Characterization of Anti-Salmonella typhi Compounds from Medicinal Mushroom Extracts from Zimbabwe

Antibiotic resistance has become a global concern and threatens the clinical efficacy of many drugs, leading to increased screening of several sources of potential antimicrobial substances. Mushrooms have long been recognized as a valuable source of nutritive and pharmacologically active compounds. Our previous studies showed that the acetone, ethanol, methanol, and cold water crude extracts of various mushrooms-Amanita and Cantharellus species, Ganoderma lucidum, and Lactarius kabansus-exhibited high antibacterial activity against Salmonella typhi. The objective of this study was to isolate, characterize, and identify antibacterial compounds from these crude mushroom extracts. The crude extracts were separated by preparative thin-layer chromatography. Fractions (n = 99) were obtained and screened for antimicrobial activity against S. typhi by using the MTT assay. Of the isolated components, 13 exhibited high inhibitory activity against the growth of S. typhi, with half-maximal inhibitory concentrations ranging from 206 to 619 µg/mL. Some of the highly potent antibacterial compounds were identified by using liquid chromatography-mass spectrometry. Terpenoids (lucidenic acid M and cavipetin D), a phospholipid (C16 sphinganine), and fatty acid amines (stearamide and palmitic amide) were some of the compounds found to be responsible for the antibacterial activity observed. The importance of local mushrooms as sources of antibacterial compounds was revealed. The high inhibitory activity of some mushroom extracts strongly suggests that the mushrooms contain compounds that have great potential for use in developing therapeutic agents against infections caused by S. typhi.