Oleanolic acid displayed anti-inflammatory activity in carrageenan and dextran-induced oedema in rats. It elicited marked anti-arthritic action in adjuvant-induced polyarthritis in rats and mice and in formaldehyde-induced arthritis in rats. Oleanolic acid checked the inflammation-induced increased serum transaminase levels. It reduced exudate volume and inhibited leucocyte infiltration in carrageenan-induced pleurisy in rats. It is devoid of any analgesic, antipyretic or ulcerogenic action. Oleanolic acid did not affect the parturition time in pregnant rats or castor oil-induced diarrhoea in rats. Oral LD50 was found to be greater than 2 g kg-1 in mice and rats.

Hydroxychavicol isolated from the chloroform extraction of aqueous extract of Piper betle leaves showed inhibitory activity against oral cavity pathogens. It exhibited an inhibitory effect on all of the oral cavity pathogens tested (MICs of 62.5 to 500 g/ml) with a minimal bactericidal concentration that was twofold greater than the inhibitory concentration. Hydroxychavicol exhibited concentration-dependent killing of Streptococcus mutans ATCC 25175 up to 4؋ MIC and also prevented the formation of water-insoluble glucan. Interestingly, hydroxychavicol exhibited an extended postantibiotic effect of 6 to 7 h and prevented the emergence of mutants of S. mutans ATCC 25175 and Actinomyces viscosus ATCC 15987 at 2؋ MIC. Furthermore, it also inhibited the growth of biofilms generated by S. mutans and A. viscosus and reduced the preformed biofilms by these bacteria. Increased uptake of propidium iodide by hydroxychavicol-treated cells of S. mutans and A. viscosus indicated that hydroxychavicol probably works through the disruption of the permeability barrier of microbial membrane structures. Hydroxychavicol also exhibited potent antioxidant and anti-inflammatory activities. This was evident from its concentration-dependent inhibition of lipid peroxidation and significant suppression of tumor necrosis factor alpha expression in human neutrophils. Its efficacy against adherent cells of S. mutans in water-insoluble glucan in the presence of sucrose suggests that hydroxychavicol would be a useful compound for the development of antibacterial agents against oral pathogens and that it has great potential for use in mouthwash for preventing and treating oral infections.Diverse microorganisms inhabit the human oral cavity, and there is always a risk of infection with bacterial pathogens associated with the oral cavity. Streptococcus constitutes 60 to 90% of the remaining bacteria that colonize the teeth within the first 4 h after professional cleaning (17). Other early colonizers include Actinomyces spp., Eikenella spp., Haemophilus spp., Prevotella spp., Propionibacterium spp., and Veillonella spp. Many of the physical interactions that occur between the organisms of this community are known. Streptococcus is the only genus of oral cavity bacteria that demonstrates extensive and intergenic coaggregation (12, 13). The ability of this genus to bind to other early colonizers and to host oral matrices may confer an opportunity to viridians streptococci in establishing early dental plaque (17). Streptococcus mutans can colonize the tooth surface and initiate plaque formation by its ability to synthesize extracellular polysaccharides, mainly water-insoluble glucan from sucrose, using its glucosyltransferase (11).The current research targeting microbial biofilm inhibition has attracted a great deal of attention, and the search for effective antimicrobial agents against these oral pathogens could lead to identification of new agents for the prevention of dental caries and periodontal diseases arising out of dental plaque formation (23...

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