Nanostructure Lipid Carrier of Curcumin Co-Delivered with Linalool and Geraniol Monoterpenes as Acetylcholinesterase Inhibitor of Culex pipiens

Abstract

(1) Background: A molecular hybridization docking approach was employed to develop and detect a new category of naturally activated compounds against Culex pipiens as acetylcholinesterase inhibitors via designing a one-pot multicomponent nano-delivery system. (2) Methods: A nanostructure lipid carrier (NLC), as a second generation of solid lipid nanoparticles, was used as a carrier to deliver the active components of curcumin (Cur), geraniol (G), and linalool (L) in one nanoformulation after studying their applicability in replacing the co-crystallized ligand imidacloprid. (3) Results: The prepared nanostructure showed spherical-shaped, polydisperse particles ranging in size from 50 nm to 300 nm, as found using a transmission electron microscope. Additionally, dynamic light scattering confirmed an average size of 169 nm and a highly stable dispersed solution, as indicated by the zeta potential (-38 mV). The prepared NLC-Cur-LG displayed competitive, high-malignancy insecticidal activity against fourth instar C. pipiens with an elevated rate of death of 0.649 µg/mL. The treatment, due to the prepared nanostructure, affects oxidative stress enzymes, e.g., hydrogen peroxide (4 ppm), superoxide dismutase (SOD) (0.03 OD/mg), and protein carbonyl (0.08 OD/mg), and there are observable upward and downward fluctuations when using different concentrations of NLC-Cur-LG, suggesting significant problems in its foreseeable insecticidal activity. The acetylcholinesterase activity was assessed by an enzyme inhibition assay, and strengthened inhibition occurred due to the encapsulated NLCs (IC₅₀ = 1.95 µg/mL). An investigation of the gene expression by Western blotting, due to treatment with NLC-Cur-LG, revealed a severe reduction of nearly a quarter of what was seen in the untreated group. As a preliminary safety step, the nanoformulation's toxicity against normal cell lines was tested, and a reassuring result was obtained of IC₅₀ = 158.1 µg/mL for the normal lung fibroblast cell line. (4) Conclusions: the synthesized nanoformulation, NLC-Cur-LG, is a useful insecticide in field conditions.

Keywords: Culex pipeins; curcumin; enzyme activity; molecular docking; nanostructure lipid carrier.

Figure 1

(a) The average particle size distribution of the prepared NLC-Cur-LG, (b) zeta potential of the prepared NLC-Cur-LG.

Figure 2

(a) Internal morphology by TEM of semi-spherical NLC-Cur-LG nanoparticles; (b) internal morphology, investigated using TEM, of spherical NLC-Cur-LG nanoparticles; (c) internal morphology, investigated using TEM, of spherical and size-varied NLC-Cur-LG nanoparticles; (d) internal morphology, investigated using TEM, of large spherical NLC-Cur-LG nanoparticles.

Figure 3

(a) Fluctuating hydrogen peroxide levels in the treated mosquito larvae group at different concentrations of NLC-Cur-LG nanoparticles compared to the untreated control; (b) elevated levels of protein carbonyls in the treated mosquito larvae group at different concentrations of NLC-Cur-LG nanoparticles compared to the untreated control; (c) Fluctuating SOD activities in the treated mosquito larvae group at different concentrations of NLC-Cur-LG nanoparticles compared to the untreated control; (d) Fluctuating ascorbic acid level activities in the treated mosquito larvae group at different concentrations of NLC-Cur-LG nanoparticles compared to the untreated control. Bars marked with the same small letters showed no significant difference between different concentration treatments (p > 0.05).

Figure 4

Effect of NLC-Cur-LG nanoformulation on acetylcholinesterase immuno-transmitter enzyme level by Western blotting of treated and untreated groups of C. pipiens.

Figure 5

Effect of NLC-Cur-LG against Vero cell line at different concentrations. It examined by inverted microscope at 10×. (a) Treatment at concentration of 31.25 µg/mL with very low cytotoxic activity, supported by good number of cells and morphology compared to the untreated control; (b) treatment at relatively high concentration of 250 µg/mL; the cell population was affected but still reserved their regular morphology if compared to the untreated control.

Figure 6

Effect of NLC-Cur-LG against the WI38 cell line at different concentrations. It examined by inverted microscope at 10×. (a) Treatment at concentration of 31.25 µg/mL with very low cytotoxic activity, supported by good number of cells and morphology compared to the untreated control; (b) treatment at relatively high concentration of 250 µg/mL; the cell population was affected but still reserved their regular morphology if compared to the untreated control.

Figure 7

Representative morphology of normal cell lines used in the cytotoxicity test. It examined by inverted microscope at 10×. (a) Adherent Vero epithelial kidney normal cell line (untreated control); (b) adherent WI38 normal lung fibroblast cell line (untreated control).

Figure 8

Self-docking of the Imidacloprid (co-crystallized ligand) interior 2ZJU pocket: (a) three-dimensional receptor interaction; (b) three-dimensional positioning in the receptor pocket; (c) two-dimensional interactions.

Figure 9

Docking of curcumin (tested ligand) interior 2ZJU pocket: (a) three-dimensional receptor interaction of curcumin ligand; (b) two-dimensional interactions of curcumin ligand.

Figure 10

Docking of geraniol (tested ligand) interior 2ZJU pocket: (a) three-dimensional receptor interaction of geraniol ligand; (b) two-dimensional interactions of geraniol ligand.

Figure 11

Docking of linalool (tested ligand) interior 2ZJU pocket: (a) three-dimensional receptor interaction of linalool ligand; (b) two-dimensional interactions of linalool ligand.

Figure 12

Three-dimensional positioning of the ligand and receptor pocket interior 2ZJU: (a) linalool three-dimensional positioning; (b) Geraniol three-dimensional positioning; (c) curcumin three-dimensional positioning.