Comparison of Antibacterial Activities of Selected Species of Zingiberaceae Family and Some Synthetic Compounds

This study describes the antibacterial activity of ginger (G), mangoginger (M) and turmeric (T) and mixtures thereof i.e.ginger and mangoginger (GM), ginger and turmeric (GT), turmeric and mangoginger (TM), and a mixture of peels (P) and 4 synthetic compounds (HC-1, HC-2, HC-3 and HC-4). Extracts of these compounds were studied on Escherichia coli, Bacillus subtilisand Staphylococcus aureus. Both aqueous (heated and unheated extracts) and organic solvents, 1, 4-Dioxan, N,N,dimethylformamide(DMF), were used for antibacterial assay. Growth inhibition was evaluated by the disc diffusion and agar ditch methods. The antibacterial activity of heated extracts was greater than that of the unheated extracts of all the 3 spices alone or mixtures thereofagainst all the 3 bacterial strains. When the organic acid extracts were studied, the antibacterial activity of 1, 4-Dioxan extracts ofT, GT and TM showed the highest activity against E. coli. The 1, 4-Dioxan and DMF extracts of M showed the highest activity againstB. subtilis. The antibacterial activity of G in 1, 4-Dioxan showed the highest activity against S. aureus. Extracts in DMF did not showany activity. The synthetic compounds in 1, 4-Dioxan showed better antimicrobial activity than did DMF extracts. In conclusion,amongst the studied members of Zingiberaceae mangoginger and mixtures containing mangoginger showed maximum antibacterial activity and the synthetic compound HC-3 showed antibacterial activity equivalent to that of mangoginger. Both natural and synthetic compounds extracted in 1, 4-Dioxan gave better results. Therefore, these 2 compounds can be used as lead molecules in drug designing.