Abstract
BackgroundNumerous health benefits have been demonstrated for curcumin which is extracted from turmeric (Curcuma longa L). However, due to its poor absorption in the free form in the gastrointestinal tract and rapid biotransformation, various formulations have been developed to enhance its bioavailability. Previous studies indicate that the free form of curcumin is more bioactive than its conjugated counterparts in target tissues. Most curcumin pharmacokinetics studies in humans designed to assess its absorption and bioavailability have measured and reported total (free plus conjugated) curcumin, but not free, bioactive curcumin in the plasma because enzymatic hydrolysis was employed prior to its extraction and analysis. Therefore, the bioavailability of free curcumin cannot be determined.MethodsEight human subjects (4 male, 4 female) consumed a single dose of 400 mg curcumin in an enhanced absorption formulation, and blood samples were collected over 6 h. Plasma was treated either with or without glucuronidase/sulfatase prior to extraction. Curcumin and its major metabolites were analyzed using HPLC-tandem mass spectrometry. In addition, the literature was searched for pharmacokinetic studies involving curcumin using PubMed and Google Scholar, and the reported bioavailability data were compared based on whether hydrolysis of plasma samples was used prior to sample analysis.ResultsHydrolysis of blood plasma samples prior to extraction and reporting the results as “curcumin” obscures the amount of free, bioactive curcumin and total curcuminoids as compared to non-hydrolyzed samples. As a consequence, the data and biological effects reported by most pharmacokinetic studies are not a clear indication of enhanced plasma levels of free bioactive curcumin due to product formulations, leading to a misrepresentation of the results of the studies and the products when enzymatic hydrolysis is employed.ConclusionsWhen enzymatic hydrolysis is employed as is the case with most studies involving curcumin products, the amount of free bioactive curcumin is unknown and cannot be determined. Therefore, extreme caution is warranted in interpreting published analytical results from biological samples involving ingestion of curcumin-containing products.Trial registrationClinicalTrails.gov, trial identifying number NCT04103788, September 24, 2019. Retrospectively registered.
Highlights
Numerous health benefits have been demonstrated for curcumin which is extracted from turmeric (Curcuma longa L)
The effects of enzymatic hydrolysis on the area under the curve (AUC) and Maximum concentration (Cmax) data of the primary curcuminoids in plasma of human subjects are presented in Tables 1 and 2, respectively
The results indicate that enzymatic hydrolysis increases the amount of total curcuminoids detected in plasma by a factor of approximately 31-fold
Summary
Numerous health benefits have been demonstrated for curcumin which is extracted from turmeric (Curcuma longa L). Unformulated and unprocessed [regular] curcumin is highly insoluble in water, and is known for its poor gastrointestinal absorption and bioavailability. This limits its biological and physiological effects at target tissues, leading to restricted usefulness in general healthcare and disease prevention. To address this issue, various formulations have been developed to facilitate the bioavailability of curcumin [12, 13]. Bioequivalence can be defined as the absence of significant differences between different products or formulations in the rate and extent [bioavailability] to which an active ingredient becomes available to the site of action when administered at the same molar dose under similar conditions such that both safety and efficacy are the same [14]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
