Garlic and its active metabolite allicin produce endothelium- and nitric oxide-dependent relaxation in rat pulmonary arteries

David D. Ku, Tarek T. Abdel-Razek, Jun Dai, Sang Ae Kim-Park, Michael B. Fallon, Gary A. Abrams

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57 Scopus citations


1. The aims of the present study were to investigate the effects of fresh garlic and one of its active metabolites, allicin, on rat isolated pulmonary arteries (RPA). 2. In endothelium-intact and phenylephrine-precontracted RPA, the addition of a water or a 5% ethanol extract of fresh garlic (1-500 μg/mL) resulted in a dose-dependent relaxation reaching a maximum (mean±SEM) of -91 ± 3 and -93 ± 2%, respectively, with an ED50 of 113 ± 12 and 106 ± 10 μg/mL, respectively. The vasorelaxation was readily reversible upon washing and no tachyphylaxis was noted. 3. An extract of the external garlic storage leaf produced a significantly greater relaxation than the inner stem. Microfiltration of extracts with a 10 000 molecular sieve did not attenuate relaxation. Inactivation of alliinase and allicin formation, with either boiling of the garlic clove for 30 min or 100% ethanol treatment, completely abolished relaxation. In contrast, similar treatment of crushed garlic with formed allicin retained the relaxation response. 4. Pure allicin produced a similar relaxation as garlic extract, with an EC50 of approximately 0.8 μg/mL. Disruption of endothelium or NG-nitro-L-arginine methyl ester pretreatment attenuated the relaxation, whereas indomethacin had no effect. 5. Prior garlic (500 μg/mL) treatment enhanced acetylcholine relaxation by shifting the response curve to the left, but had no effect on nitric oxide (NO) donor-induced responses. 6. These results demonstrate that garlic and the active metabolite allicin are capable of eliciting a NO-dependent relaxation in RPA and that this response is likely to be mediated via garlic activation of NO formation rather than its stabilization.

Original languageEnglish (US)
Pages (from-to)84-91
Number of pages8
JournalClinical and Experimental Pharmacology and Physiology
Issue number1-2
StatePublished - 2002


  • Allicin
  • Alliinase
  • Endothelium
  • Garlic
  • Nitric oxide
  • Pulmonary
  • Vasorelaxation

ASJC Scopus subject areas

  • Physiology
  • Pharmacology
  • Physiology (medical)


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