Candidate Anti-COVID-19 Medicinal Plants from Ethiopia: A Review of Plants Traditionally Used to Treat Viral Diseases

Biotransformation of selected secondary metabolites by Alternaria species and the pharmaceutical, food and agricultural application of biotransformation products

Biotransformation is a process in which molecules are modified in the presence of a biocatalyst or enzymes, as well as the metabolic alterations that occur in organisms from exposure to the molecules. Microbial biotransformation is an important process in natural product drug discovery as novel compounds are biosynthesised. Additionally, biotransformation products offer compounds with improved efficacy, solubility, reduced cytotoxic and allows for the understanding of structure activity relationships. One of the driving forces for these impeccable findings are associated with the presence of cytochrome P450 monooxygenases that is present in all organisms such as mammals, bacteria, and fungi. Numerous fungal strains have been used and reported for their ability to biotransform different compounds. This review focused on studies using Alternaria species as biocatalysts in the biotransformation of natural product compounds. Alternaria species facilitates reactions that favour stereoselectivity, regioselectivity under mild conditions. Additionally, microbial biotransformation products, their application in food, pharmaceutical and agricultural sector is discussed in this review.

Recent advances in the therapeutic potential of nobiletin against respiratory diseases

BACKGROUND

Nobiletin is a natural polymethoxylated flavonoid widely present in citrus fruit peels. It has been demonstrated to exert the effects of anti-tumor, anti-inflammation, anti-oxidative, anti-apoptotic and improve cardiovascular function. Increasing evidences suggest that nobiletin plays an important role in respiratory diseases (RDs) treatment.

OBJECTIVE

This review aimed to investigate the therapeutic potential of nobiletin against RDs, such as lung cancer, COPD, pulmonary fibrosis, asthma, pulmonary infection, acute lung injury, coronavirus disease 2019, and pulmonary arterial hypertension.

METHODS

We retrieved extensive literature of relevant literatures in English until June 26, 2023 from the database of PubMed, Web of Science, and Scopus databases. The keywords of "nobiletin and lung", "nobiletin and respiratory disease", "nobiletin and chronic respiratory diseases", "nobiletin and metabolites", "nobiletin and pharmacokinetics", "nobiletin and toxicity" were searched in pairs. A total of 298 literatures were retrieved from the above database. After excluding the duplicates and reviews, 53 were included in the current review.

RESULTS

We found that the therapeutic mechanisms are based on different signaling pathways. Firstly, nobiletin inhibited the proliferation and suppressed the invasion and migration of cancer cells by regulating the related pathway or key target, like Bcl-2, PD-L1, PARP, and Akt/GSK3β/β-catenin in lung cancer treatment. Secondly, nobiletin treats COPD and ALI by targeting classical signaling pathway mediating inflammation. Besides, the available findings show that nobiletin exerts the effect of PF treatment via regulating mTOR pathway.

CONCLUSIONS

With the wide range of pharmacological activities, high efficiency and low toxicity, nobiletin can be used as a potential agent for preventing and treating RDs. These findings will contribute to further research on the molecular mechanisms of nobiletin and facilitate in-depth studies on nobiletin at both preclinical and clinical levels for the treatment of RDs.

Medicinal Plants in Treating Hepatitis B Among Communities of Central Region of Ethiopia

Purpose

In Ethiopia, most people rely heavily on traditional therapeutic plants that have been used for years. The practice of traditional medicines use to treat hepatitis is currently gaining popularity due to the limited availability and affordability of modern drugs. The aim of this study was, therefore, to assess the traditional medicinal plants use to treat viral hepatitis among communities of Central region of Ethiopia.

Methods

Data was collected from November 2018 to December 2021 in Central Ethiopia. An open-ended semi-structured interview was used among purposively selected herbalists, traditional medicine entrepreneurs, village heads, and patients visiting traditional healers for hepatitis treatments. A 5 mL blood sample was collected from patients who visited a traditional healers' clinic for hepatitis treatment and tested for HBsAg and HCV-antibody by using ELISA. Among HBsAg-positives, further nucleic acid test for HBV-DNA load was assessed to measure the effects of prescribed medicinal plants.

