Green Extraction of Orange Peel Waste Reduces TNFα-Induced Vascular Inflammation and Endothelial Dysfunction

Abstract

Orange peel waste (OPW) is known to contain an abundant amount of polyphenols compounds such as flavonoids, well-reported for their antioxidant and anti-inflammatory properties. While OPW is generally regarded as a food waste, the opportunity to extract bioactive compounds from these “wastes” arises due to their abundance, allowing the investigation of their potential effects on endothelial cells. Hence, this study aims to use a green extraction method and pressurized hot water extraction (PHWE) to extract bioactive compounds from OPW. Liquid chromatography with UV detection (LC/UV) and liquid chromatography mass spectrometry (LC/MS) were subsequently used to identify the bioactive compounds present. Through the optimization of the extraction temperature for PHWE, our results demonstrated that extraction temperatures of 60 °C and 80 °C yield distinct bioactive compounds and resulted in better antioxidant capacity compared to other extraction temperatures or organic solvent extraction. Despite having similar antioxidant capacity, their effects on endothelial cells were distinct. Specifically, treatment of endothelial cells with 60 °C OPW extracts inhibited TNFα-induced vascular inflammation and endothelial dysfunction in vitro, suggesting that OPW possess vasoprotective effects likely mediated by anti-inflammatory effects.

Influence of industrial blanching, cutting, and freezing treatments on in vitro gastrointestinal digestion stability of orange (Citrus sinensis L.) and lemon (Citrus limon L.) peel polyphenols

“…All four phenolic acids were present in orange peels, whereas lemon peels only contained caffeic acid. The phenolic acids identified in orange and lemon peels were compatible with those reported previously 30‐32,35 …”

“…Besides flavanones, rutin, a flavonol, was identified in both citrus peels while diosmin, a flavone, was exclusively present in lemon peels. Flavonoids were identified in negative mode by analyzing the MS data, fragmentation pattern, and through comparison with existing literature data, [30][31][32][33][34][35][36] while quantification of flavonoids was carried out with Representative chromatograms of orange and lemon peels are provided in the Supporting Information, Fig. S1.…”

“…The phenolic acids identified in orange and lemon peels were compatible with those reported previously. [30][31][32]35 The influence of industrial blanching, cutting and freezing treatments on in vitro gastrointestinal digestion stability of phenolic acids in orange and lemon peels are presented in Tables 4 and 5, respectively. In undigested and untreated orange peels, chlorogenic acid was identified as the predominant compound, accounting for 50% of the total phenolic acids, in line with the findings reported in the literature.…”

3D printability and biochemical analysis of revalorized orange peel waste

“…Thereafter, we characterized the biochemical properties of OPW at each step of 3D printing: (i) formation of the powder, (ii) formulation of the ink, and (iii) extrusion by DIW 3D printing. Orange peels are a rich source of naturally occurring bioactive compounds such as flavonoids and other polyphenolic compounds [ 33 , 34 , 37 - 39 ] . Previous studies have reported the abundance of two flavones ( i.e.…”

“…The 1,1-diphenyl-2-picrylhydrazyl (DPPH) and azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays were deployed in assessing the antioxidant capacity of the extracts obtained from 3D-printed samples. The principle of both assays allowed us to determine the antioxidant properties of the extracts by quantifying their ability to scavenge free radicals [ 31 , 33 , 34 ] . In the DPPH assay, the blank (200 μL of methanol), and 100 μL of extracts from orange peel powder, ink, and printed samples were transferred into the 96-well plate.…”