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УЧЕНЫЕ ЗАПИСКИ КАЗАНСКОГО УНИВЕРСИТЕТА. СЕРИЯ ЕСТЕСТВЕННЫЕ НАУКИ
2024, Т. 166, кн. 3 С. 445-458
ISSN 2542-064X (Print) ISSN 2500-218X (Online)
ORIGINAL ARTICLE
UDC 615.322:543.8
doi: 10.26907/2542-064X.2024.3.445-458
Antioxidant and Antidiabetic Properties of the Water Extract from Sigoise Olive Cultivar (Olea europaea L.), El Oued Region (Algeria)
M.L. Tliliab, R. Hammoudib, S. Touatia, A. Belimia, S. Lamoudia
aEl Oued University, El Oued, 39000Algeria bOuargla University, Ouargla, 30000Algeria
Olive tree leaves (Olea europaea L.) have been widely used in Mediterranean traditional medicine to prevent and treat various ailments. This study investigated the effects of consuming a water extract of Sigoise olive leaves on antioxidant levels and type II diabetes. The extract was prepared by steeping 10 g of dried olive leaves in 500 mL of boiling water and then given to 20 Algerian volunteers (10 diabetic subjects and 10 healthy controls), who consumed it twice a day for a month. The volunteers were screened by biochemical blood tests before and by the end of the experiment. The antioxidant activity was assessed using DPPH (2,2-diphenyl-1-picryl-hydrazyl-based assay, 35.3 ± 0.5 mg/mL) and FRAP assays (ferric reducing antioxidant power assay, 8.3 ± 0.1 mg/mL). The quantitative analysis revealed high contents of total polyphenols (41.8 ± 0.8 mg gallic acid equivalent per 1 g of extract) and total flavonoids (14.3 ± 0.8 mg rutin equivalent per 1 g of extract). The hypoglycemic effect of the extract was shown, thus confirming that it helps improve renal function and prevents cardiovascular disorders in type II diabetic patients. No toxic effects on kidney or liver function were observed. Despite clear health-boosting benefits, further research is needed to fully validate them clinically.
Keywords: Olea europaea, Sigoise, polyphenols, flavonoids, antioxidant and antidiabetic properties
Olea europaea L. (Oleaceae), commonly known as olive, is widely grown in the Mediterranean region. Algeria cultivates more than 166 olive varieties, including Chemlali, Azeradj, Sigoise, etc. [1]. The Sigoise variety was introduced in 1990 to boost the production of table olives in Western Algeria. Sigoise olives are characterized by high flesh/stone ratio (about 6.44), high sugar content (greater than 4 %), salt-water tolerance, resistance to cold and drought, as well as precocious flowering, easy harvesting performed almost entirely by hand picking, and being a good pollinator for the Chemlali variety [2, 3].
Olive leaves have a long history of medical use. They are rich in phenolic compounds, especially oleuropein (24.54 %), which is followed by hydroxytyrosol (1.46 %), luteolin-7-O-glucoside (1.38 %), verbascoside (1.11 %), apigenin-7-O-glu-coside (1.37 %), and tyrosol (0.71 %). Luteolin, vanillic acid, and caffeic acid are present in trace amounts [4]. Recent studies have shown that the polyphenols in olive leaves exert many beneficial effects, such as antioxidant [5], anti-inflammatory, antimicrobial, hypoglycemic, antihypertensive, anticancer, anticholesterolemic [6], and antiviral. They also prevent and reduce the incidence of cardiovascular disorders.
Abstract
Introduction
Interestingly, the antioxidant properties of extracts from olive leaves vary greatly depending on the olive variety, genetic factors, and geographical conditions (Table 1).
Table 1.
Olive leaf antioxidant characteristics
Extraction type and extragent Geographical origin Variety Antioxidant parameter Results Ref.
Ethanolic extraction Lorestan (Iran) Sevillano DPPH EC50 = 231.62 mg/mL [7]
Maceration with hexane, ethyl acetate, and methanol Sfax (Tunisia) Chetoui DPPH, FRAP, ORAC, P-carotene bleaching assay The methanolic extracts obtained from stems, leaves, and seeds exhibited the highest antioxidant activities [8]
Ethanolic extraction Chlef (Algeria) Sigoise DPPH, FRAP and P-carotene bleaching assay IC50 = 16.761 ± 1.58 -147.802 ± 3.11 ^g/mL [9]
Maceration with ethanol, ethyl acetate, and hexane Ain Defla (Algeria) Nabeul (Tunisia) Chemlali, Octoubri, Gerboui, Rougette, Sayali, Sigoise, Sofiana, Verdal DPPH ABTS The ethanolic extract of the Sofiana variety represented the most active extract in the ABTS test with IC50 = 23.85 ± 0.58 mg/L. The ethanolic extract of the Verdal variety was the most potent inhibitor of DPPH with IC50 = 30.22 ± 1.34 mg/L. [10]
Aqueous extraction Alexandria (Egypt) Picual, Tofahi, Shemlali DPPH, FRAP and nitric oxide scavenging activity IC50 = 55.82 ± 0.13 -19.03 ± 0.13 ^g/mL [11]
DPPH - 2,2-diphenyl-1-picrylhydrazyl-based assay, FRAP - ferric reducing antioxidant power assay, ORAC - oxygen radical absorbance capacity assay, ABTS - 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation-based assay
Oxidative stress, an underlying trigger of diabetes mellitus and its complications, stems from overproduction of reactive oxygen species and intracellular oxidative damage. It can lead to alterations in mitochondrial morphology and function, inducing structural changes and functional abnormalities in macromolecules such as proteins, lipids and nucleic acids, ultimately resulting in apoptosis and accelerating the progression of diabetic complications [12]. Diabetes status is associated with hyperglycemia caused by insufficient insulin secretion, impaired insulin action, or both. According to the latest estimates, there are more than 150 million diabetics worldwide, and this number may double by 2025 [13, 14].
With over 35 million olive trees, Algeria [15] is well-positioned to address the widespread occurrence of diabetes mellitus by delving into the merits of olive tree leaves in treating this chronic metabolic disease.
