Eco-friendly approach using marine actinobacteria and its compounds to control ticks and mosquitoes

Ticks and mosquitoes are ectoparasitic arthropods that can transmit a variety of diseases to humans and animals during blood feeding and causing serious infectious disorders. The purpose of the present study was to assess the acaricidal and insecticidal property of ethyl acetate extract and its compounds isolated from marine actinobacteria, Streptomyces VITSTK7 sp. against the larvae of cattle ticks, Haemaphysalis bispinosa and Rhipicephalus (Boophilus) microplus (Acari: Ixodidae); fourth-instar larvae of malaria vector, Anopheles subpictus; and filarial vector, Culex quinquefasciatus (Diptera: Culicidae). The ethyl acetate extract was loaded on silica gel column and separated with chloroform, methanol, and acetone as the solvents system. The separation of fractions was visualized by the thin layer chromatography (TLC) plate, further confirmed by high-performance liquid chromatography, and followed by gas liquid chromatography. Three major fractions were analyzed in mass spectroscopy (MS) and matched with existing compounds in the data base. Based on the fragment pattern, it led to the major compounds which were predicted as cyclopentanepropanoic acid, 3,5-bis(acetyloxy)-2-[3-(methoxyimino)octyl], methyl ester (13.3 %) 1; 5-azidomethyl-3-(2-ethoxy carbonyl-ethyl)-4-ethoxycarbonylmethyl-1H-pyrrole-2-carboxylic acid, ethyl ester (18.2 %) 2; and akuammilan-16-carboxylic acid, 17-(acetyloxy)-10-methoxy, methyl ester (16R) (53.3 %) 3. The maximum efficacy was observed in compounds 1, 2, and 3, and the ethyl acetate extract of Streptomyces VITSTK7 sp. against the larvae of H. bispinosa (LC(50) = 1,573.36, 1,333.09, 1,073.29, and 409.71 ppm; r(2) = 0.0.990, 0.934, 0.935, and 0.908), R. microplus (LC(50) = 1,877.86, 815.83, 1,631.14, and 441.54 ppm; r(2) = 0.981, 0.926, 0.0970, and 0.915), A. subpictus (LC(50) = 273.89, 687.69, 464.75, and 223.83 ppm; r(2) = 0.758, 0.924, 0.841, and 0.902), and C. quinquefasciatus (LC(50) = 430.06, 881.59, 777.0, and 195.70 ppm; r(2) = 0.839, 0.859, 0.870, and 0.882), respectively. Results of the present study provide evidence that the maximum parasitic activity of ethyl acetate extract and a synergistic effect of combinations of different compounds have been suggested. The control (distilled water) showed nil mortality in the concurrent assay. In the present study, a novel, targeted, simple, and eco-friendly approach has been suggested to control blood-feeding parasites.