In Vitro Anti-Leptospiral Activity of Phyllanthus amarus Extracts and Their Combinations with Antibiotics

Abstract

Despite modern medicine, there is an increasing trend for cases of the bacterial infection leptospirosis, and this has led to the exploration of alternative medicines from various sources including plants. The aim of this study was to investigate the in vitro anti-leptospiral activity of Phyllanthus amarus extracts alone and combined with penicillin G, ceftriaxone, and doxycycline. Antimicrobial susceptibility testing was performed using the microdilution broth technique upon methanol extract (ME), aqueous extract (AE), and antibiotics against the Leptospira interrogans serovars Australis, Bataviae, Canicola, and Javanica, to determine minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs). The results were analyzed using an ELISA microplate reader combined with microscopic analysis. Synergy testing using a checkerboard assay was performed to determine the fractional inhibitory concentration index values of extracts combined with antibiotics against leptospires. Scanning electron microscopy (SEM) was used to investigate morphological changes of leptospires caused by potential anti-leptospiral agents alone and combined with antibiotics. The MICs and MBCs for P. amarus extracts ranged from 100 to 400 µg/mL for AEs and from 400 to 800 µg/mL for MEs. Penicillin G was the most effective anti-leptospiral drug, with MICs and MBCs ranging from <0.01 to 0.78 and <0.01 to 3.13 µg/mL, respectively, followed by ceftriaxone, with both MICs and MBCs ranging from 0.05 to 0.78 µg/mL, and doxycycline, with MICs and MBCs ranging from 0.39 to 3.13 µg/mL and 12.5 to 25 µg/mL, respectively. Combinations of P. amarus extracts and antibiotics did not show synergistic effects on all tested Leptospira serovars, with some combinations demonstrating antagonistic effects. SEM analysis, however, showed distorted Leptospira surfaces. P. amarus AE performed better anti-leptospiral activity than P. amarus ME. The morphological effects of P. amarus extract alone and its combination with antibiotic on Leptospira cells revealed promising anti-leptospiral properties.

Evaluating the Antimicrobial and Anti-Hemolytic Activity of Synthesized Pseudopeptide against Leptospiral Species: In Silico and In Vitro Approach

“…It is a default process to identify and analyze docking introduction in drug discovery and forms the basis for the design and analysis of novel drugs against a specific target protein [ 36 ]. Several studies have reported the use of molecular docking to understand the probable mechanism of action for various drugs, including antimicrobial agents [ 37 ]. The degree of protein–ligand complex interaction is commonly referred to as the binding affinity in molecular docking investigations.…”

Effect of bacteriophages and chamber bitter (Phyllanthus amarus) in combination on Vibrio parahaemolyticus

“…In recent years, there have been a number of studies using phages in the prevention and treatment of plant and animal diseases [2][3][4]. Besides, there are also many studies on plant extracts with high antimicrobial efficiency [5], especially Phyllanthus amarus [6,7]. Bacteriophages and P. amarus are considered potential biological agents in the treatment of bacterial diseases in aquatic animals.…”