This work aims to investigate, for the first time, the antioxidant activity and hypoglycemic effect of a fresh water extract from Sigoise olive leaves (El Oued region, Algeria) on human diabetic subjects.
1. Material and Methods
1.1. Chemicals and reagents. All chemicals (2,2-diphenyl-1-picrylhydra-zyl (DPPH), AlCl3, NH4OH, ascorbic acid, Dragendorff reagent, EtOH, Folin-Ciocalteu reagent, gallic acid, HCl, FeCl3, MgCl2, MeOH, K3[Fe(CN)6], quercetin, Na2CO3, NaCl, rutin, sodium dodecyl sulfate, NaOH, H2SO4, and trichloroacetic acid) were purchased from Sigma-Aldrich and used as received.
1.2. Plant material. The leaves of the Sigoise olive cultivar (Olea europaea L.), planted in the El Oued region (Algeria) in December 2022, were the subject of the study. To prepare the extract, 10 g of dry leaves were placed into 500 mL of boiling water and left to simmer for 10 min. The resulting extract was allowed to soak for an hour until it cooled down. Then, it was filtered and kept in the filtrate for later use.
1.3. Phytochemical tests. Following established protocols, a confirmatory qualitative phytochemical screening of the extract was conducted to determine the main classes of compounds (saponins, tannins, flavonoids, alkaloids, sterols, reducing sugars, free quinones, terpenoids, and anthraquinone) [16].
1.4. Quantification of total polyphenol contents (TPC). The TPC in the extract were assessed using the method described by Boizot & Charpentier [17], which employs the Folin-Ciocalteu reagent. With this aim, 200 ^L of the extract, 1 mL of 10 of the 10-fold diluted Folin-Ciocalteu reagent, and 2 mL of water were mixed at room temperature for 4 min and incubated. Then, 0.8 mL of sodium bicarbonate (7.5 %) was added. The TPC was determined after 2 h of incubation at room temperature. The absorbance was measured at 765 nm with a SpectraMax PC 340 UV-VIS spectrophotometer (Molecular Bioproducts Corp., USA). The concentrations were expressed as milligrams of gallic acid equivalent per 1 g of extract (mg GAE/g).
1.5. Quantification of total flavonoid contents (TFC). The concentrations of total flavonoids in the extract (TFC) were measured using AlCl3 and sodium hydroxide. 1 mL of the extract was added to 1 mL of AlCl3 diluted in methanol (2 %). The mixture was shaken and incubated for 10 min at the laboratory temperature. The absorbance was measured at 430 nm with a spectrophotometer. The results were expressed as mg of rutin equivalent per 1 g of extract (mg RE/g) [18].
1.6. DPPH radical scavenging test. The antiradical activity of the extract against DPPH was assessed with some modifications to adapt the procedure. Briefly, the DPPH solution was prepared by dissolving 2.4 mg of DPPH in 100 mL of methanol. Then, 50 ^L of the extract at various concentrations or standard ascorbic acid (vitamin C) were added to 1.95 mL of DPPH. The tubes were kept in the dark at room temperature for 30 min. The absorbance was read at 517 nm [19].
Scavenging activity was expressed as IC50 and the extract dose needed to induce 50 % inhibition. A lower IC50 value indicated a higher antioxidant activity of the extract.
1.7. Ferric reducing antioxidant power (FRAP) assay. A total of 0.5 mL of the
extract was mixed with 1.25 mL of 1 % potassium ferrocyanide and 1.25 mL of phosphate buffer (0.2 M, pH 6.6). The mixture was incubated for 20 min at 50 °C in a water bath. After that, 1.25 mL of 10 % trichloroacetic acid was added, and the mixture was centrifuged for 10 min at 3000 rpm [20].
The absorbance was measured at 700 nm using a 1.25 mL aliquot of the supernatant, 0.25 mL of FeCl3 (0.1 %), and 1.25 mL of distilled water. Ascorbic acid served as positive control.
1.8. Antidiabetic activity. The study was carried out at the Biochemistry Laboratory of El Oued University and the Public Health Institution in Guemar (Algeria). The participants were 20 adult volunteers (10 subjects with chronic diabetes and their 10 healthy relatives), all selected randomly. The two groups were matched for gender and age.
The criteria for inclusion were being aged 30-45 years and having type II diabetes. The participants were also required to undergo a series of medical tests before and after the experiment.
The criteria for exclusion were pregnancy or breastfeeding, insulin therapy, changes in medical treatment during the trials, diabetic complications, or poor metabolic control.
All subjects received a daily bottle containing the extract of boiled olive leaves, a glucometer for measuring their blood sugar, and an instruction card designed as a diabetes booklet. They were also instructed to drink two cups (2 * 250 mL; one in the morning on an empty stomach and the other in the evening, an hour before dinner) of the extract per day for a month and tasked with regularly measuring their blood glucose levels at home. Additionally, they were asked to undergo, before and after the trials, routine biochemical blood tests for blood glucose, urea, creatinine, total cholesterol, HDL cholesterol, LDL cholesterol, triglyceride, and calcemia [21].
Ethical permission for the study was granted by a certified medical specialist in diabetes treatment. Informed pre-study consent was obtained from all participants. The procedures were explained to them using simple language, and all collected data were kept confidential. The participants were free to withdraw from the study at any time.
1.9. Statistical Analysis. The experiments were carried out in three replications. The results were expressed as the mean ± standard deviation. One-way analysis of variance (ANOVA) followed by P-value adjustment for multiple comparisons were conducted using Tukey's post-hoc test. P < 0.05 was considered statistically significant. All data were processed using XLSTAT software (Lumivero, USA).
2. Results and Discussion
2.1. Phytochemical tests. Preliminary phytochemical screening revealed the presence of saponins, tannins, flavonoids, sterols, and quinones. However, the extract tested negative for alkaloids, glycosides, and terpenoids (Table 2).
