title: Chemical composition, in vitro antioxidant and anti-inflammatory properties of essential oils of four dietary and medicinal plants from Cameroon.
abstract: BACKGROUND
  In the Cameroonian traditional medicine, plants of the Capparidaceae, Euphorbiaceae and Liliaceae families are used to treat several metabolic diseases. These plants are rich in various compounds belonging to the glucosinolates and thiosulfinates family. Till date, very little studies have been done aiming at assessing the antioxidant and inflammatory properties of the essential oils (EOs) of these plants. Essential oils are volatile extracts produced by secondary metabolism. They are usually constituted of terpens and may also contain specific non terpenic components such as glucosinolates and thiosulfinates for the species that are being considered in the present study. This study highlights and compares the chemical composition, antioxidant and anti-inflammatory properties of the essential oils of the stem barks of Drypetes gossweileri (Euphorbiaceae), roots of Pentadiplandra brazzeana (Capparidaceae), red bulbs of Allium cepa and Alium sativum (Liliaceae) collected in Cameroon (Central Africa).
  
  
  METHODS
  The essential oils were extracted by hydrodistillation and analyzed by gas chromatography (GC) and gas chromatography coupled to mass spectrometry (GC-MS). In vitro antioxidant activities were determined using the radical scavenging assay, total phenolic content, ferric reducing antioxidant power (FRAP) assay and determination of antioxidant activity index (AAI) according to the method described by Scherer and Godoy. The anti-inflammatory activities were evaluated using albumin denaturation method. Differences (p < 0.05) between the experimental and the control groups were evaluated using one way analysis of variance (ANOVA) followed by Tukey's test for multiple comparisons.
  
  
  RESULTS
  The main components of Allium sativum essential oil were diallyl trisulfide (41.62 %), diallyl disulfide (19.74 %), allyl methyl trisulfide (12.95 %), diallyl sulfide (7.1 %) and diallyl tetrasulfide (4.22 %). Those of Allium cepa essential oil were diallyl trisulfide (22.17 %), dipropyl trisulfide (11.11 %), 2-methyl-3,4-dithiaheptane (9.88 %), methyl propyl trisulfide (8.14 %), dipropyl tetrasulfide (8.07 %) and 2-propenyl propyl disulfide (5.15 %). Drypetes gossweileri and Pentadiplandra brazzeana essential oils presented similar chemical compositions as compared with benzylisothiocyanate content (63.19 and 97.63 % respectively), but differed in benzylcyanide content (35.72 and 0.86 % respectively). The essential oils were rich in phenolic compounds in the following order Allium sativum < Allium cepa < D. gossweileiri < P. brazzeana. The essential oils exhibited high antioxidant and DPPH radical scavenging effect but low ferric reducing power activity. Moreover, the four essential oils showed anti-inflammatory activities (by heat denaturation of Bovine Serum Albumin). The anti-inflammatory activities of P. brazzeana and A. cepa essential oils were comparable but higher than those of D. gossweileri and sodium diclofenac used as a reference non-steroidal anti-inflammatory drug.
  
  
  CONCLUSIONS
  The essential oils of the plants were rich in organosulfur compounds. These compounds were probably responsible for their appreciable antioxidant and anti-inflammatory activities. Due to their antioxidant and anti-inflammatory properties, the essential oils of some of these plants might be used as natural additives in the pharmaceutical, cosmetic and agro-industries.
authors.affiliation: Department of Biochemistry, Faculty of Science, University of Yaounde I, P.O. Box 812, Yaounde, Cameroon. chantfoe@yahoo.com.
authors.forename: Florentine Marie-Chantal
authors.initials: FM
authors.lastname: Ndoye Foe
authors.affiliation: Department of Biochemistry, Faculty of Science, University of Yaounde I, P.O. Box 812, Yaounde, Cameroon.|Department of Microbiology, Faculty of Science, University of Yaounde I, P.O. Box 812, Yaounde, Cameroon.|Institute of Medical Research and Medicinal Plants Studies, P.O. Box 8013, Yaounde, Cameroon.
authors.forename: Tatiana Flore Kemegni
authors.initials: TFK
authors.lastname: Tchinang
authors.affiliation: Department of Microbiology, Faculty of Science, University of Yaounde I, P.O. Box 812, Yaounde, Cameroon.|Institute of Biomolecules Max Mousseron, "Equipe Glyco et nanovecteurs pour le ciblage thérapeutique", Faculty of Pharmacy, University of Montpellier II, Montpellier, France.
authors.forename: Ascencion Maximilienne
authors.initials: AM
authors.lastname: Nyegue
authors.affiliation: Institute of Medical Research and Medicinal Plants Studies, P.O. Box 8013, Yaounde, Cameroon.|Department of Organic Chemistry, Faculty of Science, University of Yaounde I, P.O. Box 812, Yaounde, Cameroon.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Abdou
authors.affiliation: Institute of Medical Research and Medicinal Plants Studies, P.O. Box 8013, Yaounde, Cameroon.|Department of Organic Chemistry, Faculty of Science, University of Yaounde I, P.O. Box 812, Yaounde, Cameroon.
authors.forename: Abel Joel Gbaweng
authors.initials: AJG
authors.lastname: Yaya
authors.affiliation: Institute of Medical Research and Medicinal Plants Studies, P.O. Box 8013, Yaounde, Cameroon.
authors.forename: Alembert Tiabou
authors.initials: AT
authors.lastname: Tchinda
authors.affiliation: Institute of Medical Research and Medicinal Plants Studies, P.O. Box 8013, Yaounde, Cameroon.
authors.forename: Jean-Louis Oyono
authors.initials: JO
authors.lastname: Essame
authors.affiliation: Department of Microbiology, Faculty of Science, University of Yaounde I, P.O. Box 812, Yaounde, Cameroon.
authors.forename: François-Xavier
authors.initials: FX
authors.lastname: Etoa
mesh_terms: D000893:Anti-Inflammatory Agents / Q000302:isolation & purification*; D000975:Antioxidants / Q000302:isolation & purification*; D002163:Cameroon; D019669:Embryophyta / Q000737:chemistry; D019665:Euphorbiaceae / Q000737:chemistry; D009822:Oils, Volatile / Q000737:chemistry*; D019697:Onions / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry*
chemical_list: D000893:Anti-Inflammatory Agents; D000975:Antioxidants; D009822:Oils, Volatile
keywords: Anti-inflammatory activity; Chemical composition; Essential oils; In vitro antioxidant; Sulphur-containing plants