Dear Label_Name,

Greetings! I hope you are well.

I am writing on behalf of an international publishing house, Science and Education Publishing, USA (http://www.sciepub.com).

Science and Education Publishing (SciEP) is a multidisciplinary open access publisher of Journals covering the fields of Science, Technology and Medicine. All SciEP publications are subject to high-quality peer review, editorial and production processes and are freely available online.

Welcome to the April, 2013 edition of SciEP newsletter, providing monthly summaries of articles on science & education related topics of interest to scientist and professionals. The mission of our journals is to provide an open access forum for publishing new findings on issues pertinent to scientific and academic field. We also invite you to submit original research papers, review articles, short reports, or case studies are considered for publication in our Multidisciplinary Journals.

American Journal of Public Health Research
DOI: 10.12691/ajphr-1-1-3

The Implementation of a Tele-Homecare System with Service Oriented Architecture and HL7 Message Transmission Standard
Ching-Sung Wang

American Journal of Medical and Biological Research
DOI: 10.12691/ajmbr-1-1-2

The Influence of Ethanol on Pyruvate Kinases Activity in Vivo, in Vitro, in Silico
Lelevich Sergey Vladimirovich, Khrustalev Vladislav Victorovich, Barkovsky Eugene Victorovich, Shedogubova Tatyana Aleksandrovna

American Journal of Medical Sciences and Medicine
DOI: 10.12691/ajmsm-1-1-1

Clinical and Histological Features in Wegener Granulomatosis
Li Cavoli Gioacchino, Passantino Rita, Bono Luisa, Tortorici Calogera, Ferrantelli Angelo, Giammarresi Carlo, Rotolo Ugo

American Journal of Infectious Diseases and Microbiology
DOI: 10.12691/ajidm-1-1-2

The Curse of Lymphatic Filariasis: Would the Continual Use of Diethylcarbamazine Eliminate this Scourge in Papua New Guinea?
Anne Lanham, Lillian Mwanri

We have released issues of some journals on February 2013.
American Journal of Public Health Research
American Journal of Medical Sciences and Medicine
American Journal of Medical and Biological Research
American Journal of Pharmacological Sciences
American Journal of Clinical Medicine Research
American Journal of Nursing Research
American Journal of Cancer Prevention
American Journal of Medicine Studies
American Journal of Infectious Diseases and Microbiology
American Journal of Cardiovascular Disease Research
American Journal of Biomedical Research
American Journal of Mechanical Engineering
American Journal of Microbiological Research
Journal of Preventive Medicine
American Journal of Food and Nutrition
American Journal of Hypertension Research
American Journal of Sports Science and Medicine
Journal of Cancer Research and Treatment
American Journal of Zoological Research
Journal of Biomedical Engineering and Technology
American Journal of Microbiological Research
Biomedical Science and Engineering

We are pleased to announce that submissions are now being accepted for peer review for all the journals across all our subject areas in SciEP.

Please submit your manuscript via our online submission system:
http://www.sciepub.com/author/signin

To unsubscribe from our mailing list, please click on the following link: unsubscribe

I am looking forward to hearing from you.

Kind regards,

David Rain
Email:join@sciepub.com
Science and Education Publishing (http://www.sciepub.com)

Phytochemical Composition and Antioxydant Capacity of Abelmoschus esculentus l. Fresh Immature Fruits

BOGNINOU G. Sophie Reine*, BIGO AGADABA Prudence Houndékon, GNANWE Marcelline, AGBANGNAN DOSSA C. Pascal, CHABI Nicodème Worou, YEDOMONHAN Hounankpon, AVLESSI Félicien

Laboratoire d’Etude et de Recherche en Chimie Appliquée (LERCA) Ecole Polytechnique d’Abomey-Calavi (EPAC/UAC)

