In an attempt to elucidate the physiological activities of (6E,12E)-tetradecadiene-8,10-diyne-1,3-diol diacetate (TDEYA), which was detected as a hydrolysis form (TDEY) in the plasma after oral administration of a decoction of Atractylodes rhizome in rats, we examined the inhibitory effects of various enzymes which are considered to participate in the regulation of body fluid levels and inflammatory reactions. TDEY and TDEYA did not show inhibitory effects on carbonic anhydrase (CA) or angiotensin converting enzyme (ACE) at concentrations less than 1.0 x 10(-3) M. However, both acetylene compounds inhibited Na+,K+ adenosine triphosphatase (Na+,K(+)-ATPase) weakly and xanthine oxidase (XO) strongly. From the results of several acetylene compounds examined on XO inhibition, it is clear that the active structure of the compounds is due to the presence of conjugated triple and double bonds. In the in vivo experiment of TDEYA, urine volume, urinary electrolytes and uric acid excretion showed no significant differences from the control. However, the administration of TDEYA to rats tended to increase xanthine excretion.