LC-ESI-QTOF-MS/MS Profiling and Antioxidant Activity of Phenolics from Custard Apple Fruit and By-Products

Abstract

Custard apple is an edible fruit grown in tropical and subtropical regions. Due to its abundant nutrient content and perceived health benefits, it is a popular food for consumption and is utilized as a medicinal aid. Although some published research had provided the phenolic compound of custard apple, the comprehensive phenolic profiling of Australian grown custard apple is limited. Hence, this research aimed to evaluate the phenolic content and antioxidant potential by various phenolic content and antioxidant assays, followed by characterization and quantification of the phenolic profile using LC-ESI-QTOF-MS/MS and HPLC-PDA. African Pride peel had the highest value in TPC (61.69 ± 1.48 mg GAE/g), TFC (0.42 ± 0.01 mg QE/g) and TTC (43.25 ± 6.70 mg CE/g), followed by Pink’s Mammoth peel (19.37 ± 1.48 mg GAE/g for TPC, 0.27 ± 0.03 mg QE/g for TFC and 10.25 ± 1.13 mg CE/g for TTC). African Pride peel also exhibited the highest antioxidant potential for TAC (43.41 ± 1.66 mg AAE/g), FRAP (3.60 ± 0.14 mg AAE/g) and ABTS (127.67 ± 4.60 mg AAE/g), whereas Pink’s Mammoth peel had the highest DPPH (16.09 ± 0.34 mg AAE/g), RPA (5.32 ± 0.14 mg AAE/g), •OH-RSA (1.23 ± 0.25 mg AAE/g) and FICA (3.17 ± 0.18 mg EDTA/g). LC-ESI-QTOF-MS/MS experiment successfully characterized 85 phenolic compounds in total, encompassing phenolic acids (20), flavonoids (42), stilbenes (4), lignans (6) and other polyphenols (13) in all three parts (pulp, peel and seeds) of custard apple. The phenolic compounds in different portions of custard apples were quantified by HPLC-PDA, and it was shown that African Pride peel had higher concentrations of the most abundant phenolics. This is the first study to provide the comprehensive phenolic profile of Australian grown custard apples, and the results highlight that each part of custard apple can be a rich source of phenolics for the utilization of custard apple fruit and waste in the food, animal feeding and nutraceutical industries.

Determination and Characterization of Phenolic Compounds from Australia-Grown Sweet Cherries (Prunus avium L.) and Their Potential Antioxidant Properties

“…Previous studies have shown the FICA of sweet cherry as 24.90 as IC 50. 41 The FICA values of custard apples were reported from 0.13 ± 0.01 to 2.17 ± 0.19 mg EDTA/g, 38 which shows a wider range of values than sweet cherries. Thus, the metal chelating abilities of sweet cherries might be similar to custard apples.…”

“…Vinitha et al studied the RPA activity of sweet cherry in India but recorded their results in the form of dry weight. The RPA values of custard apples were reported to be 1.24 ± 0.12–6.47 ± 0.03 mg AAE/g in fresh weight, which showed a higher value than sweet cherries.…”

“…Kutlu et al have studied the hydroxyl radical-scavenging effect of the leaf extracts of sweet cherry, and the values range from 43.99 to 45.33%. The ·OH-RSA values of custard apples were reported to be from 0.18 ± 0.04 to 1.14 ± 0.04 mg AAE/g, which showed a lower value than sweet cherries.…”

“…The Fe 2+ chelating activity of the cherry samples was measured according to Lee et al 68 and Du et al 38 A 15 μL of the sample extract was mixed with 85 μL of water, 50 μL of 2 mmol/L FeCl 2 (1:15 dilution in water), and 50 μL of 5 mmol/L ferrozine (1:6 dilution in water). Incubation was performed at room temperature for 10 min.…”

Screening and Characterization of Phenolic Compounds from Australian Grown Bananas and Their Antioxidant Capacity

“…• OH-RSA and FICA assays. Previously, a thorough phenolic analysis of custard apples cultivated in Australia has been performed by Du et al [60]. They found that African Pride peel possessed the greatest antioxidant capacity for RPA (5.32 ± 0.14 mg AAE/g),…”