Combined U-Pb isotopic signatures of U mill tailings from France and Gabon: A new potential tracer to assess their fingerprint on the environment.

Uranium milling activities have produced high volumes of long-lived radioactive processed wastes stored worldwide in near surface environment. The aim of this study is to highlight relevant tracers that can be used for environmental impact assessment studies involving U mill tailings. A multi-tracer study involving elemental content, 238U decay products disequilibria and stable Pb isotopes was performed in different types of U mill tailings (alkaline, acid, neutralized acid) collected from five Tailings Management Facilities in France (Le Bosc, L'Ecarpière, Le Bernardan, and Bellezane) and Gabon (Mounana). Our results showed that U and Pb concentrations range between 30 and 594 ppm and 66-805 ppm, respectively. These tailings have a strong disequilibrium of (234U/238U) and (230Th/238U) activity ratios (1.27-1.87 and 6-65, respectively), as well as higher 206Pb/207Pb (1.86-7.15) and lower 208Pb/207Pb (0.22-2.39) compared to geochemical background ((234U/238U) and (230Th/238U) equal to unity; 206Pb/207Pb = 1.20; 208Pb/207Pb = 2.47). In situ analyzes (SEM, SIMS) showed that Pb-bearing phases with high 206Pb/207Pb are related to remaining U-rich phases, S-rich phases and potentially clay minerals or oxyhydroxides. We suggest that the combination of the 206Pb/207Pb with the (234U/238U) ratio is a relevant tool for the fingerprinting of the impact of U milling activities on the environment.

Indications et résultats de la splénectomie chez le drépanocytaire au Centre Hospitalier Universitaire de Libreville / Indications and results of splenectomy in sickle cell patients at the University Hospital Center of Libreville

Introduction : la drépanocytose est une affection génétique héréditaire responsable d'une déformation des hématies en «faucilles¼. Elle peut engendrer de nombreuses complications parmi lesquelles la séquestration splénique et l'hypersplénisme. La splénectomie fait partie de l'arsenal thérapeutique, induisant un état d'hyposplénie ou d'asplénie aux conséquences parfois mortelles, surtout chez le sujet drépanocytaire. Le but de ce travail mené au service de chirurgie du centre hospitalier universitaire de Libreville au Gabon, est de déterminer les indications et les résultats à moyen terme de la splénectomie chez le drépanocytaire.Matériel et méthodes : il s'agissait d'une étude rétrospective, descriptive et monocentrique allant d'octobre 2016 à avril 2019. Tous les dossiers des patients drépanocytaires opérés d'une splénectomie seule ou associée à un autre geste chirurgical étaient retenus.Résultats : au total treize patients ont été inclus dans notre étude. L'âge moyen des patients était de 10,7 ans [3-25 ans]. L'indication opératoire était l'hypersplénisme (8 cas), la séquestration splénique (3 cas), et l'infarctus splénique (2 cas). Tous les patients étaient opérés d'une splénectomie totale par laparotomie. La vaccinothérapie et l'antibioprophylaxie post-opératoire étaient réalisées chez tous les patients. Aucune complication post-opératoire immédiate ni aucun décès n'avaient été noté chez tous les patients.Conclusion : l'indication des splénectomies chez le drépanocytaire est dominée par l'hypersplénisme. Dans notre context la splénectomie totale par laparotomie semble être la règle. La vaccination prophylactique est bien administrée. La morbi-mortalité post-opératoire immédiate est nulle.

Introduction: Sickle cell disease is a genetic inherited disorder responsible for the deformation of red blood cells into"sickles". It can lead to many complications including splenic sequestration and hypersplenism. Splenectomy is the indicated gesture. It induces a state of hyposplenia or asplenia with dreadful consequences, sometimes fatal especially in this sickle cell patient. The aim of this work, conducted at the Surgery Department of Libreville University Hospital Center in Gabon, is to determine the indications and results of splenectomy in sickle cell patients.Material and methods: this was a retrospective, descriptive and single-center study from October 2016 to April 2019.All records of sickle cell patients undergoing splenectomy alone or with other surgical procedures were included.Results: a total of thirteen patients were included in our study. The average age of the patients was 10.7 years [3-25years]. The operative indication was hypersplenism (8 cases), splenic sequestration (3 cases), and splenic infarction(2 cases). All patients underwent total splenectomy under laparotomy. Vaccine therapy and postoperative antibiotic prophylaxis were performed in all patients. No immediatepostoperativecomplications or deaths were noted in all patients. Conclusion: the indication of splenectomies in sickle cell disease is dominated by hypersplenism. In our context, total splenectomy under laparotomy was the rule. Prophylactic vaccination is well administered. Immediate postoperative morbidity and mortality is nil.

