Okra in Food Field: Nutritional Value, Health Benefits and Effects of Processing Methods on Quality

Whole genome sequencing and annotation of Pseudocercospora abelmoschi, a causal agent of black leaf mould of okra

Pseudocercospora abelmoschi causes black mould on the leaves of okra. The disease is prevalent post-rainy season when high moisture and warm temperatures prevail. Severe defoliation is observed during favourable environments, leading to a significant loss in productivity. Based on the importance of the pathogen agriculturally, the P. abelmoschi isolate Cer 86 - 18 (MCC:9491) was selected for genome sequencing. The genome assembly of P. abelmoschi resulted in a genome of 31.90 Mb with an overall GC content of 54.26%. Quantitative genome assessment using BUSCO (Benchmarking Universal Single-Copy Orthologs) identified 1,664 (97.53%) complete BUSCOs, reflecting a high representation of conserved genes with minimal duplication and strong orthologous uniqueness. Gene prediction analysis identified 11,325 protein-coding genes, of which 3,857 were annotated using the KEGG database. As per analyses, 410 genes were predicted to encode carbohydrate-active enzymes, whereas 369 genes were predicted to encode peptidases. Eighteen gene clusters involved in secondary metabolite biosynthesis were also identified. A total of 143 proteins were predicted to be effectors using the in-silico pipeline. This is the first report on the genome organisation of P. abelmoschi. This study was designed to address this gap by enhancing our understanding of the genome organisation of P. abelmoschi and gene annotation, thereby paving the way for functional genomics studies, such as identifying virulence genes to aid in resistance breeding. Also, this genome could be another addition to the available genomic resources of the genus Pseudocercospora and can provide valuable insights into host-pathogen interactions and evolutionary relationships.

Influences of physical field-assisted extraction on the chemical structures and In vitro fermentation properties of okra polysaccharides

In this study, microwave, ultrasonic, and combined ultrasonic-microwave were applied to extract polysaccharide from fermented okra extraction. The achieved polysaccharides were labeled OP-LM, OP-LU, and OP-LUM, respectively. The chemical structure and microbial fermentation characteristics of OP-LM, OP-LU, and OP-LUM were studied. The relationship between the chemical structure of three okra polysaccharides (OKPs) and the fermentation characteristics was also discussed. Results indicated that OP-LM, OP-LU, and OP-LUM could remarkably change the gut microbial composition, but they differ in physicochemical properties like molecular weight (Mw), monosaccharide content, apparent viscosity, and surface morphology, which lead to their different fermentation characteristics like bacterial density, sugar consumption rate, short-chain fatty acids (SCFAs) production, and gut microbial composition. Therefore, with the help of correlation analysis, it was found that the composition and type of monosaccharides, the length of the side chain, and the Mw could affect the modulation of OKPs on gut microbial composition. In addition, the length of the side chain also led to the change in SCFAs type and concentration. Overall, our findings contribute to revealing the potential relationship between chemical structures of OKPs and their gut microbial fermentation characteristics.

Research advances in okra polysaccharides: Green extraction technology, structural features, bioactivity, processing properties and application in foods

Okra polysaccharides, extracted from a lowcost plant, has gained abundant research interests recently for exhibiting notable antioxidant, hypoglycaemic, anti-inflammatory, and immunomodulatory capacities, catering for people's continuously increasing demand of safe, natural, and functional food ingredients. Meanwhile, okra polysaccharides are biocompatible materials with excellent processing properties such as water solubility, antimicrobial activity, elasticity, and viscosity. The present study generalizes the multiple biological activities and the extraction methods of okra polysaccharides, and discusses their various applications in food science. This review compares traditional and green extraction methods, reveals their impacts on the primary structures, and also elaborates the functional applications of okra polysaccharides in food industry including serving as emulsifiers, fat replacers, biofilms and microencapsulation materials. It aims to inform further research and discussions on okra polysaccharides. To our view, the development and application of okra polysaccharides should significantly contribute to the advancement of food industry and human health.

