#82 Preparation and antimicrobial evaluation of cationic lipid emulsion of flaxseed oil: A dual benefit emulsion

Abstract

Since time immemorial, nature has always been kind enough towards humanity to provide a plethora of natural resources that have always benefited humans. Most of the currently employed therapeutic agents are derived from natural sources, i.e., plants, animals, and other natural resources. Flaxseed or linseed (Linum usitatissimum L.) is one such annual herb that has contributed enormously to the human nutrition sector. In addition to the content of active compounds, namely omega-3, omega-6 rich oil, α-linolenic acid, α-linoleic acid, lignans, flavones, polysaccharides, alkaloids, cyanogenic glycosides, and a potential source of phenolic compounds, it also contains biologically active compounds that aid in the prevention of some chronic diseases like diabetes, CV diseases, cancers, etc. Literature also suggests using flaxseed extracts (oil/mucilage) as an antimicrobial agent. Cationic lipid emulsions provide a condensed energy source and essential fatty acids and are primarily used in parenteral nutrition (20% solution provides 2 kcal/mL). The higher concentrations have the advantage of giving higher energy value in lower fluid volume. Typically, lipid emulsions in infants and children are initiated at a dose of 1 g/kg/day and advanced by 1 g/kg/day to a maximum of 3 g/kg/day. Since lipid emulsions are derived from vegetable oils, they are also a natural source of variable amounts of vitamin K133 and E isomers. In this perspective, we aim to develop a cationic lipid emulsion of flaxseed oil and evaluate it for its antimicrobial property. This designed formulation will have both properties, i.e., providing nutrition to the user and antimicrobial activity aiding in minor microbial infections. Preparation of the lipid emulsions consists of oil suspended in an aqueous dispersion. The oil phase included: flaxseed oil, cholesterol, PEG2000, and Benzalkonium chloride (cation), while the aqueous phase included: 2.25% (w/v) glycerol for isotonicity and water (required amount). Both phases were heated to 70 °C and stirred to solubilize the components thoroughly. The oil phase was introduced to the dispersion under continuous mixing conditions and subsequently sterilized by filtration through a 0.22 mm filter device followed by storage at 4 °C for further evaluation. The prepared cationic lipid emulsion using flaxseed oil was evaluated for its physical stability, i.e., appearance, color, odor, taste, cracking, creaming, coalescence, pH, and centrifugation. Further evaluation tests like particle size, viscosity, electrophoretic properties (zeta potential), and phase separation were also carried out. Finally, the antimicrobial property of the prepared cationic lipid emulsion using flaxseed oil was evaluated using the agar well plate assay method. Antimicrobial activity was assessed against microbes like Staphylococcus aureus and Bacillus subtilis to measure the minimum inhibitory concentration (MIC) by determining the zone of inhibition. Physicochemical properties of linseed oil/flaxseed oil showed that the color of the oil is yellow-brown with a pleasant odor. The specific gravity of oil was determined to be 0.946 gm/mL. Phytochemical analysis revealed that flaxseed oil contains fats, flavonoids, glycosides, phenols, and tannins, as all tests were positive except carbohydrates. The prepared cationic lipid emulsion using flaxseed oil was physically stable as it didn’t crack and showed no creaming or coalescence upon standing/ centrifugation. The zeta potential was found to be +13.3, and the average particle size was found to be 642.0 d.nm. Variable effects were developed against Staphylococcus aureus and Bacillus subtilis and showed various degrees of inhibition against them. The cationic lipid emulsion of flaxseed oil has antimicrobial potential when used in high doses. At low doses, it has low antimicrobial potential. Hence, the prepared formulation is an excellent alternative medication that can deliver dual benefits to the user, i.e., treat infection caused by bacteria and provide nutrition. The future scope lies in further evaluating the formulation’s in-vitro effectiveness.