Malaria remains an overwhelming infectious disease with significant health challenges in African and other endemic countries globally. Resistance to antimalarial drugs has become one of the most momentous challenges to human health, and thus has necessitated the hunt for new and effective drugs. Consequently, few decades have witnessed a surfeit of research geared to validate the effectiveness of commonly used traditionally medicines against malaria fever. The present review work focuses on documenting natural products from African whose activity has been reported in vivo or in vitro against malaria parasite. Literature was collected using electronic search of published articles (Google Scholar, PubMed, Medline, Sciencedirect, and Science domain) that report on antiplasmodial activity of natural products from differernts Africa region. A total of 652 plant taxa from 146 families, 134 isolated antimalarial compounds from 39 plants species, 2 herbal formulations and 4 insect/products were found to be reported in literature from 1996 to 2015. Plants species from family Asteraceae (11.04%), Fababceae (8.128%), Euphorbiaceae (5.52%), Rubiaceas (5.52%), and Apocyanaceae (5.214%), have received more scientific validation than others. African natural products possess remarkable healing properties as revealed in the various citations as promising antimalarial agents. Some of these natural products from Africa demonstrate high, promising or low activities against Plasmodium parasite. This study also shows that natural products from Africa have a huge amount of novel antimalarial compounds that could serve as a leads for the development of new and effective antiplasmodial drugs. However, in a view of bridging the gap in knowledge, clinical validation of these natural products are of paramount importance.

Free radicals are highly reactive molecules generated during oxidation reactions which in turn initiate chain reactions resulting to cellular damage. There is substantial evidence implicating free radicals especially reactive oxygen species (ROS) in the etiology of more than one hundred degenerative disorders in humans including, arthritis, atherosclerosis, ischemia and reperfusion injury of many tissues, gastritis, diabetics, central nervous system injury, acquired immunodeficiency syndrome (AIDS) and cancer. Scientific evidence postulates that bioactive compounds especially from natural products are capable of providing protection against free radicals. Consequently, few decades have witnessed a surfeit of research geared towards validating the antioxidant and hepatoprotective potential of the natural products. In this review, African natural products whose antioxidants activities were scientifically validated either in their crude extracts and/or derived products have been discussed. A total 1076 plants species representing 287 family, 132 isolated compounds and 7 insect/mollusk secreation were found. The plant species from the following families; Fababceae, Asteraceae, Lamiaceae, Moraceae, Euphorbiaceae, Combretaceae and Malvaceae have received more scientific attention than others. Analysis of the reports revealed that Combretum apiculatum, Telfaria occidentalis, Acalypha racemosa, Garcinia lucida were the most active plant extracts from African flora. The most active ROS-detoxifying phytochemicals were moracin T, U, S and R (84-87), oleanolic acid (54), 5,7,4′-trihydroxy-3,8,3′,5′-tetramethoxyflavone (89), 5,7,3′-trihydroxy-3,8,4′,5′-trimethoxyflavone (88), luteolin (3′,4′,5,7-tetrahydroxy flavone) (117) and genistein (4′,5,7-trihydroxyisoflavone) (116). The significant antioxidant potential demonstrated by some crude extracts and their constituent compounds render them good candidates for the development of new drugs. Although, the study of the mechanisms of actions as well as clinical validation of some of these isolated compounds is lacking. It is hoped that pertinent scientist and stakeholders will look further into some of these compounds for detailed authentification and subsequent commercialization.

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Background: Zingiber officinale is a rhizome commonly consumed as a delicacy, medicine or spice. It is considered as a safe spice with several medicinal properties. The aim of this study was to evaluate in-vitro antioxidants, antimicrobial and safety of Nigerian Z. Officinale. Methods: Methanol extract of Nigerian Z. Officinale (MEZO) was evaluated for phytochemical composition, total flavonoids and phenol contents using standard procedures. Antibacterial study was carried out via the agar well diffusion method. Antioxidant activities were carried out using 2, 2′-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing antioxidant properties (FRAP) assay. Twenty five (25) wister rats were randomly grouped into five (A-E) of five animals each. Animals in Groups AD were orally administered 75,150, 300 and 600 mg/kg bwt of the extract on daily basis for 4 weeks while those in Group A (control) received distilled water. Results: Total phenolic and flavonoids contents of the extract were 15.24 ± 0.02 mg GAE/g and 19.84 ± 0. 32 mg/g CE respectively. The extract promoted an inhibition of free radicals with IC 50 values of 47.05 ± 2. 03 μg/mL and 89.15 ± 0.29 μg/mL in DPPH and FRAP assay. At extract concentration of 100 μg/mL, K. pneumoniae showed the highest susceptibility of 29.04 ± 0.35 mm, followed by P. aeuruginisa (26.03 ± 0.41 mm), while S. aureus (15.08 ± 0.20 mm) was least susceptible. The serum concentrations of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), sodium, albumin, total proteins and the computed organs/body weight ratios compared favorably (p > 0.05) with control at all extract doses tested. The bilirubin, urea and creatinine levels significantly (p < 0.05) increase while chloride decreases in rats dosed 600 mg/kg bwt. However, potassium level increases significantly (p < 0.05) in rats dose 300 mg/kg of the extract when compare with the control. Conclusion: This study revealed the strong antioxidant and antimicrobial potentials of methanol extract of Nigerian Zingiber officinale. It was also found to be relatively safe for consumption and thus could serve as a source of candidate for the development of new antioxidants and antimicrobial drugs.