2.2 Quantification of polyphenols, flavonoids, and antioxidant activity. The TPC and TFC values of the extract were determined (Table 3). The TPC assay indicated the TPC of 41.8±0.8 mg EAG/g extract, which is consistent with the results obtained by Ghasemi et al. [22], who reported the TPC ranging from 42.35 ± 0.002 mg GAE/g
to 190.65 ± 0.03 mg GAE/g for 17 cultivars of Iranian olive. Compare the above values with 1.6 mg GAE/g dry weight from [23].
Table 2.
Results of phytochemical tests of the Sigoise olive leaf extract ((+) presence; (-): absence)
Secondary metabolites Results
Saponins +
Tannins +
Flavonoids +
Alkaloids -
Sterols +
Glycosides -
Quinones +
Terpenoids -
Anthraquinone +
Table 3.
Total polyphenolic and flavonoid contents, DPPH radical and FRAP scavenging test of the Sigoise olive leaf extract
Sample Total polyphenols (mg GAE/g) Flavonoids (mg RE/g) DPPH radical scavenging test, IC5o (mg/mL) FRAP scavenging test, A0 5(mg/mL)
Olive leaf extract 41.8±0.8 14.3±0.8 35.3±0.5 8.3±0.1
Ascorbic acid - - 0.49±0.03 0.030±0.002
The flavonoid content (TFC) of the analyzed extract was estimated at 14.3±0.8 mg RE/g. This is comparable to the TFC (15.55 mg RE/g) found in another study of the aqueous methanol extract from olive leaves [24]. The differences in the concentrations of phenolic compounds can be attributed to the impact of biotic and abiotic factors, including the plant's maturity stage at harvest. The capacity of plants to produce secondary metabolites is also defined by their ontogenetic trajectories, with different metabolites being synthesized as a consequence of specific metabolic processes that are unique to each plant species. Numerous studies have demonstrated that the stage of vegetation growth affects the accumulation of specific classes of phenolic compounds [25]. Notably, a diet rich in phenolic compounds has generally been linked to many health benefits, including oxidative stress reduction, free radical scavenging, chelation of metal ions, and modulation of intracellular signaling pathways [26].
Ascorbic acid, used as a standard antioxidant for comparison, exhibited an extremely potent free radical scavenging activity (IC50 = 0.49 ± 0.03 mg/mL). In contrast, the antioxidant activity of the studied extract was 35.3 ± 0.5 mg/mL, i.e., it was less critical than that of ascorbic acid. Yet, this value was still higher than that in the aqueous extract of O. europaea leaves from [27], where the DPPH radical
scavenging activity was IC50 = 92.04 mg/mL. Compared to the methanolic extract of the Tunisian olive cultivar Chetoui (IC50 = 0.02 mg/mL) [9], the studied extract displayed lower antioxidant activity. Flavonoids and total phenols are two groups of bioactive substances that are likely responsible for the antioxidant activity observed. Tyrosol and hydroxytyrosol, the derivatives of oleuropein, have been shown to possess antiradical properties in both in vitro and in vivo studies [28]. Interestingly, there are some other phenolic compounds potentially contributing to the antioxidant activity of olive leaves. In [29], rutin, a compound identified in O. europaea leaves, decreased the oxidative stress-induced hepatotoxicity in rats fed a high-cholesterol diet. The data in [30] also suggest that luteolin may have protective effects against oxidative stress, thus slowing the development of cardiac dysfunction brought on by diabetes. The benefits of hydroxytyrosol and oleuropein due to antioxidant properties have been discovered in vivo [27, 31]. The strong antioxidant effect of olive leaves results from the synergy of phenolic components, including oleurosides (oleuropein and verbascoside), flavones (luteolin-7-glucose and diosmetin-7-glucose), flavonols (rutin), flavan-3-ols (catechin), and phenol substitutes (tyrosol, hydroxytyrosol, vanillin, vanillic acid, and caffeic acid) [32]. Therefore, the antioxidant activity depends on the extraction and drying methods, the cultivars used, and the chemical composition of the tested plants [33, 34].
Table 3 shows that the reduction potential of the studied extract was lower (8.3 ± 0.1 mg/mL) than that of standard ascorbic acid (0.03 ± 0.002 mg/mL), as indicated by the A05 values. Although the extract had higher A05, its reducing capacity was moderate. This discrepancy can be explained by variations in the concentrations of phenolic compounds. Antioxidants are commonly considered to function as reducers and inactivators of oxidants due to the presence of polyphenols and hydroxyl groups in phenolic compounds. Hence, the studied extract has a reduction potential and can act as an electron donor [35]. According to previous research, the reduction potential of a compound is a reliable indicator of its potential antioxidant activity [36].
2.3. Antidiabetic activity. To date, there is no known cure for diabetes. The primary focus has been on keeping blood sugar levels as close to normal as possible through a healthy diet, regular physical activity, maintaining a normal BMI, and taking diabetes medications. Olive leaves are widely used in complementary and alternative treatment of diabetes, but only a few human studies are available on the hypoglycemic effect of drinking boiled olive leaves.
Blood glucose levels, kidney function markers, "bad" and "good" cholesterol, and calcium levels were monitored in all subjects before the experiment (no extract consumed), over the trial days, and after the extract intake. After four weeks of consuming the extract, the participants experienced a reduction in their average blood sugar levels. Furthermore, there was a decrease in total cholesterol, "bad" cholesterol, creatinine, and urea, while "good" cholesterol and calcium levels increased. The results are summarized in Table 4.
All participants consumed the olive leaf extract twice a day for four weeks. By the end of the trial period, the blood glucose levels of the subjects with diabetes decreased significantly (from 1.96 to 1.12 g/L). The blood glucose levels of the healthy controls remained stable (1.096-0.862 g/L) throughout the experiment.
The hypoglycemic effect of O. europaea has been reported by several studies [37], in which the patients treated with the olive leaf extract had a significant decrease in
blood sugar levels compared to the untreated controls. Subsequent research on normal and diabetic rats has confirmed these findings [38-40]. Overall, from the results obtained, it is evident that olive leaves have a noticeable hypoglycemic effect on individuals with type II diabetes.
