Harumitsu Kuwano

A search for endogenous Na+,K+-ATPase inhibitor in acutely volume-expanded hog plasma led to lysophosphatidylcholine gamma-stearoyl.

An Na+,K+-ATPase inhibitor possessing inhibitory activity against the specific binding of ouabain to Na+,K+-ATPase has been purified from the plasma of acutely saline-infused hogs. The purification was performed by a combination of Amberlite XAD-2 adsorption chromatography and five steps of high-pressure liquid chromatography (HPLC). Fast atom bombardment mass and proton nuclear magnetic resonance (NMR) spectrometric studies identified the purified substance as lysophosphatidylcholine gamma-stearoyl (LPCS). The ouabain-displacing activity in plasma, due to this compound, increased with time during saline infusion. The maximal level reached was approximately 12 times higher than that in the pre-infusion plasma sample. Lysophosphatidylcholines (LPCs) containing myristoyl, palmitoyl and oleoyl groups were also inhibitory to Na+,K+-ATPase and ouabain-binding to the enzyme. These LPCs were effective at 100 mumol/l concentrations in attaining 50% inhibition of the enzyme activity and ouabain-binding activity of Na+,K+-ATPase. These results suggest that LPCs containing long chain fatty acids could play an important role as a Na+,K+-ATPase inhibitors under volume-expanded conditions.

Poilaneic acid, a cembranoid diterpene from Croton poilanei

Abstract Poilaneic acid, a cembranoid diterpene from Croton poilanei , has been characterized as (1 R *,2 E ,4 Z ,7 E , 11 Z )-12-carboxyl-1-isopropyl-4,8-dimethylcyclotetradecatetraene.

Plaunol A and B, new anti-ulcer diterpenelactones from Croton sublyratus

Abstract Two new diterpenelactones named plaunol A ( 2 ) and B ( 3 ) exhibiting anti-Shay ulcer activity were isolated from Thai medicinal plant, Croton sublyratus . Structure of 2 was determined by X-ray analysis of its p -bromobenzoate and structure of 3 was deduced from the results of chemical correlation and the spectral data.

Acyclic diterpenes from Croton kerrii

Abstract Croton kerrii ; Euphorbiaceae; acyclic diterpenes; anti-reserpine ulcer; ( E,E,Z )-11- hydroxymethyl-3,7,15-trimethyl-2,6,10,14-hexadecatetraen-1-ol; ( E,E,E )-11-formyl-3,7,15-trimethyl-2,6,10,14-hexadecatetraen-1-ol.