Potential role of metabolomics in the improvement of research on traditional African medicine

The global market for herbal medicine is growing steadily. The usage of herbal medicine is particularly common in many parts of Africa; the World Health Organization estimates that approximately 80% of Africans rely on traditional African medicines (TAMs) for treating various diseases. TAMs hold promise in preventive treatment, early disease intervention and personalized medicine. However, clinical integration of TAMs is restricted due to limited information concerning their characterization. Presently, many studies on TAMs utilize a reductionist approach, making it extremely difficult to understand the holistic modifying effects that these therapeutic agents may have on biological systems. Fortunately, emerging technologies such as metabolomics platforms adopt a ⿿top-down⿿ strategy that permits a holistic evaluation of the components, metabolic pathways and biomarkers modified by TAMs, which can aid in addressing common concerns over safety and toxicity, while also ensuring that quality control standards are met. Metabolomics approaches may also be beneficial for advancing our understanding of the efficacy and mechanism of action of TAMs, and may contribute to the advancement of research and drug discovery, early diagnosis, preventive treatment and TAMs-driven personalized medicine in Africa. This review also considers the main challenges that may hinder the adoption and integration of metabolomics approaches in research on TAMs in Africa and suggests possible solutions.     

Western equatorial Pacific planktic foraminiferal fluxes and assemblages during a La Niña year (1999)

A correlation between foraminiferal community dynamics and environmental conditions may provide a basis for establishing paleoclimatic proxies. We studied planktic foraminiferal shell fluxes and assemblages in samples collected in three time-series sediment trap deployments in the western equatorial Pacific under La Niña conditions from January to November 1999. Eleven species contributed about 90% of the total flux in all traps. Two sites (MT1, MT3) in the Western Pacific Warm Pool region (WPWP) were characterized by common occurrences of the species Globigerinoides ruber, Globigerinoides sacculifer, Globigerinoides tenellus, and Neogloboquadrina dutertrei. Site MT5 farther to the east in the equatorial upwelling region had common occurrences of Globigerina bulloides, Globigerinita glutinata, and Pulleniatina obliquiloculata. Very high abundances of G. bulloides and G. glutinata at MT5 indicate that equatorial upwelling (EU) occurred during the 1999 La Niña. The two western sites have similar assemblage compositions, but MT1 ( 135°E) has the highest fluxes (up to  3800 tests m^− 2 day^− 1), whereas MT3 ( 145° E) has fluxes below  2200 tests m^− 2 day^− 1. Relatively high fluxes (up to  3000 tests m^− 2 day^− 1) occur at site MT5 ( 176° E), where upwelling occurred.The differences in faunal composition in the WPWP and EU might be attributable to differences in the way in which nutrients are supplied to the phytoplankton: large amounts of suspended material are supplied to the WPWP by advection of waters passing through the coastal region of an archipelago, whereas upwelling of nutrient-rich waters enhances primary production in the EU. At the westernmost site in the WPWP, a peak in the G. bulloides flux coincided with southward flow of the New Guinea Coastal Current (NGCC) in late February, but the highest G. ruber flux coincided with northward flow of this current in late May. Thus, the differences in species dominance at this location may be caused by monsoon-driven variability in the flow direction of the NGGC.     

IL-10 is up regulated in early and transitional stages in vervet monkeys experimentally infected with Trypanosoma brucei rhodesiense

IL-10 has been suggested as a possible parameter for human African trypanosomiasis stage determination. However, conclusive experimental studies have not been carried out to evaluate this, which is a prerequisite before a potential test can be validated in humans for diagnostic purposes. We used the vervet monkey model of trypanosomiasis to scrutinize IL-10 in blood and cerebrospinal fluid (CSF). Five adult males were experimentally infected with T. b. rhodesiense. The infected animals became anemic and exhibited weight loss. Parasitemia was patent after 3 days and fluctuated around 3.7 × 10⁷ trypanosomes/ml throughout the experimental period. The total CSF white cell counts increased from pre-infection means around 3 cells/μl to a peak of 30 cells/μl, 42 days post-infection (DPI). IL-10 was not detectable (< 2 pg/ml) in serum prior to infection. IL-10 serum concentrations increased to 273 pg/ml 10 DPI coinciding with the first peak of parasitemia. Thereafter the levels declined to a mean value of 77 pg/ml 34 DPI followed by a significant rise to a second peak of 304 pg/ml (p < 0.008) 42 DPI. There was no detectable IL-10 in CSF. IL-10 synthesis is thus stimulated both in the early and transitional stages of experimental trypanosomiasis. That IL-10 is produced in early stage disease is an interesting finding unlikely to be detected in humans where it is difficult to determine the exact time of infection. The IL-10 peak observed on day 42 of infection might indicate onset of parasite neuroinvasion coinciding with a peak in white blood cell counts in the blood and CSF.     

