Abstract
Zeylanicobdella arugamensis (Hirudinea), a marine parasitic leech, not only resulted in the mortality of the host fish (Groupers) but also caused economic losses. The current study aimed to elucidate the antiparasitic efficacy of the aqueous extract of the Azadirachta indica leaves against Z. arugamensis and to profile the composition via LC-Q Exactive HF Orbitrap mass spectrometry. Different concentrations (25, 50 and 100 mg/mL) of A. indica extract were prepared and tested on the parasitic leeches. The total mortality of leeches was noticed with an exposure to the A. indica aqueous extract. The average times required for the aqueous extract at concentrations of 25, 50 and 100 mg/mL to kill the leeches were 42.65 ± 9.20, 11.69 ± 1.11 and 6.45 ± 0.45 min, respectively, in a dose-dependent manner. The Orbitrap mass spectrometry analysis indicated the presence of five flavonoids (myricetin 3-O-galactoside, trifolin, isorhamnetin, quercetin and kaempferol), four aromatics (4-methoxy benzaldehyde, scopoletin, indole-3-acrylic acid and 2,4-quinolinediol), three phenolics (p-coumaric acid, ferulic acid and phloretin) and two terpenoids (pulegone and caryophyllene oxide). Thus, our study indicates that A. indica aqueous extract is a good source of metabolites with the potential to act as a biocontrol agent against the marine parasitic leech in aquaculture.
Highlights
In Malaysia, parasitic infestation is a serious problem for different types of fish species, and several parasites have been reported to be reared in open floating net-cages [1,2,3]
It was proven that the application of various concentrations of A. indica aqueous extract indicated a strong antiparasitic activity with 100% mortality against the marine parasitic leech Z. arugamensis in an average time ranging from 6.45 to 42.65 min
The Q Exactive HF Orbitrap mass spectrometry analysis indicated the presence of five flavonoids, four aromatics (4-methoxy benzaldehyde, scopoletin, indole-3-acrylic acid and 2,4-quinolinediol), three phenolics (p-coumaric acid, ferulic acid and phloretin) and two terpenoids
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. In Malaysia, parasitic infestation is a serious problem for different types of fish species, and several parasites have been reported to be reared in open floating net-cages [1,2,3]. Aquacultured groupers showed a greater variety of parasites and higher intensities of infestation than wild groupers [2,4]. Some of the commonly found parasites in Malaysian cage aquacultures are monogeneans (Benedenia spp., Neobenedenia spp.), copepods (Caligus epidemicus, Caligus spp.) and piscicolids [1,3,4,5]
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