Fig. 3
From: Caffeine-inducible gene switches controlling experimental diabetes
In vitro caffeine quantification in commercial caffeine sources. a Illustration of the tested solutions with their respective caffeine concentration. From left to right, the boxes correspond to Nesquik® capsules, Forest Fruits® (herbal tea), Vivalto lungo decaffeinato®, Volluto decaffeinato®, Decaffeinato intenso®, Arpeggio decaffeinato®, Coca-Cola®, Mediterranean® (green tea), Marrakech® (green tea), Earl Grey® (black tea), Starbucks® Coffee Frappuccino, Starbucks® Caramel Macchiato, Red Bull®, Bukeela ka Ethiopia®, Vivalto lungo®, Starbucks® Coffee, Capriccio®, Livanto®, Apfelstrudel®, Volluto®, Roma®, Arpeggio®, Ristretto®, Dharkan®, Military Energy Gum®, and Kazaar®. The indicated caffeine concentrations were calculated from the specifications of the vendor regarding the amount of caffeine in each beverage. b, c Quantification of the caffeine concentration in coffee from Nespresso Grand Cru® capsules (b) and other commercially available caffeine sources (c). Caffeine-containing samples were added to C-STARDB1 cells with a dilution of 1:50,000. A standard curve obtained with pure caffeine enabled conversion of the quantified SEAP levels to caffeine concentrations in the original samples. Each beverage was prepared or bought on three separate occasions and the data represent the quantification of each replicate in triplicate (n = 3). Data in (b, c) are shown as the mean in bar graphs and symbols indicate individual data points. The caffeine concentration indicated by the vendor is shown in blue