[Gabonese traditional medicine, a complementary and alternative medical art]. / La médecine traditionnelle gabonaise, un art médical complémentaire et alternatif.

In Gabon, people use traditional medicine. This medical art has been built up over centuries upon the cultural diversity of the country and the richness of the fauna and the flora. It is an alternative and complementary medicine to the allopathic one. For the Gabonese, it is often the only option when faced with health structures that are geographically poorly distributed and that do not function well.

A Study of the Therapeutic Potential of Lentinus squarrosulus (Agaricomycetes) from Gabon.

Lentinus squarrosulus is a mushroom widely used in Gabon for its culinary and medicinal properties. The bioactive potential of mushrooms might be attributable to the presence of several pharmaceutically important mycocompounds that need to be ascertained scientifically. A study of the therapeutic potential of L. squarrosulus, the species of lignicolous fungus exploited in Gabon, was carried out on the basis of a chemical screening performed on three extracts in order to highlight different important chemical groups. This chemical screening was followed by a study of the fungus's antioxidant activity and prediction of its additional pharmacological activities. Chemical screening revealed that three extracts (aqueous, hydroethanolic, and ethanolic) of L. squarrosulus were almost free of tannins and were poor in total flavonoids and moderately rich in reducing sugars. Aqueous and ethanolic extracts were rich in total polyphenols, whereas aqueous and hydroethanolic extracts were rich in alkaloids. The aqueous extract was rich in saponosides and the hydroethanolic extract was rich in coumarins. The dosage of phenolic compounds confirmed the fungus's richness in total polyphenols, especially for aqueous and ethanolic extracts, its poverty in flavonoids and absence of tannins in ethanolic and hydroethanolic extracts. Regarding antioxidant activities, the results obtained for diphenyl picryl hydrazyl trapping tests showed that the different extracts tested had antioxidant activity ranging from low to moderate (0.12 ≤ antioxidant activity index [IAA] ≤ 0.6); the greatest activity was obtained with ethanolic extract (IAA = 0.6). Hence, we conclude that L. squarrosulus extracts can be used as easily accessible sources of natural antioxidants for potential preventative therapies.

Midwives and Post-abortion Care in Gabon: "Things have really changed".

Complications from spontaneous and induced abortion are a primary cause of death of women in sub-Saharan Africa. Le Réseau d'Afrique Centrale pour la Santé Reproductive des Femmes: Gabon, Cameroun, Guinée Équatoriale (the Middle African Network for Women's Reproductive Health, or GCG as it is commonly known) was founded in 2009 to identify and overcome obstacles to post-abortion care in Gabon. Research identified the main obstacle as lack of emergency skills and provisions among first-line health care providers. To fill the lacuna, GCG designed a program to train midwives in manual vacuum aspiration (MVA), misoprostol protocols, and the insertion of T-shaped copper IUDs. This article presents a nine-year retrospective (2009-2018) of the program. Qualitative and quantitative results confirm correlations between midwives' practice of MVA in health centers and spectacular decreases in treatment delays, with corresponding decreases in mortality from abortion complications. Our findings also demonstrate how these advances have been threatened by opposition to midwife practice in certain urban medical centers despite encouragement by the Gabon Ministry of Health to use the new protocols. Women's human right to the highest attainable standard of health, including access to safe abortion, is an assumption that GCG shares with the 40 African countries that have ratified the Protocol to the African Charter on Human and Peoples' Rights on the Rights of Women in Africa. The training program illustrates how a direct-action strategy can fully equip medical practitioners, especially those in peripheral sites with meager resources, to provide emergency post-abortion and abortion care even before governments legislate their human rights commitment.

Histone deacetylase inhibitors with high in vitro activities against Plasmodium falciparum isolates collected from Gabonese children and adults.