Seed Oil Contents, Fatty Acid Compositions, and Gossypol Concentrations of Some Okra Landraces

Okra has recently attracted attention owing to its superior tolerance to high temperatures, greater adaptation to poor soil conditions, and having a robust plant structure. The plant contains a high amount of oil and valuable fatty acids; however, the main restriction of using okra seeds as an oil crop results from its gossypol contents. The aim of this study was to determine the oil content of okra landraces and to evaluate its potential as an oil crop. For this aim, seed oil content, fatty acid compositions of cold-pressed seed oil, and gossypol concentrations of fruit, oil cake, and seed oil were investigated in a core collection of 26 okra landraces, lines, and cultivars. Individual plants were harvested at the full maturity stage, and seeds were harvested and dried under 35°C for 2 days prior to oil extraction. Oil content, fatty acid composition, and gossypol content were analyzed by NMR, GC-FID, and HPLC, respectively. The calibration coefficients (r 2 ) of all the methods were determined to be > 0.99. The seed oil content of the samples ranged between 12.15% and 18.83%. Linoleic (42.01%), palmitic (31.65%), oleic (18.39%), and stearic acids (3.20%) were found to be the largest fraction of the fatty acids. The data matrix from 19 fatty acids and oil content was subjected to Principle Component Analysis (PCA). As a result, 6 principal components (PCs, eigenvalues > 1) explained 83.84% of total variance in the data set, with PC1 contributing 32.69% of the total. Gossypol contents of the fruit, oil cake, and seed oil fractions ranged between LOQ-2.12, < LOQ-7.01, and < LOQ-62.46 mg/kg, respectively. In conclusion, okra may have the potential to be an alternative oil crop for food/feed purposes due to the presence of reasonable oil content, high-quality fatty acid variations, and very low amounts of toxic gossypols, warranting further breeding and agronomic studies.

Clinical efficacy and safety of okra (Abelmoschus esculentus (L.) Moench) in type 2 diabetic patients: a randomized, double-blind, placebo-controlled, clinical trial

AIMS

The recent trend toward the use of natural functional and medical supplements has motivated the focus on the search and revival of traditional medicinal plant applications for many years. As a valuable dietary crop, okra fruit (Abelmoschus esculentus (L.) Moench) has been used for thousands of years as a medicinal food. This clinical trial aimed to assess the efficacy and safety of the okra pod capsule as an adjuvant treatment in controlling type 2 diabetes mellitus and provide clinical trial-based evidence about its anti-inflammatory effects.

METHODS

A total of 100 type II diabetic patients, aged between 40 and 60 years, were randomly assigned into two groups of okra and placebo. The first group was administered 1000 mg of powdered okra fruit three times a day for 3 months, while the other group received a placebo capsule with the same dosage. Both groups continued the standard antidiabetic therapy (consisting of metformin and gliclazide, as well as a nutritional regimen). At the start and three months later, various factors were measured, including FBG, insulin, HbA1c, cholesterol, triglycerides, HDL, LDL, CRP, liver and renal function tests, blood pressure, and BMI changes.

RESULTS

According to the results, patients who received okra treatment exhibited a significant decrease in FBG, HbA1c, total cholesterol, and triglyceride levels when compared to both the baseline and the placebo group. Patients in the okra group have lower levels of hs-CRP compared with the placebo group after 3 months of treatment. No liver, kidney, and blood pressure or other side effects were observed in the groups associated with okra treatment.

CONCLUSIONS

The present study demonstrated that adjunctive consumption of okra, in type 2 diabetic patients with 1000 mg three times a day for three months, improves lipid profile, glycemic control, and chronic inflammation without any tangible adverse effects.

CLINICAL TRIAL REGISTRY

IRCT.Ir (IRCT20120112008712N2). https://www.irct.ir/trial/42042 .

Effect of elevated ozone on the antioxidant response, genomic stability, DNA methylation pattern and yield in three species of Abelmoschus having different ploidy levels

