| In vitro: |
| Prostaglandins Leukotrienes & Essential Fatty Acids, 1991, 42(1):73-81. | | Acetyl eugenol, a component of oil of cloves (Syzygium aromaticum L.) inhibits aggregation and alters arachidonic acid metabolism in human blood platelets.[Reference: WebLink] |
METHODS AND RESULTS:
In continuation of our studies with the oil of cloves — a common kitchen spice and a crude drug for home medicine — we have isolated yet another active component identified as acetyl eugenol (AE); the earlier reported active component being eugenol. The isolated material (IM) was found to be a potent platelet inhibitor; IM abolished arachidonate (AA)-induced aggregation at ca. 12 μM, a concentration needed to abolish the second phase of adrenaline-induced aggregation. Chemically synthesized acetyl eugenol showed similar effects on AA- and adrenaline-induced aggregation. A dose-dependent inhibition of collagen-induced aggregation was also observed. AE did not inhibit either calcium ionophore A23187- or thrombin-induced aggregation. Studies on aggregation and ATP release were done using whole blood (WB). AA-induced aggregation in WB was abolished at 3 μg/ml (14.6 μM) which persisted even after doubling the concentration of AA. ATP release was inhibited. Inhibition of aggregation appeared to be mediated by a combination of two effects: reduced formation of thromboxane and increased generation of 12-lipoxygenase product (12-HPETE).
CONCLUSIONS:
These effects were observed by exposing washed platelets to (14C)AA or by stimulating AA-labelled platelets with ionophore A23187. Acetyl eugenol inhibited (14C)TxB2 formation in AA-labelled platelets on stimulation with thrombin. AE showed no effect on the incorporation of AA into platelet phospholipids. | | Phytotherapy Research, 1990, 4(3):90-96. | | Eugenol a valuable compound for in vitro experimental research and worthwhile for further in vivo investigation.[Reference: WebLink] |
METHODS AND RESULTS:
Eugenol and isoeugenol are responsible for several pharmacological activities exhibited by nutmeg preparations. We studied their antimicrobial and antiaggregation activity in vitro and their influence on platelet function ex vivo. At the same time biogenetically or metabolically related derivatives were tested. Eugenol and isoeugenol (1 mg/mL) showed pronounced antibacterial properties: growth inhibition of 6 out of 10 Gram + and Gram – microorganisms was comparable with neomycin (500 μg/mL). Growth inhibition was even more pronounced for Candida species in comparison with nystatin (5000 U/mL). Eugenol and some of its analogues inhibited growth of Aspergillus and Trichophyton species at concentrations of 100 μg/mL. However, cytotoxicity of the compounds will limit their systemical use. The IC50, of eugenol (3.0 × 10−7M) and isoeugenol (7.2 × 10−7M), were comparable with indomethacin (2.2 × 10−7M) on platelet aggregation. Their free hydroxy group was necessary for pharmacological activity. Ex vivo results revealed a dose-dependent blocking effect on the thromboxane biosynthesis by rat blood platelets: 66% inhibition by 50 mg/kg to 96% inhibition by 400 mg/kg.
CONCLUSIONS:
Eugenol and acetyleugenol given orally to rabbits had mean biological half-lives of 95 and 60 min respectively. Eugenol might be an interesting basic structure for drug design. | | Applied Entomology & Zoology, 2003, 38(2):261-266. | | Acaricidal activity of clove bud oil compounds against Tyrophagus putrescentiae (Acari: Acaridae).[Reference: WebLink] |
METHODS AND RESULTS:
The acaricidal activity of clove (Eugenia caryophyllata) bud oil compounds (acetyleugenol, β-caryophyllene, eugenol, α-humulene), and congeners of eugenol (isoeugenol, methyleugenol) against adult Tyrophagus putrescentiae was examined using impregnated fabric disc and fumigation methods, and compared with that of benzyl benzoate. Responses varied according to compound and dose. LD50 values indicated that the compound most toxic to T. putrescentiae adults was methyleugenol (1.18 μg/cm2) followed by isoeugenol (8.21 μg/cm2), benzyl benzoate (8.85 μg/cm 2), β-caryophyllene (11.77 μg/cm2), eugenol (12. 11 μg/cm2), and α-humulene (12.90 μg/cm2). Very low activity was observed with acetyleugenol (28.72 μg/cm2). These results indicate that hydrophobicity of the four phenylpropenes (acetyleugenol, eugenol, isoeugenol, methyleugenol) plays a crucial role in T. putrescentiae toxicity. The typical poisoning symptom of the test compounds was a similar death symptom of the forelegs extended forward together, leading to death without knockdown, whereas benzyl benzoate caused death following uncoordinated behavior.
CONCLUSIONS:
In fumigation tests with adult T. putrescentiae, all four phenylpropenes were more effective against the mites in closed containers than in open ones, indicating that the mode of delivery of these compounds was largely due to action in the vapor phase. The clove bud oil compounds as well as isoeugenol and methyleugenol merit further study as potential storage mite control agents or as lead compounds. |
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