Production and Evaluation of Nanoliposomes Loaded with Capparis spinosa Extract

Abstract

Introduction Capparis spinosa is a perennial herb from the Capparidaceae family that is mainly distributed in arid and semi-arid regions. Its fruits are oval shaped, approximately 3 cm long, greenish in color with red pulp. Capparis spinosa extract is a rich source of phenolic compounds. The instability of phenolic compounds in the environmental conditions as well as their bitter or astringent taste has created challenges for the use of these compounds in the food industry. Encapsulation is a method that can positively affect bioaccessibility and bioavailability as it ensures the coating of the active component and its targeted delivery to a specific part of the digestive tract and controlled release. Encapsulation using nanoliposomes seems to be an appropriate technique to overcome these issues. Nanoliposomes are the nanometric version of liposomes. Liposomes are spherical particles composed of lipid molecules (mainly phospholipids) that tend to accumulate in polar solvents such as water in the form of bilayer membranes. Encapsulation with liposomes is an effective way to preserve the intrinsic properties of bioactive compounds during storage and production of foods fortified with them, as well as a physicochemical barrier against prooxidant agents such as free radicals, oxygen and UV. Materials and Methods Materials: Capparis spinosa fruits, were collected from subtropical regions of Ilam province (Iran). Folin ciocalteu, gallic acid and tween 80 from Merck (Germany), cholesterol and phosphatidylcholine from Sigma- Aldrich (Germany) were obtained. Methods: The extract was obtained from capparis spinosa fruit powder using ultrasonic bath (Backer, vCLEAN 1- L6, Iran). The phenolic content was measured by folin ciocalteu method. Nanoliposomes containing capparis spinosa extract were prepared in ratios of 60- 0, 50- 10, 40- 20 and 30- 30 w/w lecithin- cholesterol. Then, particle size, PI and zeta potential were measured by DLS (Horiba, Japan) at 25 oC. After calculating the encapsulation efficiency using its corresponding equation, the investigation of possible reactions between capparis spinosa extract and phospholipids was performed using FTIR at a frequency of 400- 4000 cm-1. In order to observe shape and morphology of nanoliposomes loaded with capparis spinosa extract by field emission scanning electron microscopy (FESEM), a drop of sample was poured on the laboratory slide, dried at ambient temperature and then, the sample was coated with gold layer using an ion sputtering device. The stability of the samples was evaluated by visual observation of phase separation and the release rate of phenolic compounds encapsulated in nanoliposomes at ambient temperature over a period of 60 days. Results and Discussion The amount of phenolic extract was 6.328 mg of GAE/g dry sample. The average particle size (Z- Average) was in the range of 95.05 to 164.25 nm. Increasing the cholesterol concentration resulted in enhancement of particle size of nanoliposomes. The particle size distribution was in an acceptable range of 0.3 to 0.5 (PI 0.5). The PI of the cholesterol-free nanoliposomes was maximum and significantly higher than that of the others. Addition of cholesterol increased zeta potential from -60.40 to -68.55. Higher zeta potential values indicate a higher and long term stability of the particles. Also, cholesterol led to an increase of encapsulation efficiency (EE). The stability of phenolic compounds loaded in nanoliposomes was affected by cholesterol during storage time via reducing fluidity and permeability of liposomal membrane. Presence of cholesterol also inhibited the membrane rupture and any changes into it. Results of FTIR showed interactions between wall constituents of nanoliposome and capparis spinosa extract, and confirmed successful loading of the extract within nanoliposomes. Images of FESEM were in agreement with DLS results regarding particle size and particle size distribution. Conclusion This study indicate that the nanoliposomes have potential applications in improvement of the shelf life of nutraceuticals, stability of cosmetic materials and drug delivery systems. The phenolic compounds of encapsulated extract showed good stability within two months of storage at room temperature. The results showed that the problem of instability of phenolic compounds, which leads to their limited commercial application, can be solved by encapsulation.

Keywords

• nanoliposome
• nutraceutical
• phenolic compounds