The effect of two novel cholesterol-lowering agents, disodium ascorbyl phytostanol phosphate (DAPP) and nanostructured aluminosilicate (NSAS) on the expression and activity of P-glycoprotein within Caco-2 cells

Abstract

BackgroundMany drugs are substrates for P-glycoprotein (P-gp) and interactions involving P-gp may be relevant to clinical practice. Co-administration with P-gp inhibitors or inducers changes the absorption profile as well as the risk for drug toxicity, therefore it is important to evaluate possible P-gp alterations. The purpose of this study was to investigate the effect of two novel cholesterol-lowering agents, disodium ascorbyl phytostanol phosphate (DAPP) and nanostructured aluminium silicate (NSAS), a protonated montmorillonite clay, on mdr-1 gene expression and its protein, P-glycoprotein (P-gp) within Caco-2 cells.MethodsThe effects of DAPP and NSAS on the regulation of mdr-1 gene, P-gp protein expression and activity within Caco-2 cells, were determined using cell viability and cytotoxicity tests, RT-PCR, Western Blot analysis and bi-directional transport studies.ResultsWe observed a significant down-regulation of mdr-1 mRNA (e.g. 38.5 ± 17% decrease vs. control at 5 μM DAPP and 61.2 ± 25% versus control at 10 μM DAPP; n = 6, P* < 0.05) within Caco-2 cells. Western Blot analysis of P-gp expression showed that changes in mdr-1 gene expression lead to correlating changes in P-gp protein expression. This down-regulation of P-glycoprotein also resulted in decreased activity of P-glycoprotein compared to untreated control. In contrast, when Caco-2 cells were treated with NSAS, no changes in mdr-1 gene expression, P-gp protein expression nor P-gp activity were observed.ConclusionsDAPP but not NSAS decreases P-gp mediated drug efflux through decreased mdr-1 gene expression and consequently decreased P-gp protein expression. These findings have to be taken into consideration when DAPP is concurrently given with other drugs that are substrates for P-gp since drug-drug interactions harbour a safety issue and alter bioavailability profiles.NSAS does not have any P-gp altering properties and therefore might not affect drug-drug interactions. We conclude from this study that NSAS might make a safer drug candidate compared to DAPP for lowering LDL-cholesterol.

α‐Amylase expressed in human small intestinal epithelial cells is essential for cell proliferation and differentiation

“…Forward and reverse primers for the gene of α‐amylase and differentiation markers (SI, dipeptidylpeptidase‐4 (DPP‐4), E‐cadherin, and villin) were based on previous reports and prepared by Eurofines Genomics (Tokyo, Japan) (Table ). Data were normalized by using glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) as an internal control …”

In Silico Prediction of Steroids and Triterpenoids as Potential Regulators of Lipid Metabolism

“…Two novel cholesterol-lowering agents called sodium ascorbic campestanol phosphate (27) and sodium ascorbic sitostanol phosphate (28) were synthesized, and their properties were studied [116]. Using Western blot analysis of P-GP expression, it was shown that changes in mdr-1 gene expression lead to correlating changes in P-GP protein expression.…”

“…Presented in Figure 24, the anabolic 2α,3α-epithio chlostane (111) shown dominant anticancer activity, and steroid (112) demonstrated dominant properties as an antisecretory agent with 96.7% confidence and acts as an estrogen antagonist with 94.6% confidence. (116), which was synthesized from a natural sample of 18β-glycyrrhetinic acid, showing the highest degree of confidence as lipid metabolism regulator properties, more than 95.4%. 18β-Glycyrrhetinic acid is a β-amyrin-type pentacyclic triterpenoid derived from the herb licorice (Glycyrrhiza glabra).…”

Lipid-lowering Activity of Natural and Semi-Synthetic Sterols and Stanols

“…Many attempts have been made to improve the lipidlowering activity of plant sterols by modification of their chemical structure to increase their micellar incorporation capacity. One of such well characterized phytostanol analogue is disodium ascorbyl phytostanyl phosphates, also known as FM-VP4 (21). Disodium ascorbyl phytostanyl phosphate is a novel hydrophilic stanol analogue that can be formulated into a wide range of delivery vehicles (171).…”

“…Several attempts have been made to enhance the bioavailability of crystalline sterols by reducing the crystal size or by the use of microcrystalline suspensions (18,19). Other approaches involve modification of phytosterols by esterification with fatty acids from vegetable (20,21) or fish oils (22,23), which leads to synthesis of semisynthetic sterols. Such modification can provide an easy way of introducing the daily amount of phytosterols required for optimal reduction of cholesterol (17).…”