Abstract: This work aims to study the intervariation of chemical composition and antioxidant capacity of fresh immature fruits of 12 varieties of Abelmoschus esculentus. The phytochemical screening of fresh immature fruits powder of A. esculentus was realised using the experimental methodology of Houghton. Total phenolic content was determined by using the Folin-Ciocalteu method while total flavonoids and condensed tannins content were estimated using the AlCl₃ method and vanillin method respectively. The antioxidant capacities in the forms of DPPH (2, 2-diphenyl-1-picrylhydrazyl) was evaluated by spectrophotometric method. The phytochemical screening made upon the powder of fresh immature fruits of A. esculentus revealed the presence of catechin tannins, mucilages, flavonoids, leuco-anthocyanins, reducing compounds, sterols and terpens. The results showed also that total phenolic compounds content, flavonoids and condensed tannins values were higher in V₁₆ extract: 25.514 ± 0.005 mg GAE/100mg of dry matter, 63.786 ± 0.013 mg QE/g of dry matter and 12.242 ± 0.036 mg CE/g of dry matter. At 1 mg/mL, the inhibition percentage of DPPH radical scavenging activity ranged from 60.40 to 92.71%. The variety V₁₆ had the highest DPPH scavenging capacity. Hence, the variety V₁₆ represents a potential source of phenolic compounds and antioxidants and could be used in pharmaceutical and food preparations.

Keywords: phytochemical screening, Abelmoschus esculentus, antioxidant capacity, intervariation

Received June 29, 2018; Revised August 01, 2018; Accepted August 20, 2018

Citation: BOGNINOU G. Sophie Reine, BIGO AGADABA Prudence Houndékon, GNANWE Marcelline, AGBANGNAN DOSSA C. Pascal, CHABI Nicodème Worou, YEDOMONHAN Hounankpon, AVLESSI Félicien, Phytochemical Composition and Antioxydant Capacity of Abelmoschus esculentus l. Fresh Immature Fruits. American Journal of Food Science and Technology, 6 (5). 223-227. January 2018. doi:10.12691/ajfst-6-5-6

1. Introduction

Vegetables are important sources of macronutrients and micronutrients and have played an important role in the traditional diets of many regions throughout the world. In addition to their nutritional value, it has long been recognized that vegetables are functional foods that both promote good health and have therapeutic properties [1]. Many researchers indicate that vegetables may serve as an excellent dietary source of natural antioxidants for disease prevention and health promotion [2]. This potential is linked to their richness in secondary metabolites, among which are the phenolic compounds. Polyphenols are present in high amounts in most of foods plant and beverages [3] which cannot be synthesized by humans [4]. In the 1990s, several epidemiological studies demonstrated that dietary polyphenol consumption is associated with a reduced risk of cardiovascular disease [5,6]. As the basic and clinical research progressed, multiple functions of polyphenols contributing to human health were identified [7,8]. To help the indigenous population to fight against many diseases, it is necessary to identify and propose to them the plants food rich in phenolic compounds and accessible at a lower cost.

Okra, Abelmoschus esculentus (L.), is an important vegetable crop grown mainly in the tropical or sub-tropical regions during summer and rainy season [9,10]. It is widely grown in Africa, Asia, Southern Europe and America [11]. Millions of tons have been grown in India (3.5 million tons), Nigeria (0.73 million tons), Pakistan (0.12 million tons), Ghana (0.10 million tons), Egypt (0.08 million tons) and Benin (56 564 tons) [9,12]. Okra is a multipurpose crop due to its various uses of the pods, fresh leaves, buds, flowers, stems, and seeds. Okra immature fruits, which are consumed as vegetables, can be used in salads, soups, and stews, fresh or dried, fried or boiled [13]. In addition, the plant has been used medicinally in treatment of several disorders. Anti-cancer, antimicrobial and hypoglycemic activities of plant are reported. The anti-ulcer activity of fresh fruits is recently reported [14].

But most of these studies were performed on the leaves, roots and the seeds of A. esculentus. Very few of scientific studies are focused on fruits whereas it is the most consumed part of the plant. In addition, no study is performed on the phytochemistry and antioxydant activity of the varieties of okra produced in Benin’s Republic to our knowlegde. Hence, this work aims to study the intervariation of chemical composition and antioxidant capacity in fresh immature fruits of 12 varieties of Abelmoschus esculentus.

2. Material and Methods

2.1. Plants Materials

Plants Materials: The fresh immature fruits of twelve varieties of Okra (Abelmoschus esculentus) were obtained from Department of Botanic, University of Abomey-Calavi, Republic of Benin, washed properly with distilled water and dried under shade at room temperature. This fresh immature fruits were blended into powdered form and stored in sterile flasks until analysis.

