Smith B. Babiaka

AfroDb: a select highly potent and diverse natural product library from African medicinal plants.

Computer-aided drug design (CADD) often involves virtual screening (VS) of large compound datasets and the availability of such is vital for drug discovery protocols. We assess the bioactivity and “drug-likeness” of a relatively small but structurally diverse dataset (containing >1,000 compounds) from African medicinal plants, which have been tested and proven a wide range of biological activities. The geographical regions of collection of the medicinal plants cover the entire continent of Africa, based on data from literature sources and information from traditional healers. For each isolated compound, the three dimensional (3D) structure has been used to calculate physico-chemical properties used in the prediction of oral bioavailability on the basis of Lipinski’s “Rule of Five”. A comparative analysis has been carried out with the “drug-like”, “lead-like”, and “fragment-like” subsets, as well as with the Dictionary of Natural Products. A diversity analysis has been carried out in comparison with the ChemBridge diverse database. Furthermore, descriptors related to absorption, distribution, metabolism, excretion and toxicity (ADMET) have been used to predict the pharmacokinetic profile of the compounds within the dataset. Our results prove that drug discovery, beginning with natural products from the African flora, could be highly promising. The 3D structures are available and could be useful for virtual screening and natural product lead generation programs.

A Bioactivity Versus Ethnobotanical Survey of Medicinal Plants from Nigeria, West Africa

Traditional medicinal practices play a key role in health care systems in countries with developing economies. The aim of this survey was to validate the use of traditional medicine within local Nigerian communities. In this review, we examine the ethnobotanical uses of selected plant species from the Nigerian flora and attempt to correlate the activities of the isolated bioactive principles with known uses of the plant species in African traditional medicine. Thirty-three (33) plant species were identified and about 100 out of the 120 compounds identified with these plants matched with the ethnobotanical uses of the plants.

Bioassay-guided discovery of antibacterial agents: in vitro screening of Peperomia vulcanica, Peperomia fernandopoioana and Scleria striatinux

BackgroundThe global burden of bacterial infections is high and has been further aggravated by increasing resistance to antibiotics. In the search for novel antibacterials, three medicinal plants: Peperomia vulcanica, Peperomia fernandopoioana (Piperaceae) and Scleria striatinux (Cyperaceae), were investigated for antibacterial activity and toxicity.MethodsCrude extracts of these plants were tested by the disc diffusion method against six bacterial test organisms followed by bio-assay guided fractionation, isolation and testing of pure compounds. The minimum inhibitory (MIC) and minimum bactericidal (MBC) concentrations were measured by the microdilution method. The acute toxicity of the active extracts and cytotoxicity of the active compound were performed in mice and mammalian cells, respectively.ResultsThe diameter of the zones of inhibition (DZI) of the extracts ranged from 7–13 mm on Escherichia coli and Staphylococcus aureus of which the methylene chloride:methanol [1:1] extract of Scleria striatinux recorded the highest activity (DZI = 13 mm). Twenty-nine pure compounds were screened and one, Okundoperoxide, isolated from S. striatinux, recorded a DZI ranging from 10–19 mm on S. aureus. The MICs and MBCs indicated that the Peperomias had broad-spectrum bacteriostatic activity. Toxicity tests showed that Okundoperoxide may have a low risk of toxicity with an LC50 of 46.88 μg/mL.ConclusionsThe antibacterial activity of these plants supports their use in traditional medicine. The pure compound, Okundoperoxide, may yield new antibacterial lead compounds following medicinal chemistry exploration.

The uniqueness and therapeutic value of natural products from West African medicinal plants. Part I: uniqueness and chemotaxonomy

This review gives an in depth coverage of the natural products derived from West African medicinal plants with diverse biological activities. Unique compound classes from West African flora having remarkable biological activities have been highlighted, as well as a correlation between the biological activities of the derived compounds and the uses of the plants in traditional African medicine, and their chemotaxonomic classifications have been included in the discussion. In the first part of the review, the focus is on alkaloids and flavonoids.

