Stable Isotope Ratio Analysis for the Authentication of Natural Antioxidant Curcuminoids from Curcuma longa (Turmeric)

Abstract

Curcuminoid complex, a mixture of curcumin, demethoxycurcumin and didemethoxycurcumin, is one of the most popular antioxidants of natural origin, and it has a multitude of other health benefits. It is threatened by the proliferation of counterfeit products on the market containing synthetic curcuminoids whose addition is difficult to identify as they present the three curcuminoid forms in the correct ratios. Consequently, the necessity to detect this fraudulent practice is escalating. Carbon-14 analysis is the most effective available method, but it is also expensive and difficult to implement. This paper describes the first attempt to characterize natural curcuminoids and their synthetic form, used as an adulterant, through the analysis of stable isotope ratios of carbon and hydrogen (expressed as δ13C and δ2H). Carbon values greater than −28.6‰ and hydrogen values greater than −71‰ may indicate the addition of synthetic curcuminoids to the natural ones.

Stable Isotope Ratio Analysis for Authentication of Natural Antioxidant Cannabidiol (CBD) from Cannabis sativa

“…In fact, biosynthetic CBD derives from the combination of fossil origin (e.g., olivetol) component and a natural origin one. This evidence does not allow for the identification of significant differences in terms of δ 2 H, as it has already been seen in other studies on organic molecules (e.g., vanillin or curcuminoids complex) [24,25].…”

“…The stable isotope analysis of bio-elements has already been successfully tested as a technique for distinguishing different natural molecules from their synthetic and/or biosynthetic counterparts. These molecules include, e.g., monacolin K from fermented red rice [22], theanine [23], curcuminoids [24], and vanillin [25]. The 13 C/ 12 C isotope ratios of carbon (expressed as δ 13 C), the 18 O/ 16 O ratios of oxygen (δ 18 O), and the 2 H/ 1 H ratios of deuterium (δ 2 H) proved to be effective in the discrimination between the active principal compound of interest obtained from natural sources and that obtained from fossil sources used in the industrial synthesis.…”