Kampon Sriwatanakul

Anti-inflammatory activity of (E)-1-(3,4-dimethoxyphenyl) butadiene from Zingiber cassumunar Roxb.

This study aimed to investigate the anti-inflammatory activity of (E)-1-(3,4-dimethoxyphenyl) butadiene (DMPBD), isolated from Zingiber cassumunar Roxb., using in vivo and in vitro models. The results show that DMPBD dose-dependently inhibited the rat ear edema induced by ethyl phenylpropiolate (EPP), arachidonic acid (AA) and 12-O-tetradecanoylphorbol 13-acetate (TPA) and it was more potent than any other standard drugs being used. In EPP-induced edema IC(50) of DMPBD and oxyphenbutazone were 21 and 136nmol per ear, respectively. The IC(50) of DMPBD and phenidone were 60 and 2520nmol per ear, respectively, in AA-induced edema whereas DMPBD was 11 times more potent than diclofenac in TPA-induced edema (IC(50)=660 and 7200pmol per ear, respectively). DMPBD and diclofenac inhibited the rat paw edema induced by carrageenan but not by platelet activating factor (PAF). In in vitro study DMPBD, aspirin and phenidone inhibited collagen-induced platelet aggregation with IC(50) of 0.35, 0.43 and 0.03mM, respectively. Whereas IC(50) of these agents in ADP, AA and PAF inductions were 4.85, 3.98 and 1.30mM; 0.94, 0.13 and 0.04mM; and 1.14, 6.96 and 2.40mM, respectively. These results indicate that DMPBD possesses a potent anti-inflammatory activity through the inhibition of CO and LO pathways and seems to have more prominent effects on the LO pathway.

Ethnic differences in the renal sodium-dopamine relationship: a possible explanation for regional variation in the prevalence of hypertension?

SummaryTwenty-four-h urinary sodium and dopamine output by normotensive adults from 5 different ethnic groups have been measured. The groups differed substantially in the correlation between the urinary output ot sodium and dopamine. Those with a traditionally salt rich diet (Thais, Caucasians, Zimbabweans) showed a strong positive correlation (p<0.001), whereas no such relationship was found in West Africans and Iranians, who come from traditionally salt scarce environments.It is hypothesised that in some races the lack of or uncoupling of the renal sodium-dopamine relationship, possibly as a mechanism to help conserve dietary sodium, predisposes to the development of hypertension when the individuals encounter a salt rich diet.

Further ethnic differences in the renal sodium-dopamine relationship: its uncoupling in Iranian but not in Thai normotensive subjects.

Dopamine is a natriuretic hormone and is synthesized in the kidney in response to a sodium load. This relationship results in a positive correlation between urinary sodium and dopamine outputs. Uncoupling of the renal sodium-dopamine relationship is reflected in a loss of this correlation and will result in the sluggish excretion of a sodium load. We measured 24-h urinary sodium and dopamine outputs in Thais and Iranians, who traditionally have very different dietary salt environments (salt-rich and salt-scarce, respectively). There was a highly significant positive correlation between sodium and dopamine in the Thais (r = 0.53, P < 0.001) but no suggestion of such a correlation in the Iranians (r = 0.03). We hypothesize that in some races the uncoupling of the renal sodium-dopamine relationship, possibly as a mechanism to help conserve dietary sodium, predisposes the race to the development of hypertension when the individuals encounter a salt-rich diet.