Results

Herbalists cited 24 plants that were used for hepatitis treatment; of which Rumex nepalensis, Vangueria apiculata, and Solanum incanum were the most frequently cited plants. Remedies were commonly prepared by crushing or powdering, mixing them with water, and taken orally. Forty-two individuals were diagnosed and treated as hepatitis patients by herbalists, of which eight of them were HBsAg-positive but no positives for anti-HCV ELISA. At the third and sixth months of viral load assessment among HBsAg-positive, serum HBV-DNA suppression was observed in three individuals treated with different combinations of frequently cited plants.

Conclusion

In this study, traditional healers used various plants to treat hepatitis. HBV-DNA suppressive activity was detected in three NAT-positive individuals who were treated by using a mixture of these frequently cited and highest preference-ranked plants. This suggests that these plants have antiviral properties and serve as a basis for more pharmacological research in the quest for new antiviral agents.

Review of Medicinal Plants Traditionally Used to Treat Diarrhea by the People in the Amhara Region of Ethiopia

Background

Diarrheal illness is the second-most common cause of death in under-five children. Worldwide, it results in about 1.7 billion illnesses and 525,000 deaths among under-five children annually. It is the leading cause of malnutrition among under-five children. Different people use medicinal plants to treat diarrhea. The present study aimed to review the medicinal plants used to treat diarrhea by the people in the Amhara region and to diagnose whether the antidiarrheal activities of the medicinal plants have been confirmed by studies using animal models.

Methods

The author searched 21 articles from worldwide databases up to December 2022 using Boolean operators ("AND" and "OR") and the terms "ethnobotanical studies," "ethnobiology," "traditional medicine," "ethnobotanical knowledge," and "Amhara region."

Results

From the 21 studies reviewed, 50 plant species grouped into 28 families were reported to treat diarrhea by the people in the Amhara region. The top most used families were Lamiaceae (12%), Fabaceae (8%), Asteraceae, Cucurbitaceae, Euphorbiaceae, and Poaceae (6% each). The modes of administration of the plant parts were orally 98.88% and topically 1.12%. The different extracts of 18 (or 36%) of the medicinal plants traditionally used to treat diarrhea by the people in the Amhara region have been proven experimentally in animal models.

Conclusions

The people in the Amhara region use different medicinal plants to treat diarrhea. Most of them take the medicinal plants orally. The traditional claim that 60% of medicinal plants are antidiarrheal has been confirmed in in vitro studies.

An Insight into In Vitro Antioxidant, Antimicrobial, Cytotoxic, and Apoptosis Induction Potential of Mangiferin, a Bioactive Compound Derived from Mangifera indica

Due to their low cost, toxicity, and health risks, medicinal plants have come to be seen as useful products and sources of biologically active compounds. Mangifera indica L., a medicinal plant with a long history, has a high bioactive metabolites content. Mangiferin (C₁₉H₁₈O₁₁) is primary isolated from M. indica's leaves, which has many pharmacological benefits. In this investigation, ultrasonic-assisted extraction with ethanol as the extraction solvent was applied to obtain mangiferin from a local type of M. indica leaves. HPLC was performed after a dichloromethane-ethyl acetate liquid-liquid fractionation method. Further, UV-vis, FTIR, and NMR spectroscopy were utilized to elucidate the structure. Interestingly, purified mangiferin displayed promising antimicrobial efficacy against a diverse variety of fungal and bacterial pathogens with MICs of 1.95-62.5 and 1.95-31.25 µg/mL, respectively. Time-kill patterns also showed that mangiferin had both bactericidal and fungicidal action. Furthermore, it exhibited strong radical dosage-dependent scavenging activity (IC₅₀ = 17.6 μg/mL) compared to vitamin C (Vc, IC₅₀ = 11.9 μg/mL), suggesting it could be developed into a viable antioxidant agent. To our delight, the IC₅₀ values of mangiferin for the MCF-7 and HeLa cell lines were 41.2 and 44.7 μg/mL, respectively, from MTT cell viability testing, and it was less harmful when tested against the noncancerous cell line. Notably, it significantly induced cell apoptosis in MCF-7 cells by 62.2-83.4% using annexin V-FITC/PI labeling. Hence, our findings suggest that mangiferin can be used in the medical industry to create therapeutic interventions and medication delivery systems for society.