Histone deacetylase (HDAC) enzymes are targets for the development of antimalarial drugs with a different mode of action to established antimalarials. Broad-spectrum HDAC-inhibitors show high potency against Plasmodium falciparum, but displayed some toxicity towards human cells. Inhibitors of human HDAC6 are new drug candidates with supposed reduced toxicity to human cells and favorable activities against laboratory P. falciparum strains. We investigated the potency of 12 peptoid-based HDAC-inhibitors against asexual stages of P. falciparum clinical isolates. Parasites representing different genetic backgrounds were isolated from adults and children with uncomplicated malaria in Gabon. Clinical studies on (non-HDAC-inhibitors) antimalarials, moreover, found lower drug efficacy in children, mainly attributed to acquired immunity with age in endemic areas. Therefore, we compared the in vitro sensitivity profiles of adult- and child-derived isolates to antimalarials (HDAC and standard drugs). All HDAC-inhibitors showed 50% inhibitory concentrations at nanomolar ranges with higher activities than the FDA approved reference HDAC-inhibitor SAHA. We propose peptoid-based HDAC6-inhibitors to be lead structures for further development as antimalarial chemotherapeutics. Our results further suggest no differences in activity of the tested antimalarials between P. falciparum parasites isolated from children and adults.

[Behavior and attitudes towards smoking among student midwives in Libreville]. / Comportements et attitudes des élèves sages-femmes de Libreville vis-à-vis du tabagisme.

BACKGROUND: The midwife, in taking on a public health role, is one of the most important resources for the prevention of smoking and in helping smoking cessation among women of childbearing age thanks to their numerous contacts with pregnant women. With this in mind, we conducted a study among student midwives to examine their smoking behavior, their attitudes towards smoking, and their participation in prevention. METHOD: This was a descriptive cross-sectional study conducted from 15 January to 15 February 2018 using a self-administered questionnaire and included the student midwives of the University of Health Science at Libreville (Gabon). RESULTS: A total of 188 student midwives completed the questionnaires (70.7% of students of the 1st year, 15.0% of students of the 2nd year and 14.3% of students of the 3rd year). Gaps exist in the knowledge of student midwives regarding the risks of cigarette smoking in pregnancy and its role in the development of complications for the mother and foetus. Overall, 17.1% of student midwives think that smoking is responsible for the occurrence of ectopic pregnancies, 20.3% believe it is responsible for retro-placental haematoma, 17.6% for premature rupture of the membranes. The prevalence of smoking was 11.1% and was most frequent in 2nd year students (25.0%) and 3rd year students (14.8%) (P<0.023). The mean age of beginning smoking was 19.0±4.4 years. The main initiating factors were peer influence (28.6%), pleasure (19.0%) and stress (14.3%). Nicotine dependence was weak to moderate among 48.8% of smokers and absent in 52.2%. CONCLUSION: Gaps exist in the knowledge of student midwives regarding the risks of cigarette smoking to complications of pregnancy. There is need therefore to include formal training on tobacco control strategies at an early stage in the medical curriculum.

Treatment of chronic inflammatory rheumatism by biotherapy in Gabon : eligibility and follow-up of the first 8 patients in sub-Saharan Africa.

OBJECTIVE: to clarify the eligibility criteria for biotherapies in patients with chronic inflammatory rheumatism (CIR) in sub-Saharan Africa and to describe the characteristics of the first 8 patients treated with biotherapy in Gabon. MATERIALS AND METHODS: Patients who responded inadequately to treatments by cDMARDs (EULAR criteria) had a face-to-face interview to inform them about and obtain their consent to biotherapy for at least 3 months, with details of the cost and side effects of each available biotherapy and a certificate of "necessity of biotherapy". The inclusion and follow-up of patients took place in the outpatient rheumatology consultations at the University Hospital of Libreville (Gabon) between January 2010 and December 2016. RESULTS: Of the 30 patients who failed cDMARDs and required biologic treatment, 8 (26.6%) were able to start a biotherapy: 4 men and 4 women with rheumatoid arthritis (n = 4.50%), spondyloarthritis or psoriatic rheumatism (n = 2.25% each). The biotherapy was etanercept (n = 4, 50%), adalimumab, golimumab, infliximab and rituximab (n = 1, 12.5% each). The average duration of the biotherapy was 27.4 months (9-54). Biotherapy was stopped in 4 cases (50%), one each (12.5%) for multifocal tuberculosis, pregnancy, financial reasons, and remission. CONCLUSION: Our study shows that biotherapies, which are currently very expensive, can be prescribed in Africa provided that the usual recommendations are followed strictly. Here, access to biotherapies is only possible through private insurance and the rheumatologist must play the role of facilitator for needy and consenting patients.

