Imaël Henri Nestor Bassolé

Composition and Antimicrobial Activities of Lippia multiflora Moldenke, Mentha x piperita L. and Ocimum basilicum L. Essential Oils and Their Major Monoterpene Alcohols Alone and in Combination

Essential oils from leaves of Lippia multiflora, Mentha x piperita and Ocimum basilicum from Burkina Faso were analysed by GC–FID and GC–MS. Major components were p-cymene, thymol, β-caryophyllene, carvacrol and carvone for L. multiflora, menthol and iso-menthone for M. x piperita and, linalool and eugenol for O. basilicum. The essential oils and their major monoterpene alcohols were tested against nine bacterial strains using the disc diffusion and broth microdilution methods. The essential oils with high phenolic contents were the most effective antimicrobials. The checkerboard method was used to quantify the efficacy of paired combinations of essential oils and their major components. The best synergetic effects among essential oils and major components were obtained with combinations involving O. basilicum essential oil and eugenol, respectively. As phenolic components are characterized by a strong spicy aroma, this study suggests that the selection of certain combinations of EOs could help to reduce the amount of essential oils and consequently reduce any adverse sensory impact in food.

Chemical composition and antimicrobial activity of Cymbopogon citratus and Cymbopogon giganteus essential oils alone and in combination.

As part of ongoing research on the chemical composition and the antimicrobial properties of Burkinabe plants essential oils alone and in combination, essential oils (EOs) from leaves of Cymbopogon citratus and Cymbopogon giganteus from Burkina Faso were analyzed by GC-FID and GC-MS. Five constituents, which accounted for 96.3% of the oil, were identified in the EO of C. citratus. Geranial (48.1%), neral (34.6%) and myrcene (11.0%) were the major constituents. For C. giganteus a total of eight compounds were identified which represented 86.0% of the oils extracted. The dominant compounds were limonene (42%) and a set of monoterpene alcohols: trans-p-mentha-1(7),8-dien-2-ol (14.2%), cis-p-mentha-1(7),8-dien-2-ol (12%), trans-p-mentha-2,8-dien-1-ol (5.6%) and cis-p-mentha-2,8-dien-1-ol (5.2%). The EOs were tested against nine bacteria by using disc diffusion and microdilution methods. C. giganteus EO showed antimicrobial effects against all microorganisms tested whereas C. citratus EO failed to inhibit Pseudomonas aeruginosa. The antimicrobial activity of combinations of the two EOs was quantified by the checkerboard method. Combinations of the two EOs exerted synergistic, additive and indifferent antimicrobial effects. Results of the present investigation provide evidence that the combinations of plant EOs could be assessed for synergistic activity in order to reduce their minimum effective dose.

Chemical Composition, Antioxidant, Anti-Inflammatory and Anti-Proliferative Activities of Essential Oils of Plants from Burkina Faso

This research highlights the chemical composition, antioxidant, anti-inflammatory and anti-proliferative activities of essential oils from leaves of Ocimum basilicum, Ocimum americanum, Hyptis spicigera, Lippia multiflora, Ageratum conyzoides, Eucalyptus camaldulensis and Zingiber officinale. Essential oils were analyzed by gas chromatography–mass spectrometry and gas chromatography–flame ionization detector. Major constituents were α-terpineol (59.78%) and β-caryophyllene (10.54%) for Ocimum basilicum; 1, 8-cineol (31.22%), camphor (12.730%), α-pinene (6.87%) and trans α-bergamotene (5.32%) for Ocimum americanum; β-caryophyllene (21%), α-pinene (20.11%), sabinene (10.26%), β-pinene (9.22%) and α-phellandrene (7.03%) for Hyptis spicigera; p-cymene (25.27%), β-caryophyllene (12.70%), thymol (11.88), γ-terpinene (9.17%) and thymyle acetate (7.64%) for Lippia multiflora; precocene (82.10%)for Ageratum conyzoides; eucalyptol (59.55%), α-pinene (9.17%) and limonene (8.76%) for Eucalyptus camaldulensis; arcurcumene (16.67%), camphene (12.70%), zingiberene (8.40%), β-bisabolene (7.83%) and β-sesquiphellandrène (5.34%) for Zingiber officinale. Antioxidant activities were examined using 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) methods. O. basilicum and L. multiflora exhibited the highest antioxidant activity in DPPH and ABTS tests, respectively. Anti-inflammatory properties were evaluated by measuring the inhibition of lipoxygenase activity and essential oil of Z. officinale was the most active. Anti-proliferative effect was assayed by the measurement of MTT on LNCaP and PC-3 prostate cancer cell lines, and SF-763 and SF-767 glioblastoma cell lines. Essential oils from A. conyzoides and L. multiflora were the most active on LNCaP and PC-3 cell lines, respectively. The SF-767 glioblastoma cell line was the most sensitive to O. basilicum and L. multiflora EOs while essential oil of A. conyzoides showed the highest activity on SF-763 cells. Altogether these results justify the use of these plants in traditional medicine in Burkina Faso and open a new field of investigation in the characterization of the molecules involved in anti-proliferative processes.

