Evaluation of extraction and entrapment efficiency of black seed oil-containing emulsion as a delivery system for thymoquinone

Abstract

Black seed oil (BSO) or Nigella sativa contains numerous bioactive components, in which thymoquinone (TQ) becomes a functional key compound and serves as an analytical marker. With its non-polar characteristic, lipid-based delivery systems can be a solution to improve the solubility of BSO. Thus, it is necessary to have a valid basis for TQ quantification, especially in the emulsion as the delivery system of BSO. This study aimed to validate a Gas Chromatography-Flame Ionization Detector (GC-FID) method for quantifying TQ, and subsequently employ the method to evaluate TQ extraction from BSO and BSO-containing emulsion and determine the entrapment efficiency of the emulsion. The method indicated a linearity between 10 and 1280 µg/ml with detection and quantification limits of 13,59 and 41,19 µg/ml, respectively. The extraction of TQ with the sample:methanol ratio of 1:9 and 30-min centrifugation yielded the maximum TQ recovery from BSO and BSO-containing emulsion. The entrapment efficiency in emulsion reached 64,83% obtained with the density-changing centrifugation method. Overall, this validated GC-FID method demonstrated that the selected condition in the methanol extraction could effectively separate TQ from both BSO and its emulsion matrices and support the determination of the entrapment efficiency of the BSO-containing emulsion.