The phytochemical constituents in B. owariensis include alkaloids, anthraquinone, carbohydrate, cardiac-glycoside, unsaturated steroid/triterpenes, saponin glycoside, tannin and flavonoid. The presence of phytochemicals such as alkaloids, flavonoids, tannin, anthraquinone, and saponin, as revealed by the phytochemical screening of methanol extract of B. owariensis has been reported in other medicinal plants such as Severinia buxifolia (Truong et al. 2019), in Brillantaisia patula (Faparusi et al. 2012), in Cassia arereh (Abbas et al. 2017), and Abrus precatorius seeds (Nwodo and Nwodo 2012). Phytochemical investigations of the whole plant extract of B. owariensis by Akuru and Amadi (2018) revealed high concentrations of spartein, anthocyanin, oxalate, phenol, epicatechin, lunamarin, saponin, ribalinidine, phytate, rutin, kaempferol, catechin, sapogenin and the presence of antioxidants properties. The GC-MS analysis of the concentrated methanol extract presented many compounds with diverse use. The most abundant bioactive compounds are Phytol, 9 Octadecinamide Z, Hexadecanoic acid methyl ester, 7-Hexadecenoic acid, methyl ester (Z), 3, 8-Nonadien-2-one, (E), Heptanoic acid. These six primary bioactive metabolites have been reported to act as an anti-trypanosomal (Saad et al. 2020), anti-inflammatory compounds (Phatangare et al. 2017; Basile et al. 1999), anti-schistosomal (Eraky et al. 2016), antioxidant (Santos et al. 2013), anti-bacterial and antifungal, nematicidal, anti-bacterial and antifungal (Chandrasekaran et al. 2011; Idan et al. 2015) and hypnotic property (Idan et al. 2015). New compounds, Iridolactone and Owariensisone, together with six known compounds (Nepetin-7-O-glucoside, choline, sucrose, mannitol, xylitol, and 1-O-palmitoyl-2eicosanoyl-3-O-(6-amino-6-deoxy)-β-D glucopyranosyl glycerol) were isolated from the whole plant extract of B. owariensis (Perrin et al. 2016). Therefore, these findings suggest the presence of multiple compounds in B. owariensis, which could be used as possible potential additives in treating several ailments of animals and plants.
The extracts' in-vivo anti-trypanosomal activity revealed no cessation or complete elimination of parasites from the bloodstream of infected mice when administered methanol extract of B. owariensis, but only reduced parasitaemia. The extract was unable to eliminate parasitaemia and has been reported to demonstrate a significant haemanitic activity capable of reversing anaemia, a typical characteristic of African Trypanosomiasis (Akah et al. 2009; Ayawa et al. 2021). Trypanosoma brucei brucei is one of the parasites that show tissues tropism to the heart, skeletal muscle, liver, spleen, brain, lungs, kidney, testes, and adipose tissue (Silva et al. 2019). Tissues affected have characteristic lesions from extensive inflammation, which are mediated by levels of increased cytokines such as Tissue Necrotic Factor (TNF-a) and Interleukin 6(IL-6), with cellular infiltrations primarily by lymphocytes accompanied by plasma cells, macrophages and neutrophils (Abenga 2014). Lymphocyte hyperplasia is generally a reactive or immune response and immunological protection to the tissue. It is not considered a preneoplastic lesion in the lymph node (Elmore 2006). The Lymphocyte proliferation in tissues observed in this study is also reported by Wada et al. (2016b) in 'Yankasa T. brucei brucei, and T. evansi infected Rams.
The normal myocardium of the heart observed in this study could be that the parasites might not have extravasated into the extracellular matrix, just as reported by McCarrol et al. (2015). Slight necrosis of the myocardium could be associated with stress, where cardiomyocytes undergo apoptotic responses (Woodcock and Matkovich 2005).
Significant histopathology of the lungs was alveoli congestion and lymphocyte hyperplasia. The lungs' congestion might be an inflammatory response to the parasite, thus leading to vasodilatation and exudation. Bal et al. (2012) made a similar observation in the lungs of mice experimentally infected with Trypanosoma evansi.
The spleen is essential to the lymphatic tissues, playing a defensive role during parasite invasion. Spleen damage varies in parasitic infections (Biswas et al. 2001). The report in this study presents normal spleen histology with normal red and white pulp distribution. It could be that trypanosome organisms are not able to destroy the erythrocytes, which is in contrast with that of Aremu et al. (2018), where photomicrographs of the spleen in the study showed marked congestion of the splenic sinuses and sinusoids, suggesting marked splenic depletion in T. brucei brucei-infected Rats treated with the methanolic extract of Moringa oleifera.
The kidney is vulnerable to blood diseases. Structural impairment and kidney malfunction are usually from toxins produced by parasites and the accumulation of immune complexes (Biswas et al. 2001). In this study, Glomerular and tubular necrosis and tubular distortion of the kidney are similar to the pathological changes observed by Ghaffar et al. (2016) in T. evansi-infected mice.
Histopathology of the liver sections of mice reveals normal hepatocytes to moderate necrosis; this could be a result of the presence of Methionine (essential amino acid) in the plant extracts, which can protect the liver from damage by poisons such as carbon tetrachloride, arsenic and Chloroform (Akuru et al. 2018). The presence of flavonoids and alkaloids in the plant extracts might have prevented further liver cell necrosis and inflammation, as their hepatoprotective /anti- hepatotoxic ability is similar to previous studies (Cheedella et al. 2013; Meharie et al. 2020). This result contrasts with Biswas et al. (2001) reports, where severe liver cell necrosis was observed in the bandicoot rat infected with T. evansi.
The prolonged survival period of the extract-treated mice could be due to the presence of flavonoids as it reduces trypanosomiasis-induced inflammatory reaction by aiding the antioxidant defence system (Chen et al. 2004). For instance, flavonoids' ability to transport electrons to free radicals, chelate metals, activate antioxidant enzymes, diminish alpha-tocopherol radicals or inhibit oxidases are all antioxidant effects in biological systems (Akuru and Amadi 2018). Further infiltration of leucocytes which might have led to neutrophils infiltration in tissues stimulated by oxidative stress, has been managed/minimised by the extract in this study, attributable to the presence of 9- Octadecinamide Z, Hexadecanoic acid methyl ester, Phytol which is highly abundant in the plant extracts. For instance, Hexadecanoic acid methyl ester and phytols have been reported to reduce inflammation by inhibiting neutrophils proliferations caused by interleukin (IL)-1β, TNF-α and oxidative stress (Silva et al. 2013; Obaseki et al. 2016).
Furthermore, Phytol can also be presented as a redox monitoring compound when it is not redox-active. Its anti-inflammatory effects can be seen in its ability to trigger reactive oxygen species production (ROS) from the phagocyte NADPH oxidase (NOX2) complex. Contrary to the fact that ROS has been reported to cause damage in tissues and cells, it is suggested that increased ROS production could ameliorate tissues (Olofsson et al. 2003; Hultqvist et al. 2006; Gelderman et al. 2007; Olofsson et al. 2014). From these antecedents, the extracts of B. owariensis may have promising anti-inflammatory potentials in managing inflammatory diseases such as trypanosomosis.