Toxicity assessment and analgesic activity investigation of aqueous acetone extracts of Sida acuta Burn f . and Sida cordifolia L. (Malvaceae), medicinal plants of Burkina Faso

BackgroundSida acuta Burn f. and Sida cordifolia L. (Malvaceae) are traditionally used in Burkina Faso to treat several ailments, mainly pains, including abdominal infections and associated diseases. Despite the extensive use of these plants in traditional health care, literature provides little information regarding their toxicity and the pharmacology. This work was therefore designed to investigate the toxicological effects of aqueous acetone extracts of Sida acuta Burn f. and Sida cordifolia L. Furthermore, their analgesic capacity was assessed, in order to assess the efficiency of the traditional use of these two medicinal plants from Burkina Faso.MethodFor acute toxicity test, mice were injected different doses of each extract by intraperitoneal route and the LD50 values were determined. For the subchronic toxicity evaluation, Wistar albinos rats were treated by gavage during 28 days at different doses of aqueous acetone extracts and then haematological and biochemical parameters were determined. The analgesic effect was evaluated in mice by the acetic-acid writhing test and by the formalin test.ResultsFor the acute toxicity test, the LD50 values of 3.2 g/kg and 3.4 g/kg respectively for S. acuta Burn f. and S. cordifolia L. were obtained. Concerning the haematological and biochemical parameters, data varied widely (increase or decrease) according to dose of extracts and weight of rats and did not show clinical correlations. The extracts have produced significant analgesic effects by the acetic acid writhing test and by the hot plate method (p <0.05) and a dose-dependent inhibition was observed.ConclusionThe overall results of this study may justify the traditional uses of S. acuta and S. cordifolia .

Biodepollution of wastewater containing phenolic compounds from leather industry by plant peroxidases

This study deals with the use of peroxidases (POXs) from Allium sativum, Ipomoea batatas, Raphanus sativus and Sorghum bicolor to catalyze the degradation of free phenolic compounds as well as phenolic compounds contained in wastewater from leather industry. Secretory plant POXs were able to catalyze the oxidation of gallic acid, ferulic acid, 4-hydroxybenzoic acid, pyrogallol and 1,4-tyrosol prepared in ethanol 2% (v:v). Efficiency of peroxidase catalysis depends strongly on the chemical nature of phenolic substrates and on the botanical source of the enzymes. It appeared that POX from Raphanus sativus had the highest efficiency. Results show that POXs can also remove phenolic compounds present in industrial wastewater such as leather industry. Removal of phenolic compounds in wastewater from leather industry by POX was significantly enhanced by polyethylene glycol.

Insecticide resistance in Bemisia tabaci Gennadius (Homoptera: Aleyrodidae) and Anopheles gambiae Giles (Diptera: Culicidae) could compromise the sustainability of malaria vector control strategies in West Africa.

