Effect of guggulsterone and cembranoids of Commiphora mukul on pancreatic phospholipase A(2): role in hypocholesterolemia.
Guggulsterone (7) and cembranoids (8-12) from Commiphora mukul stem bark resin guggul were shown to be specific modulators of two independent sites that are also modulated by bile salts (1-6) to control cholesterol absorption and catabolism. Guggulsterone (7) antagonized the chenodeoxycholic acid (3)-activated nuclear farnesoid X receptor (FXR), which regulates cholesterol metabolism in the liver. The cembranoids did not show a noticeable effect on FXR, but lowered the cholate (1)-activated rate of human pancreatic IB phospholipase A2 (hPLA2), which controls gastrointestinal absorption of fat and cholesterol. Analysis of the data using a kinetic model has suggested an allosteric mechanism for the rate increase of hPLA2 by cholate and also for the rate-lowering effect by certain bile salts or cembranoids on the cholate-activated hPLA2 hydrolysis of phosphatidylcholine vesicles. The allosteric inhibition of PLA2 by certain bile salts and cembranoids showed some structural specificity. Biophysical studies also showed specific interaction of the bile salts with the interface-bound cholate-activated PLA2. Since cholesterol homeostasis in mammals is regulated by FXR in the liver for metabolism and by PLA2 in the intestine for absorption, modulation of PLA2 and FXR by bile acids and selected guggul components suggests novel possibilities for hypolipidemic and hypocholesterolemic therapies.
Yu
Bao-Zhu
BZ
Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19713, USA.
Kaimal
Rajani
R
Bai
Shi
S
El Sayed
Khalid A
KA
Tatulian
Suren A
SA
Apitz
Rafael J
RJ
Jain
Mahendra K
MK
Deng
Ruitang
R
Berg
Otto G
OG
D000818:Animals; D000924:Anticholesteremic Agents / Q000494:pharmacology*; D001647:Bile Acids and Salts / Q000378:metabolism*; D002784:Cholesterol / Q000378:metabolism*; D029744:Commiphora; D004268:DNA-Binding Proteins / Q000819:agonists / Q000037:antagonists & inhibitors; D004224:Diterpenes / Q000494:pharmacology*; D006801:Humans; D008958:Models, Molecular; D015394:Molecular Structure; D010179:Pancreas / Q000201:enzymology; D064801:Phospholipase A2 Inhibitors; D054467:Phospholipases A2 / Q000187:drug effects; D010936:Plant Extracts / Q000494:pharmacology; D053149:Plant Gums / Q000494:pharmacology; D011282:Pregnenediones / Q000494:pharmacology*; D018160:Receptors, Cytoplasmic and Nuclear / Q000819:agonists / Q000037:antagonists & inhibitors; D013552:Swine; D014157:Transcription Factors / Q000819:agonists / Q000037:antagonists & inhibitors; D000099150:Receptor, Farnesoid X-Activated
D000924:Anticholesteremic Agents; D001647:Bile Acids and Salts; D002784:Cholesterol; D004268:DNA-Binding Proteins; D004224:Diterpenes; D064801:Phospholipase A2 Inhibitors; D054467:Phospholipases A2; D010936:Plant Extracts; D053149:Plant Gums; D011282:Pregnenediones; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors; D000099150:Receptor, Farnesoid X-Activated; C018562:guggulu extract; C023617:pregna-4,17-diene-3,16-dione