Despite the frightening mortality rate associated with COVID-19, there is no known approved drug to effectively combat the pandemic. COVID-19 clinical manifestations include fever, fatigue, cough, shortness of breath, and other complications. At present, there is no known effective treatment or vaccine that can mitigate/inhibit SARS-CoV-2. Available clinical intervention for COVID-19 is only palliative and limited to support. Thus, there is an exigent need for effective and non-invasive treatment. This article evaluates the possible mechanism of actions of SARS-CoV-2 and present Nigeria based medicinal plants which have pharmacological and biological activities that can mitigate the hallmarks of the pathogenesis of COVID-19. SARS-CoV-2 mode of actions includes hyper-inflammation characterized by a severe and fatal hyper-cytokinaemia with multi-organ failure; immunosuppression; reduction of angiotensin-converting enzyme 2 (ACE2) to enhance pulmonary vascular permeability causing damage to the alveoli; and further activated by open reading frame (ORF)3a, ORF3b, and ORF7a via c-Jun N- terminal kinase (JNK) pathway which induces lung damage. These mechanisms of action of SARS-CoV-2 can be mitigated by a combination therapy of medicinal herbs based on their pharmacological activities. Since the clinical manifestations of COVID-19 are multifactorial with co-morbidities, we strongly recommend the use of combined therapy such that two or more herbs with specific therapeutic actions are administered to combat the mediators of the disease.

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Graphical abstract Schematic illustration of the neuroprotective action of Curcuma longa in brain regions (midbrain, cerebrum, & cerebellum) nitrobenzene-induced neurodegenerative rats. MPO: myeloperoxidase, NO: nitric oxide, AChE: acetylcholinesterase, DOPA: dopamine, GSH: glutathione, CAT: catalase, SOD: superoxide dismutase, LPO: lipid peroxidation, H 2 O 2 : hydrogen peroxide generation.

Background: Jatropha tanjorensis is a commonly consumed green leafy plant that has found usage in folk medicine. Sodium benzoate (C 6 H 5 COONa) is a widely used preservative in food/drink industries with potential cytotoxicity. Protective effect of some leafy plants on xenobiotic-induced toxicity have been established. Hence, this study sought to investigate the protective effect of methanolic leaf extract of Jatropha tanjorensis on sodium benzoate mediated renal and hepatic dysfunction in rats. Results: Sodium benzoate treatment caused significant (P < 0.05) alteration in kidney (serum urea, uric acid, and creatinine) and liver (aspartate and alanine transaminases, acid and alkaline phosphatases) damage markers, serum albumin, globulin and total protein levels as well as cellular architecture which were significantly reversed in groups treated with the leaf extracts. Phytochemical screening of the leaf extract revealed the presence of terpenoids, saponins, cardiac glycosides, flavonoids and tannins. Conclusion: Sodium benzoate-induced alterations in the renal and hepatic indices were mitigated following treatment with J. tanjorensis leaf extracts which suggests protective effect of the extract against sodium benzoate intoxication.

Background: Infertility is a global health burden which affect more than 15% of couples' population. An impaired hormonal balance, oxidative stress and alteration in the physiological function of the reproductive organ are factors leading to infertility. The present study investigated the protective role of methanolic leaf extract of Vernonia amygdalina (MLVA) against Nitrobenzene-induced oxidative testicular damage and hormonal imbalance in rats. Thirty sexually active male wistar rats were sorted into five groups, each group containing six rats. Group I received distilled water while 100 mg/kg bw of Nitrobenzene was administered to groups (II, III, IV and V) to induce testicular damage and hormonal imbalance. Group III and IV were treated with oral administration of 200 mg/kg bw and 400 mg/kg bw of MLVA respectively and group V with vitamin E for 14 days. Results: Nitrobenzene-treated rats showed significant (P < 0.05) decrease in the body weight gain, testis and epididymis weights. However, upon administration of MLVA or vitamin E, these changes were significantly reversed in Nitrobenzenetreated rats. Also, Nitrobenzene significantly (P˂0.05) induced endocrine disruption as shown by decreased activities level of serum Thyroid stimulating hormone (TSH), luteinizing hormone (LH), follicle stimulating hormone (FSH), prolactin, testosterone, triiodothyronine (T3), and tetraiodothyronine (T4). Administration of Nitrobenzene also induced oxidative damage as shown by increased level of testicular lipid peroxidation (MDA), and decreased levels of glutathione (GSH). Histological studies of the testes revealed mild congestion of interstitial vessels and oedema in rats administered Nitrobenzene only. Conclusion: Taken together, MLVA obliterated the adverse effects of Nitrobenzene on the antioxidant enzymes, markers of testicular oxidative damage, endocrine and testicular structure in rats.