The majority of polyploids can withstand many stresses better than their monoploid counterparts; however, there is no proven mechanism that can fully explain the level of tolerance at the biochemical and molecular levels. Here, we make an effort to provide an explanation for this intriguing but perplexing issue using the antioxidant responses, genomic stability, DNA methylation pattern and yield in relation to ploidy level under the elevated level of ozone in Abelmoschus cytotypes. The outcome of this study inferred that the elevated ozone causes an increase in reactive oxygen species leading to enhanced lipid peroxidation, DNA damage and DNA de-methylation in all the Abelmoschus cytotypes. The monoploid cytotype of Abelmoschus, that is Abelmoschus moschatus L., experienced the highest oxidative stress under elevated O₃, resulting in maximum DNA damage and DNA de-methylation leading to the maximum reduction in yield. While the diploid (Abelmoschus esculentus L.) and triploid (Abelmoschus caillei A. Chev.) cytotypes of Abelmoschus with lower oxidative stress result in lesser DNA damage and DNA de-methylation which ultimately leads to lower yield reduction. The result of this experiment explicitly revealed that polyploidy confers better adaptability in the case of Abelmoschus cytotypes under ozone stress. This study can further be used as a base to understand the mechanism behind the ploidy-induced stress tolerance in other plants mediated by gene dosage effect.

Understanding the traditional values and use of okra among pregnant women in western Ethiopia: a qualitative study

OBJECTIVES

This study explored the traditional values and use of okra among pregnant women, how okra plants are obtained, prepared and used by pregnant women, and the associated beliefs and meanings attached to it in western Ethiopia.

DESIGN

Qualitative research.

SETTING

Rural areas of western Ethiopia.

PARTICIPANTS

A purposive sampling technique was used to select a total of 86 pregnant women (14 for in-depth interviews and 72 for focus group discussions) in western Ethiopia.

RESULTS

Traditionally okra is used as a source of income and is a common food for guests visiting homes. In line with this, pregnant women in the western part of Ethiopia mainly consumed okra pods. For future consumption and preservation for a long period, they usually transform okra into powder.

CONCLUSIONS

Other parts of the okra plant rather than pods are not known as a food source and are the most neglected food sources in rural districts of western Ethiopia. The study provides evidence that supports nutritional behavioural change communication interventions on promoting the utilisation of different parts of okra and awareness creation on the nutritional values of okra.

Optimization of near-infrared reflectance models in determining flavonoid composition of okra (Abelmoschus esculentus L.) pods

Okra pods have been utilized as a functional food due to their rich active ingredient composition, especially the high content of flavonoid compounds. This study conducted near-infrared spectroscopy (NIRS) modeling optimization and external validation based on the flavonoid components of 219 pod samples. Spectral correlation analyses identified two types of spectral response patterns classified as quercetin-3-O-xylose (1-2) glucoside (QOXG) and total flavonoid content (TFC), consisting of six different spectral regions. Different modeling effects were observed for QOXG and TFC with various spectral region combination analyses, where the lower wave-number region contributed more to both flavonoids calibration models. The combination of standard normal variate / "1, 9, 3" / partial least squares was found to be the most effective for developing calibration models for both flavonoids. The resulting models had small root mean square errors of prediction for external validation and high determination coefficients, indicating their usefulness for rapid prediction of flavonoid composition in okra pods.

Investigating the in vitro mode of action of okra (Abelmoschus esculentus) as hypocholesterolemic, anti-inflammatory, and antioxidant food

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Okra leaf butanol extract and fruit extract induce the LDLR expression in human hepatoma cell line Huh7.

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Okra leaf butanol extract reduced the mRNA levels of proinflammatory cytokines IL-1β, IL-6 and TNF-α in THP1-derived macrophages.

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Okra fruit extract showed a sequestering ability of cholic acid providing an additional mechanism of hypocholesterolemic activity.

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Leaf ethyl acetate extract exerted significant antioxidant activity with IC₅₀ comparable to ascorbic acid.

Okra (Abelmoschus esculentus) have been introduced as food relatively recently in Europe. It is native to India and one of the most important vegetables in Nigeria. The leaves can be consumed but also the fruit is rich in nutrients and bioactive compounds (i.e., dietary fiber, vitamins, oils, polysaccharides, polyphenols) and several health promoting actions have been ascribed, including a lipid-lowering properties. In this work the effects of fruit and leaf extracts on expression of key mediators of cholesterol metabolism, i.e., the low-density lipoprotein receptor (LDLR) and proprotein convertase subtilisin/kexin type 9 (PCSK9), were investigated in human hepatoma cell line Huh7. Furthermore, effects on proinflammatory cytokines (IL-1β, IL-6 and TNF-α) expressed by THP1-derived macrophages were studied to assess potential anti-inflammatory actions.

