Evaluation of the Medicinal Uses and Antimicrobial Activity of Piper guineense Schumach &Thonn

Piper guineense is a medicinal plant that has wide application in African traditional medicine where it is often used in the treatment of bacterial and fungal infections. It is an economic plant with numerous health benefits which is also consumed regularly as a functional food. The fruits, leaves and seeds are used as spices and flavouring agents in commercial food preparations in West Africa. The extracts are also used for the treatment of various diseases ranging from diarrhea, intestinal diseases, rheumatoid arthritis, bronchitis, cough, stomach ache, asthma to febrile convulsions, fever and mental disorders. There is also recent interest on the biological and pharmacological properties of its bioactive compounds such as piperine, the main alkaloid constituents of P. guineense which is responsible for its pungent aroma. Based on these numerous ethnobotanical, traditional and economic uses of this plant, it became interesting to evaluate the bioactive compounds present in the extracts and to further screen the extracts against some selected human pathogenic bacterial and fungal strains so as to ascertain the efficacy of the extracts and its compounds as potent antibacterial and antifungal lead compounds. Microbial resistance to the currently available antibiotics is a global problem that has resulted to a constant search for a new antimicrobial drug with strong efficacy and low cost. There is need to screen the extracts and bioactive compounds from P. guineense for possible lead compounds for antibacterial and antifungal drug discovery. In this study, first, a method was developed for the chemical profiling, qualitative and quantitative analysis of P. guineense extracts and a good mobile phase composition was developed for the high performance liquid chromatography (HPLC) and thin layer chromatographic (TLC) analysis of the extracts. The effect of the chamber type on the separation was also evaluated using unsaturated horizontal chamber in sandwich configuration, horizontal chamber in non-sandwich configuration and twin-trough vertical chamber. Furthermore, the in vitro antibacterial activity of the extracts were evaluated using 8 pathogenic Gram-positive and Gram-negative bacterial strains. An ethnobotanical survey was also conducted on the use of P. guineense extracts in the treatment of fungal infections in West African traditional medicine. The study area was chosen to be Imo state, South Eastern Nigeria were P. guineense is mostly used by traditional healers for the treatment of fungal infections which is often common among those suffering from HIV and AIDS. The aim of the survey was to document the various methods of preparations and administrations of these extracts for the treatment of fungal diseases. From this ethnobotanical approach, the leaves and fruits extracts of the plant was further tested against 5 fungal strains including Cryptococcus neoformans which causes meningitis in immunocompromised individuals. HPLC and TLC methods were developed for the analysis of P. guineense extracts with emphasis on the shortest analysis time and minimal solvent consumption, and the best mobile phase giving favourable resolution of bands was found to be toluene: ethyl acetate (PS 6-4 corresponding to 60:40 % v/v). The result of the TLC analysis showed that the developing chamber conditions does not affect the TLC separation efficacy in the analysis of P. guineense extracts. The extracts were active against the tested bacterial and fungal strains with minimum inhibitory concentration (MIC) values ranging from 19 to 2500 µg/mL