BackgroundInsecticide resistance in sub-Saharan Africa and especially in Benin is a major public health issue hindering the control of the malaria vectors. Each Anopheles species has developed a resistance to one or several classes of the insecticides currently in use in the field. Therefore, it is urgent to find alternative compounds to conquer the vector. In this study, the efficacies of essential oils of nine plant species, which are traditionally used to avoid mosquito bites in Benin, were investigated.MethodsEssential oils of nine plant species were extracted by hydrodistillation, and their chemical compositions were identified by GC-MS. These oils were tested on susceptible “kisumu” and resistant “ladji-Cotonou” strains of Anopheles gambiae, following WHO test procedures for insecticide resistance monitoring in malaria vector mosquitoes.ResultsDifferent chemical compositions were obtained from the essential oils of the plant species. The major constituents identified were as follows: neral and geranial for Cymbopogon citratus, Z-carveol, E-p-mentha-1(7),8-dien-2-ol and E-p-mentha-2,8-dienol for Cymbopogon giganteus, piperitone for Cymbopogon schoenanthus, citronellal and citronellol for Eucalyptus citriodora, p-cymene, caryophyllene oxide and spathulenol for Eucalyptus tereticornis, 3-tetradecanone for Cochlospermum tinctorium and Cochlospermum planchonii, methyl salicylate for Securidaca longepedunculata and ascaridole for Chenopodium ambrosioides. The diagnostic dose was 0.77% for C. citratus, 2.80% for E. tereticornis, 3.37% for E. citriodora, 4.26% for C. ambrosioides, 5.48% for C. schoenanthus and 7.36% for C. giganteus. The highest diagnostic doses were obtained with S. longepedunculata (9.84%), C. tinctorium (11.56%) and C. planchonii (15.22%), compared to permethrin 0.75%. A. gambiae cotonou, which is resistant to pyrethroids, showed significant tolerance to essential oils from C. tinctorium and S. longepedunculata as expected but was highly susceptible to all the other essential oils at the diagnostic dose.ConclusionsC. citratus, E. tereticornis, E. citriodora, C. ambrosioides and C. schoenanthus are potential promising plant sources for alternative compounds to pyrethroids, for the control of the Anopheles malaria vector in Benin. The efficacy of their essential oils is possibly based on their chemical compositions in which major and/or minor compounds have reported insecticidal activities on various pests and disease vectors such as Anopheles.

BackgroundExtracts from Polygonum senegalensis (Polygonaceae) and Pseudocedrela kotschyi (Meliaceae) are two important traditionally used medicinal plants in rural Benin to treat many diseases and notably type 2 diabetes. The aim of the study was to investigate the α-glucosidase inhibition, antioxidant and antibacterial activities of those plants extract: Polygonum senegalensis leaves, and Pseudocedrela kotschyi root.MethodsHydro-alcoholic (50%) extracts were analyzed for their phytochemical content and tested for their inhibition potency on α-glucosidase from Saccharomyces cerevisiae. Antioxidant activities were assessed using the DPPH, ORAC, FRAP and DCFH-DA (cell based) assay. Finally, the antibacterial activity was evaluated using MIC determination on four Gram-positive cocci (Bacillus subtilis, Clostridium difficile, Enterococcus faecalis, Staphylococcus aureus), three Gram-negative bacilli (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae), and the yeast Candida albicans.ResultsEach extract presented significant α-glucosidase inhibition and antioxidant activities. Polygonum senegalensis leaf extracts were the most active in each in vitro assay with an IC50 = 1.5 μg/ml for α-glucosidase inhibition and an IC50 = 6.8 μg/ml for DPPH scavenging, - 4.5 μmol Fe II/g of dry matter - 9366 μmol Trolox / g DW - for FRAP and ORAC values, respectively. IC50 = 2.3 μg GA / ml for DCFH-DA assay. Concerning its antibacterial activity, a growth inhibitory effect was observed only against three Gram negative bacilli: B. subtilis, E. faecalis, S. aureus and the yeast C. albicans at high concentration.ConclusionThe results showed that the semi alcoholic extract of the two studied plants possess α-glucosidase inhibitory activity, antioxidant potency, and low antibacterial effect.