Medicinal uses, chemical constituents and biological activities of Rumex abyssinicus: A Comprehensive review

Rumex abyssinicus is a valuable medicinal plant species that is native to tropical Africa. Traditionally, R. abyssinicus is used to treat different disease such as, liver diseases, hepatitis, malaria, scabies, blood pressure, jaundice, wound and pneumonia. The purpose of the current study was to review the literature on the ethnomedicinal uses, chemical constitutes and biological activities of R. abyssinicus in an attempt to create information for future studies aimed towards exploring the therapeutic ability of the species. A scientific search engines, namely Google Scholar, PubMed, Scopus, Science Direct and Web of knowledge for the search terms: Rumex abyssinicus, ethnomedicinal studies, phytochemical investigations, and pharmacological activities were undertaken. The search strategy included all articles with descriptors that were available until December 30, 2021. Only published works in English have been used on this study. The data was collected using textual descriptions of the studies, tabulation, grouping, and figures. The principal phytochemicals of R. abyssinicus are anthraquinones, flavonoids, terepenoids and phenolic compounds. The in vitro and in vivo studies on the crude extracts and compounds of R. abyssinicus showed antibacterial, antioxidant, anticancer, anti-inflammatory, antifungal, wound healing, antialzeimer’s and hepatoprotective activities of it. R. abyssinicus afforded drug leads such as helminthosporin (4) with anti-alzheimer and physicon (3) with antifungal and antioxidant activity. R. abyssinicus have traditionally been used to cure a variety of diseases. Pharmacological actions of phytochemicals were shown to be promising. Despite this, further studies on crude extracts and promising compounds are needed to find new drug candidates.

Role of ethno-phytomedicine knowledge in healthcare of COVID-19: advances in traditional phytomedicine perspective

Background

Since the outbreak of the COVID-19 virus, ethnomedicinal plants have been used in diverse geographical locations for their purported prophylactic and pharmacological effects. Medicinal plants have been relied on by people around the globe for centuries, as 80% of the world’s population rely on herbal medicines for some aspect of their primary health care needs, according to the World Health Organization.

Main body

This review portrays advances in traditional phytomedicine by bridging the knowledge of ethno-phytomedicine and COVID-19 healthcare. Ethnomedicinal plants have been used for symptoms related to COVID-19 as antiviral, anti-infective, anti-inflammatory, anti-oxidant, antipyretic, and lung–gut immune boosters. Traditionally used medicinal plants have the ability to inhibit virus entry and viral assembly, bind to spike proteins, membrane proteins, and block viral replications and enzymes. The efficacy of traditional medicinal plants in the terms of COVID-19 management can be evaluated by in vitro, in vivo as well as different in silico techniques (molecular docking, molecular dynamics simulations, machine learning, etc.) which have been applied extensively to the quest and design of effective biotherapeutics rapidly. Other advances in traditional phytomedicines against COVID-19 are controlled clinical trials, and notably the roles in the gut microbiome. Targeting the gut microbiome via medicinal plants as prebiotics is also found to be an alternative and potential strategy in the search for a COVID-19 combat strategy.

Conclusions

Since medicinal plants are the sources of modern biotherapeutics development, it is essential to build collaborations among ethnobotanists, scientists, and technologists toward developing the most efficient and the safest adjuvant therapeutics against the pandemic of the twenty-first century, COVID-19.

Antiviral potential of anthraquinones from Polygonaceae, Rubiaceae and Asphodelaceae: Potent candidates in the treatment of SARS-COVID-19, A comprehensive review

Medicinal plants are being used as an alternative source of health management to cure various human ailments. The healing role is attributed to the hidden dynamic groups of various phytoconstituents, most of which have been recorded from plants and their derivatives. Nowadays, medicinal plants have gained more attention due to their pharmacological and industrial potential. Aromatic compounds are one of the dynamic groups of secondary metabolites (SM) naturally present in plants; and anthraquinones of this group are found to be attractive due to their high bioactivity and low toxicity. They have been reported to exhibit anticancer, antimicrobial, immune-suppressive, antioxidant, antipyretic, diuretic and anti-inflammatory activities. Anthraquinones have been also shown to exhibit potent antiviral effects against different species of viruses. Though, it has been reported that a medicinal plant with antiviral activity against one viral infection may be used to combat other types of viral infections. Therefore, in this review, we explored and highlighted the antiviral properties of anthraquinones of Polygonaceae, Rubiaceae and Asphodelaceae families. Anthraquinones from these plant families have been reported for their effects on human respiratory syncytial virus and influenza virus. They are hence presumed to have antiviral potential against SARS-CoV as well. Thus, anthraquinones are potential candidates that need to be screened thoroughly and developed as drugs to combat COVID-19. The information documented in this review could therefore serve as a starting point in developing novel drugs that may help to curb the SARS-COVID-19 pandemic.

