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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