An overview of anti-diabetic plants used in Gabon: Pharmacology and toxicology.

ETHNOPHARMACOLOGICAL RELEVANCE: The management of diabetes mellitus management in African communities, especially in Gabon, is not well established as more than 60% of population rely on traditional treatments as primary healthcare. The aim of this review was to collect and present the scientific evidence for the use of medicinal plants that are in currect by Gabonese traditional healers to manage diabetes or hyperglycaemia based here on the pharmacological and toxicological profiles of plants with anti-diabetic activity. There are presented in order to promote their therapeutic value, ensure a safer use by population and provide some bases for further study on high potential plants reviewed. MATERIALS AND METHODS: Ethnobotanical studies were sourced using databases such as Online Wiley library, Pubmed, Google Scholar, PROTA, books and unpublished data including Ph.D. and Master thesis, African and Asian journals. Keywords including 'Diabetes', 'Gabon', 'Toxicity', 'Constituents', 'hyperglycaemia' were used. RESULTS: A total of 69 plants currently used in Gabon with potential anti-diabetic activity have been identified in the literature, all of which have been used in in vivo or in vitro studies. Most of the plants have been studied in human or animal models for their ability to reduce blood glucose, stimulate insulin secretion or inhibit carbohydrates enzymes. Active substances have been identified in 12 out of 69 plants outlined in this review, these include Allium cepa and Tabernanthe iboga. Only eight plants have their active substances tested for anti-diabetic activity and are suitables for further investigation. Toxicological data is scarce and is dose-related to the functional parameters of major organs such as kidney and liver. CONCLUSION: An in-depth understanding on the pharmacology and toxicology of Gabonese anti-diabetic plants is lacking yet there is a great scope for new treatments. With further research, the use of Gabonese anti-diabetic plants is important to ensure the safety of the diabetic patients in Gabon.

[Susceptibility status of Anopheles gambiae s.s. and An. coluzzii to Organophosphates and Carbamates in the Agricultural Exploitation Zones of oil Palm at Mouila, Gabon]. / Susceptibilité d'Anopheles gambiae s.s. et An. coluzzii aux organophosphorés et aux carbamates en zones d'exploitation industrielle de palmiers à huile à Mouila, Gabon.

This study was conducted during the rainy season of 2017 in the agricultural areas at Mouila, with the aim to assess the determination of susceptibility of Anopheles gambiae complex to insecticides and the detection of Ace 1R mutation. Mosquito larvae were collected by using the dipping method and nursed to adult stage. The susceptibility of adult Anopheles gambiae s.l. populations to organophosphates and carbamates was assessed using the standard WHO susceptibility test protocol. The tested mosquitoes species were identified by PCR. These tested mosquitoes were used to search for the Ace 1R mutation. The insecticides used were pirimiphos-methyl 0.25% and 1.25%, fenitrothion 1%, malathion 5%, propoxur 0.1%, bendiocarb 0.1%, 0.5% and 1%. In the prospected areas, An. gambiae s.l. included An. gambiae s.s. and An. coluzzii sympatric in their larval habitats. However, An. gambiae s.s. was predominant in all studied areas (99.1%) comparatively to An. coluzzii Moreover, the susceptibility tests of Anopheles to organophosphates and carbamates revealed mortality rates of 100% regardless of the origin of the mosquitoes. PCR diagnosis of Ace 1R mutation showed that none tested mosquito (An. gambiae s.s. and An. coluzzii) from prospected areas harbored the Ace 1R gene in all prospected areas. The lack of Ace 1R mutation in An. gambiae s.l. reveals the current effectiveness of organophosphates and carbamates for the control of these mosquitoes. Bboth these classes of insecticides could be used for the anopheline populations control in the agricultural spaces at Mouila.

