Review on the secondary metabolites, biological properties, and ethnomedicinal uses of the component species of the buheri wa afya formula used to treat COVID-19 in Tanzania

Abstract

Background: It has proven difficult to treat viral infections like SARS-CoV, MERS-CoV, and SARS-CoV-2 that cause severe respiratory disorders with the currently available medications. Alternative strategies for combating viral infections are required to adequately treat infectious diseases like COVID-19. The most potent of them all may be plant-based products or herbal remedies. Following the advent of the COVID-19 epidemic, a number of alter- native medicine practitioners in Tanzania developed herbal medicine formulations, claiming that they were effective in treating COVID-19 patients. One among the formulations is Buheri wa Afya, meaning "good health". The rationale for choosing Buheri wa Afya over the other formulations was justified by its efficacy in treating COVID-19 patients at different stages of the illness. Purpose: This review aimed to collect information on the chemical composition, biological properties, and eth- nomedicinal uses of the constituents of Buheri wa Afya formula, a plant-fungi complex formula made of Adansonia digitata L., Ficus sur Forssk, Securidaca longipedunculata Fresen, Syzygium cumini (L.) Skeels, and Zan- thoxylum chalybeum Engl., and a fungus, Ganoderma tsugae Murrill, that was and is still used for the treatment of COVID-19 in Tanzania. Methods: All information regarding ethnomedical applications, chemical compositions, and biological properties related to the constituents of the herbal formula was collected from PubMed, Research4Life, Google Scholar, Science Direct, Web of Science, Wiley Online Library, Springer, Research Gate link, and published books. Results: The search, which mostly focused on COVID-19 and other viral infectious diseases produced a total of 183 publications, with publication dates ranging from 1984 to 2023. Most of the articles originated from African and Asian (specifically China and India) countries. A total of 16 articles spanning between 1984 through 1999 reporting on a variety of topics, such as isolation of compounds and biological testing were collected. During that time, Ganoderma species had the highest number of reported occurrences. In contrast to the 25 papers collected between 2000 and 2009, 78 articles covering the years 2010 through 2019 were collected. These 103 articles reported studies on ethnomedicinal uses, pharmacological properties, and chemical compositions of the plants and mushrooms under review. During the 2020–2023 period, a total 67 different articles were gathered, the major focus being the fight against COVID-19 and other viral infectious diseases. Twelve of them reported the ethnomedical applications of the investigated plant and mushroom species in the Buheri wa Afya formula in the management and treatment of COVID-19 and associated symptoms. The majority of articles reported the pres- ence of a variety of biologically active compounds, including vitamins, flavonoids, phenols, coumarins, alkaloids, terpenoids, macronutrients, and micronutrients. According to the studies, the compounds have been reported to exhibit anti-inflammatory, immunomodulatory, antiviral, antioxidant, antimalarial and many other biological properties. The combination of the observed biological properties of the plant and mushroom species in the Buheri wa Afya formula may be responsible for its effectiveness in the treatment of COVID-19 in Tanzania