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Directed crystallization is found in many natural systems, where the inorganic material provides the organism with superior barrier and mechanical properties. Using this principle of controlled nucleation and growth on a biopolymer (pectin) substrate, hollow shells of calcium carbonate were formed in certain reaction conditions that were generally more perfect at lower reactant concentrations. The nucleation mechanism required the presence of calcium-binding acidic groups on the biopolymer. These served to initially gel the biopolymer, thus providing the template upon which crystallization could occur, and then provided the calcium-rich sites at the template surface that promoted crystallization. The propensity of the system to crystallize on the gel particle surface thereby led to the formation of a complete shell of calcium carbonate, in the form of calcite, which in certain conditions was shown to effectively encapsulate small molecular weight hydrophilic species such as sodium chloride. Importantly, h...

The ethyl acetate extract of the gum of the guggul tree, Commiphora mukul (guggulipid), is marketed for the treatment of dyslipidaemia and obesity. We have found that it protects Lep(ob)/Lep(ob) mice from diabetes and have investigated possible molecular mechanisms for its metabolic effects, in particular those due to a newly identified component, commipheric acid. Both guggulipid (EC(50)=0.82 microg/ml) and commipheric acid (EC(50)=0.26 microg/ml) activated human peroxisome proliferator-activated receptor alpha (PPARalpha) in COS-7 cells transiently transfected with the receptor and a reporter gene construct. Similarly, both guggulipid (EC(50)=2.3 microg/ml) and commipheric acid (EC(50)=0.3 microg/ml) activated PPARgamma and both promoted the differentiation of 3T3 L1 preadipocytes to adipocytes. Guggulipid (EC(50)=0.66 microg/ml), but not commipheric acid, activated liver X receptor alpha (LXRalpha). E- and Z-guggulsterones, which are largely responsible for guggulipid's hypocholesterolaemic effect, had no effects in these assays. Guggulipid (20 g/kg diet) improved glucose tolerance in female Lep(ob)/Lep(ob) mice. Pure commipheric acid, given orally (960 mg/kg body weight, once daily), increased liver weight but did not affect body weight or glucose tolerance. However, the ethyl ester of commipheric acid (150 mg/kg, twice daily) lowered fasting blood glucose and plasma insulin, and plasma triglycerides without affecting food intake or body weight. These results raise the possibility that guggulipid has anti-diabetic activity due partly to commipheric acid's PPARalpha/gamma agonism, but the systemic bioavailability of orally dosed, pure commipheric acid appears poor. Another component may contribute to guggulipid's anti-diabetic and hypocholesterolaemic activity by stimulating LXRalpha.