Table 4.
Effect of the Sigoise olive leaf extract on the biochemical parameters of healthy and diabetic participants before and after the extract intake
Parameter Groups of participants
Diabetic patients before taking the extract Diabetic patients after taking the extract Healthy participants before taking the extract Healthy participants after taking the extract
Glucose (g /L) 2.0±0.3a 1.1±0.3b 1.1±0.1b 0.86±0.07b
Urea (g/L) 0.3±0.1 0.21±0.04 0.25±0.09 0.21±0.08
Creatinine (g/L) 9±2 7±1 10±2 8±3
Total cholesterol (g/L) 2.1±0.3a 1.4±0.2b 2.5±0.4a 1.9±0.1a
HDL cholesterol (g/L) 0.5±0.2 0.64±0.04 0.5±0.3 0.6±0.1
LDL cholesterol (g/L) 1.3±0.2a 0.8±0.3b 1.6±0.2a 1.2±0.3a
Triglycerides (g/L) 1±1a 0.8±0.7a 1.4±0.5a 1.0±0.4a
Calcium contents (mg/L) 82±8 84±11 74±3 76±7
Means in the same raw followed by different letters are significantly different (P < 0.05)
Al-Azzawie and Alhamdani suggested treating diabetic patients with oleuropein, a potent antioxidant contained in olive leaves, to reduce oxidative stress and thus blood glucose. They found that the levels of blood glucose and most antioxidants in the treated participants were close to the control ones [41]. These results confirm the anti-hyperglycemic and antioxidant effects of oleuropein, indicating that crude oleuropein, responsible for the hypoglycemic activity of olive leaves, possesses both hypogly-cemic and antidiabetic activities. The observed effects may be due to two possible mechanisms: increased insulin release and enhanced peripheral glucose uptake [42].
Another mechanism by which olive leaf extract exerts the hypoglycemic effect is through inhibiting the activity of pancreatic amylase. It has been revealed that oleuropein reduces blood glucose levels by inhibiting a-amylase activity in vivo [37].
Olive leaf extract is known to inhibit starch digestion and glucose uptake, as well as stimulate hepatic glycogen synthesis, resulting in reduced hyperglycemia. Starch digestion by intestinal enzymes and intestinal disaccharidase inhibition explain the hypoglycemic effect of olive leaf extract [43].
The studied extract also reduced the levels of serum urea and creatinine, the bio-markers of diabetes-related nephropathy, in the diabetic subjects. Elevated serum urea and creatinine, as important markers, are often associated with diabetic hyperglycemia. Many studies have claimed that consuming olive leaves decreases creatinine and urea levels in patients with diabetes. For example, in [18], the consumption of the olive leaf extract effectively lowered creatinine, urea, and uric acid levels in streptozoto-cin-induced diabetic male rats. In our study, the olive leaf extract had a positive effect on the lipid profile of both diabetic and healthy participants.
Type II diabetes raises the risk of cardiovascular disorders. Diabetic patients are two to four times more likely to develop cardiovascular complications compared with
healthy individuals. This is due to lipid and lipoprotein abnormalities that are common in type II diabetes, such as exceptionally high levels of total triglycerides, total cholesterol, low-density lipoprotein, and reduced levels of high-density lipoprotein [44].
The therapeutic utility of O. europaea as a powerful cholesterol-lowering agent has been widely recognized in traditional medicine [45]. The effectiveness of polyphenols in olive leaves, such as oleuropein, hydroxytyrosol, and rutin, in managing hypocholes-terolemia caused by hyperglycemia has been highlighted, and oleuropein and hydroxy-tyrosol, both abundant in O. europaea leaves, are known for their cholesterol-lowering effects. Wang et al. confirmed that these compounds reduced serum levels of total cholesterol, triglycerides, and low-density lipoproteins in Wistar rats fed cholesterol-rich diets [30]. These results suggest that the phenolic components of olive leaves could represent a new valuable cholesterol-lowering source for developing new cholesterol-lowering medications and treatments for various heart diseases related to type II diabetes.
Levy et al. claimed that total serum calcium levels are higher in patients with diabetes than in healthy people [46]. Thus, calcium may be involved in developing and maintaining type II diabetes. Kim et al. observed an increased risk of diabetes in middle-aged and elderly Koreans with elevated serum calcium levels [47]. Over recent decades, the resistance and secretion of insulin has been proved to depend on calcium homeostasis, which means that insulin secretion in response to an increase in plasma glucose concentration is a Ca2+ dependent process. Alterations in insulin secretion have also been implicated in disorders of blood glucose homeostasis [48], and elevated cytosolic calcium has been associated with increased expression of GLUT4 transporters in the myocyte. It enhances the insulin-stimulated glucose transport activity in these cells [49]. Since defects in insulin secretion and action are linked to type II diabetes, abnormal calcium homeostasis is expected to play an essential role in developing type II diabetes [50].
The hypoglycemic effect of olive leaves found in this study needs to be further examined in order to identify the ideal dose, duration, preparation methods, and timing of consumption for maximizing their impact on blood glucose.
Conclusions
The water extract from Sigoise olive leaves, rich in phenolic compounds and characterized by high antioxidant activity, offers clear benefits for preventing and treating diabetes. By the end of the experiment, all subjects with diabetes demonstrated a significant decrease in their blood sugar, total cholesterol, "bad" cholesterol, creatinine, and urea levels, while the levels of calcium and "good" cholesterol increased. The hypogly-cemic capacity of the extract appears to be linked to the antioxidative action of olive leaves. However, further research is needed in order to uncover and fully understand the molecular mechanisms behind the active constituents of olive leaves.
Institutional Review Board Statement. The study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of the Faculty of Natural and Life Sciences, University of El Oued (protocol code 001 dated December 2023).
Informed Consent Statement. Informed consent was obtained from all subjects involved in the study.
Conflicts of Interest. The authors declare no conflicts of interest.
