Aline Lamien-Meda

Polyphenol Content and Antioxidant Activity of Fourteen Wild Edible Fruits from Burkina Faso

A total of fourteen (14) species of wild edible fruits from Burkina Faso were analyzed for their phenolic and flavonoid contents, and their antioxidant activities using the DPPH, FRAP and ABTS methods. The data obtained show that the total phenolic and total flavonoid levels were significantly higher in the acetone than in the methanol extracts. Detarium microcarpum fruit had the highest phenolic and the highest flavonoid content, followed by that of Adansonia digitata, Ziziphus mauritiana, Ximenia americana and Lannea microcarpa. Significant amounts of total phenolics were also detected in the other fruit species in the following order of decreasing levels: Tamarindus indica > Sclerocarya birrea > Dialium guineense > Gardenia erubescens > Diospyros mespiliformis > Parkia biglobosa > Ficus sycomorus > Vitellaria paradoxa. Detarium microcarpum fruit also showed the highest antioxidant activity using the three antioxidant assays. Fruits with high antioxidant activities were also found to possess high phenolic and flavonoid contents. There was a strong correlation between total phenolic and flavonoid levels and antioxidant activities.

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.

Investigation of antioxidant and rosmarinic acid variation in the sage collection of the genebank in Gatersleben.

The total phenolic and flavonoid contents and 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reduction antioxidant power (FRAP) antioxidant capacities of 19 accessions of Salvia officinalis from the sage collection of the genebank in Gatersleben (Germany) were evaluated. The major phenolic compounds of sage, that is, rosmarinic acid, caffeic acid, carnosol, and carnosic acid, were quantified by reverse-phase high-performance liquid chromatography. The aerial parts of different individual plants of each accession were collected in two consecutive years from the same experimental field at the beginning of their flowering period. The results demonstrated a high variability between accessions. A general decreasing tendency from 2007 to 2008 was observed in most of the estimated parameters, that is, total phenolic, total flavonoid, rosmarinic acid, and caffeic acid contents and DPPH antioxidant activity. A slight opposite trend was obtained with the FRAP antioxidant capacity. Low but variable quantities of carnosol and carnosic acid were evaluated in the sample extracts. Individual plants within accessions were identified with high phenolic content and strong antioxidant activity. The rosmarinic acid content showed up to 8-fold differences between the lowest and the highest values. Overall, the study demonstrated a high variability in secondary metabolites present in sage, which could be used for breeding of highly antioxidative genotypes of S. officinalis.

Validation of a quantitative assay of arbutin using gas chromatography in Origanum majorana and Arctostaphylos uva-ursi extracts

INTRODUCTION Arbutin is a skin-whitening agent that occurs naturally in the bark and leaves of various plants. It is commonly quantified in plant extracts and skin-whitening products by HPLC. OBJECTIVE To develop an alternative gas chromatographic method for the separation and quantification of arbutin in Origanum majorana and Arctostaphylos uva-ursi extracts. METHODOLOGY N,O-Bis(trimethylsilyl)acetamide and trimethylchlorosilane were used as silylation reagents, and the gas chromatographic separation of silylated extracts and standards was performed using a DB-5 narrow bore column. GC-MS was used for the compound identification, and the quantification was carried out by GC-FID. The quantitative results were compared with those of HPLC analysis. RESULTS The developed method gave a good sensitivity with linearity in the range 0.33-500 mg/mL and recovery >98%, allowing the quantification of arbutin in O. majorana and A. uva-ursi extracts. The relative standard deviations (RSD) relating to intra-day and inter-day precision were <0.002% and <4.8%, respectively. The GC results correlated well with those obtained by HPLC analysis. CONCLUSION The analysis of marjoram and bearberry samples showed that the established GC method was rapid, selective, and demonstrated that arbutin could be screened alternatively by gas chromatography.

