ANTIMICROBIAL ACTIVITY OF WARBURGIA UGANDENSIS, EUCLEA DIVINORUM, RHUS VULGARIS, OCIMUM GRATISSIMUM AND CLAUSENA ANISATA AGAINST ORAL PATHOGENIC MICROORGANISMS

Abstract

Oral infections are the most prevalent diseases in man. Oral microbiota, which cause oral diseases, have developed resistance against some antibacterial agents such as metronidazole, tetracycline, erythromycin, cephalosporin and penicillin. Adverse side effects such as toxicity, teeth staining, diarrhea and vomiting have resulted from the use of some of these antimicrobials. Medicinal plants have been found to be effective against bacterial, fungal and viral pathogens. This study was conducted to determine the effect of plant extracts against selected oral pathogenic microorganisms, cells and animal models. Methanol extracts were screened for major classes of compounds known to be bioactive. The methanol, MeOH:DCM and aqueous extracts from Warburgia ugandensis, Euclea divinorum, Rhus vulgaris, Ocimum gratissimum and Clausena anisata were tested for any inhibitory and bactericidal effects against Methicillin Resistant S. aureus (MRSA), Staphylococcus aureus, Streptococcus mutans and Candida albicans. Cytotoxicity of the active extracts was determined using Vero cells while in vivo safety was evaluated using mice and rats. Out of 24 extracts, methanol extracts of C. anisata (stem bark) and R. vulgaris (stem bark) showed significant antimicrobial activity (13.00±0.00mm and 12.00±0.00 mm with a p-value of <0.05; MIC values of 0.055 mg/ml and 0.391 mg/ml; MBC values of 0.781 mg/ml and 1.563 mg/ml respectively, against MRSA). R. vulgaris extracts showed no cytotoxicity at the highest tested concentrations. C. anisata had an IC50 value of 114.6 µg/ml. In acute dermal irritation testing, C. anisata (stem bark) methanol extract resulted in no significant skin reactions while R. vulgaris methanol extract resulted in moderate erythema and flaking of the skin, all of which cleared within 8 days. There were no observable adverse effects from oral administration of the extracts (acute oral toxicity testing) for all the doses tested. Based on the results obtained in this study, the antimicrobial potential demonstrated by methanol extracts of C. anisata and R. vulgaris supports their traditional use in the maintenance of oral hygiene. However, the cytotoxicity demonstrated by methanol extracts of C. anisata and R. vulgaris as well as the mild irritation caused by R. vulgaris needs further study before C. anisata and R. vulgaris can be recommended for treatment of oral/dermal diseases.