References
1. Issaad F.Z., Abdessemed A., Bouhedjar K., Bouyahmed H., Derdour M., Ouffroukh K., Fellak A., Dems M.A.S., Chihoub S., Bechlem R., Mahrouk A., Houasnia M., Belaidi A., Moumed K., Sebai Z., Saidani F., Akmouche H. Classification of Algerian olive oils: Physicochemical properties, polyphenols and fatty acid composition combined with machine learning models. J. Food Compos. Anal., 2024, vol. 125, art. 105812. https://doi.org/10.1016/j.jfca.2023.105812.
2. Mendil M., Sebai A. Catalogue des variétés algériennes de l'olivier. Ministère de l'Agriculture et du Développement Rural. ITAF, 2006. 99 p. (In French)
3. Idoui T., Bouchefra A. The black olive fruits of Jijelian Sigoise variety (Eastern Algeria): Quality evaluation for possible use as table olives and pesticides research. Online J. Sci. Technol., 2014, vol. 4, no. 1, pp. 45-52.
4. Zugcic T., Abdelkebir R., Alcantara C., Collado M.C., García-Pérez J.V., Meléndez-Martínez A.J., Rezek Jambrak A., Lorenzo J.M., Barba F.J. From extraction of valuable compounds to health promoting benefits of olive leaves through bioaccessibility, bioavailability and impact on gut microbiota. Trends Food Sci. Technol., 2019, vol. 83, pp. 63-77. https://doi.org/10.1016/j.tifs.2018.11.005.
5. Rostamzadeh A., Amini-Khoei H., Mardani Korani M.J., Rahimi-Madiseh M. Comparison effects of olive leaf extract and oleuropein compounds on male reproductive function in cyclophosphamide exposed mice. Heliyon, 2020, vol. 6, no. 4, art. e03785. https://doi.org/10.1016/j.heliyon.2020.e03785.
6. Nunes M.A., Pimentel F.B., Costa A.S.G., Alves R.C., Oliveira M.B.P.P. Olive by-products for functional and food applications: Challenging opportunities to face environmental constraints. Innovative Food Sci. Emerging Technol., 2016, vol. 35, pp. 139-148. https://doi.org/10.1016/j.ifset.2016.04.016.
7. Kaeidi A., Esmaeili-Mahani S., Sheibani V., Abbasnejad M., Rasoulian B., Hajializadeh Z., Afrazi S. Olive (Olea europaea L.) leaf extract attenuates early diabetic neuropathic pain through prevention of high glucose-induced apoptosis: In vitro and in vivo studies. J. Ethnopharmacol., 2011, vol. 136, pp. 188-196. https://doi.org/10.1016/jjep.2011.04.038.
8. Khlif I., Jellali K., Michel T., Halabalaki M., Skaltsounis A.L., Allouche N. Characteristics, phytochemical analysis and biological activities of extracts from Tunisian chetoui Olea europaea variety. J. Chem., 2015, vol. 2015, no. 1, art. 18731. https://doi.org/10.1155/2015/418731.
9. Saiah H., Saiah W., Mokhtar M., Aburjai T. Antioxidant and hepatoprotective potentials of olive (Olea europaea L. var. Sigoise) leaves against carbon tetrachloride-induced hepatic damage in rats, and investigation of its constituents by high-performance liquid chromatography-mass spectrometry. Int. Food Res. J., 2022, vol. 29, no. 3. pp. 607-618. https://doi.org/10.47836/ifrj.29.3.13.
10. Khelouf I., Karoui I.J., Lakoud A., Hammami M., Abderrabba M. Comparative chemical composition and antioxidant activity of olive leaves Olea europaea L. of Tunisian and Algerian varieties. Heliyon, 2023, vol. 9, no. 12, art. e22217. https://doi.org/10.1016/j.heliyon.2023.e22217.
11. Mansour H.M.M.,ZeitounA.A., Abd-Rabou H.S., El Enshasy H.A., Dailin D.J., ZeitounM.A.A., El-Sohaimy S.A. Antioxidant and anti-diabetic properties of olive (Olea europaea) leaf extracts: In vitro and in vivo evaluation. Antioxidants, 2023, vol. 12, no. 6, art. 1275. https://doi.org/10.3390/antiox12061275.
12. Zhang Z., Huang Q., Zhao D., Lian F., Li X., Qi W. The impact of oxidative stress-induced mitochondrial dysfunction on diabetic microvascular complications. Front. Endocrinol., 2023, vol. 14, art. 1112363. https://doi.org/10.3389/fendo.2023.1112363.
13. Patel D.K., Prasad S.K., Kumar R., Hemalatha S. An overview on antidiabetic medicinal plants having insulin mimetic property. Asian Pac. J. Trop. Biomed., 2012, vol. 2, no. 4, pp. 320-330. https://doi.org/10.1016/S2221-1691(12)60032-X.
14. Tlili M.L., Hammoudi R., Hadj-Mahammed M. In vivo and in vitro antidiabetic properties of alkaloids extract from Salvia chudaei. Acta Period. Technol., 2021, vol. 52, pp. 45-53. https://doi.org/10.2298/APT2152045T.
15. Halimi C.W., Laamari M., Goldarazena A. A preliminary survey of olive grove in Biskra (Southeast Algeria) reveals a high diversity of thrips and new records. Insects, 2022, vol. 13, no. 5, art. 397. https://doi.org/10.3390/insects13050397.
16. Bruneton J. Pharmacognosie, phytochimie, plantes médicinales. 4e ed. Tech & Doc, EM inter, 2009. 1269 p. (In French)
17. Boizot N., Charpentier J.-P. Méthode rapide d'évaluation du contenu en composés phéno-liques des organes d'un arbre forestier. Cah. Tech. l'INRA., 2006, numero spec., p. 79-82. (In French)
18. Quettier-Deleu C., Gressier B., Vasseur J., Dine T., Brunet C., Luyckx M., Cazin M., Cazin J.-C., Bailleul F., Trotin F. Phenolic compounds and antioxidant activities of buckwheat (Fagopyrum esculentum Moench) hulls and flour. J. Ethnopharmacol., 2000, vol. 72, nos. 1-2, pp. 35-42. https://doi.org/10.1016/S0378-8741(00)00196-3.
