Metabolite Composition and Bioactivity of Murdannia loriformis against Marine Parasitic Leech and Vibrio Species

Abstract

Vibriosis and parasitic infestation pose significant challenges in aquaculture. The parasitic leech Pterobdella arugamensis harms fish and makes them more susceptible to Vibrio secondary infections. While toxic chemical treatments are commonly used, there is a growing demand for safer, eco-friendly alternatives. Consequently, research has increasingly focused on natural products derived from plants. In the current study, we investigated the anti-Vibrio and antiparasitic potentials of the aqueous extract of Murdannia loriformis (Hassk.) Rolla Rao et Kammathy, a medicinal plant belonging to the Commelinaceae family. The extract was tested against five Vibrio species and the parasitic leech P. arugamensis. Additionally, its metabolite composition was analysed using mass spectrometry techniques, including liquid chromatography quadrupole orbitrap mass spectrometry (LC-q-Orbitrap-MS). The extract of M.  loriformis exhibited bactericidal activities against Vibrio species at concentrations of 100 and 50 mg.mL^-1 with inhibition zones ranging from 7.33 ± 0.47 mm to 17.33 ± 0.45 mm, in a dose-dependent manner. The extract also demonstrated dose-dependent antiparasitic effects against P. arugamensis, with mortality time ranging from 10.37 ± 1.77 to 67.02 ± 5.38minutes at concentrations of 100 to 12.5 mg.mL^-1. The LC-q-Orbitrap-MS analysis detected 39 metabolites in both positive and negative modes, including numerous important metabolites such as orientin, corchorifatty acid F, pyridoxine, nicotinic acid, schaftoside, corymboside, vicenin-2, hexadecanamide, pinolenic acid, eleutherazine B, dimethylfraxetin, paprazine, and trigonelline. These findings highlight the significant anti-Vibrio and antiparasitic potential of M.  loriformis extract, making it a promising natural substitute for controlling Vibrio infections and parasitic leech infestations in aquaculture systems.