In vitro antibacterial activity of pineapple peel extracts and chemical composition of dimethyl sulfoxide extract

In this study, ethanol, methanol, and dimethyl sulfoxide (DMSO) extracts were obtained from pineapple (Ananas comosus L.) peel by ultrasonication, and their antibacterial activity was evaluated in vitro using the agar well diffusion and microdilution methods. Pineapple peel extracts obtained by the agar well diffusion method did not form any inhibitory zones against the tested bacteria (Escherichia coli (ATCC 1301, ATCC 25922, ATCC 8739, and NRRL B-3704), Klebsiella pneumoniae ATCC 700603, Salmonella enterica subsp. enterica ATCC 13076, and Salmonella enterica subsp. typhimurium ATCC 51812, Pseudomonas aeruginosa (ATCC 10145 and ATCC 27853), Bacillus cereus, Bacillus subtilis, Enterococcus faecalis ATCC 29212, and Staphylococcus aureus ATCC 29213). Furthermore, MIC values were determined to be >125 µL/mL by microdilution. Moreover, the chemical composition of the DMSO extract from pineapple peel was determined by headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS), and the main component was identified as pinostrobin (44.66%), a flavanone. In conclusion, the extracts obtained from pineapple peel do not exhibit antibacterial activity, and the results are consistent with the chemical composition. This study demonstrates the importance of evaluating chemical composition together with in vitro biological activities in determining the biological potential of plant and food wastes