19. Sharma A., Bhardwaj S., Mann A.S., Jain A., Kharya M.D. Screening methods of antioxidant activity: An overview. Pharmacogn. Rev., 2007, vol. 1, no. 2, pp. 232-238.
20. Benzie I.F., Strain J.J. The ferric reducing ability of plasma (FRAP) as a measure of "antioxidant power": The FRAP assay. Anal. Biochem., 1996, vol. 239, no. 1, pp. 70-76. https://doi.org/10.1006/abio.1996.0292.
21. Almutairi R.A., Alharbi W.A., Alhazmi M.H., Alkheraiji D.A., Altaifi L.A., Almohammadi R.A., Hammouda S.A. Impact of olive leaves consumption on blood sugar level in adults with type-2 diabetes. A clinical trial: Almadinah Almunawrah, Ksa. Int. J. Adv. Res., 2017, vol. 5, no. 1, pp. 210-217. http://dx.doi.org/10.21474/IJAR01/2740.
22. Ghasemi S., Koohi D.E., Emmamzadehhashemi M.S.B., Khamas S.S., Moazen M., Hashemi A.K., Amin G., Golfakhrabadi F., Yousefi Z., Yousefbeyk F. Investigation of phenolic compounds and antioxidant activity of leaves extracts from seventeen culti-vars of Iranian olive (Olea europaea L.). J. Food Sci. Technol., 2018, vol. 55, no. 11, pp. 4600-4607. https://doi.org/10.1007/s13197-018-3398-1.
23. Hayes J.E., Allen P., Brunton N., O'Grady M.N., Kerry J.P. Phenolic composition and in vitro antioxidant capacity of four commercial phytochemical products: Olive leaf extract (Olea europaea L.), lutein, sesamol and ellagic acid. Food Chem., 2011, vol. 126, no. 3, pp. 948-955. https://doi.org/10.1016/j.foodchem.2010.11.092.
24. Feng S., Zhang C., Liu L., Xu Z., Chen T., Zhou L., Yuan M., Li T., Ding C. Comparison of phenolic compounds in olive leaves by different drying and storage methods. Separations, 2021, vol. 8, no. 9, art. 156. https://doi.org/10.3390/separations8090156.
25. Akli H., Grigorakis S., Kellil A., Loupassaki S., Makris D.P., Calokerinos A., Mati A., Lydakis-Simantiris N. Extraction of polyphenols from olive leaves employing deep eutec-tic solvents: The application of chemometrics to a quantitative study on antioxidant compounds. Appl. Sci, 2022, vol. 12, no. 2, art. 831. https://doi.org/10.3390/app12020831.
26. Cosme P., Rodriguez A.B., Espino J., Garrido M. Plant phenolics: Bioavailability as a key determinant of their potential health-promoting applications. Antioxidants, 2020, vol. 9, no. 12, art. 1263. https://doi.org/10.3390/antiox9121263.
27. Cheurfa M., Abdallah H.H., Allem R., Noui A., Picot-Allain C.M.N., Mahomoodally F. Hypocholesterolaemic and antioxidant properties of Olea europaea L. leaves from Chlef
province, Algeria using in vitro, in vivo and in silico approaches. Food Chem. Toxicol., 2019, vol. 123, pp. 98-105. https://doi.Org/10.1016/j.fct.2018.10.002.
28. Visioli F., Galli C. Biological properties of olive oil phytochemicals. Crit. Rev. Food Sci. Nutr., 2002, vol. 42, no. 3, pp. 209-221. https://doi.org/10.1080/10408690290825529.
29. Al-Sharari S.D., Al-Rejaie S.S., Abuohashish H.M., Ahmed M.M., Hafez M.M. Rutin attenuates hepatotoxicity in high-cholesterol-diet-fed rats. Oxid. Med. Cell. Longevity, 2016, vol. 2016, no. 1, art. 5436745. https://doi.org/10.1155/2016/5436745.
30. Wang C., Li J., Lv X., Zhang M., Song Y., Chen L., Liu Y. Ameliorative effect of berberine on endothelial dysfunction in diabetic rats induced by high-fat diet and streptozotocin. Eur. J. Pharmacol., 2009, vol. 620, nos. 1-3, pp. 131-137. https://doi.org/10.1016/j.ejphar.2009.07.027.
31. Jemai H., Bouaziz M., Fki I., El Feki A., Sayadi S. Hypolipidimic and antiox-idant activities of oleuropein and its hydrolysis derivative-rich extracts from Chemlali olive leaves. Chem.-Biol. Interact., 2008, vol. 176, nos. 2-3, pp. 88-98. https://doi.org/10.1016/j.cbi.2008.08.014.
32. Benavente-Garcia O., Castillo J., Lorente J., Ortuno A., Del Rio J.A. Antioxidant activity of phenolics extracted from Olea europaea L. leaves. Food Chem., 2000, vol. 68, no. 4, pp. 457-462. https://doi.org/10.1016/S0308-8146(99)00221-6.
33. Bordevic T., Saric- Krsmanovic M., Gajic Umiljendic J. Phenolic compounds and alle-lopathic potential of fermented and unfermented wheat and corn straw extracts. Chem. Biodiversity, 2019, vol. 16, no. 2, art. e1800420. https://doi.org/10.1002/cbdv.201800420.
34. Edziri H., Jaziri R., Chehab H., Verschaeve L., Flamini G., Boujnah D., Hammami M., Aouni M., Mastouri M. A comparative study on chemical composition, antibiofilm and biological activities of leaves extracts of four Tunisian olive cultivars. Heliyon, 2019, vol. 5, no. 5, art. e01604. https://doi.org/10.1016/j.heliyon.2019.e01604.
35. Siddhuraju P., Becker K. The antioxidant and free radical scavenging activities of processed cowpea (Vigna unguiculata (L.) Walp.) seed extracts. Food Chem., 2007, vol. 101, no. 1, pp.10-19. https://doi.org/10.1016/j.foodchem.2006.01.004.