2.2. Phytochemical Screening

Screening is a qualitative chemical analysis based on differential staining and/or precipitation reactions of the major chemical compounds groups contained in plants. The experimental methodology adopted in this study was that of [15]. The targeted compound were alkaloids, phenolic compounds (catechin tannins, gallic tannins, flavonoids, anthocyanins, leucoanthocyanin), quinine derivatives, saponosides, triterpenoids, steroids, mucilages, coumarins, reducing compounds and anthracene derivatives.

2.3. Extraction

10 g of fresh immature fruit powder of each variety of Abelmoschus esculentus were extracted for 24 hours by maceration with 100 mL of ethanol-water (50: 50) at room temperature under magnetic stirring. The extracts were filtered and the filtrate was concentrated by rotary vacuum evaporation at 40°C until obtaining a solid residue.

2.4. Estimation of Total Phenolic Compounds, Total Flavonoids and Condensed Tannins Contents

2.4.1. Total Phenolic Contents

The total phenolic compounds content (TPC) was determined by a Folin Ciocalteu assay [16] using gallic acid as the standard. The mixture of the sample solution (400 µL), 2 mL of Folin-Ciocalteu’s reagents solution, and 1.6 mL Na₂CO₃ (7%) was vortexed. The mixture was allowed to stand for 2 h at room temperature. The absorbance was measured at 765 nm against distilled water as a blank. The total phenolic content was expressed as gallic acid equivalents (mg of GAE/g dry matter) through the calibration curve of gallic acid.

2.4.2. Total Flavonoids Contents

Total flavonoid content was determined using a colorimetric method described previously [2]. Briefly, a dose of 0.25 mL of extract or catechin standard solution was mixed with 1.25 mL of distilled water in a test tube, followed by adding 75µL of a 5% NaNO₂ solution. After 6 min, 150 µL of a 10% AlCl₃ solution was added and allowed to stand for another 5 min before adding 0.5 mL of 1 M NaOH. The mixture was brought to 2.5 mL with distilled water and mixed well. The absorbance was measured immediately against the blank (the same mixture without the sample) at 510 nm using a UV-Visible Spectrophotometer. The results were calculated and expressed as micrograms of quercetin equivalents (mg of QE/g dry matter) using the calibration curve quercetin. Linearity range of the calibration curve was 10 to 1000 µg/mL.

2.4.3. Condensed tannins contents

Analysis of condensed tannin content was carried out according to the method of [17]. To 50 µL of the suitably diluted sample, 3 mL of a 4% methanol vanillin solution and 1.5 mL of concentrated hydrochloric acid were added. The mixture stood for 15 min, and the absorption was measured at 500 nm against methanol as a blank. The amount of condensed tannin was calculated and expressed as mg catechin equivalents (mg of CE/g dry matter) using the calibration curve of catechin. Linearity range of the calibration curve was 50 to 1000 µg/mL (r = 0.99).

2.5. In vitro Antioxidant Potential DPPH Radical-Scavenging Activity

The ability of the extract scavenge of the 2,2-diphenyl-1-picrylhydrazyl radical was evaluated. In the presence of antioxidant which is typical for DPPH free radical decays, the change in absorbency at 517 nm is followed spectrophotometrically. The antioxidant activity was determined according to the method previously described [18]. Briefly, 1.5 ml of a freshly prepared methanolic solution of DPPH (2%) was mixed with 0.75 mL of extract solution (1 0.007 mg/ml). After 15 min of incubation in the dark, at room temperature, absorbance was read at 517 nm against a blank sample consisting of a 1.5 ml of methanol and 0.75 ml of extract solution. All tests were performed in triplicate. DPPH radical inhibition percentage was calculated according to the following formula:

AS: is the sample (tested extract solution) absorbance and AB: is the blank absorbance.

2.6. Statistical Analysis

Data were presented as mean ± SD. The graphical representation of the data was performed using the Microsoft Excel 2007. The difference was considered statistically significant when the p ˂ 0.05.

