From Kitchen Spice to Lab Bench Screening of Antibacterial Properties of Parmotrema parlatum on Shigella spp. and Molecular Docking of the Lysates with Pathogenic Strains

Medicinal plants are known to produce a wide array of secondary metabolites, many of which possess potent antimicrobial properties. Continuous research into new plant species expands the potential for discovering novel therapeutic agents. This study focuses on Parmotrema perlatum, a foliose lichen traditionally used as a spice (known as Kalpasi), to explore its antiparasitic potential. Three protozoan pathogens—Plasmodium falciparum, Toxoplasma gondii, and Entamoeba histolytica—remain major global health threats. P. falciparum, the causative agent of malaria, has claimed countless lives across human history. It is transmitted by the female Anopheles mosquito and causes recurring cycles of fever, chills, and anemia by attacking red blood cells. T. gondii, primarily hosted in cats, infects humans via contaminated food or water, often lying dormant in the brain and muscles. While asymptomatic in healthy individuals, it poses serious risks to fetuses and immunocompromised patients. E. histolytica spreads via contaminated food or water, invades the intestinal wall, and causes severe gastrointestinal complications such as dysentery and liver abscesses. To address the growing resistance to conventional drugs, this research investigates phytochemicals derived from P. perlatum as potential antiparasitic agents. The powdered form of the plant was subjected to Gas Chromatography-Mass Spectrometry (GC-MS) analysis to identify its active compounds. Two phytochemicals—Thujopsene and Resibufogenin—were selected based on their potential bioactivity.Before targeting the protozoan pathogens, these compounds were initially evaluated against Shigella flexneri using both bioinformatics (molecular docking) and in vitro antibacterial assays. Key proteins from each pathogen were selected based on structural relevance and docking compatibility.The primary goal of this study is to assess whether the identified compounds from P. perlatum can serve as effective drug candidates against parasitic infections, offering a natural alternative to synthetic drugs in the fight against endemic protozoan disease.