Identification of Phenolic Compounds in Australian-Grown Bell Peppers by Liquid Chromatography Coupled with Electrospray Ionization-Quadrupole-Time-of-Flight-Mass Spectrometry and Estimation of Their Antioxidant Potential

Zexing Leng; Biming Zhong; Hanjing Wu; Ziyao Liu; Abdur Rauf; Sami Bawazeer; Hafiz Ansar Rasul Suleria

doi:10.1021/acsomega.1c06532

Identification of Phenolic Compounds in Australian-Grown Bell Peppers by Liquid Chromatography Coupled with Electrospray Ionization-Quadrupole-Time-of-Flight-Mass Spectrometry and Estimation of Their Antioxidant Potential

ACS Omega. 2022 Jan 25;7(5):4563-4576. doi: 10.1021/acsomega.1c06532. eCollection 2022 Feb 8.

Authors

Zexing Leng¹, Biming Zhong¹, Hanjing Wu¹, Ziyao Liu¹, Abdur Rauf², Sami Bawazeer³, Hafiz Ansar Rasul Suleria¹

Affiliations

¹ School of Agriculture and Food, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria 3010, Australia.
² Department of Chemistry, University of Swabi, Anbar, Swabi, Khyber Pakhtunkhwa 23561, Pakistan.
³ Department of Pharmacognosy, Faculty of Pharmacy, Umm Al-Qura University, P.O. Box 42, Makkah 21421, Kingdom of Saudi Arabia.

Abstract

Bell peppers are widely considered as healthy foods that can provide people with various phytochemicals, especially phenolic compounds, which contribute to the antioxidant property of bell peppers. Nevertheless, the acknowledgment of phenolic compounds in bell peppers is still limited. Therefore, this study aimed to determine the phenolic content and the antioxidant potential in pulps and seeds of different bell peppers (green, yellow, and red) by several in vitro assays followed by the characterization and quantification of individual phenolics using liquid chromatography coupled with electrospray ionization-quadrupole-time-of-flight-mass spectrometry (LC-ESI-QTOF-MS/MS) and high-performance liquid chromatography photodiode array (HPLC-PDA) quantification, respectively. The captured results showed that the pulp of red bell peppers exhibited the highest phenolic content in the total polyphenol content (1.03 ± 0.07 mg GAE/g_f.w.), total flavonoid content (137.43 ± 6.35 μg QE/g_f.w.), and total tannin content (0.22 ± 0.01 mg CE/g_f.w.) as well as the most antioxidant potential in all antioxidant capacity estimation assays including total antioxidant capacity (3.56 ± 0.01 mg AAE/g_f.w.), 2,2'-diphenyl-1-picrylhydrazyl (0.89 ± 0.01 mg AAE/g_f.w.), 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (1.36 ± 0.12 mg AAE/g_f.w.), and ferric reducing antioxidant power (0.15 ± 0.01 mg AAE/g_f.w.). LC-ESI-QTOF-MS/MS isolated and identified a total of 59 phenolic compounds, including flavonoids (21), phenolic acids (20), other phenolic compounds (12), lignans (5), and stilbenes (1) in all samples. According to HPLC-PDA quantification, the seed portions showed a significantly higher amount of phenolic compounds. These findings indicated that the waste of bell peppers can be a potential source of phenolic compounds, which can be utilized as antioxidant ingredients in foods and nutritional products.