Phytochemical screening and antimicrobial activity of pineapple (Ananas comosus) crown leaf extracts

Abstract

This study aimed to determine the phytochemicals present in the methanolic, ethanolic, and aqueous extracts of pineapple crown leaves and test their antimicrobial activities against Escherichia coli (BIOTECH 1634), Bacillus subtilis (BIOTECH 1573),and Candida albicans (ATCC 14053). Determination of the minimum inhibitory concentrations (MICs) through broth dilution method revealed no inhibitory effects by all the extracts. Zones of inhibition (ZOIs) were also not observed for all the extracts in the agar well diffusion method. Inactivity could be explained by the limited types of phytochemicals extracted; only flavonoids (ethanolic and methanolic extracts) and carbohydrates (methanolic, ethanolic, and aqueous extracts) were detected. Carbohydrates could promote microbial growth instead; flavonoids on the other hand, are proved to have an antimicrobial property, but perhaps the amount of flavonoids extracted were not enough to elicit the effect. Also, the protease bromelain, could have degraded during the drying process. If further pineapple leaves antimicrobial studies would be conducted, the researchers recommend using fresh, non-dried leaves to avoid bromelain degradation, or utilizing specifically the leaves’ fibers alone with acetone as solvent. Plate counting could be performed to check partial inhibition of microbial growth. Researchers also recommend studying and verifying other possible uses of pineapple crown leaves according to folkloric medicine. Identifying the specific types of flavonoids and carbohydrates present in the crown leaves is also suggested.