Development and Characterization of Solid Lipid Nanoparticles Containing Herbal Extract: In Vivo Antidepressant Activity

In alternate systems of medicine like Ayurveda and traditional Chinese medicine, Hibiscus rosa sinensis and its extracts have been traditionally prescribed for their antidepressant activity. Crude extracts and rudimentary formulations approaches are good for proof-of-concept studies; however, these formulations are fraught with problems like poor oral bioavailability and high variability between subjects. Systematic drug delivery approaches could prove effective in addressing some of these problems. In this study, we report the development of Hibiscus rosa sinensis extract loaded solid lipid nanoparticles (HSLNs) using glycerol monostearate or beeswax as lipids. The HSLNs were evaluated for their size, surface charge, and morphology. The optimized HSLNs were tested for antidepressant activity in male Swiss albino mice. It was found that, with the optimized procedure, HSLNs of ~175 nm, carrying negative charge and nearly spherical shape, could be obtained. The in vivo test results suggested that there were marked differences in the immobility times of the test animals. Moreover, with HSLNs, it was found that at doses several times lower than the native crude extract dose, similar pharmacological effect could be obtained. These initial findings suggest that encapsulating phytopharmaceuticals into advanced delivery systems like solid lipid nanoparticles can be an effective strategy in improving their in vivo performance.