Antinociceptive Activity of Borreria verticillata: In vivo and In silico Studies

Abstract

Borreria verticillata (L.) G. Mey. known vassourinha has antibacterial, antimalarial, hepatoprotective, antioxidative, analgesic, and anti-inflammatory, however, its antinociceptive action requires further studies. Aim of the study evaluated the antinociceptive activity of B. verticillata hydroalcoholic extract (EHBv) and ethyl acetate fraction (FAc) by in vivo and in silico studies. In vivo assessment included the paw edema test, writhing test, formalin test and tail flick test. Wistar rats and Swiss mice were divided into 6 groups and given the following treatments oral: 0.9% NaCl control group (CTRL), 10 mg/kg memantine (MEM), 10 mg/kg indomethacin (INDO), 500 mg/kg EHBv (EHBv 500), 25 mg/kg FAc (FAc 25) and 50 mg/kg FAc (FAc 50). EHBv, FAc 25 and 50 treatments exhibited anti-edematous and peripheral antinociceptive effects. For in silico assessment, compounds identified in FAc were subjected to molecular docking with COX-2, GluN1a and GluN2B. Ursolic acid (UA) was the compound with best affinity parameters (binding energy and inhibition constant) for COX-2, GluN1a, GluN2B, and was selected for further analysis with molecular dynamics (MD) simulations. In MD simulations, UA exhibited highly frequent interactions with residues Arg120 and Glu524 in the COX-2 active site and NMDA, whereby it might prevent COX-2 and NMDA receptor activation. Treatment with UA 10 mg/Kg showed peripheral and central antinociceptive effect. The antinociceptive effect of B. verticillata might be predominantly attributed to peripheral actions, including the participation of anti-inflammatory components. Ursolic acid is the main active component and seems to be a promising source of COX-2 inhibitors and NMDA receptor antagonists.

Keywords: Borreria verticillata; COX-2; NMDA receptor; molecular docking; molecular dynamics simulations.

Figure 1

Paw edema induced by subplantar administration of 1% carrageenan in mice treated orally with NaCl 0.9%, indomethacin 10 mg/kg, memantine 10 mg/Kg, EHBv 500 mg/Kg and FAc (25 and 50 mg/Kg). ^*p < 0.05; ^**p < 0.01; ^***p < 0.001 vs. CTRL (ANOVA; Newman Keuls).

Figure 2

Writhing induced by the intraperitoneal administration of 0.8% acetic acid (10 ml/kg) in mice treated orally with NaCl 0.9%, indomethacin 10 mg/kg, memantine 10 mg/Kg, EHBv 500 mg/Kg and FAc (25 mg/kg and 50 mg/Kg). ^**p < 0.01; ^***p < 0.001 vs. CTRL (ANOVA; Newman Keuls).

Figure 3

Formalin test induced by subplantar formalin administration of 2.5% in mice treated orally with NaCl 0.9%, indomethacin 10 mg/kg, memantine 10 mg/Kg, EHBv 500 mg/Kg and FAc (25 and 50 mg/Kg). ^*p < 0.05; ^**p < 0.01; ^***p < 0.001 vs. CTRL (ANOVA; Newman Keuls).

Figure 4

Tail flick test in rats treated orally with NaCl 0.9%, indomethacin 10 mg/kg, memantine 10 mg/Kg, EHBv 500 mg/Kg and FAc (25 mg/kg and 50 mg/Kg). ^*p < 0.05; ^**p < 0.01 vs. CTRL (ANOVA; Newman Keuls).

Figure 5

Spatial conformation obtained by molecular docking of ursolic acid (yellow) and indomethacin (blue) with the COX-2 enzyme (PDB: 1DDX) (A). LIGPLOT diagrams for ursolic acid (B) and indomethacin (C) interaction in COX-2.

Figure 6

Spatial conformation obtained by molecular docking of ursolic acid ligands (yellow) and memantine (green) with N-methyl-D-aspartate (NMDA). (A) GluN1a, (B) GluN2B. Image generated by VMD.

Figure 7

Frequency of hydrophobic contacts (green) and hydrogen bonding (orange) of ursolic acid + COX-2 (A) and indomethacin + COX-2 (B). The frequencies correspond to the end 4 of molecular dynamics simulations.

Figure 8

Frequency of hydrophobic contacts (green) and hydrogen bonding (orange) between ursolic acid + GluN1a (A), ursolic acid + GluN2B (B), memantine + GluN1a (C), and memantine + GluN2B (D).

Figure 9

Paw edema induced by subplantar administration of 1% carrageenan in mice treated orally with NaCl 0.9%, indomethacin 10 mg/kg, memantine 10 mg/Kg, and ursolic acid 10 mg/Kg. ^*p < 0.05; ^**p < 0.01; ^***p < 0.001 vs. CTRL (ANOVA; Newman Keuls).

Figure 10

Tail flick test in rats treated orally with NaCl 0.9%, indomethacin 10 mg/kg, memantine 10 mg/Kg, and ursolic acid 10 mg/Kg. ^*p < 0.05; ^**p < 0.01; ^***p < 0.001 vs. CTRL (ANOVA; Newman Keuls).