Effect of Extraction Solvents on Total Polyphenolic Content and Antioxidant Capacity of Syzygium Aromaticum L. Flower Bud from Ethiopia

In this study, the antioxidative activity and polyphenolic content of Syzygium aromaticum's flower bud were compared under different extraction solvents including chloroform, ethyl acetate, methanol, and aqueous. The antioxidant activity was assessed via established in vitro assay models such as 2, 2-diphenyl-1-Picrylhydrazyl (DPPH) radical scavenging assay, NO- radical scavenging assay, H2O2 scavenging assay and Fe3+ reducing capacity. Total phenolic content was measured according to Folin-Ciocalteu's method, and total flavonoid content was estimated by using the aluminum chloride colorimetric method. The results showed that aqueous extract possessed the highest TPC (19.11 ± 2.76 mg GAE/g DW) and TFC (15.32 ± 1.53 mg CtE/g DW). Among the extracts, methanol extract exerted the strongest radical DPPH quenching activity with an IC50 value of 303.56 ± 13.14 μg/mL. The highest NO- radical scavenging activity was shown by methanol extract (IC50192.94 ± 1.9 μg/mL) which is stronger than BHT (IC50247.64 ± 12.89 μg/mL). Methanol extract showed a strong H2O2 scavenging activity (IC50233.71 ± 3.72 μg/mL). The highest Fe3+ reducing capacity was shown by methanol extract (Absorbance = 0.36 ± 0.05). Strong and positive correlations were observed between total phenolic and flavonoid contents and the antioxidant assays. The results of the present work revealed that the tested spice demonstrated high antioxidant activity, total phenolics, and flavonoids. Thus, this spice is worth considering as important source of natural antioxidant agents.

Perception Towards COVID-19 Related Symptoms and Traditional Medicine Used for Their Management Among Patients and Their Attendants in Ethiopian Comprehensive Specialized Hospitals: A Cross-Sectional Study

Background

Methods

Results

Conclusion

Natural products can be used in therapeutic management of COVID-19: Probable mechanistic insights

The unexpected emergence of the new Coronavirus disease (COVID-19) has affected more than three hundred million individuals and resulted in more than five million deaths worldwide. The ongoing pandemic has underscored the urgent need for effective preventive and therapeutic measures to develop anti-viral therapy. The natural compounds possess various pharmaceutical properties and are reported as effective anti-virals. The interest to develop an anti-viral drug against the novel severe acute respiratory syndrome Coronavirus (SARS-CoV-2) from natural compounds has increased globally. Here, we investigated the anti-viral potential of selected promising natural products. Sources of data for this paper are current literature published in the context of therapeutic uses of phytoconstituents and their mechanism of action published in various reputed peer-reviewed journals. An extensive literature survey was done and data were critically analyzed to get deeper insights into the mechanism of action of a few important phytoconstituents. The consumption of natural products such as thymoquinone, quercetin, caffeic acid, ursolic acid, ellagic acid, vanillin, thymol, and rosmarinic acid could improve our immune response and thus possesses excellent therapeutic potential. This review focuses on the anti-viral functions of various phytoconstituent and alkaloids and their potential therapeutic implications against SARS-CoV-2. Our comprehensive analysis provides mechanistic insights into phytoconstituents to restrain viral infection and provide a better solution through natural, therapeutically active agents.