3. Results and Discussion

3.1. Phytochemical Screening

The powders of fresh immature fruits of twelve varieties of Abelmoschus esculentus were subjected to preliminary phytochemical analysis so as to find out the phytoconstituents present in the samples. Table 1 shows the different metabolites identified in the plant materials studied. Various secondary metabolites have been identified in the fresh immature fruits of these varieties by a series of color and precipitation reactions more or less specific to each class of active ingredients. Among these secondary metabolites were catechin tannins, mucilages, flavonoids, leuco-anthocyanins, reducing compounds, sterols and terpenes. However, the fresh immature fruits of these varieties do not contain alkaloïds, coumarins, saponins, anthocyans, free anthraquinones, combined anthraquinones, cyanogenic derivatives, and quinone derivatives.

3.2. Total Phenolic Compounds, Flavonoids and Condensed Tannins Contents of Hydroethanolic Extracts of Abelmoschus Fresh Immature Fruits.

The total phenolic compounds, flavonoïds and condensed tanins of hydroethanolic extracts of fresh immature fruits of these varieties of Okra expressed respectively out of equivalent mg of gallic acid per hundred milligrams (mg GAE /100mg) out of equivalent mg of quercetin per gram (mg QE/g) and out of equivalent mg catechin (mg CE /g) of dry matter (DM) are indicated by the Table 2.

3.2.1. Total Phenolic Compounds Contents

The total phenolic compounds contents among the extracts was determined using the standard curve equations (y= 1.0033x + 0.0586; R2 = 0.993). The amount of total phenolics measured by Folin-Ciocalteu method dependent ranged from 20.210 ± 0.005 to 25.514 ± 0.005 mg GAE/100 mg DM. The highest content of total phenolics was detected in variety V₁₆ with 25.514 ± 0.005 mg GAE/100 mg DM followed respectively by the varieties V₃ (25.247 ± 0.010 mg GAE/100 mg) and V₃₂ (25.016 ± 0.042 mg GAE/100 mg DM). The lowest total phenolics content were obtained with the variety V₆ (20.210 ± 0.005 mg GAE/100 mg DM).

3.2.2. Total Flavonoids Contents

The estimation of total flavonoids in the hydroethanolic extracts of fresh immature fruits of these varieties of okra was showed in Table 2. The total flavonoids content among the various extracts was determined using standard curve equations (y = 2.5177x + 0.0437; R2 = 0.999). The total flavonoids content in hydroethanolic extracts of fresh immature fruits showed different results ranging from 50.525 ± 0,013 to 63.786 ± 0.013 mg QE/g DM. The variety V₁₆ had the highest total flavonoids content (63.786 ± 0.013 mg QE/g DM), however the variety V₆ had the lowest one (50.525 ± 0.013 mg QE/g DM).

Table 1. Main Metabolites of fresh immature fruits powder of twelve varieties of Abelmoschus esculentus

Table 2. Total phenolic compounds, flavonoids and condensed tannins contents in fresh immature fruits of Abelmoschus esculentus varieties

3.2.3. Total Condensed Tannins Contents

The total condensed tannins content among the extracts was determined using the standard curve equations (y = 1.0033x + 0.0586; R2 = 0.993). The amount of total phenolic measured by vanillin method dependent ranged from 5.955 ± 0.073 to 12.867 ± 0.073 mg CE/g DM. The highest content of total phenolic was detected in variety V₃ with 12.867 ± 0.073 mg CE/g DM followed respectively by the varieties V₃₃ (5.955 ± 0.073 mg CE/g DM), V₆ (6.801 ± 0.036 mg CE/g DM) and V₄₂ (6.911 ± 0.147 mg CE/g DM). The lowest total condensed tannins content were obtained with the variety V₃₃ (5.955 ± 0.073 mg CE/g DM).