Cette étude a été menée en 2017 pendant la saison des pluies dans les zones d'exploitations agricoles à Mouila, afin de déterminer le statut de sensibilité des membres du complexe Anopheles gambiae aux insecticides et de rechercher la présence de la mutation Ace 1R. Les moustiques ont été collectés au stade larvaire par la méthode du « dipping ¼, puis élevés jusqu'au stade adulte. La susceptibilité des adultes d'An. gambiae s.l. aux organophosphorés et aux carbamates a été évaluée par la méthode standard de l'OMS concernant les tests de sensibilité aux insecticides. Les classes d'insecticides testées étaient les organophosphorés (pirimiphos-méthyl 0,25 % et 1,25 %, fénitrothion 1 %, malathion 5 %) et les carbamates (propoxur 0,1 %, bendiocarb 0,1 %, 0,5 % et 1 %). Les moustiques testés ont été identifiés par PCR. Les anophèles issus des tests ont été utilisés pour la recherche de la mutation Ace 1R par PCR. Dans les sites d'étude, Anopheles gambiae s.l. était composé d'An. gambiae s.s. et An. coluzzii vivant en sympatrie dans leurs habitats larvaires, avec une prédominance d'An. gambiae s.s. (99,1 %) sur An. coluzzii. Les tests de sensibilité des anophèles aux organophosphorés et aux carbamates ont révélé des taux de mortalité de 100 % quelle que soit l'origine des anophèles. La PCR diagnostique de la mutation Ace 1R a montré qu'aucun moustique issu des tests de sensibilité n'était porteur de gènes de résistance Ace 1R. L'absence de mutation Ace 1R chez An. gambiae s.l. révèle l'efficacité actuelle des carbamates et des organophosphorés dans la lutte contre ces moustiques. Ces familles d'insecticides pourraient être utilisées pour la lutte contre les anophèles dans les espaces agricoles de Mouila.

Supplémentation en fer de l'enfant africain: évolution des marqueurs biologiques, et facteurs associés

Introduction : La supplémentation par les sels de fer constitue un des piliers de la lutte contre la carence en fer. Le but de cette enquête était de déterminer la cinétique des marqueurs de la carence en fer lors d'une supplémentation. Méthodologie : Etude prospective, qui incluait des enfants de 6 mois à 5 ans, anémiés et carencés en fer, supplémentés en sels de fer après déparasitage anti helminthes intestinaux. Une numération formule sanguine et le dosage de ferritine, transferrine, fer sérique et capacité de saturation de la transferrine étaient réalisés avant le début, à 6 semaines et 12 semaines de traitement. Résultats : Sur les 121 enfants du départ, 103 sont allés au bout de l'enquête. Les enfants étaient âgés en moyenne de 36,2 ± 12,8 mois, ils provenaient de familles classées comme « moyennes riches » pour 39,8% (n=41), « moyennes pauvres » pour 42,7 % (n=44), et « pauvres » pour 11,7% (n=12). A l'induction du traitement le taux moyen d'hémoglobine était de 9,8 g/dl ± 1,4, à 6 semaines 10,9 g/dl ±1,1, à 12 semaines 12,8 ±0,7. Le taux moyen de ferritine à l'induction était 27,3 ± 19,3, à 6 semaines 42,1±13,4, à 12 semaines 58±12,2. Il n'existait aucun lien entre facteurs sociaux les résultats biologiques à 12 semaines. Conclusion : les paramètres érythrocytaires évoluent au cours de la supplémentation et ne se normalisent qu'à la 12e semaine. Ils permettent un bon suivi de l'efficacité de la supplémentation par sels de fer

Probing for the presence of glucosinolates in three Drypetes spp. (Drypetes euryodes (Hiern) Hutch., Drypetes gossweileri S. Moore, Drypetes laciniata Hutch.) and two Rinorea spp. (Rinorea subintegrifolia O. Ktze and Rinorea woermanniana (Büttner) Engl.) from Gabon.