Insecticides from the organophosphate (OP) and pyrethroid (PY) chemical families, have respectively, been in use for 50 and 30 years in West Africa, mainly against agricultural pests, but also against vectors of human disease. The selection pressure, with practically the same molecules year after year (mainly on cotton), has caused insecticide resistance in pest populations such as Bemisia tabaci, vector of harmful phytoviruses on vegetables. The evolution toward insecticide resistance in malaria vectors such as Anopheles gambiae sensus lato (s.l.) is probably related to the current use of these insecticides in agriculture. Thus, successful pest and vector control in West Africa requires an investigation of insect susceptibility, in relation to the identification of species and sub species, such as molecular forms or biotypes. Identification of knock down resistance (kdr) and acetylcholinesterase gene (Ace1) mutations modifying insecticide targets in individual insects and measure of enzymes activity typically involved in insecticide metabolism (oxidase, esterase and glutathion-S-transferase) are indispensable in understanding the mechanisms of resistance. Insecticide resistance is a good example in which genotype-phenotype links have been made successfully. Insecticides used in agriculture continue to select new resistant populations of B. tabaci that could be from different biotype vectors of plant viruses. As well, the evolution of insecticide resistance in An. gambiae threatens the management of malaria vectors in West Africa. It raises the question of priority in the use of insecticides in health and/or agriculture, and more generally, the question of sustainability of crop protection and vector control strategies in the region. Here, we review the susceptibility tests, biochemical and molecular assays data for B. tabaci, a major pest in cotton and vegetable crops, and An. gambiae, main vector of malaria. The data reviewed was collected in Benin and Burkina Faso between 2008 and 2010 under the Corus 6015 research program. This review aims to show: (i) the insecticide resistance in B. tabaci as well as in An. gambiae; and (ii) due to this, the impact of selection of resistant populations on malaria vector control strategies. Some measures that could be beneficial for crop protection and vector control strategies in West Africa are proposed.

Physicochemical Characteristics and Composition of Three Morphotypes of Cyperus esculentus Tubers and Tuber Oils

Tuber characteristics and nutrient composition of three morphotypes of Cyperus esculentus tubers and tuber oils were determined. The mean value for length and width of the tuber and one thousand dried tuber weights ranged from 0.98 to 1.31 cm, 0.90 to 1.19 cm, and 598 to 1044 g, respectively. Tubers displayed high level of starch (30.54–33.21 g 100 g−1), lipid (24.91–28.94 g 100 g−1), and sucrose (17.98–20.39 g 100 g−1). The yellow tubers had significantly higher content in lipid compared to black ones. Levels of ascorbic acid, tocopherol, and β-carotene of the three morphotypes differed significantly. Yellow ones (morphotypes 1 and 2) were the richest in tocopherol and the poorest in β-carotene. Saturated fatty acid content of morphotype 2 was significantly lower than that of morphotypes 1 and 3. Morphotype 3 had the significantly lowest PUFA content compared to morphotypes 1 and 2. Morphotype 1 was found to be richer in Ca, Cu, and Mn contents. Al, Mg, P, S, and Si were most abundant in morphotype 2. Morphotype 3 had the highest content of Cl, K, and Zn.

Characteristics, Composition and Oxidative Stability of Lannea microcarpa Seed and Seed Oil

The proximate composition of seeds and main physicochemical properties and thermal stability of oil extracted from Lannea microcarpa seeds were evaluated. The percentage composition of the seeds was: ash (3.11%), crude oil (64.90%), protein (21.14%), total carbohydrate (10.85%) and moisture (3.24%). Physicochemical properties of the oil were: refractive index, 1.473; melting point, 22.60°C; saponification value, 194.23 mg of KOH/g of oil; iodine value, 61.33 g of I2/100 g of oil; acid value, 1.21 mg of KOH/g of oil; peroxide value, 1.48 meq of O2/kg of oil and oxidative stability index, 43.20 h. Oleic (43.45%), palmitic (34.45%), linoleic (11.20%) and stearic (8.35%) acids were the most dominant fatty acids. Triacylglycerols with equivalent carbon number (ECN) 48 and ECN 46 were dominant (46.96% and 37.31%, respectively). The major triacylglycerol constituents were palmitoyl diolein (POO) (21.23%), followed by dipalmitoyl olein (POP) (16.47%), palmitoyl linoleyl olein (PLO) (12.03%), dipalmitoyl linolein (PLP) (10.85%) and dioleoyl linolein (LOO) (9.30%). The total polyphenol and tocopherol contents were 1.39 mg GAE g−1 DW and 578.56 ppm, respectively. γ-Tocopherol was the major tocopherol (437.23 ppm). These analytical results indicated that the L. microcarpa seed oil could be used as a frying oil and in the cosmetic industry.

