Gymnema lactiferum (G. lactiferum) is a medicinal plant that contains potent bioactive phytochemicals, which are prone to degradation during processing and digestion. In this study, G. lactiferum extract was prepared and encapsulated into soy lecithin primary liposomes (PL) and then coated with chitosan to form secondary liposomes (chitosomes, CS) to enhance stability. Physicochemical characteristics, morphology, thermal behavior, and storage stability were evaluated. Extract loading significantly (p < 0.05) increased the mean diameter of PL from 128.6 nm to 146.3 nm and of CS from 359.1 nm to 408.9 nm compared with unloaded liposomes. Both liposomal systems exhibited homogeneous size distributions and good colloidal stability, with zeta potentials of −39.4 mV for PL and +35.8 mV for CS and low polydispersity indices (<0.25) for both systems. Transmission electron microscopy demonstrated predominantly spherical morphologies in both systems. Chitosan coating significantly (p < 0.05) improved both encapsulation efficiency (77.3%) and encapsulation yield (82.4%) compared with PL (73.7% and 79.1%, respectively). HPLC-based quantification using rutin as a reference analyte further indicated EE-R% values of 59.8% for PL-GE and 70.3% for CS-GE, supporting improved extract retention following chitosan coating. Fourier transform infrared spectroscopy confirmed successful encapsulation without apparent chemical alterations or reactions. Differential scanning calorimetry indicated that chitosan coating modified the thermal transition behavior of the liposomal membrane, consistent with altered bilayer packing and increased membrane fluidity, while incorporation of the extract partially restored thermal order within the coated system. Overall, chitosan coating effectively enhanced the encapsulation efficiency, stability, and yield of G. lactiferum extract-loaded liposomes towards their incorporation into functional food formulations.
Weerasinghe et al. (Wed,) studied this question.