Drypetes euryodes (Hiern) Hutch., Drypetes gossweileri S. Moore, Drypetes laciniata Hutch. (Putranjivaceae), Rinorea subintegrifolia O. Ktze, and Rinorea woermanniana (Büttner) Engl. (Violaceae) from Gabon were probed for the presence of glucosinolates (GLs). When present, the GLs were identified and quantified by HPLC analysis. 2-Hydroxy-2-methyl GL (1) was the major GL in the cork of D. euryodes. Moreover, 4-hydroxybenzyl GL (2) was the major GL in the seed of D. gossweileri whereas the bark contained 2 as the minor GL and benzyl GL (3) was the major one. In addition, 4-methoxybenzyl GL (4), 3-methoxybenzyl GL (5), and 3 were found in the root of R. subintegrifolia. However, no GL was detected in D. laciniata (leaf and stem), D. euryodes (leaf and stem), and R. woermanniana (leaf and stem-branch). Our results support the hypothesis of the existence of GLs in plants of the Putranjivaceae and Violaceae families (order Malpighiales).

Ethnobotanical survey of medicinal plants used as anthelmintic remedies in Gabon.

ETHNOPHARMACOLOGICAL RELEVANCE: In this article, we report on an ethnobotanical survey realized at the Peyrie market in Libreville on Gabonese medicinal plants used to treat helminthiasis. While several alerts about cases of resistance to conventional anthelmintic treatments are causing to fear a public and animal health issue, the search for new sources of active compounds becomes an urgent issue. In Gabon like in many developing countries, people regularly turn to traditional medicine in case of physical ailments and/or spiritual healing therapies. MATERIALS AND METHODS: To determine which medicinal plants are traditionally used by the populations of Libreville to fight against nematodes, medicinal plant traders were interviewed with standardized questionnaires. The surveys were conducted in the main market of Libreville. Ethnobotanical data such as frequency and percentage of families, species, administrations pathways, modes of preparations and parts of plants used were analyzed and summarized. RESULTS: Thirty-four (34) traders were interviewed belonging to five (5) different ethnic groups. Twenty-four 24 plants used to treat intestinal, cutaneous and ocular helminthiasis were listed. The healers mainly turned towards to ligneous species. The parts of the plant used are mostly leaves and trunk bark. Most of the traditional remedies are prepared directly in water and four (4) principal routes were used for administration namely, oral, rectal, ocular and dermal. CONCLUSION: This study allowed us to list anthelmintic species which will be subjected to a series of chemical and pharmacological assays.

Why ritual plant use has ethnopharmacological relevance.

ETHNOPHARMACOLOGICAL RELEVANCE: Although ritual plant use is now recognised both for its socio-cultural importance and for its contribution to nature conservation, its potential pharmacological effects remain overlooked. AIM OF THE STUDY: Our objective was to see whether ritual plant use could have ethnopharmacological relevance through practices that involve direct physical contact with the human body. We hypothesise that ritual practices reflect traditional knowledge on biological activities of plant species, even if plants are used in a symbolic way. MATERIALS AND METHODS: Data were collected in collaboration with traditional healers and ritual plant vendors and harvesters in Benin (West Africa) and Gabon (Central Africa). Both ritual and medicinal uses of plants were recorded. Voucher specimens were collected and identified. We documented different administration routes of ritual plants and selected those whose uses involved direct contact with the human body. Based on our quantitative market surveys and field inventories, we identified 24 commercially or otherwise culturally important species and compared their ritual uses with proven biological activity from the literature. RESULTS: We recorded 573 plant species with 667 ritual uses, of which ca. 75% (442 species and 499 uses) implied direct contact with the human body. The most common route of administration for ritual treatments was baths, followed by oral ingestion and skin rubbing. One third (186 species) of all ritual plants doubled as medicine for physical ailments. In contrast to previous research that explained the effectiveness of ritual plant use to be a matter of belief, our results hint at the potential medicinal properties of these plants. Ritual treatment of madness caused by evil spirits by the consumption of Rauvolfia vomitoria roots, for example, may be based on the species' proven anticonvulsant properties. DISCUSSION AND CONCLUSION: We discuss some of the possible implications of ritual plant use for public health and conclude by suggesting that ritual plant uses that do not involve contact with the human body may also be vehicles for the transmission of traditional medicinal knowledge.

Antidiabetic potential of two medicinal plants used in Gabonese folk medicine.

