Pterostilbene, a new agonist for the peroxisome proliferator-activated receptor alpha-isoform, lowers plasma lipoproteins and cholesterol in hypercholesterolemic hamsters

Resveratrol, a stilbenoid antioxidant found in grapes, wine, peanuts and other berries, has been reported to have hypolipidemic properties. We investigated whether resveratrol and its three analogues (pterostilbene, piceatannol, and resveratrol trimethyl ether) would activate the peroxisome proliferator-activated receptor alpha (PPARalpha) isoform. This nuclear receptor is proposed to mediate the activity of lipid-lowering drugs such as the fibrates. The four stilbenes were evaluated at 1, 10, 100, and 300 microM along with ciprofibrate (positive control), for the activation of endogenous PPARalpha in H4IIEC3 cells. Cells were transfected with a peroxisome proliferator response element-AB (rat fatty acyl CoA beta-oxidase response element)-luciferase gene reporter construct. Pterostilbene demonstrated the highest induction of PPARalpha showing 8- and 14-fold increases in luciferase activity at 100 and 300 microM, respectively, relative to the control. The maximal luciferase activity responses to pterostilbene were higher than those obtained with the hypolipidemic drug, ciprofibrate (33910 and 19460 relative luciferase units, respectively), at 100 microM. Hypercholesterolemic hamsters fed with pterostilbene at 25 ppm of the diet showed 29% lower plasma low density lipoprotein (LDL) cholesterol, 7% higher plasma high density lipoprotein (HDL) cholesterol, and 14% lower plasma glucose as compared to the control group. The LDL/HDL ratio was also statistically significantly lower for pterostilbene, as compared to results for the control animals, at this diet concentration. Results from in vitro studies showed that pterostilbene acts as a PPARalpha agonist and may be a more effective PPARalpha agonist and hypolipidemic agent than resveratrol. In vivo studies demonstrate that pterostilbene possesses lipid and glucose lowering effects.     

Evaluation of promoters and visual markers for transformation of eastern white pine

This report serves to evaluate possible promoters for use in theproduction of transgenic eastern white pine (Pinus strobus L.).Embryogenic cultures of eastern white pine were bombarded with goldparticles coated separately with a variety of gene constructs containingthe UidA -glucuronidase (GUS) or green fluorescentprotein (GFP) reporter gene. Transient expression of the UidAgene, driven by a novel algal virus adenine methyl transferase genepromoter, as well as five other promoters used in angiospermtransformation, were evaluated. The maize alcohol dehydrogenase promoterwas not effective in eastern white pine cultures. The construct with thedoubled Cauliflower Mosaic Virus 35S promoter plus Alfalfa Mosaic Virusenhancer showed the highest levels of expression. GUS expression wasdetected within 24 hours, but decreased after 5 days and was notdetectable 15 days after bombardment. Expression of GUS activity wasrecorded mainly in somatic embryonal heads of various stages ofdevelopment and occasionally in suspensor cells. Similar to GUSexpression, modified green fluorescent protein (GFP) was detected in theembryonal head cells 24 hours after bombardment. GFP-expressingsuspensor cells were both more infrequent and difficult to detect, astheir highly vacuolate nature rendered the GFP presence less visibleagainst the yellow background autofluorescence.