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The chemical composition of essential oils obtained from the leaves of Cymbopogon giganteus Chiov. and Cymbopogon schoenanthus (L.) Spreng, two Poaceae growing wild in Benin were analyzed by GC and GC/MS. The main constituents of Cymbopogon giganteus were cis-p-mentha-1(7),8-dien-2-ol (19.4%), transp-mentha-2,8-dien-1-ol (16.4%) and limonene (13.7%). The major components identified in the oil of Cymbopogon schoenanthus were piperitone (68.4%), and δ-2-carene (11.5%). The antimicrobial activity of the essential oil of Cymbopogon giganteus was found to be moderate on Staphylococcus aureus ATCC 25923 with MIC equal to 0.32 ± 0.02 mg/mL and Escherichia coli ATCC 25922 with MIC equal to 0.64 ± 0.34 mg/mL. This same oil induced the death of 57.84% of ticks at 8µL. Therefore, essential oil of Cymbopogon schoenanthus had a low antimicrobial activity on Staphylococcus aureus ATCC 25923 with MIC equal to 2.63 ± 0.16 mg/mL and Escherichia coli ATCC 25922 with MIC equal to 2.63 ± 0.16 mg/mL.

The chemical composition of the essential oils obtained by hydrodistillation from leaves of three samples of Aeollanthus pubescens Benth. (Lamiaceae) growing wild in Benin were analyzed by GC and GC-MS. To date the biological functions of A. pubescens essential oils have not been demonstrated scientifically even if this plant is traditionally used by local population in alimentary and medicine. We investigated the chemical composition of A. pubescens essential oils and their antiradical and anti-inflammatory activities. Twenty four compounds were identified and quantified in the essential oils, the major compounds being thymol (63.6 %; 9.5 %; 63.4 %), carvacrol (3.1 %; 51.1 %; 2.1 %), thymyl acetate (9.8 %; 0.8 %; 10.2 %), carvacryl acetate (0.8 %; 6.1 %; 0.7 %), p-cymene (5.6 %; 9.0 %; 5.5 %) and γ-terpinene (6.4 % ; 11.2 %; 6.6 %). The antiradical activity of these oils was found to be high and a low anti-inflammatory activity was observed. Fractionation of a thymol rich sample allowed the identification of the bioactive fractions and their contribution to the efficiency of the whole extract. This study suggests that A. pubescens essential oils may be useful in the food industry where the antioxidants are used to retard the degradation of fatty substances, but also in cosmetics or in the field of herbal medicine, where the radical species are associated with the concept of antiaging.

Aim::This study aimed to report medicinal plants that are likely to be used in the control of salmonellosis.Materials and Methods::A cross-sectional study was conducted in Southern Benin. Semi-structured questionnaires were administered to 150 farmers and 100 traditional therapists in seven high municipalities. This step helped to collect plants that are used in the treatment of animal salmonellosis and typhoid fever in human.Results::The results revealed a low level of use of medicinal plants among breeders who prefer antibiotics such as oxytetracycline (53.55%), tylosine + sulfadimerazine (15.30%), and alphaceryl (19.13%). However, plants such as Moringa oleifera (leaves), Carica papaya (leaves and seeds), and Vernonia amygdalina (leaves) were mostly used by some farmers. From traditional therapists, 57 plant species of 32 families were identified as typhoid fever cures; among which Leguminosae, Asteraceae, and Euphorbiaceae were predominant. Persea americana (22.72%), V. amygdalina (7.57%), and Corchorus olitorius (7.57%) were the most cited by traditherapists for the treatment of typhoid fever in human.Conclusion::This study provides a database for further studies on the in vitro and in vivo efficacy of Benin plant species on Salmonella spp. These evaluations will guarantee the availability of new therapeutic solutions for populations.