Phenetic investigation of non-nodulating African species ofAcacia (Leguminosae) using morphological and molecular markers

Morphological and RAPD markers were used to assess the relationships among nodulating and non-nodulating species of AfricanAcacia. Non-nodulating species of AfricanAcacia are only found within subg.Aculeiferum sect.Monacanthea. African species of sect.Monacanthea examined were found to form a group distinct from the other African species examined on a morphological and molecular basis. All lack the ability to nodulate, suggesting that non-nodulation may be used as a taxonomic tool. The species of sect.Aculeiferum were separated by RAPD and morphological analysis into two groups depending on whether they were armed with prickles in pairs and/or prickles in threes, or solitary. A third group of species was identified within sect.Acacia: further subdivision of this group was achieved into subsectt.Pluriseriae andUniseriae. The position ofA. albida relative to other AfricanAcacia species was found to be distinct but not totally independent of the genus. The partitioning and distribution of the genetic variability within the genus is further elucidated by the RAPD analysis of populations ofAcacia species. A population analysis ofA. polyacantha demonstrated geographical and site-specific variation.     

Agrobacterium-mediated transformation of African violet

A method for genetic transformation of Saintpaulia ionantha by co-cultivation of in vitro-grown leaves and petioles with Agrobacterium tumefaciens is described. Two bacterial strains, EHA105 and A281 both harbouring the binary plasmid pKIWI105 carrying the genes uidA and nptII, were used in the experiments. Regenerants were not obtained using the disarmed strain EHA105. The oncogenic strain A281 resulted in efficient transient and stable expression of the transferred traits for petiole explants only. After transformation and regeneration, the integration of the transgenes in the plant genome was confirmed by PCR analysis and Southern hybridization.     

Insight on Propolis from Mediterranean Countries: Chemical Composition,Biological Activities and Application Fields

This review updates the information upon the chemical composition of propolis from all Mediterranean countries as well as their biological properties and applications. The non‐volatile fraction of propolis was characterized by the presence of phenolic acids and their esters and flavonoids. Nevertheless, in some countries, diterpenes were also present: Sicily (Italy), Croatia, Malta, Creta (Greece), Turkey, Cyprus, Egypt, Libya, Algeria and Morocco. The volatile fraction of propolis was characterized by the presence of benzoic acid and its esters, mono‐ and sesquiterpenes, being the oxygenated sesquiterpene β‐eudesmol characteristic of poplar propolis, whereas the hydrocarbon monoterpene α‐pinene has been related with the presence of conifers. Regardless the chemical composition, there are common biological properties attributed to propolis. Owing to these attributes, propolis has been target of study for applications in diverse areas, such as food, medicine and livestock.     

Complex interaction between serum folate levels and genetic polymorphisms in folate pathway genes: biomarkers of prostate cancer aggressiveness

Little is known about the role of folate and polymorphisms associated with folate metabolism on prostate cancer risk in populations of African origin. We examined the relationship between serum folate and prostate cancer and whether any association was modified by genetic polymorphisms for folate metabolism. The study was case–control in design and consisted of 218 men 40–80 years old with newly diagnosed, histologically confirmed prostate cancer and 236 cancer-free men attending the same urology clinics in Jamaica, March 2005–July 2007. Serum folate was measured by an immunoassay method and genomic DNA evaluated for MTHR (C677T and A1298C), MTRR A66G, and MTR A2756G polymorphisms. Mean serum folate concentration was higher among cases (12.3 ± 4.1 nmol/L) than controls (9.7 ± 4.2 nmol/L). Serum folate concentration showed a positive association with prostate cancer (OR, 4.41; CI, 2.52–7.72 per 10 nmol/L) regardless of grade. No interactions were observed between genotype and folate concentration, but a weak gene effect was observed for MTHFR A1298C and low-grade prostate cancer. Larger studies to investigate the role of gene–gene/gene–diet interactions in Black men are needed.     

