Antitrypanosomal potential of Salvia officinalis terpenoids-rich fraction in Trypanosoma evansi-infected rat model

Abstract

BACKGROUND TRYPANOSOMA EVANSI : (T. evansi) is a major protozoan disease that affects animals, including camels, and causes substantial economic detriments. The failure to control T. evansi infections is due to the unavailability of vaccines and the development of resistance to existing chemical drugs. In this study, we evaluated the effect of Salvia officinalis terpenoids-rich fraction on the degree of parasitemia and associated pathological alterations in rats experimentally infected with T. evansi.

Method: Eighty adult male rats were equally divided into 4 groups. The first group was a negative control. The second group was intraperitoneally infected with T. evansi at a dose of 1 × 10⁴ trypanosomes. The third group was similarly infected and subsequently treated intramuscularly with diminazene aceturate at a dose of 7 mg/kg body weight (b.wt.). The fourth group received a daily oral administration of Salvia officinalis terpenoids-rich fraction at a dose of 300 mg/kg b.wt. throughout the experimental period and was also infected with T. evansi.

Result: The infection with T. evansi resulted in normocytic normochromic anemia, leukocytosis, hypoglycemia, hypertriglyceridemia, an increase in very low-density lipoprotein (VLDL) cholesterol, and reductions in high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterols. Additionally, the infection induced upregulation of the pro-inflammatory cytokines such as interleukin-1beta (IL-1β) and interleukin-6 (IL-6), and downregulation of the anti-inflammatory cytokines such as interleukin-10 (IL-10) and transforming growth factor beta (TGF-β). Besides histopathological changes in the brain and spleen, T. evansi markedly elevated brain oxidative stress and acetylcholinesterase (AChE) activity. The treatment with salvia fraction significantly decreased the degree of parasitemia and mitigated the T. evansi-induced pathological alterations.

Conclusion: The terpenoids-rich fraction from Salvia officinalis exhibits antitrypanosomal activity and may serve as a promising candidate for developing novel trypanocidal agents.

Keywords: Salvia officinalis; Trypanosome evansi; Antitrypanosomal activity; Terpenoids.

Fig. 1

Parasitemia degree in the infected groups. Data are expressed as means ± SE (n = 5) with dissimilar superscript letters (significantly differing at P < 0.05): a) significantly different from CP group; b) significantly different from DA group. CP: positive control group (infected); DA: infected and diminazene aceturate-treated group; SF: salvia fraction-treated and infected group. DPI: day post-infection

Fig. 2

Brain oxidant/ antioxidant biomarkers and AChE activity in different experimental groups on the 14^th DPI. Data are expressed as means ± SE (n = 5) with dissimilar superscript letters (significantly differing at P<0.05): a) significantly different from CN group; b) significantly different from CP group; c) significantly different from DA group. CN: negative control group; CP: positive control group (infected); DA: infected and diminazene aceturate-treated group; SF: salvia fraction-treated and infected group. MDA: malondialdehyde; GSH: reduced glutathione; GPx: glutathione peroxidase; AChE: acetylcholinesterase; DPI: day post-infection

Fig. 3

The transcript levels of inflammatory cytokines in the blood of different experimental groups. Data are expressed as means ± SE (n = 5) with dissimilar superscript letters (significantly differing at P < 0.05): a) significantly different from CN group; b) significantly different from CP group; c) significantly different from DA group. CN: negative control group; CP: positive control group (infected); DA: infected and diminazene aceturate-treated group; SF: salvia fraction-treated and infected group. IL-1β: interleukin-1beta; IL-6: interleukin-6; IL-10: interleukin-10; TGF-β: transforming growth factor beta; DPI: day post-infection

Fig. 4

Representative photomicrographs of rat cerebral cortex sections stained with H&E on the 14^th DPI (magnification 200X). (a) The cerebrum of normal rats revealed the regular arrangement of cerebral cortex layers. (b) The cerebrum in the CP group showed disarrangement of cerebral cortical layers, congestion (arrowhead), perineuronal edema (red arrow), and pyknotic nuclei of some neurons (black arrow). (c) Cerebral tissues of DA group showed similar cerebral neuropathology but in a lesser degree of severity: congestion (arrowhead) and perivascular edema (red arrow). (d) Rats in the SF group had similar cerebral neuropathology to the DA group with more amelioration: congestion (arrowhead)

Fig. 5

Representative photomicrographs of rat cerebellar cortex sections of rats stained with H&E on the 14^th DPI (magnification 200X). (a) Normal rats showed a regular arrangement of the cerebellar cortex layer. (b) Cerebellar tissues of the CP group exhibited multifocal Purkinje cell necrosis and loss (arrow), congestion, and atrophy of the granular cell layer. (c) Rats in the DA group showed the above-described cerebellar lesions but in a lesser degree of severity and distribution: Purkinje cell necrosis (arrow) and congestion (arrowhead). (d) The cerebellum of rats in the SF group revealed similar cerebellar neuropathology to the DA group but with more improvement

Fig. 6

Representative photomicrographs of rat splenic sections stained with H&E on the 14^th DPI (magnification 400X). (a) Rats in the CN group showed normal histological architecture of the spleen composed of white and red pulps. (b) Rats in the CP group revealed proliferation of reticuloendothelial cells and lymphoid cells with many extra-medullary megakaryocytes (arrow). (c) Splenic tissue in the DA and (d) in the SF groups showed improvement compared to those of the rats in the CP group