3.5. In Vitro Antioxidant Activity DPPH Radical Scavenging Activity

The reduction of the DPPH radical by the antioxidants is evaluated by the decrease of the absorbance of the DPPH solution at 517 nm. This decrease is due to the reaction between antioxidant molecules and free radicals which results in the scavenging of the radical by hydrogen donation [19]. DPPH is usually used as a substance to evaluate the antioxidant potential of medicinal plants [20]. In this study, the DPPH radical scavenging activities of extracts increased gradually in a dose concentration dependent (7.81-1000 μg/mL).The results show that at 1mg/mL the variation in antioxidant activities ranging from 60.40 to 92.71% (Figure 1). The results show that from 250 μg/mL to 1000 μg/mL, all varieties except the varieties V₃₃, V₃₇, V₄₁, V₄₂ and V₅₂ showed significant activity (45 ≤ IP % ≤ 92.71) in comparison with the vitamin C (89.7 ≤ IP % ≤ 99.88) at 250 μg/mL. The varieties V₅, V₆, V₁₆ and V₂₃ showed a inhibition percentage greater than 55%. At 500 μg/mL, the varieties V₆ (IP% = 83.96) and V₁₆ (IP % = 87.17) showed considerable activity compared with the control (Vitamin C. IP% = 97.2). From 7.81 to 125 μg/mL, all varieties showed an inhibition percentage (IP %) less than 50 %.

Immature fresh fruits are the most consumed vegetables in most parts of the world. Previous studies [21,22] have reported the wealth of fresh immature fruits of okra in phenolic compounds and their antioxidant effects. However, there were no studies regarding antioxidant potential of fresh immature fruit of different varieties of A. esculentus produced in Benin’s Republic. Several methods were used to determine the antioxidant activity of plants. Thus, our study involved one method to assess the antioxidant activity of fresh immature fruits from okra, namely, DPPH scavenging activity analysis. Among the most widely used procedures for measurement of antioxidant activity capacity, the DPPH radical scavenging analysis is one of the best known, accurate, and frequently employed to measure the electron transfer ability of the plant extracts [23,24]. DPPH is a stable radical commonly used to determine the antioxidant activity of various compound. It is a stable free radical because of its spare electron delocalization over the whole molecule. In the current study, the results revealed that at the same concentration, the inhibitory percentage of DPPH radical was not the same. At each concentration, the variety V₁₆ gave the highest percentage inhibition. These results showed that all extracts showed different percentages of inhibition of the DPPH scavenging activity on the concentration-dependent approach. Similar observations have been reported in previous studies [21,22].

Figure 1. Radical scavenging activity of okra’s varieties

4. Conclusion

In summary, the results of this study clearly showed significantly different phenolic contents and antioxidant activities in fresh immature fruits of extracted different varieties from okra. The richest out of all varieties in phenolic compounds was the variety V₁₆. In addition, this variety had showed the hightest DPPH scavenging activity. Hence, the variety V₁₆ represents a source of phenolic compounds and potential antioxidants that could be recommanded in pharmaceutical and food preparations.

