Guy Alain Alitonou

Variability in the Chemical Compositions of the Essential Oils of Five Ocimum Species from Tropical African Area

Abstract As part of our research on aromatic plants from Africa, we have analyzed, via GC and CG/MS, the essential oils from fresh leaves of five Ocimum species from tropical Africa: Ocimum basilicum L., O. gratissimum L., O. americanum L. (syn: O. canum Sims), O. lamiifolium Hochst. ex Benth. and O. minimum L. The chemical compositions of O. basilicum, O. gratissimum and O. minimum essential oils could be related to some chemotypes already defined for these three species: linalool- or methyl chavicol-types for the first species, thymol- or eugenol- or ocimenes/far- nesenes-types for the second one; finally, a high content of methyl chavicol (34.3%) and linalool (17.8%) was found in O. minimum oil, similar to that already described for a Brazilian species. On the other hand, an essential oil dominated by 1,8-cineole was described for the first time for a sample of O. americanum. Finally, the oil of O. lamiifolium, which was rich in sabinene, is chemically described for the first time.

Aromatic Plants of Tropical West Africa. Part XIV. Chemical and Biological Investigation of Lippia multiflora Mold. Essential Oil from Benina

Abstract The essential oil of the leaves of Lippia multiflora collected in Benin was obtained by hydrodistillation and analyzed by capillary GC and GC/MS. Thirty-six components, representing 96.5% of oil were identified. The sample consisted mainly of monoterpenes. The major constituents were 1,8-cineole (39.9%), sabinene (11.1%), linalool (10.9%) and α-terpineol (10%). The antioxidant and antiradical activities of the oil was found to be low comparatively to that of butylated hydroxytoluene (BHT).

Aromatic Plants of Tropical West Africa. Part XV. Chemical and Biological Evaluation of Leaf Essential Oil of Commiphora africana from Benin

Abstract The essential oil from leaves of Commiphora africana collected in Benin was analyzed by capillary GC and GC/MS. The essential oil was characterized by a majority of sesquiterpenoid constituents with bisabolane skeleton among them bisabolone (38.4%) and β-sesquiphellandrene (19.1%) were the most abundant. The radical scavenging activity of the oil was found to be low comparatively to that of butylated hydroxytoluene (BHT).

Chemical and Biological Investigation on Volatile Constituents of Pentadesma butyracea Sabine (Clusiaceae) From Benin

Abstract The essential oils obtained by hydrodistillation of leaves, bark and roots of Pentadesma butyracea collected in Natitingou (Benin) were investigated by capillary GC and GC/MS. Twenty-eight components, representing 97–99% of oils, were identified. The samples were exclusively sesquiterpenic, dominated in all cases by β-caryophyllene (58.0–75.0%) and α-humulene (10.1–14.2%); the leaf oil was characterized by a high content of α-copaene (14.2%). Finally, no significant antiradical activity (DPPH method) or inhibitory effect on the soybeen lipoxygenase activity could be observed.

Biological control of spoilage and pathogens moulds in culture medium and Beninese traditional cheese wagashi by Syzygium aromaticum essential oil

The investigation highlighted the antifungal effectiveness in culture medium and traditional cheese wagashi foodsystem of Syzygium aromaticum (Eugenia caryophyllata) essential oil (EO) against spoilage and toxinogenic moulds isolated from wagashi produced in Benin. The chemical composition of the EO obtained by hydrodistillation, characterized through GC-FID and GC-MS analysis, revealed eugenol (75.2%) and trans--caryophyllene (12.0%) as major components. The evaluation of in vitro antifungal activity of this oil showed a significant fungistatic activity against Aspergillus (flavus, tamarii, niger, aculeatus, ustus, terreus), Penicillium (brevicompactum, citrinum, griseofulvum), Fusarium (poae, verticillioides) and Scopulariopsis brevicaulis with MIC ranged from 200 to 600 mg/L due probably to its richness in eugenol. Moreover, this EO had fungicidal activity against Aspergillus terreus and S. brevicaulis which were the most sensitive respectively at 600 and 400 mg/L. The assessment of antifungal activity of the oil studied in wagashi foodsystem against the less sensible isolates at in vitro assay revealed high sporale reduction rate (55% at least at 1000 mg/L) on all species investigated above all on Penicillium citrinum and Aspergillus aculeatus, two harmful mycotoxins producers in cheese. Results obtained indicate the possibility of exploiting S. aromaticum EO to preserve wagashi against moulds contamination and probably mycotoxins inhibition during wagashi storage.

Aeollanthus pubescens Benth. from Benin: A Potential Source of Essential Oil with High Antiradical Efficiency

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.

Ovicide and Larvicide Activities of the Essential Oils Extracted from Polyalthia longifolia and Clausena anisata on Sitotroga cerealella

This work has objectives to study the chemical composition of volatile extracts obtained from leaves of Polyalthia longifolia and Clausena anisata and to evaluate their ovicide and larvicide effects by fumigation against Sitotroga cerealella, as alternative to the pesticides of synthesis. The analyses of the extracts by GC-MS showed that the essential oil of P. longifolia contains 57 compounds representing 86.1% of oil and 26 compounds corresponding to 97.3% of the essential oil of C. anisata. The main compounds identified for the extract of P. longifolia are the β-Caryophyllene (24.5%), Allo-Aromadendrene (13.5%), the α-Zingiberene (9.4%), the α-Humulene (8.5%) and the α-Selinene (2.6%). The extract of C. anisata mainly composed of methyl chavicol (69.9%) is characterized by the presence of oxygenated monoterpens (1.4%), hydrogenated monoterpens (7.8%), hydrogenated sesquiterpens (16.2%), oxygenated sesquiterpens (1.7%) and of aromatic compounds (69.9%). The biological test results showed that the treatments by fumigation done with the essential oils reduce meaningfully (p<0.001) the bursting of the ovums on the paddy rice. The essential oil of C. anisata has completely inhibited the viability of the larvas and the emergence of adult butterflies from the dose 0.5 µl mL-1 contrary to P. longifolia that recorded respectively 10.0±0.3% and 50.0±0.2% at the strong dose 3 µl mL-1. The study has, otherwise, shown that the essential oils delayed the cycle of development “ovums to adult” of S. cerealella (29.0±0.4 to 35.4±0.5 days) in relation to the witness (25±0.1 days). The essential oil of C. anisata proved to be more poisonous for the juvenile stages of S. cerealella. These results provide the scientific basis for potential alternatives to the synthetic fumigants in subsistence and commercial agriculture.