This certain antioxidants like carotenoids have the
Thisresearch proposal mainly revolves around the need of considering food asmedicine. The concept is not new, as it was first introduced in 1989 by Stephen L. DeFelice,who also introduced the term ‘Nutraceuticals’, combining nutrition withpharmaceuticals. Nutraceuticals are a class of compounds that are generallyused to improve health, delay the aging process, prevent chronic diseases,increase life expectancy, or support the structure or function of the body.These include nutrients like vitamins, minerals, structural lipids, aminoacids, polyphenols and Isoprenoids etc., which are mostly extracted from plantand dietary sources. It has been widely reported that flavonoids which aremainly plant extracts have an active role in preventing and curing cardio vasculardiseases.
These flavonoids block the angiotensin-converting enzyme, whichfurther helps in blocking the cyclooxygenase enzymes that break downprostaglandins, and prevent platelet aggregation. They also protect thevascular system that carries oxygen and nutrients to cells. Recent interest inNutraceuticals has grown due to the fact that certain antioxidants like carotenoidshave the ability to inhibit cancer growth. Lycopene is one of the majorcarotenoids and is found exclusively in tomatoes, guava, pink grapefruit, watermelon and papaya. Because of the unsaturated nature of lycopene it isconsidered to be a potent antioxidant and a singlet oxygen quencher. Lycopeneconcentrates in the prostate, testes, skin and adrenal where it protectsagainst cancer.
However,even today after nearly 30 years of introduction of such a novel concept we areyet to completely implement the use of these nutritional elements as medicine.They are merely used as extra supplements without genuinely studying their fateonce consumed or how much is the actual bioavailability of these nutrients afteringestion. Bioactive compounds like vitamins, minerals, polyphenols,isoprenoids etc. are highly lipophilic in nature.
Direct intake of thesebioactive compounds poses problems like poor solubility in aqueous phase,crystallization, chemical instability and low bioavailability etc. In order toencapsulate these bioactive compounds, a more technical matrix is required thatcan provide controlled release during chewing and digestion, protection againstacidic conditions in our body, and long term stability with a targeted andefficient delivery to the desired site. Conventionallyemulsions have proven to be useful in this particular interest, where thelipophilic component can be encapsulated within the core of hydrophobic part ofemulsifier (surfactant) and remain solubilized in aqueous phase for easyconsumption/ handling. These emulsions are generally macro emulsions where theparticle size lies between a distributions of 1-100 µm in size. Due to largersize ratios these emulsions are often prone to droplet aggregation, andsedimentation leading to phase separation. A significant improvement in termsof stability, release and bioavailability of nutraceuticals from the emulsion droplets can be achieved with thehelp of nanotechnology, viz.
makingnano-emulsions. Nano-emulsions (1-100 nm) based delivery systems havealready captured much of the interest in drug delivery applications due theircontrolled, selective and efficient delivery of drugs to desired parts of thebody, but their application in food industry is relatively new. Thesenano-emulsions are found to be nearly monodisperse, highly stable againstaggregation, and hence do not undergo phaseseparation owing to relatively small droplet size that have Brownian motioneffects dominating over gravitational forces. Due to high surface area tovolume ratios chemical reactions like lipid digestion occurring at theoil-water interface are accelerated which offers promising ways for improvingbioavailability of lipophilic compounds like phytosterols, carotenoids and vitaminsetc. For this reason, the bioavailability of lipophilic substances encapsulatedwithin nano-emulsions is often considerably higher than that in conventional macro-emulsions.Different classes of nanocarriers such as liposomes, polymeric nanoparticles,nanocrystals, nano-emulsions, micro-emulsions, solid lipid nanoparticles (SLN’s)etc. have been used to improve drug and gene delivery, targeted therapy, and diagnostics.
Although most of these systems have proven to be ideal systems for drugdelivery applications but their use in food industry is highly limited as theyrequire high surfactant concentrations for production, low payload, lackchemical stability during storage and can undergo Ostwald ripening /flocculation and, become structurally unstable in acidic conditions. Oneof the solutions to this problem can be encapsulating these bioactive compoundsin Nanostructured Lipid Crystals (NLC’s). These are basically modified SLN inwhich the lipidic phase contains both solid (fat) and liquid (oil) lipids atroom temperature. The NLC contains lipid droplets that are partiallycrystallized and amorphous solid structure. The purpose of NLC formulation isto produce particles in which the oil is incorporated into the core of a solid lipid.This helps in dissolving the bioactive lipophilic content in the solid &liquid based lipid inside the NLC’s, which increases the payload efficiency andprovides controlled release. In combination to the oilbased core in the NLC, the spherical shape of the particle mayaccount for improvement of the overall properties.
It therefore seems that NLC overcomethe drawbacks, and at the same time possess the advantages of other lipidnano-carriers. With the help of these NLC’s one can expect todispel the limitations of poorwater-solubility, chemical instability, and low bioavailability encounteredduring fortification of aqueous-based foods with nutraceutical ingredients. Acombination of high payload and controlled release with targeted delivery ofthese nutraceutical compounds can help large sect of masses in promotinggeneral well-being of individuals, control and prevent virulent conditions,deal with deficiency and malnutrition and in post disease related conditions. Afteringestion these carrier systems have to travel through varying environments interms of temperature and pH changes (ranging from 7 to 1) accompanied by theaction of different enzymes like amylase, lipase, protease etc.
at differentlocations. To be a carrier system that can provide a better targeted deliverywith high bioavailability these NLC’s can be surface modified with biopolymersthat can provide physical and chemical barriers to resist the action ofdigestive enzymes that defy the active compound from reaching Gastrointestinal (GI)tract.The bioavailability is largely dependent on three factors viz. (1) Bio-accessibilitycoefficients that define the amount of active compound released into thedigestive juices, (2) Transportcoefficient that is mainly the active compound that reaches the intestinalepithelium, and (3) Metabolism coefficient which is the content that finally reachessystematic circulation without getting metabolized where it finally getsdistributed between different tissues. Currently the industrial scaleproduction of these NLC’s is restricted to medicines due to unavailability offood grade (Generally recognized as safe, GRAS) ingredients.
Studies arerequired for appropriate grade materials that can beused in large quantities. This would further ask for carrying out stabilitystudies of NLC starting from processing, storing, heat treatment, freezing,drying, changes in pH and ionic strength etc. Working closely on these aspects can help us in finding a wayto make supplements act like medicines in the form of functional food atreasonable and more affordable prices so that they can be made available topeople who can be genuinely benefitted.