Okra fruit extract significantly induced the mRNA and protein levels of the LDLR by 1.4 ± 0.3 and 4.8 ± 1.5-fold, respectively without any significant modification of PCSK9 expression. In addition, fruit extract showed a significant sequestering ability of cholic acid. Leaf butanol extract exerted similar action by inducing the expression of both the LDLR (+3.1 ± 1.6-fold vs control) and PCSK9 (+1.3 ± 0.4-fold vs control). The evaluation of the potential anti-inflammatory effect revealed a significant action of leaf butanol extract with reduced mRNA levels of IL-1β (−28 ± 8 % vs control), IL-6 (−11 ± 1 % vs control) and TNF-α (−43 ± 8 % vs control), while fruit extract did not show any anti-inflammatory activity. Finally, leaf ethyl acetate extract showed a significant antioxidant capacity comparable to ascorbic acid. Taken together, we provided evidence that leaf butanol extract and, more effectively, fruit extract induced the LDLR expression, effect that may explain the previously reported hypocholesterolemic action of okra. In addition, okra’s extracts reduced the expression of pro-inflammatory cytokines from THP1-derived macrophages, an effect that may suggest a vascular protective action of okra.

The effect of high humidity hot air impingement blanching on the changes in cell wall polysaccharides and phytochemicals of okra pods

BACKGROUND

Okra pods contain heat-sensitive substances, such as phenolic compounds and other phytochemicals that can be degraded when okra pods are subjected to heat treatment. The understanding of the impact of high humidity hot air impingement blanching (HHAIB) on the changes in physicochemical properties of polysaccharides and phytochemicals of okra pods is of great importance because over-blanching may result in cell membrane disruption and changes in biologically active compounds under prolonged exposure to the thermal treatment. Therefore, the present study aimed to investigate the effect of HHAIB on the changes in physicochemical properties of pectins and phytochemicals extracted from okra pods.

RESULTS

Both the HHAIB time and method of extraction influenced their physicochemical characteristics and biological activity. Pectin fractions subjected to HHAIB were composed of polygalacturonic acid, rhamnogalacturonan, glucomannan, galactan, mannose, arabinose, rhamnose, calcium pectate and arabinogalactan. The contents of total phenolics, total flavonoids and antioxidant activity of extracts mostly increased during HHAIB (i.e. up to 19.0%, 13.2% and 35.3%, respectively). However, HHAIB reduced the chlorophyll-a (up to 55.7%) and lycopene (up to 52.6%) contents of okra pods.

CONCLUSION

The acquired knowledge may be useful for better understanding and optimization of technologies based on HHAIB treatment. The HHAIB treated okra can be a promising natural alternative in different applications, including its use as a replacement of some ingredients in food or non-food systems as a result of richness in polysaccharides and polyphenols, as well as high antioxidant properties. © 2022 Society of Chemical Industry.

Review on nutraceuticals: phase transition from preventive to protective care

Nutraceuticals are essential for healthcare which is an alternative medicine that has gained popularity in recent years. Nutraceuticals consist of nutrients, herbals, and dietary supplements, which make them useful in preserving and promoting health, fighting illness, and improving overall quality of life. Its success or failure will be determined by its rapid expansion, research advances, lack of standards, marketing enthusiasm, quality assurance, and regulations. Nutraceuticals have been used in different regions under different names/categories. however, globally there are no stringent pharmaceutical standards for nutraceutical health products till date, but slowly regulators are paying attention on it. Nutraceuticals can be broadly classified according to it clinical significance, source and therapeutic effects. Nutraceuticals and functional foods have grown to be a multibillion-dollar business worldwide in recent years and personalization is the emerging approach to deliver the best therapeutic effect in future. This review carries extensive information about nutraceutical history, classification, regulatory aspects and industrial perspective.