Essential Oils: New Perspectives in Human Health and Wellness

Essential oils are natural products, derived from aromatic plants, traditionally used all over the world for disinfection, as anti-inflammatory, relaxing, and stimulating substances, and with potential and modern exploitation in clinical medicine. The earliest recorded mention of the techniques and methods used to produce essential oils is believed to be that of Ibn al-Baitar (1188–1248). The chemical composition of these essential oils varies widely depending upon the geographical location, botanical origin, genetics, bacterial endophytes, and extraction techniques. Essential oils are commonly used in food and cosmetic industries. They can be used as natural alternatives to synthetic preparations to prevent and treat infectious diseases. They are used traditionally to treat other diseases like respiratory tract, digestive system, gynecological, andrological, endocrine, cardiovascular, nervous system, and skin infections. Many of them have shown anticancer activities, too. For this special issue we received seventeen papers, confirming the interest shown by the scientific community on a great number of old and new issues still open about essential oil, particularly chemical characterization and standard methods to control quality; human clinical and experimental pharmacology and toxicology of essential oils; safety; pharmacological actions and interactions; new biomedical targets of the biological responses; clinical assays to pharmaceutical products with essential oils in biotechnology; nanotechnology and nanomedicine. We have selected seven papers, with the aim of showing some progress made by the pharmaceutical point of view and the new perspectives of pharmacological research to facilitate their transition into clinical practice. In the study “Hepatoprotective effect of pretreatment with Thymus vulgaris essential oil in experimental model of acetaminophen-induced injury,” R. Grespan et al. investigated the hepatoprotective effect of Thymus vulgaris essential oil on acetaminophen-induced hepatic damage in mice. Thymus vulgaris is used popularly such as its antiseptic, carminative, and antimicrobial effects, and this study is very interesting for new possible clinical applications. The positive results are confirmed by reduction of the serum marker enzymes aspartate aminotransferase (AST), alanine aminotransferase (ALT), and myeloperoxidase (MPO) and by histopathological analysis. Acute liver damage caused by acetaminophen overdose is a significant clinical problem and could benefit from new therapeutic strategies. In the paper entitled “Exploring the anti-Burkholderia cepacia complex activity of essential oils: a preliminary analysis,” I. Maida et al. have checked the ability of the essential oils extracted from six different aromatic plants to inhibit the growth of 18 known species of the Burkholderia cepacia complex (Bcc), an opportunistic human pathogen that can cause severe infection in immunocompromised patients, especially those affected by cystic fibrosis (CF) and who are often resistant to multiple antibiotics. Eugenia caryophyllata, Origanum vulgare, and Thymus vulgaris essential oils were particularly active versus the Bcc strains, including those exhibiting a high degree or resistance to ciprofloxacin, active toward both environmental and clinical strains isolated from CF patients. N. El Abed et al. in the work “Chemical composition, antioxidant and antimicrobial activities of Thymus capitata essential oil with its preservative effect against Listeria monocytogenes inoculated in minced beef meat” evaluated the preservative effect of Thymus capitata essential oil (TCEO) against Listeria monocytogenes inoculated in minced beef meat. The antioxidant activity was assessed in vitro by using both the DPPH and the ABTS assays. The essential oil was evaluated for its antimicrobial activity using disc agar diffusion and microdilution methods. The results demonstrated that the minimum inhibition concentration values ranged from 0.32 to 20 mg/mL, and essential oil evaluated in vivo against Listeria monocytogenes showed clear and strong inhibitory effect. The application of 0.25 or 1% (v/w) of TCEO to minced beef significantly reduced the L. monocytogenes population. In the paper “Essential oils for complementary treatment of surgical patients: state of the art” S. Stea et al. revised the available literature to determine the effectiveness of aromatherapy in surgical patients (to treat anxiety and insomnia, pain