36. Jeong S.-M., Kim S.-Y., Kim D.-R., Jo S.-C., Nam K.C., Ahn D.U., Lee S.-C. Effect of heat treatment on the antioxidant activity of extracts from citrus peels. J. Agric. Food Chem, 2004, vol. 52, no. 11, pp. 3389-3393. https://doi.org/10.1021/jf049899k.
37. Komaki E., Yamaguchi S., Maru I., Kinoshita M., Kakehi K., Ohta Y., Tsukada Y. Identification of anti-a-amylase components from olive leaf extracts. Food Sci. Technol. Res., 2003, vol. 9, no. 1, pp. 35-39. https://doi.org/10.3136/fstr9.35.
38. Sato H., Genet C., Strehle A., Thomas C., Lobstein A., Wagner A., Mioskowski C., Auwerx J., Saladin R. Anti-hyperglycemic activity of a TGR5 agonist isolated from
Olea europaea. Biochem. Biophys. Res. Commun., 2007, vol. 362, no. 4, pp. 793-798. https://doi.org/10.1016/j.bbrc.2007.06.130.
39. Jemai H., El Feki A., Sayadi S. Antidiabetic and antioxidant effects of hydroxytyrosol and oleuropein from olive leaves in alloxan-diabetic rats. J. Agric. Food Chem., 2009, vol. 57, no. 19, pp. 8798-8804. https://doi.org/10.1021/jf901280r.
40. Eidi A., Eidi M., Darzi R. Antidiabetic effect of Olea europaea L. in normal and diabetic rats. Phytother. Res., 2009, vol. 23, no. 3, pp. 347-350. https://doi.org/10.1002/ptr.2629.
41. Al-Azzawie H.F., Alhamdani M.-S.S. Hypoglycemic and antioxidant effect of oleuropein in alloxan-diabetic rabbits. Life Sci., 2006, vol. 78, no. 12, pp. 1371-1377. https://doi.org/10.1016/j.lfs.2005.07.029.
42. Gonzalez M., Zarzuelo A., Gamez M.J., Utrilla M.P., Jimenez J., Osuna I. Hypoglycemic activity of olive leaf. Planta Med., 1992, vol. 58, no. 6, pp. 513-515. https://doi.org/10.1055/s-2006-961538.
43. Wainstein J., Ganz T., Boaz M., Bar Dayan Y., Dolev E., Kerem Z., Madar Z. Olive leaf extract as a hypoglycemic agent in both human diabetic subjects and in rats. J. Med. Food, 2012, vol. 15, no. 7, pp. 605-610. https://doi.org/10.1089/jmf.2011.0243.
44. Laaksonen D.E., Lakka T.A., Lakka H.-M., Nyyssönen K., Rissanen T., Niskanen L.K., Salonen J.T. Serum fatty acid composition predicts development of impaired fasting glycaemia and diabetes in middle- aged men. Diabetic Med, 2002, vol. 19, no. 6, pp. 456-464. https://doi.org/10.1046/j.1464-5491.2002.00707.x.
45. Shen Y., Song S.J., Keum N., Park T. Olive leaf extract attenuates obesity in high-fat diet-fed mice by modulating the expression of molecules involved in adipogenesis and thermogenesis. Evidence-Based Complementary Altern. Med., 2014, vol. 2014, no. 1, art. 971890. https://doi.org/10.1155/2014/971890.
46. Levy J., Stern Z., Gutman A., Naparstek Y., Gavin III J.R., Avioli L.V. Plasma calcium and phosphate levels in an adult noninsulin-dependent diabetic population. Calcif. Tissue Int., 1986, vol. 39, no. 5, pp. 316-318. https://doi.org/10.1007/BF02555197.
47. Kim M.K., Kim G., Jang E.H., Kwon H.S., Baek K.H., Oh K.W., Lee J.H., Yoon K.-H., Lee W.C., Lee K.W., Son H.Y., Kang M.I. Altered calcium homeostasis is correlated with the presence of metabolic syndrome and diabetes in middle-aged and elderly Korean subjects: The Chungju Metabolic Disease Cohort study (CMC study). Atherosclerosis, 2010, vol. 212, no. 2, pp. 674-681. https://doi.org/10.1016Zj.atherosclerosis.2010.07.005.
48. Mears D. Regulation of insulin secretion in islets of Langerhans by Ca2+ channels. J. Membr. Biol, 2004, vol. 200, no. 2, pp. 57-66. https://doi.org/10.1007/s00232-004-0692-9.
49. Ojuka E.O., Jones T.E., Nolte L.A., Chen M., Wamhoff B.R., Sturek M., Holloszy J.O. Regulation of GLUT4 biogenesis in muscle: Evidence for involvement of AMPK and Ca2+. Am. J. Physiol.-Endocrinol. Metab., 2002, vol. 282, no. 5, pp. E1008-E1013. https://doi.org/10.1152/ajpendo.00512.2001.
50. Lorenzo C., Hanley A.J., Rewers M.J., Haffner S.M. Calcium and phosphate concentrations and future development of type 2 diabetes: The insulin resistance atherosclerosis study. Diabetologia, 2014, vol. 57, no. 7, pp. 1366-1374. https://doi.org/10.1007/s00125-014-3241-9.