Plant lectins as prospective antiviral biomolecules in the search for COVID-19 eradication strategies

Lectins or clusters of carbohydrate-binding proteins of non-immune origin are distributed chiefly in the Plantae. Lectins have potent anti-infectivity properties for several RNA viruses including SARS-CoV-2. The primary purpose of this review is to review the ability of lectins mediated potential biotherapeutic and bioprophylactic strategy against coronavirus causing COVID-19. Lectins have binding affinity to the glycans of SARS-COV-2 Spike glycoprotein that has N-glycosylation sites. Apart from this, the complement lectin pathway is a "first line host defense" against the viral infection that is activated by mannose-binding lectins. Mannose-binding lectins deficiency in serum influences innate immunity of the host and facilitates infectious diseases including COVID-19. Our accumulated evidence obtained from scientific databases particularly PubMed and Google Scholar databases indicate that mannose-specific/mannose-binding lectins (MBL) have potent efficacies like anti-infectivity, complement cascade induction, immunoadjuvants, DC-SIGN antagonists, or glycomimetic approach, which can prove useful in the strategy of COVID-19 combat along with the glycobiological aspects of SARS-CoV-2 infections and antiviral immunity. For example, plant-derived mannose-specific lectins BanLac, FRIL, Lentil, and GRFT from red algae can inhibit and neutralize SARS-CoV-2 infectivity, as confirmed with in-vitro, in-vivo, and in-silico assessments. Furthermore, Bangladesh has a noteworthy resource of antiviral medicinal plants as well as plant lectins. Intensifying research on the antiviral plant lectins, adopting a glyco-biotechnological approach, and with deeper insights into the "glycovirological" aspects may result in the designing of alternative and potent blueprints against the 21st century's biological pandemic of SARS-CoV-2 causing COVID-19.

Characterization of a Caffeic Acid 8-O-Methyltransferase from Citrus and Its Function in Nobiletin Biosynthesis

Nobiletin (3',4',5,6,7,8-hexamethoxyflavone) is a polymethoxylated flavonoid specifically accumulated in citrus fruit with numerous beneficial effects to human health. In this study, a novel O-methyltransferase (CitOMT2) was isolated from three citrus varieties, Ponkan mandarin (Citrus reticulata Blanco), Nou 6 ("King mandarin" × "Mukaku-kishu"), and Satsuma mandarin (Citrus unshiu Marc.), and its functions were characterized in vitro. The gene expression results showed that CitOMT2 was highly expressed in the two nobiletin abundant varieties of Ponkan mandarin and Nou 6. However, the expression level of CitOMT2 was low in the flavedo of Satsuma mandarin, in which only a small amount of nobiletin was accumulated. Functional analysis suggested that CitOMT2 was a caffeic acid 8-O-methyltransferase, and it catalyzed the O-methylation of 7,8-dihydroxyflavone at 8-OH. As the methylation of flavone at 8-OH was required for nobiletin biosynthesis, the results presented in this study suggested that CitOMT2 was a key gene regulating nobiletin accumulation in citrus fruit.

Traditional Medicine Practice in the Context of COVID-19 Pandemic: Community Claim in Jimma Zone, Oromia, Ethiopia

Purpose

To assess traditional medicine practice claims by the community for the prevention and treatment of COVID-19.

Methods

A community-based cross-sectional study design was conducted among 422 households of Jimma Zone, and the data were collected by interviewing individuals from the selected households. The medicinal plants were recorded on Microsoft excel 2010 with their parts used, dosage form, route of administration and source of plants and tabulated in the table. Descriptive statistics were used to describe and organize the data. The Relative Frequency of Citation (RFC) was calculated for each traditional medicine to identify the top 10 medicinal products.

Results

Around 46% of participants used traditional medicines for the prevention and treatment of COVID-19. The study recorded 32 herbal and non-herbal medicinal products. Garlic (RFC: 0.166), ginger (RFC: 0.133), lemon (RFC: 0.133), garden cress (RFC: 0.069) and “Damakase” (RFC: 0.031) were the frequently used herbal medicines. Seeds (47.22%) and leaves (30.56%) were the most used parts of medicinal plants. Most preparation of medicinal plants (90.63%) was administered through the oral route. The majority of medicinal plants were from home gardens.

Conclusions and Recommendations

Around half of the participants practiced traditional medicines for COVID-19. Garlic, ginger, lemon, garden cress and “Damakase” were the frequently used herbal products. Seeds and leaves were regularly used parts. The oral route is the most used route of administration. The majority of medicinal plants were from home gardens. This quantity of traditional medicine practice is probably challenging to control the pandemic. However, it might open possibilities for pharmaceutical industries and researchers to look into the effectiveness and safety of claimed medicinal products. Therefore, all responsible bodies are advocated to behave accordingly.