and nausea, or to dress wounds). Efficacy studies of lavender or orange and peppermint essential oils, to treat anxiety and nausea, respectively, have shown positive results. Therefore there are encouraging data for the treatment of infections, especially for tea tree oil (TTO). The authors conclude that it is important that the therapeutic use of essential oils be performed in compliance with clinical safety standards. In the article “Effect of eugenol on cell surface hydrophobicity, adhesion, and biofilm of Candida tropicalis and Candida dubliniensis isolated from oral cavity of HIV-infected patients” S. B. de Paula et al. evaluated the effect of eugenol on the adherence properties and biofilm formation capacity of Candida dubliniensis and Candida tropicalis isolated from the oral cavity of HIV-infected patients. Eugenol showed inhibitory activity against planktonic and sessile cells of Candida spp. Scanning electron microscopy demonstrated that eugenol drastically reduced the number of sessile cells on denture material surfaces. The paper corroborates the effectiveness of eugenol against Candida species other than C. albicans, reinforcing its potential as an antifungal applied to limit both the growth of planktonic cells and biofilm formation on different surfaces. In the work “Essential oils loaded in nanosystems: a developing strategy for a successful therapeutic approach” A. R. Bilia et al. revised the nanoencapsulation of essential oils in drug delivery systems, for their capability of decreasing volatility, improving the stability, water solubility, and efficacy of essential oil-based formulations, by maintenance of therapeutic efficacy. Two categories of nanocarriers can be proposed: polymeric nanoparticulate formulations, extensively studied with significant improvement of the essential oil antimicrobial activity, and lipid carriers, including liposomes, solid lipid nanoparticles, nanostructured lipid particles, and nano/microemulsions. Lastly, the paper by A. R. Bilia et al. entitled “Essential oil of Artemisia annua L.: an extraordinary component with numerous antimicrobial properties” describes the qualitative composition and the antimicrobial activities of essential oil of Artemisia annua L., a medicinal plant from China, well known and used in the treatment of the chloroquine-resistant and cerebral malaria. The essential oil of A. annua is rich in mono- and sesquiterpenes (camphor, germacrene D, artemisia ketone, and 1,8 cineole) exciting a lot of antibacterial and antifungal activities: against gram-positive bacteria (Enterococcus, Streptococcus, Staphylococcus, Bacillus, and Listeria spp.), gram-negative bacteria (Escherichia, Shigella, Salmonella, Haemophilus, Klebsiella, and Pseudomonas spp.), and mycetes (Candida, Saccharomyces, and Aspergillus spp.). The authors believe that this review will serve to prepare the most appropriate microbiological studies also useful for clinical practice. Fabio Firenzuoli Vikas Jaitak Gyorgyi Horvath Imael Henri Nestor Bassole William N. Setzer Luigi Gori

Essential Oils as an Alternative to Pyrethroids’ Resistance against Anopheles Species Complex Giles (Diptera: Culicidae)

Widespread resistance of Anopheles sp. populations to pyrethroid insecticides has led to the search for sustainable alternatives in the plant kingdom. Among many botanicals, there is great interest in essential oils and their constituents. Many researchers have explored essential oils (EOs) to determine their toxicity and identify repellent molecules that are effective against Anopheles populations. Essential oils are volatile and fragrant substances with an oily consistency typically produced by plants. They contain a variety of volatile molecules such as terpenes and terpenoids, phenol-derived aromatic components and aliphatic components at quite different concentrations with a significant insecticide potential, essentially as ovicidal, larvicidal, adulticidal, repellency, antifeedant, growth and reproduction inhibitors. The current review provides a summary of chemical composition of EOs, their toxicity at different developmental stages (eggs, larvae and adults), their repellent effects against Anopheles populations, for which there is little information available until now. An overview of antagonist and synergistic phenomena between secondary metabolites, the mode of action as well as microencapsulation technologies are also given in this review. Finally, the potential use of EOs as an alternative to current insecticides has been discussed.