Enhanced in vivo absorption and biodistribution of curcumin loaded into emulsions with high medium-chain triglyceride content

The health benefits of curcumin have been demonstrated by several clinical studies, but its low bioavailability compromises its functionality. In this regard, emulsions have proven to be effective encapsulation systems for curcumin. Nevertheless, emulsions with a high oil content (50%) may offer some advantages due to the large amount of compound they can incorporate. Therefore, the aim of this work was to study the pharmacokinetics and biodistribution of curcumin when carried in optimized emulsions containing 50% MCT oil and a plant-based emulsifier (soybean lecithin) at 2 h or 4 h post-oral administration to rats. The most stable emulsion was obtained using 50% of oil and a surfactant-oil-ratio 0.1, through a microfluidization process. After the oral administration of the systems (150 mg curcumin/kg body weight), curcumin glucuronide was the main compound present in plasma (AUC_0-t = 1556.3 ng·h·ml^-1), especially at 2-4 h post-administration. The total curcuminoid bioavailability was increased by 10.6-fold when rats were fed with the curcumin emulsion rather than with a control suspension. Moreover, rats fed with the emulsion showed the highest accumulation of free curcuminoids, which present the highest biological activity, in the liver (129 ng curcumin/g tissue) and brown adipose tissue (193 ng curcumin/g tissue). The obtained results are of great interest since the presence of curcumin in the brown adipose tissue has been shown to play a relevant role in the prevention of obesity and its related metabolic disorders.