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The genus Phyllanthus (Phyllantaceae) is widely used in the african system of traditional medicine and is reported to have various biological activities. In this study, antimicrobial and antioxidant activities of nhexane and ethyl acetate fractions of Phyllanthus fraternus leaves were investigated. The antimicrobial screening was carried out against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomonas aeruguinosa, Salmonella typhi and Klebsiella pneumoniae, using Agar-well diffusion method. The antioxidant activity was carried out using DPPH free radical scavenging capacity. The results show that fractions of Phyllanthus fraternus leaves have DPPH radical scavenging activities with IC50 value of 263.53 mg/mL and 143.56 mg/mL for n-hexane and ethyl acetate fractions respectively. For n-hexane fraction, the MICs of the extract were; 80 mg/mL against K. pneumoniae and S. aureus,120 mg/mL against P. aeruginosa and S. typhi, and 160 mg/mL against E. Coli. However, ethyl acetate fraction had MICs of 80 mg/mL against all test organisms except S. aureus (40 mg/mL). The nhexane and ethyl acetate fractions of Phyllanthus fraternus leaves exhibited considerable antioxidant and antimicrobial properties, with ethyl acetate fraction been the most potent. This plant extract can be regarded as promising resource for antimicrobial and antioxidant drugs.

BackgroundSeveral studies described the phytochemical constituents of plants in relation with the free radical scavenging property and inhibition of lipid peroxidation. This study investigated the in vitro antioxidant property, and the protective effects of ethanolic and aqueous ethanol extract of the leaves and barks of Afrostyrax lepidophyllus (Huaceae) against ion mediated oxidative damages.MethodsFour extracts (ethanol and aqueous-ethanol) from the leaves and barks of A. lepidophyllus were used in this study. The total phenols content, the antiradical and antioxidant properties were determined using standard colorimetric methods.ResultsThe plant extracts had a significant scavenging potential on the 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl (OH), nitrite oxide (NO) and 2,2-azinobis (3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) radicals with the IC50 varied between 47 and 200 µg/mL depending on the part of plant and the type of extract. The ethanol extract of A. lepidophyllus bark (GEE) showed the highest polyphenolic (35.33 ± 0.29) and flavonoid (12.00 ± 0.14) content. All the tested extracts demonstrated a high protective potential with the increased of superoxide dismutase, catalase and peroxidase activities.ConclusionAfrostyrax lepidophyllus extracts exhibited higher antioxidant potential and significant protective potential on liver enzymes.Electronic supplementary materialThe online version of this article (doi:10.1186/s13104-015-1304-8) contains supplementary material, which is available to authorized users.

Despite the growing scientific interest in finding effective treatment, SARS-CoV-2 virus remains a global major health burden and public health emergency. SARS-CoV main protease (Mpro) also known as chymotrypsin-like protease (3CLpro) is an important protein identified to be vital for SARS-CoV-2 survival. However, to date, there are no clinically approved drugs or antibodies specific for SARS-CoV-2. In the present study, we evaluated the interaction of 3CLpro with azadirachtin-A a bioactive compound from Azadiracta indica using in silico molecular docking study. Our results revealed that Azadiractin A docked well into the binding cavity of 3CLproSARS-CoV-2 with binding affinities ranges between -6.3 and -5.20 kcal/mol, and Pkd of 5.82~6.10 for the ten best binding modes. Azadiractin interacted with the active site of 3CLpro-SARS-CoV-2 by 2 conventional hydrogen bonding to HIS163 and GLU166, C-H interactions with HIS127, and alkyl interaction with PRO168 of the 3CLpro-SARS-CoV-2. We also found that the Azadiractin-A_3CLpro-SARS-CoV-2 complex is stabilized by various Vander wall forces with ASN142, LEU141, PHE140, MET165, GLN189, LEU167, THR190, and ALA191. In conclusion, our results suggested that Azadirachtin-A could be a potential inhibitor of SARS-CoV-2 main protease, thus worthy of further preclinical study.