Abstract

Leaf extracts of Senna italica, Ricinus communis, Lantana camara, Lippia javanicaand Ziziphus mucronata were screened for biological activity against bacteria which infect wounds. The leaves were extracted using different solvents of varying polarity (hexane, dichloromethane, acetone and methanol). Phytochemical analyses of the extracts were performed using thin layer chromatography (TLC). The extracts were loaded on TLC plates and developed in three solvent systems that isbenzene/ethanol/ammonium solution (BEA), chloroform/ethyl acetate/formic acid (CEF) and ethyl acetate/methanol/water (EMW). Antibacterial activity of the plants was evaluated using micro-dilution and bioautography methods. The test organisms used were Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus andEnterococcus faecalis. Acetone extracts were chosen for antioxidant activity. Methanol was the best extractant, followed by acetone and dichloromethane (DCM). Inthe phytochemical analysis, more compounds were observed on BEA, followed by EMW and CEF plates. Lantana camara had no activity against any of the bacteria used. P. aeruginosa was the most resistant bacterium with only two plants active against it. E. faecalis and E. coli were sensitive to the extracts. More antibacterial compounds were observed on BEA plates against all the test bacteria in bioautographic method. The R_f values calculated from bioautography indicated that the selected plants have different active compounds. The most active compounds were from S. italica and Z. mucronata. BEA and EMW plates had good antioxidant activity. No antioxidant activity was observed on the CEF plate. Most extracts were active against wound pathogens; their application on the wound area may prevent infection. Further studies are required to identify the active compounds in the plant extracts which showed significant anti-bacterial activities.

Key words: Thin layer chromatography (TLC), plant extract, bacteria.