Chemical composition profiling and antifungal activity of the essential oil and plant extracts of Mesembryanthemum edule (L.) bolus leaves.
BACKGROUND
Essential oil from Mesembryanthemum edule leaves have been used by the Eastern Cape traditional healers for the treatment of respiratory tract infections, tuberculosis, dysentery, diabetic mellitus, laryngitis and vaginal infections. The investigation of bioactive compounds in the essential oil of this plant could help to verify the efficacy of the plant in the management or treatment of these illnesses.


METHODS
Various concentrations of the hydro-distilled essential oil, ranging from 0.005-5 mg/ml, were tested against some fungal strains, using the micro-dilution method. Minimum inhibitory activity was compared with four other different crude extracts of hexane, acetone, ethanol and aqueous samples from the same plant. The chemical composition of the essential oil, hexane, acetone and ethanol extracts was determined using GC-MS.


RESULTS
GC/MS analysis of the essential oil resulted in the identification of 28 compounds, representing 99.99% of the total oil. Phytoconstituents of hexane, acetone and ethanol extracts yielded a total peak chromatogram of fifty nine compounds. A total amount of 10.6% and 36.61% of the constituents were obtained as monoterpenes and oxygenated monoterpenes. Sesquiterpene hydrocarbons (3.58%) were relatively low compared to the oxygenated sesquiterpenes (9.28%), while the major concentrated diterpenes and oxygenated diterpenes were 1.43% and 19.24 %, respectively and phytol 12.41%. Total amount of fatty acids and their methyl esters content, present in the oil extract, were found to be 19.25 %. Antifungal activity of the oil extract and four solvent extracts were tested against five pathogenic fungal strains. The oil extract showed antifungal activity against Candida albican, Candida krusei, Candida rugosa, Candida glabrata and Cryptococcus neoformans with MIC ranges of 0.02 0.31 mg/ml. Hexane extract was active against the five fungal strains with MICs ranging between 0.02-1.25 mg/ml. Acetone extracts were active against C. krusei only at 0.04mg/ml. No appreciable antifungal activity was found in either ethanol or water extracts when compared with commercial antibiotics.


CONCLUSIONS
The profile of chemical constituents found in M. edule essential oil and its antifungal properties support the use of M. edule by traditional healers as well as in the pharmaceutical and food industries as a natural antibiotic and food preservative.
Department of Biochemistry and Microbiology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa.
Beauty Etinosa
BE
Omoruyi
Department of Botany, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa.
Anthony Jide
AJ
Afolayan
Department of Biochemistry and Microbiology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa.
Graeme
G
Bradley
D000935:Antifungal Agents / Q000032:analysis / Q000494:pharmacology*; D002175:Candida / Q000187:drug effects; D003454:Cryptococcus / Q000187:drug effects; D004224:Diterpenes / Q000032:analysis / Q000494:pharmacology; D005227:Fatty Acids / Q000032:analysis; D005658:Fungi / Q000187:drug effects*; D008401:Gas Chromatography-Mass Spectrometry; D035723:Mesembryanthemum / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D039821:Monoterpenes / Q000032:analysis / Q000494:pharmacology; D009822:Oils, Volatile / Q000737:chemistry / Q000494:pharmacology*; D010836:Phytol / Q000032:analysis / Q000494:pharmacology; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D012717:Sesquiterpenes / Q000032:analysis / Q000494:pharmacology; D013729:Terpenes / Q000032:analysis / Q000494:pharmacology*
D000935:Antifungal Agents; D004224:Diterpenes; D005227:Fatty Acids; D039821:Monoterpenes; D009822:Oils, Volatile; D010936:Plant Extracts; D012717:Sesquiterpenes; D013729:Terpenes; D010836:Phytol
Antifungal activity; Essential oil; GC/MS; Mesembryanthemum edule; Opportunistic fungi