title: Strong and Long-Lasting Antinociceptive and Anti-inflammatory Conjugate of Naturally Occurring Oleanolic Acid and Aspirin.
abstract: The conjugate 8 was obtained as a result of condensation of 3-hydroxyiminooleanolic acid morfolide (7) and aspirin in dioxane. Analgesic effect of OAO-ASA (8) for the range of doses 0.3-300.0 mg/kg (p.o.) was performed in mice using a hot-plate test. Anti-inflammatory activity was assessed on carrageenan-induced paw edema in rats for the same range of doses. The conjugate OAO-ASA (8) did not significantly change locomotor activity of mice, therefore sedative properties of the compound should be excluded. The compound 8 proved a simple, proportional, dose-dependent analgesic action and expressed strong anti-inflammatory activity showing a reversed U-shaped, dose-dependent relation with its maximum at 30.0 mg/kg. After its combined administration with morphine (MF, 5.0 mg/kg, s.c.) the lowering of antinociceptive activity was found; however, the interaction with naloxone (NL, 3.0 mg/kg, s.c.) did not affect the antinociceptive effect of OAO-ASA (8), therefore its opioid mechanism of action should be rather excluded. After combined administration with acetylsalicylic acid (ASA, 300.0 mg/kg, p.o.) in hot-plate test, the examined compound 8 enhanced the antinociceptive activity in significant way. It also shows that rather the whole molecule is responsible for the antinociceptive and anti-inflammatory effect of the tested compound 8, however, it cannot be excluded that the summarizing effect is produced by ASA released from the compound 8 and the rest of triterpene derivative. The occurrence of tolerance for triterpenic derivative 8 was not observed, since the analgesic and anti-inflammatory effects after chronic administration of the conjugate OAO-ASA (8) was on the same level as after its single treatment. It seemed that the anti-inflammatory mechanism of action of OAO-ASA (8) is not simple, even its chronic administration lowered both blood concentration of IL-6 and mRNA IL-6 expression. However, the effects of the conjugate OAO-ASA (8) on TNF-α level and mRNA expression were opposite. Moreover, compound 8 did not change unequivocally mRNA TLR1, and TLR3 expression. Concluding, the obtained results regarding the antinociceptive and anti-inflammatory activity of new conjugate of oleanolic acid oxime and acetylsalicylic acid (OAO-ASA 8) are very interesting, but for explanation of its mechanism of action, more detailed studies are necessary.
authors.affiliation: Department of Organic Chemistry, Faculty of Pharmacy, Poznan University of Medical Sciences Poznan, Poland.
authors.forename: Barbara
authors.initials: B
authors.lastname: Bednarczyk-Cwynar
authors.affiliation: Department of Pharmacology, Poznan University of Medical Sciences Poznan, Poland.
authors.forename: Natalia
authors.initials: N
authors.lastname: Wachowiak
authors.affiliation: Department of Pharmacology, Poznan University of Medical Sciences Poznan, Poland.
authors.forename: Michal
authors.initials: M
authors.lastname: Szulc
authors.affiliation: Department of Pharmacology, Poznan University of Medical Sciences Poznan, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Kamińska
authors.affiliation: Laboratory of Experimental Pharmacogenetics, Department of Clinical Pharmacy and Biopharmacy, Poznan University of Medical Sciences Poznan, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Bogacz
authors.affiliation: Laboratory of Experimental Pharmacogenetics, Department of Clinical Pharmacy and Biopharmacy, Poznan University of Medical Sciences Poznan, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Bartkowiak-Wieczorek
authors.affiliation: Department of Organic Chemistry, Faculty of Pharmacy, Poznan University of Medical Sciences Poznan, Poland.
authors.forename: Lucjusz
authors.initials: L
authors.lastname: Zaprutko
authors.affiliation: Department of Pharmacology, Poznan University of Medical SciencesPoznan, Poland; Department of Pharmacology and Phytochemistry, Institute of Natural Fibres and Medicinal PlantsPlewiska, Poland.
authors.forename: Przemyslaw L
authors.initials: PL
authors.lastname: Mikolajczak
keywords: acetylsalicylic acid; acyloxyimino derivatives; anti-inflammatory activity; antinociceptive activity; cytokine levels; mRNA expression; oleanolic acid; triterpenes