Novel pepper extract for enhanced P-glycoprotein inhibition

Objectives Piperine is one of the most promising bioenhancers to date. Methods used for its extraction suffer from drawbacks such as use of organic solvents, poor extraction efficiency, tedious and expensive methodology. These methods are not encouraged with a view to reducing global warming. The objective was therefore to develop an alternative solvent-free extraction method. Methods An aqueous extract of long pepper fruits was prepared using hydrophilic lipid Gelucire 44/14 as the extracting aid and this was compared with an alcoholic extract. Extracts were characterized using high-performance thin layer chromatography and differential scanning calorimetry. P-glycoprotein (P-gp) inhibitory activity of the aqueous and alcoholic extracts and pure piperine was compared using an in-vitro everted rat intestinal model using ornidazole as the model drug. The study was performed using two oral pretreatment dose levels (10 and 20 mg/kg) and durations (1 and 3 days). Exsorption of ornidazole from serosal to mucosal surface was monitored. Key findings P-gp inhibitory activity of the aqueous extract was comparable with that of pure piperine (P > 0.05) and was significantly higher than the alcoholic extract (P < 0.05). Pure piperine and the aqueous extract exhibited significant P-gp inhibitory activity compared with control, which was irrespective of oral pretreatment dose and duration levels. No significant effect of oral pretreatment duration of the aqueous extract was observed. The observed enhancement in P-gp inhibitory activity of the aqueous extract may have been attributed to the P-gp inhibitory potential of Gelucire 44/14 and its efficient extraction and solubility enhancement ability. Conclusions In the field of phytopharmaceuticals efficient and eco-friendly extraction processes are still a goal to be achieved. Extraction with Gelucire 44/14 could be a potential method of extraction for phytopharmaceuticals. Compared with conventional methods of extraction it is more efficient, easier to prepare, eco-friendly and scalable.