PREPARATION AND CHARACTERIZATION OF NIGELLA SATIVA MICROEMULSIONS
The aims of this study were to develop and characterize an oil-in-water (o/w) Nigella sativa (N. sativa) microemulsion. The microemulsions were prepared by drop-wise titration of N. sativa oil into mixtures of surfactant blends (Span 20, Span 80, Tween 20, Tween 80, Tween 85) and water. All transparent ternary mixtures were characterized for their viscosity and droplet size. The stability of the microemulsion was evaluated by subjecting them to stressful conditions, namely centrifugation (2000 g for 20 minutes) and heating in a drying oven (60 Â°C to 105 Â°C for 5 hours) and the droplet size was determined following one month storage at room temperature (25 Â°C) thereafter. Based on the results, a phase diagram was constructed from corresponding volumes of those 3 components. N. sativa mixtures (ranging from 7.4% to 10.7%) prepared at HLB 16 of surfactant blends (Tween 20: Tween 80; 6:4) with water (ranging from 17.9% to 18.5%) yielded transparent liquids. The constructed phase diagram displayed regions of a few types of microemulsion and emulsion. Interestingly, droplet size of freshly prepared mixtures was wider in range (5 to 15.6 nm) than the size following stressful condition (11.3 to 12.4 nm). It was concluded that N. sativa oil could be formulated into microemulsion at specific HLB value of surfactant blends. Such system was envisaged to enable routine rapid in vitro test on neuron cell lines loaded with N. sativa oil or possibly other lipophilic materials whenever viewing of neurite extension is required.
2. Al-Majed A, Al-Omar F, Nagi M. Neuroprotective effects of Thymoquinone against transient forebrain ischemia in the rat hippocampus. Eur J Pharmacol 2006;543 Suppl 1-3:40-7.
3. Kanter M. Effects of Nigella sativa and Its Major Constituent, Thymoquinone on Sciatic Nerves in Experimental Diabetic Neuropathy. Neurochem Res 2008;33 Suppl 1:87-96.
4. Kanter M. Nigella sativa and derived thymoquinone prevents hippocampal neurodegeneration after chronic toluene exposure in rats. Neurochem Res 2008;33 Suppl 3:579-88.
5. He CX, He ZG, Gao JQ. Microemulsions as drug delivery systems to improve the solubility and the bioavailability of poorly water-soluble drugs. Expert Opin Drug Delivery 2010;7:445-60.
6. Nagarajan R, Ruckenstein E. Molecular Theory of Microemulsions. Langmuir; 2000. p. 6400-15.
7. Bagwe RP, Kanicky JR, Palla J, Patanjali PK, Shah DO. Improved drug delivery using microemulsion: rationale, recent progress, and new horizons. Crit Rev Ther Drug Carrier Syst 2001;18(1):77-140.
8. Shiau BJ, Sabatini DA, Harwell JH. Solubilization and microemulsification of chlorinated solvents using direct food additive (edible) surfactants. Ground Water 1994;32 Suppl 4:561-9.
9. Cho YH, Kim S, Bae EK, Mok CK, Park J. Formulation of a cosurfactant-free o/w microemulsion using nonionic surfactant mixtures. J Food Sci 2008;73 Suppl 3:115-21.
10. Patel MR, Patel RB, Parikh JR, Bhatt KK, Kundawala AJ. Microemulsion: as novel drug delivery vehicle. Pharm Info net [Internet] 2007 [cited 22 May 2012]. Available from: http: //www.pharmainfo.net/reviews/microemulsions-novel-drug-delivery-vehicle.
11. Parekh K. Preparation, characterization, and in vitro protein release studies in pharmaceutically relevant lecithin microemulsions. The University of Toledo; 2011.
12. Bayrak Y, Iscan M. Studies on the phase behavior of the system non-ionic surfactant/alcohol/alkane/H2O. Colloids and Surfaces A: Physicochemical and Engineering Aspects 2005;268 Suppl 1-3:99-103.
13. Rukmini A, Raharjo S, Hastuti P, Supriyadi S. Formulation and stability of water-in-virgin coconut oil microemulsion using ternary food grade nonionic surfactants. Int Food Res J 2012;19 Suppl 1:259-64.
14. Yuwanti S, Raharjo S, Hastuti, Pudji, Supriyadi. Stable o/w microemulsion formulation using combination of three nonionic surfactants with low, high and med. J Agritech Fakultas Teknologi Pertanian 2012;31 Suppl 1.
15. Flanagan J, Singh H. Microemulsions: a potential delivery system for bioactives in food. Crit Rev Food Sci Nutr 2006;46:221-37.
16. Fanun M. Properties of microemulsions based on mixed nonionic surfactants and mixed oils. J Molecular Liquids 2009;150 Suppl 1-3:5-32.
17. Yaghmur A, Aserin A, Garti N. Phase behaviour of microemulsions based on food-grade nonionic surfactants: effect of polyols and short-chain alcohols. Colloids and Surfaces A: Physicochemical and Engineering Aspects 2002;209:71-81.
18. Food Safety Commission (Japan). Evaluation report of food additives. Polysorbates (Polysorbates 20, 60, 65 and 80);2007.
19. Li P, Ghosh A, Wagner RF, Krill S, Joshi YM, Serajuddin ATM. Effect of combined use of nonionic surfactant on formation of oil-in-water microemulsions. Int J Pharm 2005;288:27-34.
20. Warisnoicharoen W, Lansley AB, Lawrence MJ. Nonionic oil-in-water microemulsions: the effect of oil type on phase behaviour. Int J Pharm 2000;198:7-27.