title: Thermostability of allicin determined by chemical and biological assays.
abstract: The garlic-derived antibacterial principle, alk(en)yl sulfinate compounds, has long been considered as very short-lived substance. However, there are some data showing a rather more stable nature of allicin. We determined here the thermostability of allicin by a systematic analyses employing chemical quantification and an antibacterial activity assay. Allicin in an aqueous extract of garlic was degraded stoichiometrically in proportion to the temperature; we estimated the half-life of allicin to be about a year at 4 degrees C (from 1.8 mg/ml to 0.9 mg/ml) and 32 d at 15 degrees C, but only 1 d at 37 degrees C (from 2.0 mg/ml to 1.0 mg/ml). The half-life values for antibacterial activity showed a similar trend in results: 63 d or more at 4 degrees C for both antibacterial activities, 14 d for anti-staphylococcal activity, and 26 d for anti-escherichia activity at 15 degrees C, but only 1.2 d and 1.9 d for the respective activities at 37 degrees C. Such antibacterial activities were attributable to the major allicin, allyl 2-propenylthiosulfinate. Surprisingly, the decline in the quantity of allicin was not accompanied by its degradation; instead, allicin became a larger molecule, ajoene, which was 3-times larger than allicin.
authors.affiliation: Nihon University Graduate School of Applied Life Sciences, Kanagawa, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Fujisawa
authors.forename: Kaoru
authors.initials: K
authors.lastname: Suma
authors.forename: Kana
authors.initials: K
authors.lastname: Origuchi
authors.forename: Taiichiro
authors.initials: T
authors.lastname: Seki
authors.forename: Toyohiko
authors.initials: T
authors.lastname: Ariga
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D001681:Biological Assay; D002851:Chromatography, High Pressure Liquid; D004220:Disulfides; D004926:Escherichia coli / Q000187:drug effects; D005737:Garlic / Q000737:chemistry; D006207:Half-Life; D010936:Plant Extracts / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects; D013441:Sulfinic Acids / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D004220:Disulfides; D010936:Plant Extracts; D013441:Sulfinic Acids; D014867:Water; C006452:allicin