Browsing by Author "Asma Benafri"

The Malaysian medicinal plants are used in the society for traditional medicine. They have shown a good effect to cure some diseases. Nowadays, more researches are focusing on natural products such as plants to find new antimicrobial agents, to overcome the problem of bacterial resistance. Hence, the aim of this study is to investigate for antibacterial activity of different extracts obtained from selected medicinal plants and to analyze the presence of antibacterial peptides in the active extracts. Four promising plants, Eurycoma longifolia, Labisia pumila (var. alata), Annona muricata and Annona squamosa have been selected based on their ethnomedicinal use to conduct this research. A broad range of methods and protocols were applied through experimental work. Leaves stems and roots of the plants chosen were screened for antibacterial activity using several solvents and buffers, with different concentrations ranging from 10 w/v to 100 w/v. The antibacterial activity was evaluated based on the diameter of inhibition zone by using agar well diffusion assay. Most of the extracts of selected plants prepared in ethanol, methanol and acetone exhibited antibacterial activity against both groups of bacteria Gram positive and Gram negative. Whereas only three aqueous extracts, E. longifolia leaves, Labisia pumila leaves and stems were active against B.subtilis, P. aeruginosa and M. luteus. The range of diameter of inhibition zone of the active extracts screened is from 8mm to 25mm. All the extracts were concentrated and re-suspended in phosphate buffer, then tested again for antibacterial activity. Only, the active aqueous extracts were fractionated by size exclusion chromatography using Sephadex G50. The eluted fractions were tested for antibacterial activity and then analyzed by their loading in 15% SDS -PAGE and stained by silver nitrate to visualize the quality of the peptides purified. The molecular weight of purified antibacterial peptide in E. longifolia and L. pumila aqueous leaves extract was estimated to be approximately 10.6 KDa and 9.9 KDa respectively. In conclusions, Eurycoma longifolia and Labisia pumila may contain antibacterial peptides which will be more purified, tested again for antibacterial activity, sequenced and commercialized in the future.