Exploring the Potential of <i>Amaranthus tricolor</i> (L.) in Combating Multidrug-resistant Uropathogens

Background: Urinary Tract Infections (UTIs) rank among the most frequently occurring bacterial infections and can impact people of all ages and genders. Multidrug Resistance (MDR) among uropathogens has emerged as a global health crisis. The World Health Organisation (WHO) states that Antimicrobial Resistance (AMR) poses a serious threat to the successful treatment of infections, leading to increased mortality and healthcare expenditures. Aim: This study investigates the antibacterial potential of Amaranthus tricolor (L.) leaves phytoconstituents against multidrug-resistant uropathogens. Method: The methanolic leaf extract of the plant (ATME) was prepared by a cold maceration process and subsequently screened for phytoconstituents. The ATME extract was partitioned using an equal volume of chloroform and water. Upon evaporation and purification with acetonitrile, the aqueous fraction yielded a colourless compound, designated as SOWIS-P. Meanwhile, the chloroform fraction underwent further partitioning using N-hexane: ethyl acetate (6:4 v/v) as the mobile phase, guided by HPTLC analysis. Bio-autography identified the third fraction as the most significant, and it was labelled as SOWIS-III. The antibiotic resistance profile of pathogens isolated from urine samples was evaluated using the Resazurin Microtiter Plate Assay (REMA). Results: The structural analysis of the isolated compound SOWIS-III revealed it to be a flavonol glycoside, 24-methylene cycloartanol, while SOWIS-P was identified as a gallic acid derivative, methyl 3,4,5-trihydroxybenzoate. The isolated pathogens exhibited substantial resistance to ampicillin (81.4%), moderate resistance to azithromycin and doxycycline (74.6%) as well as nitrofurantoin (74.4%), and lower resistance to gentamicin (67.7%). Major Findings: The compounds demonstrated potent broad-spectrum antibacterial activity, effectively inhibiting the tested multidrug-resistant UTI pathogens at concentrations ranging from 6.25 μg/ml to 12.5 μg/ml.