References

[1]   | Geil PB., Anderson JW. Nutrition and health implications of dry beans: a review. Journal of the American College Nutrition, 13, 549-558, 1994.
[2]   | Xu B.J., Chang S.K.C.A., Comparative study on phenolic profiles and antioxidant activities of legumes as affected by extraction solvents. Journal of Food Science, 72, 160-161, 2007.
[3]   | Manach C., Scalbert A., Morand C., Remesy C., Jimene L. Polyphenols: Food sources and bioavailability. American Journal of Clinical Nutrition, 79, 727-747, 2004.
[4]   | Crozier A., Jaganath. I.B., Clifford M.N. Dietary phenolics: Chemistry, bioavailability and effects on health. Natural Production Reports, 26, 1001-1043, 2009.
[5]   | Hertog M.G., Kromhout D., Aravanis C., Blackburn H., Buzina. R., Fidanza F., Giampaoli S., Jansen A., Menotti A., Nedeljkovic S.. Flavonoid intake and long-term risk of coronary heart disease and cancer in the seven countries study. Archives of Internal Medicine, 155, 381-386, 1995.
[6]   | Hertog M.G., Feskens E.J., Kromhout. D. Antioxidant flavonols and coronary heart disease risk. Lancet; 349, 699, 1997.
[7]   | Landete. J.M. Dietary intake of natural antioxidants: Vitamins and polyphenols. Crit. Rev. Food Science Nutrition, 53, 706-721, 2013.
[8]   | Del Rio. D.; Rodriguez-Mateos. A.; Spencer. J.P.; Tognolini. M.; Borges. G.; Crozier. A. Dietary phenolics in human health: Structures. bioavailability. and evidence of protective effects against chronic diseases. Antioxidant Redox Signal,18, 1818–1892, 2013.
[9]   | Cyril. C.N.. Chibundu. N.E.. Anokwuru. K.O. Prosper. C.. Ivie. K.E. Cytomorphological and antifungal analysis of Acalypha wilkesiana. Moringa oleifera extracts. and sodium hypochlorite on Abelmoschus esculentus L. Moench treated seeds. Nature and science, 11, 32-39, 2013.
[10]   | Adelakun. O.E., Oyelade. O.J., Ade-Omowaye. B.I.O., Adeyemi. I.A., Venter. M. Chemical composition and the antioxidative properties of Nigerian Okra Seed (Abelmoschus esculentus Moench) Flour. Food Chemistry and Toxicology, 47, 1123-1126, 2008.
[11]   | Khomsug. P., and Thongjaroenbuangam. W. Antioxidative activities and Phenolic content of extracts from Okra (Abelmoschus esculentus L.). Research Journal of Biological Sciences, 5, 310-313, 2010.
[12]   | MAEP. Centre Régional pour la Promotion Agricole de l’Atacora-Donga : plan régional de développement de la filière cultures maraichères. 13-14, 2011.
[13]   | Habtamu. F., N. Ratta., G. D. Haki., A. Z. Woldegiorgis. and F. Beyene. Nutritional quality and health benefits of okra (Abelmoschus esculentus): A review. Journal of Food Science and. Quality Management, 33, 87-96, 2014.
[14]   | Ravi Kumar. M. B., Patil. Sachin R., Patil. Mahesh S. Paschapur. Evaluation of Abelmoschus esculentus Mucilage as Suspending Agent in Paracetamol Suspension. International Journal of Pharmacy Technology Research, 3, 658-665, 2009.
[15]   | Houghton P.J., Raman A. from book: Laboratory handbook for the fractionnation of natural extracts, 139-153, 1998.
[16]   | Singleton. V.I., Lamuela-Raventos. R.M., Analysis of Total Phenols and Other Oxidation Substrates and Antioxidants by Means of Folin-Ciocalteu Reagent. Method in Enzymology, 15, 152-178 2012.
[17]   | Agbangnan P. D. C, Tachon C., Bonin H., Chrostowka A., Fouquet E., Sohounhloue D. C. K. Phytochemical study of a tinctorial plant of benin traditional pharmacopoeia: the red sorghum (sorghum caudatum) of benin. Scientific Study and Research, 13, 121-135, 2012.
[18]   | Velazquez E., Tournier HA,. Mordujovich de Buschiazzo P., Saavedra G., Schinella GR. Antioxydant activity of Paraguayan plant extracts. Fitoterapia, 74, 91-97, 2003.
[19]   | Nalini R. Anuradha R. Phytochemical Screening and “In- Vitro” Antioxidant Activity of Ethanolic Flower Extracts of Punica granatum. International Journal of Pharmaceutical Sciences and Research.30, 353-360, 2015.
[20]   | Shah R., Kathad H., Sheth R., Sheth N. In vitro antioxidant activity of roots of Tephosia purpurea Linn. International Journal of Pharmaceutical Sciences, 3, 30-33, 2010.
[21]   | Lianmei Hu., Wenlan Yu., Ying Li., Nagendra Prasad., and Zhaoxin Tang. Antioxidant Activity of Extract and Its Major Constituents from Okra Seed on Rat Hepatocytes Injured by Carbon Tetrachloride. BioMed Research International, 1-9, 2014.
[22]   | Fangbo Xia., Yu Zhong., Mengqiu Li., Qi Chang., Yonghong Liao., Xinmin Liu and Ruile Pan. Antioxidant and Anti-Fatigue Constituents of Okra. Nutrients, 7, 8846-8858, 2015.
[23]   | Figueroa LA., Navarro LB., Vera MP., Petricevich VI. Antioxidant activity. Total phenolic and flavonoid contents. and Cytotoxicity evaluation of Bougainvillea xbuttiana. International Journal of Pharmaceutical Sciences, 6, 497-502, 2014.
[24]   | Ahmad B., Khan MR., Shah NA., Khan RA., In vitro antioxidant potential of Dicliptera roxburghiana. BMC Complementary and Alternative Medicine. 13- 140; 2013.