Antibacterial Activity and Toxicity Study of Selected Piper Leave Extracts Against the Fish Pathogen ( Aeromonas hydrophila )

Abstract

The extensive use of antibiotics in aquaculture has resulted in the emergence of bacterial resistance strains. The medicinal importance of the herb such as Piper betle, Piper sarmentosum, and Piper nigrum evidently proved as one of the most promising commercial botanicals with earlier reported to possess a lot of therapeutic values. Thus, this present study was conducted to evaluate the antibacterial activity of crude aqueous extracts from these three local Piper extracted using the decoction method. The bioassays involved disc diffusion and resazurin microdilution assays against aquacultural pathogenic strain; Aeromonas hydrophila ATCC49140. Further minimum bactericidal concentration (MBC) also was determined. Piper nigrum crude aqueous extract showed the largest inhibition zone (12.71±2.14 mm), followed by P. betle crude aqueous extract (11.79±1.36 mm) and P. sarmentosum (7.33±0.81 mm). The lowest values for minimum inhibitory concentration (MIC) were obtained from P. sarmentosum and P. nigrum crude aqueous extract with the same concentration of 12.5 mg•mL-1 and the lowest MBC was obtained from P. betle crude aqueous extract (50 mg•mL-1). In the brine shrimp assay, all crude aqueous Piper extracts of the study demonstrated no toxicity levels. The findings suggested that these three crude aqueous Piper extracts prepared by decoction have the potential to prevent bacterial diseases, particularly in aquaculture. The extract preparation method is pursuing the green technic of plant extraction and is safer to be practiced.