Antibacterial activity of several Indonesian plant extracts and combination of antibiotics with Syzygium malaccense extract as the most active substance

Abstract

Natural products have an important role in the development of drugs, especially as an antibacterial. Some plant extracts in Indonesia such as Syzygium (Myrtaceae) and Graptophyllum (Acanthaceae) have been used empirically for the treatment of non-infectious diseases, and are also for management infections such as throat, mouth and vaginal infections, dysentery and diarrhea. The objectives of this study are to investigate antibacterial activity of 11 extracts from ten plants which were used in traditional medicine in Indonesia to treat infection disease and to evaluate interaction between potential antibacterial extract and antibiotics. Antibacterial activity and combination extract with antibiotics were evaluated using agar diffusion method on Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. Among the ten plants, Syzygium malaccense leaves extract, and Nephelium lappaceum peel and leaves extracts showed significant antibacterial activity. They have antibacterial activity against Gram positive and Gram negative. S. malaccense extract had better antibacterial activity against P. aeruginosa compared to the other tested bacteria and provided better activity compared to N. lappaceum leaves extract. Phytochemical screening showed that S. malaccense leaves extract contained flavonoid, tannin, quinone, phenol and triterpenoid/steroid. The combination of S. malaccense extract with antibiotics showed that the usage of S. malaccense extract together with ciprofloxacin gave antagonistic result, so the usage of S. malaccense extract together with ciprofloxacin needs caution because it can reduce the effect of ciprofloxacin.