Traditional herbs against COVID-19: back to old weapons to combat the new pandemic

BACKGROUND: Recently, the coronavirus (COVID-19) pandemic is a chief public health disaster caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). There are no established effective preventive or therapeutic anti-COVID-19 drugs available except for some recently approved vaccines. Still, countless recent studies recommend various alternative and complementary approaches against COVID-19, which are medicinal herbs employed as traditional remedies to enhance immunity to struggle with viral infections. In addition, physicians worldwide are highly interested in vitamin and mineral supplements to help them combat COVID-19 either through protection or treatment. Dietary supplements specifically vitamin D, vitamin C, and zinc provide good prophylactic and therapeutic support to the presently available treatment regimens. In the present work, we have focused on plant-based remedies with promising anti-COVID-19 activities. AIM: To enable investigators and researchers to identify potential herbal compounds with anti-COVID activity to be used as promising therapies to combat this pandemic. MAIN BODY: This review highlights the recently published studies concerning natural traditional herbs, herbal bioactive metabolites, dietary supplements, and functional foods that could help prevent and/or treat COVID-19. Herein, we explored medicinal herbs as potential inhibitors of SARS-CoV-2 and discussed how these studies help form larger discussions of diet and disease. Moreover, by investigating the herbal bioactive components, we have outlined several medicinal herbs that can fight against COVID-19 by hindering SARS-CoV-2 replication and entry to its host cells, deterring the cytokine storm, and several other means. Finally, we have summarized various herbal products, functional foods, and dietary supplements with potent bioactive compounds which can inhibit and/or prevent COVID-19 disease progression. CONCLUSIONS: Based on the studies reviewed in this work, it was concluded with no doubt that phytochemical components present in various herbs could have a starring role in the deterrence and cure of coronavirus contagion.