Africans in the diaspora: black-white earnings differences among America's Africans

The condition of Africans in the diaspora proffers insight into not just their adaptation to their new countries, but also the nature of racial stratification at their destinations. We examine race differences in earnings between black and white Africans in America and find sizeable differences among immigrants who have relatively similar human capital profiles. Whites have annual earnings 80 per cent higher than their black counterparts, and the gap in hourly wage is almost 48 per cent. More significantly, more than half (53 per cent) of the race difference in wages remains unexplained by earnings-related attributes such as education, occupation, and hours worked. We discuss these results against the backdrop of the ongoing debate on discrimination and the significance of race for socio-economic attainment in America.     

Effects of Azadirachtin on reproduction in the African armyworm (Spodoptera exempta)

Azadirachtin, applied topically to final instar larvae of the African armyworm (Spodoptera exempta, Walker) (Lepidoptera: Noctuidae), adversely affected oogenesis and reproductive maturation in subsequent female moths. Moths obtained from such treated larvae failed to mature their oocytes, probably as a result of interference of azadirachtin with vitellogenin synthesis and/or its uptake by developing oocytes. Such larval treatment also caused substantial decreases in fecundity and although fertility in affected females was not decreased significantly, emerging larvae were less viable, less than 40% reaching the fourth instar.Closer examination revealed that protein levels as well as fat body development in female moths were suppressed by azadirachtin. Prospects for field control of this pest with neem are discussed in the light of these findings.

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Résumé L'application locale d'azadirachtine sur des chenilles de dernier stade de S. exempta Walker nuit à l'ovogenèse et à la maturation des ovaires des futures femelles. Les papillons provenant des chenilles traitées ne produisent pas d'ovocytes mûrs, probablement par suite de l'interférence de l'azadirachtine avec la synthèse de la vitellogénine et/ou son incorporation dans les ovocytes en développement. De tels traitements larvaires provoquent aussi une diminution importante de la fécondité et bien que la fertilité des femelles touchées ne diminue pas significativement, les chenilles néonates sont moins viables, moins de 40% atteignant le 4^e stade. Un examen plus précis a révélé que la teneur en protéines et le développement du corps gras des papillons femelles étaient altérés par l'azadirachtine. Des perspectives d'utilisation du NEEM dans la lutte contre cet insecte ont été discutées à la lumière de ces résultats.

     

Distribution,degree of damage and risk of spread of Trioza erytreae (Hemiptera: Triozidae) in Kenya

The African citrus triozid (ACT), Trioza erytreae Del Guercio, is a destructive pest particularly on citrus, and vectors, “Candidatus” Liberibacter africanus (CLaf), which is the causal agent of the African citrus greening disease. Our study seeks to establish the distribution and host‐plant relationship of ACT across citrus production areas in Kenya. We also modelled the risk of spread using the maximum entropy modelling algorithm with known occurrence data. Our results infer that ACT is widely distributed and causes severe damage to four alternative host plants belonging to the family Rutaceae. The adults, immature stages (eggs and nymphs), galls and the percentage of infested leaves were significantly higher in shaded than unshaded trees. However, adult ACTs preferred Kenyan highlands to Victoria Lake and coastal regions. The average area under the curve of the model predictions was 0.97, indicating an optimal model performance. The environmental variables that most influenced the prediction were the precipitation of wettest quarter, precipitation of wettest month, mean diurnal range, temperature seasonality and mean temperature of the coldest quarter. The current prediction of ACT exceeded its existing range, especially in the Western, Nyanza, Central, Rift valley and Eastern regions of Kenya. The model predicted a contraction of suitable habitats for a potential spread in 2040 with an inland shift to higher altitudes in the cooler regions. The potential for further expansion to climatically suitable areas was more pronounced for the 2080 forecast. These findings provide relevant information to improve monitoring/surveillance and designing IPM strategies to limit its spread and damage.