Antiacetylcholinesterase and antioxidant activity of essential oils from six medicinal plants from Burkina Faso

In this investigation, we evaluated essential oils from six medicinal plants from Burkina Faso for their antiacetylcholinesterase and antioxidant abilities. The chemotype of most active were also determined. The best antiacetylcholinesterase activities were recorded for the essential oils of Eucalyptus camaldulensis (IC50 18.98 µ g/mL) and Ocimum canum (IC50 36.16 µ g/mL). Their chemotype have been related to the 1,8-cineole one. Both essential oils demonstrated a linear mixed non competitive inhibition. The essential oil of Ocimum basilicum which belong to the linalool-eugenol chemotype exhibited the best radical scavenging activity (IC50 3.82 µ g/mL) and reducing power (531.75 mg AAE/g). In comparison with gallic and ascorbic acids, O. basilicum essential oil evidenced interesting antioxidant activities. The antiacetylcholinesterase and antioxidant activities of essential oils were discussed in regard with their chemical composition.

Effects of root colonization by symbiotic arbuscular mycorrhizal fungi on the yield of pharmacologically active compounds in Angelica archangelica L.

The major effects of arbuscular mycorrhizal fungi (AMF) colonization on plant growth, monoterpenoids and coumarins were determined in two genotypes of angelica (Angelica archangelica L., Apiaceae). Genetically uniform experimental plants were used, which was achieved by in vitro propagation of two genotypes (individual plants). The effects of Glomus mosseae (Funneliformis mosseae, BEG 12), Glomus intraradices (Rhizophagus intraradices, BB-E) and the AMF mixture Symbivit® were tested against a negative (without AMF and without additional phosphorus) and a positive (KH2PO4 without AMF) control in five plants per treatment. All in all 50 plants were investigated. Fifteen monoterpenoid and seven coumarin compounds were quantitatively determined in the rhizome and coarse root fractions by means of GC/MS using an internal standard. The sum of the monoterpenoids and coumarins was calculated. Concentrations of compounds rather slightly decreased upon inoculation with AMF when compared to the control. In contrast, biomass increased showing the highest amounts for plants treated with G. mosseae. These results finally caused a marked increase in yield for G. mosseae treated plants compared to the control. Phosphorus treatment led to the lowest yield with significant results for coumarins and in particular for osthole compared to G. mosseae treatment. This is also evidence of an independent effect from an increased phosphorus uptake due to root colonization by AMF. In summary, the results showed a marked increase in yield of all investigated compounds through treatment with G. mosseae compared to the control group, even if the level of significance was just barely missed presumably on account of the small sample size.

Quality assessment and antiplasmodial activity of West African Cochlospermum species

The present study focuses on development of phytochemical methods for quality assessment of two West-African Cochlospermum species (Cochlospermum planchonii and Cochlospermum tinctorium) traditionally used for malaria treatment in Burkina Faso. Antimalarial activity of preparations from dried rhizomes (decoction) was tested against the chloroquine-sensitive Plasmodium strain 3D7 using the histidine-rich protein II (HRP2) drug susceptibility assay and compared with extract preparations using organic solvents of different polarity. Two main apocarotenoids were isolated from rhizomes of C. planchonii and unambiguously identified as dihydrocochloxanthine and cochloxanthine by spectroscopic methods. Comparative HPLC analyses of thirty-nine (39) samples from markets and from collections in natural habitats of both species showed a high variability in the accumulation of cochloxanthines and related carotenoids which were proven to be characteristic for rhizomes of both species and generally absent in leaves. Furthermore, content of total phenolics and antioxidant activities (DPPH and FRAP) as well as haemolytic activity of various extracts was tested. The HPLC method presented here was validated and provides a good separation of both compounds including 10 minor carotenoids. Extracts from both species and pure cochloxanthine offered pronounced antioxidant activities and weak haemolytic activity while, in contrast, dihydrocochloxanthine had a strong haemolytic effect at the highest concentration analysed. However, cochloxanthine as well as dihydrocochloxanthine showed erythroprotective effects against the haemolytic activity of the reference saponin. Moderate antiplasmodial activity between 16 and 63 μg/ml were observed with all tested extracts, and lower IC50 values were obtained with pure dihydrocochloxanthine (IC50=6.9 μg/ml), cochloxanthine (IC50=6.8 μg/ml), the DCM fraction (IC50=2.4 μg/ml) and the ethyl acetate fraction (IC50=11.5μg/ml) derived from a methanolic extract of C. planchonii. This study shows a major variability of carotenoid content and antiplasmodial activity of both C. planchonii and C. tinctorium. The high haemolytic activity of dihydrocochloxanthine (at 100 μg/ml) should be considered as a selection criterion for choosing species phenotypes for treatment.