Antioxidant and antidiabetic activities of a polyphenol rich extract obtained from Abelmoschus esculentus (okra) seeds using optimized conditions in microwave-assisted extraction (MAE)

Abstract

Functional foods have gained popularity in recent decades. They are exploited for their bioactive compounds like polyphenols, which are highly demanded in cosmetic, pharmaceutical and nutraceutical industries. However, extractive techniques and conditions used up to recently are almost obsolete and must be optimized for higher efficiency. The current study aimed to evaluate the antidiabetic potential of an optimized extract of Abelmoschus esculentus (okra) seeds. The optimal conditions for extracting polyphenolic compounds from okra seeds were determined using Microwave Assisted Extraction (MAE). A Face Center Composite Design (FCCD) was used for optimization. Solvent/dry matter ratio, wavelength and time were considered while the response studied was the polyphenolic content. The extract obtained at optimal conditions was characterized using Thin Layer Chromatography (TLC) and Fourier Transform Infra-Red (FTIR) spectroscopy, then tested for its antioxidant, alpha amylase inhibitory and antidiabetic activities. Response Surface Methodology (RSM) permitted the determination of the optimal conditions for phenols extraction as: microwave power 330 W, with a solvent ratio of 97.04/1 mL/g for 9.5 min of extraction time. The optimized extract showed a phenolic content up to 86.37 ± 1.13 mg GAE/g containing quercetin and catechin as revealed by the TLC. Functional groups characteristic of polyphenols were identified on FTIR spectra, and the extract exhibited good in vitro antioxidant capacities with DPPH (2, 2-diphenyl-1-picrylhydrazyl) radical scavenging capacity and FRAP (Ferric Reducing Antioxidant Power Assay). An IC50 of 3.99 ± 0.15 μg/mL was obtained with the DPPH scavenging test. Alpha amylase inhibitory assay revealed that the optimized okra extract behaved as a non-competitive inhibitor of porcine pancreatic amylase with an IC50 of 484.17 ± 2.33 μg/mL. Antidiabetic activity of the extract was observed in streptozotocin-induced diabetic males Wistar rats, as shown by the fasting blood glucose levels, food intake, changes in body weight and serum lipid profile among others.

Molecular docking and in vivo protective effects of okra (Abelmoschus esculentus) against metabolic dysfunction in high-fat, high-sodium diet-fed rats

“…These two peaks were typical of how carbohydrates were absorbed. As confirmed by Alba et al 50 and Woumbo et al , 14 the peaks at 1620 cm −1 , 1720 cm −1 and 1030 cm −1 suggest that the polysaccharide may include stretching vibration of free and methyl-esterified carboxyl and glycosidic groups, respectively. The peak at 820 cm −1 refers to the α-configuration in the polysaccharide, according to Zhang et al 51 The peaks between 1152 and 995 cm −1 indicate the presence of arabinoxylan in okra mucilage, as reported by Wang et al 19 The FTIR findings shown above are consistent with those of earlier investigations.…”

“…The peak at 820 cm −1 refers to the α-configuration in the polysaccharide, according to Zhang et al 51 The peaks between 1152 and 995 cm −1 indicate the presence of arabinoxylan in okra mucilage, as reported by Wang et al 19 The FTIR findings shown above are consistent with those of earlier investigations. 14,52 3.4. Scanning electron microscope of okra mucilage and flesh Fig.…”

“…13 According to reports, okra seeds and fruits are rich sources of polyphenols and flavonoids with antioxidant activity such as catechin, quercetin and procyanidin. 14 Nikpayam et al 15 confirmed that different okra portions have anti-diabetic effects. Okra functional components may help reduce other metabolic dysfunctions brought on by the HF/NaCl diet; however, this hasn't been evaluated yet.…”

Sample preparation for planar chromatography

“…Sonic treatment, either by immersion in a sonic water bath or using horn and probe devices, is used to increase the rate of extraction for granular solids and to disrupt the cellular structure of biological samples. Sonic water baths allow samples to be batched and processed in parallel, but the extraction efficiency may depend on the location of the (ii) Microwave-assisted solvent extraction Okra seeds Polyphenols P = 330 W, t = 9.5 min, sample/solvent = 0.01, ethanol-water (1:1), particle size < 0.5 mm (domestic microwave oven) [45].…”

“…Capital costs for closed vessel systems are high compared with traditional extraction methods. Applications for HPTLC analysis are limited so far to botanicals and are summarized in Table 3 [21–23, 45, 46]. In most cases, open vessels using domestic microwave ovens were used, which fail to take full advantage of the possibilities of MASE.…”