Phytochemical profile and antioxidant activity of torch ginger (Etlingera elatior) inflorescence extract after in vitro simulated digestion

Background: Torch ginger (Etlingera elatior) is an edible flower whose inflorescence is utlized for culinary purposes to enchance the taste of traditional dishes containing polyphenols and antioxidant compounds. However, investigation on the phytochemical profile and antioxidant activity of torch ginger inflorescence extract following simulated gastrointesinal digestion is still limited. Objective: This study aims to determine the phytochemical profile and evaluate the antioxidant activity of the inflorescence extract after in vitro simulated digestion. Methods: Torch ginger inflorescence (TGI) was extracted by ultrasound-assisted extraction with different solvents (water,50%, and 80% aqueous ethanol). Total phenolics content (TPC), total flavonoid content (TFC), and antioxidant activity were determined by ORAC, DPPH, FRAP, and metal ion (Fe2+) chelating activity. The solvent extraction that gave the highest value of TPC, TFC, and antioxidant activities was used for an in vitro digestion and identification of phytochemicals profile by LC-ESI-QTOF-MS/MS. Furthermore, the TPC, TFC, and antioxidant capacities of digested TGI extract were compared to those of undigested extract. Results: TGI contained 90.24% moisture. The 80% aqueous ethanol extract exhibited the highest antioxidant capacity, with an ORAC value of 1,156.61 ± 11.55 mM TE/g extract, DPPH radical scavenging capacity of 1,087.68 ± 14.37 mM TE/g extract, FRAP value of 799.30 ± 1.45 mM TE/g extract, and Fe2+ chelating capacity of 42.32 ± 3.48% /mg extract. The 39 phytochemicals were identified for 9 flavonoids and 5 phenolic acids. The putative bioactive compounds for antioxidant, anticancer, anti-inflammatory, and anticholesterol were detected in TGIE, such as catechin, 2-hydroxycinnamic acid, astragalin, chlorogenic acid, coumarin, and procyanidin B2. After passing through an in vitro simulated mouth, gastric, and intestinal digestion, the TGI extract exhibited higher values of TPC, TFC, and antioxidative capacities than the undigested extract. Conclusion: This study reviewed the phytochemical components presented in the 80% aqueous ethanol TGIE. The expressed antioxidant capacity was increased when the TGIE passed through the in vitro simulated digestion, which could potentially represent a promising source of endogenous antioxidants in food and nutraceutical applications. Keywords: Antioxidant, edible flower, gastrointestinal digestion, phytochemicals, Torch ginger inflorescence