Supercritical carbon dioxide extraction of compounds with antimicrobial activity from Origanum vulgare L.: determination of optimal extraction parameters

• Published in: Journal of food protection 2006-02, Vol.69 (2), p.369-375
• Main Authors: Santoyo, S, Cavero, S, Jaime, L, Ibanez, E, Senorans, F.J, Reglero, G
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - analysis; Anti-Bacterial Agents - pharmacology; antibacterial properties; antifungal properties; Aspergillus niger; Aspergillus niger - drug effects; Aspergillus niger - growth & development; Bacillus subtilis; Bacillus subtilis - drug effects; Bacillus subtilis - growth & development; bacterial contamination; Biological and medical sciences; Candida albicans; Candida albicans - drug effects; Candida albicans - growth & development; carbon dioxide; Carbon Dioxide - pharmacology; chemical composition; Chemical Fractionation; Colony Count, Microbial; culture media; Cymenes; Escherichia coli; Escherichia coli - drug effects; Escherichia coli - growth & development; essential oils; food contamination; Food industries; Food microbiology; food pathogens; Food Preservation - methods; food preservatives; Fundamental and applied biological sciences. Psychology; Gas Chromatography-Mass Spectrometry; Gram-negative bacteria; Gram-positive bacteria; Microbial Sensitivity Tests; minimum inhibitory concentration; molds (fungi); Monoterpenes - analysis; Monoterpenes - isolation & purification; Monoterpenes - pharmacology; Oils, Volatile - analysis; Oils, Volatile - chemistry; Oils, Volatile - pharmacology; oregano; Origanum - chemistry; Origanum vulgare; plant extracts; Plant Extracts - analysis; Plant Extracts - pharmacology; Plant Leaves - chemistry; Pseudomonas aeruginosa; Pseudomonas aeruginosa - drug effects; Pseudomonas aeruginosa - growth & development; Staphylococcus aureus; Staphylococcus aureus - drug effects; Staphylococcus aureus - growth & development; supercritical fluid extraction; yeasts
• ISSN: 0362-028X; 1944-9097
• DOI: 10.4315/0362-028X-69.2.369

Oregano leaves were extracted using a pilot-scale supercritical fluid extraction plant under a wide range of extraction conditions, with the goal of determining the extraction and fractionation conditions to obtain extracts with optimal antimicrobial activity. In this investigation, the essential oil-rich fractions were selectively precipitated in the second separator, and their chemical composition and antimicrobial activity were investigated. Gas chromatography-mass spectrometry analysis of the various fractions resulted in the identification of 27 compounds of the essential oil. The main components of these fractions were carvacrol, trans-sabinene hydrate, cis-piperitol, borneol, terpinen-4-ol, and linalool. Antimicrobial activity was investigated by the disk diffusion and broth dilution methods against six different microbial species, including two gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), two gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), a yeast (Candida albicans), and a fungus (Aspergillus niger). All of the supercritical fluid extraction fractions obtained showed antimicrobial activity against all of the microorganisms tested, although the most active fraction was the one obtained in experiment 5 (fraction was obtained with 7% ethanol at 150 bar and 40 degrees C). C. albicans was the most sensitive microorganism to the oregano extracts, whereas the least susceptible was A. niger. Carvacrol, sabinene hydrate, borneol, and linalool standards also showed antimicrobial activity against all of the microorganisms tested, with carvacrol being the most effective. Consequently, it was confirmed that essential oil from experiment 5, with the best antimicrobial activity, also presented the highest quantity of carvacrol.