Asparagus racemosus root extracts (AR) have been reported to possess a variety of pharmacological properties. The aim of the present study was to develop liposomes of AR and to assess their physicochemical characteristics and anti-inflammatory activity in the monocytic leukemia cell line THP-1. Liposomes containing various ratios of AR to lipid and a phosphatidylcholine to cholesterol molar ratio of 7:3 were prepared by thin-film hydration (TF), reverse-phase evaporation (REV) and polyol dilution (PD). The results showed that AR liposomes prepared by TF had a multilamellar structure and a large size, whereas those prepared by REV and PD were oligolamellar in structure, and of a smaller size. The particle sizes and zeta potentials of the liposomes ranged from 196.5 to 456.6 nm and from -4.34 to -18.94 mV, respectively. The AR to lipid ratio was shown to have no significant influence on particle size, while the zeta potential generally increased with increasing AR to lipid ratio. The highest entrapment efficiency values were detected in liposomes with an AR to lipid ratio of 1:5, and for liposomes prepared by TF, REV and PD methods, the entrapment efficiencies were 55.71±2.04, 56.21±3.59 and 67.68±1.37%, respectively. AR was found to exert no toxicity on THP-1 cells. The maximum anti-inflammatory activities of AR and AR liposomes, evaluated in terms of the percentage inhibition of tumor necrosis factor-α in THP-1 cells, were ~52% at a concentration of 1 µg/ml. It can be concluded from the present study that AR liposomes have the potential to be used a formulation for topical and/or transdermal drug delivery to provide anti-inflammatory activity.
Keywords: Asparagus racemosus; anti-inflammatory activity; cytotoxicity; liposomes; polyol dilution; reverse-phase evaporation; thin-film hydration.