BACKGROUND: Diabetes mellitus is a metabolic disorder which is rising globally in rich and developing countries. In the African region this rate is the highest, with 20 million diagnosed diabetics. Despite a noticeable progress in the treatment of diabetes mellitus by synthetic drugs, the search for new natural anti-diabetic agents is going on. Nauclea diderrichii (De Wild.) Merr. (ND) and Sarcocephalus pobeguinii Hua ex Pellegr. (SP) are used as traditional medicines in Gabon for the treatment of different diseases, especially in the case of diabetes. The aim of this study was to evaluate the antidiabetic potential of these two medicinal plants traditionally used in Gabon. METHODS: Pharmacological (inhibitory action on α and ß-glucosidases) and toxicological (effect on human T cell proliferation) studies were conducted on aqueous extracts of ND (leaves and bark) and SP (bark) collected in Gabon. All raw extracts were analyzed by HPTLC and their content in phenolic compounds was determined by using standard method. The most active extracts were submitted to preparative HPLC in order to evidence the most efficient subfractions by biological evaluation. RESULTS: The results showed that two extracts from ND were potent α-glucosidase inhibitors, the leaf extract being more active that the bark extract: the first one was more than 60 fold more active than Acarbose, which is an oral medication used to treat type 2 diabetes; the extract from SP bark was less efficient. The HPLC subfractions of the extracts of ND leaves and SP bark were tested in the same experimental conditions. In each case, the most active subfractions still show very potent inhibitory effect on α-glucosidase (80-90% inhibition at 0.1 mg/mL). The most efficient extract, from ND leaves, was also characterized by the highest percentage of phenolic compounds, which suggests a relationship between its inhibitory potential on α-glucosidase and its content in phenolic compounds. Conversely, only a moderate inhibitory activity of the three extracts was observed on ß-glucosidase. CONCLUSION: These results clearly indicated that active compounds present in N. diderrichii and S. pobeguinii leaves or/and bark were selective and highly potent inhibitors of α-glucosidase and validate their popular use for the treatment of diabetes.

Decaying toxic wood as sodium supplement for herbivorous mammals in Gabon.

African rainforest harbors herbivores at high density. However, because plants and soils typically lack in some essential minerals, rainforest is not always a suitable habitat for herbivores. How they fulfill the mineral requirements is therefore an important question to animal ecology and conservation. Although large marshes, called 'bais', are often mentioned as efficient mineral-resource, little information on other sodium resources has still been available. Our laboratory works and field surveys found that a peculiar item, decaying wood stumps of Anthostema aubryanum, played as a major sodium resource for herbivores in Moukalaba-Doudou National Park, Gabon. When A. aubryanum is alive, the sodium content of its bark is low and its latex is toxic. Sodium is accumulated in decaying stumps (mean=1,343 mg/kg dry matter). Eight herbivores visited stumps to ingest the dead wood. Fecal sample analysis revealed that western lowland gorillas, a species most-frequently using the stumps, consumed large amount of the dead wood as regular food. Our findings suggest that decaying A. aubryanum is critical sodium-resources and is a key species for herbivores in our study area. Importance of the A. aubryanum may be particularly large there, because it is a limited sodium-rich material that is available year round. Our study site is known as the site where the densities of several herbivores are among the highest at Central Africa. The relatively high herbivores density in our study site may partly depend on decaying A. aubryanum as sodium resources.

Evidence of a link between taboos and sacrifices and resource scarcity of ritual plants.

BACKGROUND: One of the main obstacles for the mainstreaming of religious traditions as tools for the conservation of nature is the limited applicability of research results in this field. We documented two different restrictions implemented by local people (taboos and sacrifices) related to the use of ritual plants in Benin (West Africa) and Gabon (Central Africa). METHODS: To see whether these restrictions reflected plant scarcity from an etic perspective (official threat status) and an emic viewpoint (perceived scarcity by local people), we conducted 102 interviews with traditional healers and adepts of traditional faiths. RESULTS: We documented a total of 618 ritual plants, from which 52 species were used in both countries. In Benin, the use of 63 of the 414 ritual plant species was restricted; while in Gabon 23 of the 256 ritual plants were associated with taboos and sacrifices. In Benin, restricted plants were significantly more often officially threatened, perceived as scarce, and actively protected than non-restricted plants. In the more forested and less densely populated Gabon, plants that were perceived as scarce were more often associated to local restrictions than officially threatened species. CONCLUSIONS: These results prove the presence of a form of adaptive management where restrictions are related to resource scarcity and protection of ritual plant species. By providing baseline data on possibly endangered species, we demonstrate how plant use in the context of religious traditions can yield important information for conservation planning.

