Cyclodextrins[edit]
Curcuminoids form a more stable
complex with solutions which contain
cyclodextrin towards hydrolytic degradations.
[4] The stability differs between size and characterization of the cyclodextrins that are used.
[1] Dissolution of demethoxycurcumin, bisdemethoxycurcumin and curcumin are greatest in the hydroxypropyl-γ-cyclodextrin (HPγCD) cavity. The curcuminoids which have a
substituent connected to the phenyl groups show more affinity for the HPγCD compound. Degradation rate is depended on pH of the solution and how much protection the cyclodextrins provide the curcuminoids. The derivatives are usually more stable than curcumin against hydrolysis in cyclodextrin solution. No
covalent bonds are present between the cyclodextrins and the curcuminoids so they are easily released from the complex by simple solvent effects.
[2]
Micelles and nanoparticles[edit]
A drug design with curcuminoids in complex with
micelles could be one solution of the insolubility of the curcuminoids. The curcuminoids would be in complex with the core of the micelles similar to the complex inside the cyclodextrins. The micelles are dissolved in a suitable
solvent where the headgroups of the micelles interact with the solvent. Curcuminoids as loaded
solid lipid nanoparticles (SLN) have been developed with great success by using
microemulsion technique. The loading capacity, the mean particle size and size distribution are all factors that have to be considered when the effects of curcuminoids in different strength are observed because it could variate.
[2] The advantages of SLN are the possibilities of controlled drug release and
drug targeting, protection of incorporated
compound against
chemical degradation, no biotoxicity of the
carrier, avoidance of organic solvent and no problems with respect to large scale production.
[2] In vitro studies show a prolonged release of curcuminoids from the nanoparticle preparate up to 12 hours and the curcuminoids maintained their physical and chemical stability after 6 months of storage in the absence of
light at
room temperature. The sensitivity of curcuminoids to light and oxygen is greatly reduced by
formulation of curcuminoids in SLN.
[2]
Solid lipid nanoparticles for cosmetics[edit]
Solid lipid nanoparticles preparate has been developed for
cosmetics where the curcuminoids are used in
cream base. But there are some stability issues which have not been overcome yet, further studies need to be done to find a suitable formulation which can be carried out in order to prolong the stability of the curcuminoids. Nevertheless, there have been improvements in formulation of some stable model cream preparations with SLN curcuminoids.
[2] It is suggested that most of the curcuminoids are incorporated at the SLN surface where they are diffused into the cream matrix until a
steady state is reached. At this state the curcuminoids go from the cream to the dissolution medium. A possible burst release in creams containing curcuminoids have been reported where the curcuminoids are rapidly released in a sufficient amount from the cream into the skin and is followed by a controlled release.
[2] When SLN are prepared by microemulsion at a temperature with the range of 70–75 °C an
oil-in-water microemulsion is spontaneously formed. The SLN are obtained immediately when they are
dispersed in the warm microemulsion into cold water, with the help of a
homogenizer. The cold water facilitates a rapid
crystallization of the lipids and therefore prevents
aggregation of the lipids. After
freeze dryingthe yellow curcuminoids containing SLN were obtained and could easily be redispersed in water and the model cream. The SLN have uniform distribution and according to
electron micrograph scan they had a
spherical shape and smooth surface.
[2] It has been reported that increasing the lipid content over 5–10%(w/w) increased the mean particle size and broader size distribution in most common cases. That range should there for be ideal
concentration for formulation of the SLN.
[2]
Incorporation and formulation[edit]
Incorporation is one thing that needs to be considered in formulation of SLN. Concentration of the lipid,
emulsifier and
co-emulsifier solution is a key factor on this
conversion of the SLN. If the amount of emulsifier and co-emulsifier are increased but the lipid amount is constant the surface of the SLN which is formed will be too small to
adsorb all the surfactant and co-surfactant molecules, and a formation of curcuminoids solution micelles will be created. This will then increase the water solubility of the curcuminoids and they could
partition from the SLN into the micelles that were formed during a wash procedure. This will reduce the final incorporation efficacy on the surface of the SLN.
[2]
Anti-oxidant activity[edit]
The curcumin derivatives demethoxycurcumin and bisdemethoxycurcumin have, like curcumin itself, been tested for their
antioxidant activities
in vitro.
[3] Antioxidants can be used to extend the
shelf life for food and maintain their safety,
nutritional quality,
functionality and
palatability.
[3] Pure chemicals of curcumin and its derivatives are not available in the open market. Commercially available curcumin contains 77% curcumin, 17% demethoxycurcumin and 3% bisdemethoxycurcumin from the
herbCurcuma longa. Curcumin is mainly produced in
industry as
pigment by using
turmeric oleoresin as the starting material which curcuminoids can be isolated from. After the isolation of the curcuminoids, the
extract which is about 75%
liquor mainly contains
oil,
resin and more curcuminoids which can be isolated further. This isolation method was used to demonstrate the antioxidant activities of curcuminoids, where they isolated pure curcuminoids from the main liquor.
[3] One
research reported that curcumin was the strongest antioxidant, demethoxycurcumin the second strongest and bisdemethoxycurcumin the least
effective. Curcuminoids nevertheless showed activity against
oxidation. Curcuminoids act as a
superoxide radical scavenger as well as
singlet oxygen quencher and gives the antioxidant its effectiveness.
[3]Tetrahydrocurcumin, one of the main
metabolites of curcumin, is the most potent antioxidant among the naturally occurring curcuminoids.
[3] The curcuminoids are capable of inhibiting damage to
super coiled plasmid DNA by
hydroxyl radicals. It was concluded that the derivatives of curcumin are good in trapping the
2,2-diphenyl-1-picrylhydrazyl(DPPH) radical as efficiently as curcumin which is a well known antioxidant.
[3]
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