Food Loss and Food Waste for Green Cosmetics and Medical Devices for a Cleaner Planet

To stay wealthy in a world where all can live in prosperity and wellbeing, it is necessary to develop sustainable growth at net zero emissions to stop climate change, neutralizing both risks and diseases such as the COVID-19 pandemic and inequalities. Changing the worldwide use of the great quantity of food loss and waste can help to move in this direction. At this purpose, it seems useful to transform food waste into richness, extracting and using its content in natural ingredients and biopolymers to make new sustainable products and goods, including cosmetics and medical devices. Many of these ingredients are not only bioactive molecules considered of interest to produce these consumer products but are also useful in reducing the environmental footprint. The active agents may be obtained, for example, from waste material such as grapes or olive pomace, which include, among others natural polymers, phythosterols, vitamins, minerals and unsaturated fatty acids. Among the polymers, chitin and lignin have shown particular interest because biodegradable, nontoxic, skin- and environmentally friendly ingredients can be obtained at low cost from food and forestry waste, respectively. According to our experience, these polymers may be used to make nanocomposites and micro-nanoparticles that encapsulate different active ingredients, and which may be embedded into gel and non-woven tissues to realize advanced medications and smart cosmeceuticals. However, to utilize food waste in the best possible way, a better education of both industry and the consumer is considered necessary, introducing all to change the ways of production and living. The consumer has to understand the need to privilege, food, cosmetics and goods by selecting products known to be effective that also have a low release of carbon dioxide. Thus, they must pay heed to purchasing cosmetics and medical devices made by natural ingredients and packaged by biodegradable and/or reusable containers that are possibly plastic free. Conversely, the industry must try to use natural raw materials obtained from waste by changing their actual production methods. Therefore, both industry and the consumer should depart from the linear economy, which is based on taking, making, and producing waste, to move into a circular economy, which is based on redesigning, reducing, reusing and recycling. Some examples will report on the possibility to use natural polymers, including chitin and lignin, to produce new cosmeceutical tissues. These innovative tissues, to be used as biodegradable carriers for making smart cosmetics and medical devices, may be produced at zero waste to save our health and the planet biodiversity.

Biological activity and development of functional foods fortified with okra (Abelmoschus esculentus)

The Abelmoschus esculentus plant, better known as okra, is an interesting crop from a nutritional standpoint. The okra plant is native to the African region but can now be found throughout tropical and subtropical areas of the world. This plant, known for its healing abilities, has been used as a traditional medicine to treat several diseases and external ailments, such as wounds or boils. This article reviews the potential health benefits from okra consumption, as well as the bioactive compounds that are suggested to be responsible. Furthermore, the okra plant and its derivatives have been evaluated in the formulation and manufacture of new functional food products. The latest advances in this direction, which includes characterizing the technical properties of functional foods fortified with okra are also presented in this review. A series of bioactive compounds such as flavonoids and catechins have been found in the okra plant, which were associated with numerous biological properties observed in research studies that reported potential anti-diabetic, anti-cancer, anti-hypertensive, and antimicrobial effects, among others, as a result of their consumption. These potential health benefits contribute to the development of new and useful functional foods, with okra (or its derivatives) being used as the highlighted ingredient.

Foliar application of silver nanoparticles differentially intervenes remediation statuses and oxidative stress indicators in Abelmoschus esculentus planted on gold-mined soil

The study assessed the intervention of foliar application of silver nanoparticles (AgNPs) on heavy metal toxicity and phytoremediation status of Abelmoschus esculentus planted in gold-mined soil. The green synthesized AgNPs absorbed maximally at 425 nm, had an average particle size of 55 ± 2.3 nm and peaks at 3,443 and 1,636 cm^-1. A. esculentus seeds were grown in gold-mined soil and its seedlings were wetted with water and different concentrations of AgNPs (0.75, 0.50 and 0.25 mg/mL). Foliar applications of AgNPs significantly improved percentage heavy metal remediation and reduced contamination intensity by 60% and 44%, respectively in A. esculentus. Heavy metals induced oxidative stress in A. esculentus wetted with water which manifested in the reduction of growth performance and photosynthetic pigments by 43% and 15% in that order. Significant overexpression of superoxide dismutase activity and malondialdehyde by 70% and 86%, respectively together with a significant reduction in carotenoid contents and antioxidant activity by 92% and 15%, respectively were obtained for A. esculentus in control. The intervention of foliar application considerably protected A. esculentus with improved physiology, enzymic and non-enzymic antioxidant activities. These results conclude that foliar application AgNPs beneficially mediated toxicities of heavy metals in plants. Novelty statementGold mining is an economic venture but contamination of ecological matrixes by heavy metals usually accompanies it. Farming on either an active or abandoned gold site can predispose residents to the toxicity of heavy metals. Therefore, remediation before or during cultivation is key to ensuring safety. Silver nanoparticles have proved effective in remediating heavy metals and improving biochemical activities in plants due to their intrinsic properties and adsorptive potentials.