Ethnopharmacological surveys and pharmacological studies of plants used in traditional medicine in the treatment of HIV/AIDS opportunistic diseases in Gabon.

ETHNOPHARMACOLOGICAL RELEVANCE: Ethnopharmacological surveys were conducted in two regions of Gabon. This led to highlighting some of the medicinal plants used by local populations in the management of HIV/AIDS opportunistic diseases. Two regions with the highest occurrence of HIV/AIDS cases were visited and ethnopharmarcological data was gathered. These regions were the Estuaire Province (Libreville and its neighborhood) and the Haut-Ogooué Province (Franceville and its neighborhood). The opportunistic diseases and symptomatic conditions considered during this study were: diarrhea, respiratory tract infections, cough, tuberculosis, abscesses, stomach ache, skin rashes, venereal diseases, typhoid fever, anemia, general tiredness, hepatitis and vomiting. MATERIALS AND METHODS: The reported species were evaluated through three parameters: specificity, reliability and frequency. Plant parts of relevant species were harvested and extracted with an aqueous alcohol solution (ethanol/water: 1/1). The extracts obtained were submitted to phytochemical screening and in vitro microbiological assays on some clinical isolates and ATCC strains, involved in HIV/AIDS opportunistic diseases through the Agar well diffusion and Microbroth dilution methods. RESULTS: Among the 52 species identified during this survey, Coelocaryon klainei Pierre ex Heckel (Myristicaceae), Dacryodes klaineana (Pierre) H.J. Lam (Bursecaceae), Phyllanthus diandrus Pax (Euphorbiaceae), Saccoglotys gabonensis (Baill.) Urb. (Humiriaceae) and Tetrorchidium didymostemon (Baill.) Pax & K. Hoffm. (Euphorbiaceae) were submitted to in vitro microbiological assays. Phyllanthus diandrus bark and leaves show best antibacterial activities against Pseudomonas aeruginosa and Klebsiella pneumoniae with MIC value of 0.25 respectively. Phytochemical screening revealed the presence in all the plant parts extracts of potentially bioactive molecules, including polyphenols, especially flavonoids and tannins. CONCLUSION: It is concluded that some of these plants might be submitted to further scientific studies, including the identification and isolation of bioactive principles, that could be developed to drugs for the treatment of HIV/AIDS opportunistic diseases.

Molecular characterization of Shigella spp. from patients in Gabon 2011-2013.

BACKGROUND: Shigella spp. dysentery is widespread in developing countries; the incidence is particularly high in children between 1-2 years of age. In sub-Saharan Africa, there is a paucity of epidemiological data on Shigella spp., with possible negative consequences for recognition and correct treatment choice for this life-threatening bacterial infection. We therefore characterized Shigella spp. isolates from Gabon. METHODS: The antimicrobial resistance, virulence factors, genotypes and mobile genetic elements of Shigella isolates (29 S. flexneri; 5 S. boydii; 3 S. sonnei) from a retrospective strain collection were analyzed. RESULTS: High resistance rates were found for gentamicin and tetracycline (100%, 37/37), cotrimoxazole (92%, 34/37) and ampicillin (84%, 31/37). All isolate harbored ial and ipaH; no isolate produced Shiga toxins (stx1/2); enterotoxins (set1A/B) were only found in S. flexneri (n=19). Multilocus sequence types (MLST) clustered with global clones. A high prevalence of atypical class 1 integrons harboring blaOXA30 and aadA1 were detected in S. flexneri, while all S. sonnei carried class 2 integrons. CONCLUSIONS: There is a strong link of Gabonese Shigella spp. isolates with pandemic lineages as they cluster with major global clones and frequently carry atypical class 1 integrons which are frequently reported in Shigella spp. from Asia.