Effect of Freeze Drying and Simulated Gastrointestinal Digestion on Phenolic Metabolites and Antioxidant Property of the Natal Plum (Carissa macrocarpa)

Abstract

Natal plums (Carissa macrocarpa) are a natural source of bioactive compounds, particularly anthocyanins, and can be consumed as a snack. This study characterized the impact of freeze drying and in vitro gastrointestinal digestion on the phenolic profile, antioxidant capacity, and α-glucosidase activity of the Natal plum (Carissa macrocarpa). The phenolic compounds were quantified using high performance liquid chromatography coupled to a diode-array detector HPLC-DAD and an ultra-performance liquid chromatograph (UPLC) with a Waters Acquity photodiode array detector (PDA) coupled to a Synapt G2 quadrupole time-of-flight (QTOF) mass spectrometer. Cyanidin-3-O-β-sambubioside (Cy-3-Sa) and cyanidin-3-O-glucoside (Cy-3-G) were the dominant anthocyanins in the fresh and freeze-dried Natal plum powder. Freeze drying did not affect the concentrations of both cyanidin compounds compared to the fresh fruit. Both cyanidin compounds, ellagic acid, catechin, epicatechin syringic acid, caffeic acid, luteolin, and quercetin O-glycoside from the ingested freeze-dried Natal plum powder was quite stable in the gastric phase compared to the small intestinal phase. Cyanidin-3-O-β-sambubioside from the ingested Natal plum powder showed bioaccessibility of 32.2% compared to cyanidin-3-O-glucoside (16.3%). The degradation of anthocyanins increased the bioaccessibility of gallic acid, protocatechuic acid, coumaric acid, and ferulic acid significantly, in the small intestinal digesta. The ferric reducing antioxidant power (FRAP), 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) activities, and inhibitory effect of α-glucosidase activity decreased in the small intestinal phase. Indigenous fruits or freeze-dried powders with Cy-3-Sa can be a better source of anthocyanin than Cy-3-G due to higher bioaccessibility in the small intestinal phase.

An Evaluation of Phenolic Compounds, Carotenoids, and Antioxidant Properties in Leaves of South African Cultivars, Peruvian 199062.1 and USA's Beauregard

“…Trolox solution ranging from (0 to 30 mM) was prepared for quantification as a reference standard; results were expressed as mM TEACg −1 . The radical scavenging activity was assessed using the 2,2 ′diphenyl-1-picrylhydrazyl radical (DPPH) scavenging ability assay with slight modifications, according to the method described by Seke et al (13), using.1 g of a freeze-dried sample mixed with 1 ml of 80% methanol. The sample mixture was centrifuged at 3,000 × g for 5 min at 4 • C using a Hermle centrifuge (Model Hermle Z326k, HermleLabortechnik GmbH, Wehingen, Germany).…”

Cooking African Pumpkin Leaves (Momordica balsamina L.) by Stir-Frying Improved Bioactivity and Bioaccessibility of Metabolites—Metabolomic and Chemometric Approaches

“…The Infogest static in vitro simulation of gastrointestinal food digestion procedure according to Brodkorb et al [14] and Seke et al [15] was performed. An amount of 10 mL of simulated salivary fluid at pH 7 containing 75 U mL −1 α-amylase enzyme was added to 10 g of African pumpkin leaves, and the mixture was homogenised with a pestle and mortar for 10 s to mimic chewing then incubated in a shaking water bath at 170 rpm for 2 min at 37 • C. The simulated gastrointestinal fluids were as described before [15]. Simulated gastric fluid (20 mL) was added to the oral digesta, and the gastric phase was initiated, adjusting the pH to 2.5 using 6 M HCl, then adding pepsin solution (2000 U mL −1 in 0.1 M HCl, pH 2.2).…”

“…A radical scavenging assay was conducted using the 2,2-diphenyl-2-picrylhydrazyl (DPPH) method previously described by Seke et al [15]. The reaction mixture contained 250 µL of DPPH (90 mM) solution and 20 µL of the sample (various concentrations); the absorbance read 517 nm.…”

“…The ferric reduction antioxidant capacity (FRAP) assay was conducted according to Seke et al [15]. The reaction mixture included the 220 µL of FRAP reagent solution and 15 µL of the homogenised leaf extract; the absorbance was at 593 nm, and antioxidant activity was expressed as Trolox equivalent antioxidant activity (TEAC)100 g −1 .…”

“…The α-glucosidase inhibitory activity of extracts of cooked African pumpkin leaves was determined using the method described by Seke et al [15]). The sample (50 µL different concentrations) and 100 µL of 0.1 M phosphate buffer (pH 6.9) containing αglucosidase solution (1 U mL −1 ) were incubated at 25 • C for 10 min.…”