green tea catechins.

Extracts of leaves from the tea plant Camellia sinensis contain polyphenolic components with activity against a wide spectrum of microbes. Studies conducted over the last 20 years have shown that the green tea polyphenolic catechins, in particular (-)-epigallocatechin gallate (EGCg) and (-)-epicatechin gallate (ECg), can inhibit the growth of a wide range of Gram-positive and Gram-negative bacterial species with moderate potency. Evidence is emerging that these molecules may be useful in the control of common oral infections, such as dental caries and periodontal disease.

Anti-Staphylococcus aureus activity and oxacillin resistance modulating capacity of 3-O-acyl-catechins.

Epicatechin gallate (ECg), a component of green tea with weak activity against Staphylococcus aureus, reduces oxacillin resistance in methicillin-resistant S. aureus at concentrations below the MIC. Because catechins bind to artificial lipid bilayers, we investigated whether the anti-staphylococcal activity of catechins could be improved by increasing their capacity to interact with the cytoplasmic membrane.

Modulation of beta-lactam resistance in Staphylococcus aureus by catechins and gallates.

Aqueous extracts of Japanese green tea (Camellia sinensis) are able to reverse beta-lactam resistance in methicillin-resistant Staphylococcus aureus (MRSA). We have attributed the capacity to reverse oxacillin resistance in the homogeneous PBP2a producer BB568 and in EMRSA-16 to (-)-epicatechin gallate (ECG) and (-)-catechin gallate (CG). Minimum inhibitory concentration (MIC) values for oxacillin were reduced from 256 and 512 to 1-4 mg/l, respectively, in the presence of these polyphenols.

Chemical and microbiologic aspects of penems, a distinct class of beta-lactams: focus on faropenem.

Many beta-lactam antimicrobials were developed between the 1960s and 1980s, with continuing development driven by the emergence of microbial resistance. Penems form a discrete class of beta-lactams that comprises structural hybrids of penicillins (penams) and cephalosporins (cephems). The chemistry and microbiology of the representative penems MEN 10700, ritipenem, CGP 31608, sulopenem, BRL 42715, and faropenem are reviewed.