Pharmacological activities of 6-(4-hydroxy-3-methoxyphenyl)-hexanonic acid (HMPHA), a phenolic compound, isolated from the extract of Pycnocycla spinosa was investigated on ileum motility in vivo and in vitro. Ileum motility was examined by measuring charcoal movement through the gut in mice. In addition, antidiarrhoeal activity of HMPHA was assessed and compared with standard drug; loperamide (2 mg/kg) and the hydroalcoholic extract of P. spinosa (2 mg/kg). Furthermore, concentration response curve to contraction induced by acetylcholine (ACh), 5-hydroxy triptamine (5-HT) and electrical field stimulation (EFS) were obtained after incubation of ileum segment with various concentrations of HMPHA or hydroalcoholic extract of P. spinosa. HMPHA (2 mg/kg and 5 mg/kg, orally) significantly inhibited gut movements in vivo and reduced diarrhoea induced by castor oil or sulphate magnesium. In addition, HMPHA reduced ileum contraction induced by ACh (IC50=33 ± 6 μg/ml), 5-HT (IC50=87 ± 12 μg/ml) and EFS (IC50=36 ± 3 μg/ml) in vitro in a concentration-dependent manner. The inhibitory effect was reversible following washing off the drug. These studies indicate that HMPHA as an active component of P. spinosa extract has significant antispasmodic and antidiarrhoeal activities and therefore, has the potential as a lead compound for further development of a new spasmolytic remedy.
Keywords: 6-(4-hydroxy-3-methoxyphenyl)-hexanonic acid; Antidiarrhoeal; Antispasmodic; Pycnocycla spinosa extract.