METHODS: MTT assay, DNA fragmentation, ELISA and cell cycle analysis were carried out.

RESULTS: Nordamnacanthal and damnacanthal at IC50 values of 1.7 μg/mL and10 μg/mL, respectively. At the molecular level, these compounds caused internucleosomal DNA cleavage producing multiple 180-200 bp fragments that are visible as a "ladder" on the agarose gel. This was due to the activation of the Mg2+/Ca2+-dependent endonuclease. The induction of apoptosis by nordamnacanthal was different from the one induced by damnacanthal, in a way that it occurs independently of ongoing transcription process. Nevertheless, in both cases, the process of dephosphorylation of protein phosphates 1 and 2A, the ongoing protein synthesis and the elevations of the cytosolic Ca2+ concentration were not needed for apoptosis to take place. Nordamnacanthal was found to have a cytotoxic effect by inducing apoptosis, while damnacanthal caused arrest at the G0/G1 phase of the cell cycle.

AIM: The present study was conducted to investigate the possible mechanism of actions underlying the systemic antinociception activity of the essential oil of Zingiber zerumbet (EOZZ) in chemical-induced nociception tests in mice.

MATERIALS AND METHODS: Acetic acid-induced abdominal constriction, capsaicin-, glutamate- and phorbol 12-myristate 13-acetate-induced paw licking tests in mice were employed in the study. In all experiments, EOZZ was administered systemically at the doses of 50, 100, 200 and 300 mg/kg.

RESULTS: It was shown that EOZZ given to mice via intraperitoneal and oral routes at 50, 100, 200 and 300 mg/kg produced significant dose dependent antinociception when assessed using acetic acid-induced abdominal writing test with calculated mean ID(50) values of 88.84 mg/kg (80.88-97.57 mg/kg) and 118.8 mg/kg (102.5-137.8 mg/kg), respectively. Likewise, intraperitoneal administration of EOZZ at similar doses produced significant dose dependent inhibition of neurogenic pain induced by intraplantar injection of capsaicin (1.6 μg/paw), glutamate (10 μmol/paw) and phorbol 12-myristate 13-acetate (1.6μg/paw) with calculated mean ID(50) of 128.8 mg/kg (118.6-139.9 mg/kg), 124.8 mg/kg (111.4-139.7 mg/kg) and 40.29 (35.39-45.86) mg/kg, respectively. It was also demonstrated that pretreatment with l-arginine (100mg/kg, i.p.), a nitric oxide precursor significantly reversed antinociception produced by EOZZ suggesting the involvement of l-arginine/nitric oxide pathway. In addition, methylene blue (20mg/kg, i.p.) significantly enhanced antinociception produced by EOZZ. Administration of glibenclamide (10mg/kg, i.p.), an ATP-sensitive K(+) channel antagonist significantly reversed antinociceptive activity induced by EOZZ.