Phenolic Compounds, Antioxidant Activities, and Inhibitory Effects on Digestive Enzymes of Different Cultivars of Okra (Abelmoschus esculentus)

Abstract

In this study, the phenolic profiles and bioactivities of five representative cultivars of okra collected in China were investigated. Noticeable variations of phenolic compounds and their bioactivities were observed among these different cultivars of okra. The contents of total flavonoids (TFC) in “Shuiguo”, “Kalong 8”, “Kalong 3”, “Wufu”, and “Royal red” ranged from 1.75 to 3.39 mg RE/g DW, of which “Shuiguo” showed the highest TFC. Moreover, five individual phenolic compounds were found in okra by high performance liquid chromatography analysis, including isoquercitrin, protocatechuic acid, quercetin-3-O-gentiobioside, quercetin, and rutin, while isoquercitrin and quercetin-3-O-gentiobioside were detected as the main phenolic compounds in okra. Moreover, all tested okra exhibited significant antioxidant activities (2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity, 2,2’-azino-bis (3-ethylenzthiazoline-6-sulphonic acid) radical scavenging capacity, and ferric reducing antioxidant power) and inhibitory effects on digestive enzymes (lipase, α-glucosidase, and α-amylase). Indeed, “Shuiguo” exhibited much better antioxidant activities and inhibitory activities on digestive enzymes, which might be attributed to its high TFC. Results suggested that okra, especially “Shuiguo”, could be developed as natural antioxidants and inhibitors against hyperlipidemia and hyperglycemia in the fields of functional foods and pharmaceuticals, which could meet the increasing demand for high-quality okra with health-promoting properties in China.

Identification and Quantification of Flavonoids in Okra (Abelmoschus esculentus L. Moench) and Antiproliferative Activity In Vitro of Four Main Components Identified

“…The results are in agreement with D'Urso et al [35] and one more flavonoid (Q7G) was identified in our research. In addition, the separation and identification of flavonoids in okra in this study is much further based on previous studies [14,36,37]. Among the six components, Q3G, ISO, Q3S and Q3M were the main individual flavonoids, accounting for more than 96% of the total flavonoid.…”

In Vitro Antilipidic and Antithrombotic Activities of Plectranthus glandulosus (Lamiaceae) Leaves Extracts and Fractions

“…The interaction of phenolic compounds with cholesterol esterase is due to the presence of potent cholesterol esterase inhibitory sites, especially the interaction with the catalytic triad and oxyanion hole residues [ 49 ]. Our previous study also reported that hydroethanolic extract and ethyl acetate fraction have antioxidant properties [ 28 , 29 ], and it is shown that a positive correlation exists between phenolic compounds, antioxidant activity of plant extracts, and digestive enzyme inhibitory activity [ 50 , 51 ].…”

“…The pancreatic cholesterol esterase inhibition activity of leaves extracts and fractions of P. glandulosus were performed spectrophotometrically based on the method of Adisakwattana et al [36]. The extract/fraction (50 μL) at different concentrations (12,5,25,50, 100, 200 μg/mL) was incubated with mixtures containing 50 μL of taurocholic acid (5.16 mM), 50 μL of p-nitrophenyl butyrate substrate (0.2 mM), and 90 μL of sodium phosphate buffer (100 mM, pH 7.0). The reaction was initiated by adding 50 μl of porcine pancreatic cholesterol esterase (1 μg/mL).…”

Okra (Abelmoschus esculentus L.) as a Potential Functional Food Source of Mucilage and Bioactive Compounds with Technological Applications and Health Benefits

“…Polysaccharides and phenolic compounds are the main bioactive components of okra. In the fruit and its extracts, one can find the phenolic compounds catechin, isoquercitrin, protocatechuic acid, quercetin, quercetin-3-O-gentiobioside, and rutin [ 63 ]. In okra mucilage, Nampuak and Tongkhao [ 64 ] observed the presence of catechin, epigallocatechin gallate, and quercetin compounds.…”