Structural Properties, Bioactivities, and Applications of Polysaccharides from Okra [Abelmoschus esculentus (L.) Moench]: A Review

Okra [Abelmoschus esculentus (L.) Moench], as a kind of nutritive vegetable, is rich in flavonoids, polyphenols, polysaccharides, amino acids, and other bioactive substances and has various biological activities. As one of main bioactive components, okra polysaccharides (OPs), mainly comprising pectic polysaccharides, have various biological activities. OPs have been extensively investigated in recent years. Many studies characterized structures of OPs obtained by different extraction methods, which were confirmed to be rhamnogalacturonan-I-type polysaccharides in most cases. OPs have a thick and slimy texture, suggesting that they can be a promising source of texture modifiers for complex food matrices. They have various biological activities, such as antioxidant activity, immunomodulatory activity, hypoglycaemic activity, and improving intestinal function. Therefore, OPs may potentially serve as novel immunomodulators or an adjuvant for diabetic nephropathy. Up to now, there is no specific summary on the research progress of OPs. In this paper, the latest research progress on the extraction, purification, characterization, rheological properties, biological activities, and applications of OPs is reviewed, to provide the reference for the processing and comprehensive utilization of OPs in the future.

Evaluation and comparison of the microbial communities and volatile profiles in homemade suansun from Guangdong and Yunnan provinces in China

BACKGROUND

Suansun is a traditional salt-free fermented bamboo shoot product that has been widely consumed as a cooking ingredient in south China for centuries. The aim of this study was to evaluate and compare the microbial and metabolic diversity in samples of two kinds of suansun, namely Guangdong suansun (GD) and Yunnan suansun (YN), using high-throughput sequencing (HTS) and headspace solid-phase microextraction-gas chromatograph-mass spectrometry (HS-SPME/GC-MS), respectively, and then to assess the influence of environmental factors on the microbial communities.

RESULTS

The results showed that Lactobacillus and Serratia were the most abundant bacterial genera in both the GD and YN groups. For the fungi, Pichia, Candida, and Debaryomyces were the major genera in the GD group, whereas Pichia and Zygosaccharomyces were the dominant genera in the YN group. The canonical correlation analysis (CCA) results demonstrated that three environmental factors - temperature, longitude, and altitude - play a more important role in affecting the microbial community composition of suansun than physical and chemical factors. The fugal community composition was more influenced by environmental factors than the bacterial community. The volatile profile of the GD group differed from that of the YN group, and the difference was mainly reflected in the relative alcohol, aldehyde, ester, and aromatic compound content.

CONCLUSIONS

This study provided insights into the microbial and metabolic profiles of suansun products. The findings might be useful for the improvement and standardization of suansun production. © 2020 Society of Chemical Industry.

Chemical Composition, Nutritional Value, and Biological Evaluation of Tunisian Okra Pods (Abelmoschus esculentus L. Moench)

The aim of this work was to perform an unprecedented in-depth study on the bioactive phytochemicals of Abelmoschus esculentus L. Moench Tunisian landrace (Marsaouia). For this purpose, its nutritional, aroma volatile, and phenolic profiles were characterized, and sundry biological activities were assessed in vitro. The approximate composition revealed that total dietary fiber as the most abundant macronutrient, mainly insoluble dietary fiber, followed by total carbohydrates and proteins. In addition, okra pods were rich in K, Ca, Mg, organic acids, tocopherols, and chlorophylls. Gas Chromatography-Electron Impact Mass Spectrometry (GC-EIMS) analysis showed that oxygenated monoterpenes, sesquiterpene hydrocarbons, and phenylpropanoids were the predominant essential volatile components in A. esculentus pods. A total of eight flavonols were detected by High-Performance Liquid Chromatography coupled to a DAD detector and mass spectrometry by electrospray ionization (HPLC-DAD-MS/ESI); with quercetin-3-O-glucoside being the majority phenolic component, followed by quercetin-O-pentosyl-hexoside and quercetin-dihexoside. This pioneering study, evidences that Tunisian okra display promising antioxidant and cytotoxic actions, in addition to relevant inhibitory effects against α-amylase and α-glucosidase enzymes, and interesting analgesic activity.