The uniqueness and therapeutic value of natural products from West African medicinal plants, part II: terpenoids, geographical distribution and drug discovery

In this review series, an attempt has been made to give indepth coverage of natural products derived from West African medicinal plants with diverse biological activities. In part II of this series, emphasis has been laid on terpenoids from West African flora having remarkable biological activities, as well as a correlation between biological activities of the derived compounds and the uses of the plants in African traditional medicine. The impact of geographical distribution on the chemical contents of selected plant genera and their chemotaxonomic classifications have also been included in the discussion. Suggestions for drug discovery projects beginning with natural products from West Africa have also been provided.

The uniqueness and therapeutic value of natural products from West African medicinal plants, part III: least abundant compound classes

In this review, a continuation of our in-depth coverage of natural products derived from West African medicinal plants with diverse biological activities has been given. In the previous parts of this review series, the most abundant bioactive compound classes: terpenoids, flavonoids and alkaloids from West Africa were thoroughly investigated. We now focus on the least abundant compound classes (quinones, steroids, phenolics, glycosides, and other classes), having remarkable biological activities. A correlation between the biological activities of the derived compounds and the uses of the plants in African traditional medicine has been established.

The chemistry and bioactivity of Southern African flora II: flavonoids, quinones and minor compound classes

This review is intended to highlight the relevance of natural products in drug discovery paying particular attention to those derived from Southern African medicinal plants with diverse biological activities. In this review series, a literature survey led to the collection of 864 secondary metabolites from 101 plant species from 57 plant families. A correlation between the known biological activities of isolated compounds and the ethnobotanical uses of the plants has been attempted. Part I focused on alkaloids and terpenoids, while this part is focused on the bioactivities of flavonoids, quinines and other minor, unique compound classes which correlate with their ethnobotanical uses in African traditional medicine (ATM).

The chemistry and bioactivity of Southern African flora I: a bioactivity versus ethnobotanical survey of alkaloid and terpenoid classes

As a whole, the African continent is highly endowed with a huge floral biodiversity. Natural products which have been isolated from plants growing in this region have shown interesting chemical structures with diverse biological activities, which could serve as a starting point for drug discovery. In this study, a literature survey led to the collection of 864 secondary metabolites from 101 plant species from 57 plant families. A correlation between the known biological activities of isolated compounds and the ethnobotanical uses of the plants has been attempted. This review is a survey of the bioactivities of alkaloids and terpenoids which have been isolated from Southern African flora versus the ethnobotanical uses of the plants used in Southern African traditional medicine.

Isolation of natural product hits from Peperomia species with synergistic activity against resistant Plasmodium falciparum strains.

Aims :This study investigated the antiplasmodial activity of crude extracts, fractions and pure isolates ofP. vulcanicaand P. fernandopoioana(Piperaceae). Toxicity and interaction between the most active natural products were also assessed. Study Design: Bioassay-guided approach was used to identify and further investigate the most active components against chloroquine -sensitive and resistant P. falciparumstrains. Place and Duration of Study:Departments of Biochemistry and Molecular Biology, Chemistry and Biotechnology Unit, Faculty of Science, University of Buea, Cameroon for one year. Methodology: Test substances were prepared fromthe two plants and screened on four strains of P. falciparum(chloroquine-sensitive 3D7, multidrug resistant W2mef and Dd2, and a field isolate

Molecular modeling of plant metabolites with anti-Onchocerca activity

Onchocerciasis or river blindness is a parasitic disease of man, caused by the filarial worm Onchocerca volvulus. It afflicts an estimated 37 million people, among whom 300,000 are blind and an additional 500,000 are visually impaired. The only class of drug targets whose X-ray crystal structure has been solved is the glutathione transferases, co-crystallized with a cofactor and a competitive inhibitor (glutathione and S-hexylglutathione). In a quest to identify potential hit compounds for drug discovery and to further explore potential inhibitory mechanisms of plant-derived anti-Onchocerca compounds, we have carried out an in silico study. The goal has been to devise molecular modeling approaches for virtual screening simulations, which could lead to the identification of potential inhibitors of this drug target from plant chemical libraries. Docking studies have been carried out for eight known plant-derived compounds showing in vitro activities against Onchocerca species. The computed binding affinities of the naturally occurring anti-Onchocerca compounds are comparable to the known co-crystallized inhibitor. Our study has laid a foundation for further investigations of naturally occurring O. volvulus drug targets. Explorations of the protein–ligand interactions from the docking poses have provided insight for potential binding interactions of interest, which could be exploited in searching for lead compounds.