Received January 13, 2024 Accepted April 30, 2024
Mohammed Laid Tlili, Doctor of Biochemistry, Lecturer, Department of Cellular and Molecular Biology, Laboratory of Biology, Environment, and Health; Research Associate, Department of Biological Sciences, Biogeochemistry of Desert Environments Laboratory
El Oued University
N48 Hwy., El Oued, 39000 Algeria Ouargla University
1er November 1954 Ave., Ouargla, 30000 Algeria E-mail: tlili-laid@univ-eloued.dz Roukia Hammoudi, Doctor of Biochemistry, Lecturer, Department of Biological Sciences, Biogeochemistry of Desert Environments Laboratory Ouargla University
1er November 1954 Ave., Ouargla, 30000 Algeria E-mail: rokia1811@yahoo.com Said Touati, Doctor of Biology, Lecturer, Department of Cellular and Molecular Biology El Oued University
N48 Hwy., El Oued, 39000 Algeria E-mail: sd.touati@gmail.com
Asma Belimi, PhD in Biochemistry, Lecturer, Department of Cellular and Molecular Biology El Oued University
N48 Hwy., El Oued, 39000 Algeria E-mail: monsof2001@gmail.com Sara Lamoudi, PhD in Biochemistry, Lecturer, Department of Cellular and Molecular Biology El Oued University
N48 Hwy., El Oued, 39000 Algeria E-mail: besseimohcen17@gmail.com
ОРИГИНАЛЬНАЯ СТАТЬЯ
УДК 615.322:543.8 doi: 10.26907/2542-064X.2024.3.445-458
Антиоксидантные и антидиабетические свойства водного экстракта листьев оливы сорта Sigoise (Olea europaea L.), регион Эль-Уэд (Алжир)
М.Л. Тлили12, Р. Хаммуди1, С. Туати1, А. Белими1, С. Ламуди1
'Университет Эль-Уэд, г. Эль-Уэд, 39000, Алжир
2Университет Касди Мерба де Уаргла, г. Уаргла, 30000, Алжир
Аннотация
Листья оливы (Olea europaea L.) широко используются в традиционной медицине Средиземноморья для профилактики и лечения различных заболеваний. В статье рассматриваются антиоксидантные и антидиабетические свойства водного экстракта листьев оливы сорта Sigoise (Алжир). Экстракцию проводили путем настаивания 10 г сухих листьев в 500 мл кипящей воды. Исследование выполнено при участии 20 добровольцев (10 пациентов с диабетом II типа и 10 здоровых лиц контрольной группы), которые принимали экстракт дважды в день в течение месяца. Биохимические показатели крови фиксировали до и после эксперимента. Антиоксидантную активность оценивали по результатам DPPH-теста (в реакции с 2,2-дифенил-1-пикрилгидразилом, 35.3 ± 0.5 мг/мл), а также FRAP-теста (по железо-восстанавливающей способности, 8.3 ± 0.1 мг/мл). Количественный анализ полученного экстракта показал высокое содержание полифенолов (41.8 ± 0.8 мг галловой кислоты/г экстракта) и флавоноидов (14.3 ± 0.8 мг рутина/г экстракта). Установлено, что экстракт листьев оливы оказывает выраженный гипогликемический эффект, тем самым нормализуя функцию почек и снижая риск сердечно-сосудистых заболеваний у пациентов с диабетом II типа. Токсического поражения почек и печени не обнаружено. Однако, несмотря на общую положительную динамику у пациентов с диабетом, терапевтический потенциал водного экстракта листьев оливы должен быть подтвержден в дальнейших клинических исследованиях.
Ключевые слова: Olea europaea, Sigoise, полифенолы, флавоноиды, антиоксидантные и антидиабетические свойства.
Заключение Комитета по этике. Исследование проведено в соответствии с положениями Хельсинкской декларации Всемирной медицинской ассоциации и одобрено этическим комитетом факультета естественных и биологических наук Университета Эль-Уэд (протокол № 001, декабрь 2023 г.).
Информированное согласие. Информированное согласие было получено от всех субъектов, участвовавших в исследовании.
Конфликт интересов. Авторы заявляют об отсутствии конфликта интересов.
Поступила в редакцию 13.01.2024 Принята к публикации 30.04.2024
Мухаммед Лаид Тлили, доктор биохимических наук, преподаватель, кафедра клеточной и молекулярной биологии, лаборатория биологии, состояния окружающей среды и здоровья; научный сотрудник, кафедра биологических наук, лаборатория биогеохимии пустынных ландшафтов Университет Эль-Уэд
ш. 48, г. Эль-Уэд, 39000, Алжир Университет Касди Мерба де Уаргла
Авеню 1-го ноября 1954 года, г. Уаргла, 30000, Алжир E-mail: tlili-laid@univ-eloued.dz Рукия Хаммуди, доктор биохимических наук, преподаватель, кафедра биологических наук, лаборатория биогеохимии пустынных ландшафтов Университет Касди Мерба де Уаргла
Авеню 1-го ноября 1954 года, г. Уаргла, 30000, Алжир E-mail: rokia1811@yahoo.com Саид Туати, доктор биологических наук, преподаватель, кафедра клеточной и молекулярной биологии
Университет Эль-Уэд
ш. 48, г. Эль-Уэд, 39000, Алжир E-mail: sd.touati@gmail.com
Асма Белими, доктор философии в области биохимических наук, преподаватель, кафедра клеточной и молекулярной биологии Университет Эль-Уэд
ш. 48, г. Эль-Уэд, 39000, Алжир E-mail: monsof2001@gmail.com Сара Ламуди, доктор философии в области биохимических наук, преподаватель, кафедра клеточной и молекулярной биологии Университет Эль-Уэд
ш. 48, г. Эль-Уэд, 39000, Алжир E-mail: besseimohcen17@gmail.com
For citation: Tlili M.L., Hammoudi R., Touati S., Belimi A., Lamoudi S. Antioxidant and antidiabetic properties of the water extract from Sigoise olive cultivar (Olea europaea L.), El Oued region (Algeria). Uchenye Zapiski Kazanskogo Universiteta. Seriya Estestvennye Nauki, 2024, vol. 166, no. 3, pp. 445-458. https://doi.org/10.26907/2542-064X.2024.3.445-458.
Для цитирования: Tlili M.L., Hammoudi R., Touati S., Belimi A., Lamoudi S. Antioxidant and antidiabetic properties of the water extract from Sigoise olive cultivar (Olea europaea L.), El Oued region (Algeria) // Учен. зап. Казан. ун-та. Сер. Естеств. науки. 2024. Т. 166, кн. 3. С. 445-458. https://doi.org/10.26907/2542-064X.2024.3.445-458.
