ReseaRch aRticle Journal of Agricultural and Marine Sciences 2021, 26(2): 56–63 DOI: 10.24200/jams.vol26iss2pp56-63 Received 11 Nov 2020 Accepted 08 April 2021 Anti-diabetic Potential Properties of Two Edible Omani Wild Plants (Pteropyrum scoparium and Oxalis corniculata) Iman R. S. Al-Qalhati, Mostafa I. Waly*, Lyutha Al-Subhi, Zaher Al-Attabi Mostafa I. Waly*( ) mostafa@squ.edu.om, Department of Food Science and Nutrition, College of Agricultural and Marine Sciences, Sultan Qaboos Universit y, P. O. Box 34 -123, Sultanate of Oman Introduction Diabetes is a major health concern due to its high incidence coupled with complications includ-ing cardiovascular problems, renal failure, and compromised immune system that in turn contribute to the increased mortality rate in adults (Waly et al., 2010). Oxidative stress has been involved in the etiolo- gy of various human chronic diseases including diabetes (Suresh et al., 2017), and more than 1200 plant species have been suggested for the treatment of these diseases (Krishnaiah et al., 2011). Recent studies have declared the effectiveness of some therapeutic plants and herb- al preparations in the improvement of hyperglycemia (Petrovska, 2012). Edible wild plants are considered as natural therapeutic agents due to their antioxidant prop- erties, minimum side reactions, and low cost (Petrovska, 2012). The traditional use of plants as medicine precedes اخلصائص احملتملة املضادة ملرض السكري الثنني من النبااتت الربية العمانية: السيداف )Oxalis corniculata( و احلُمَّْيض )Pteropyrum scoparium( إميان القلهايت و مصطفى وايل* و ليوثة الصبحي و زاهر العطايب Abstract. The use of plants for medicinal purposes has a long history worldwide. There is a lack of research that identifies the antidiabetic effect of edible Omani wild plants. Oxidative stress mediates the pathogenesis of diabetes and it has been suggested that natural antioxidants might be considered as an effective intervention for combating diabetes. This study aimed to assess the anti-diabetic and antioxidant potential properties of two edible Omani wild plants (Pteropyrum scoparium and Oxalis corniculata) or their mixture in streptozotocin (STZ)-induced diabetic rats. Thirty-seven male Sprague Dawley rats, weighing 250–300 g, were allocated into 5 groups: non-diabetic (9 rats/group), diabetic group (7 rats/group), and three diabetic groups that received oral feeding of either Pteropyrum scoparium, Oxalis corniculata, or their mixture (7 rats/group). Diabetes was induced by a single intraperitoneal injection dose of STZ drug, 50 mg/kg body weight. At the end of the experimental trial, after 8 weeks, all rats were fasted overnight and sacrificed; blood glucose was measured, meanwhile, pancreatic tissues were dissected and homogenized for the bio- chemical assessment of oxidative stress markers (glutathione, GSH, and total antioxidant capacity, TAC). STZ resulted in hyperglycemia and oxidative stress (GSH depletion and TAC impairment) in the diabetic group as compared to the non-diabetic group. Meanwhile, the concomitant treatment of diabetic groups with the two wild edible Omani plants or their mixture has shown a protective effect against the STZ-induced hyperglycemia, but with no effect on oxidative stress. It was noted that for the final body weight, the improvement was not significant. Histopathological examination of the pancreatic tissues showed that the STZ injection leads to pathological changes associated with diabetes in the pancreatic tissues of all diabetic groups. Pteropyrum scoparium and Oxalis corniculata combated the STZ-induced hyperglycemia with no effect on oxidative stress. There was no synergistic effect of Pteropyrum scoparium and Oxalis corniculata on hyperglycemia or oxidative stress. Keywords: Diabetes, Pteropyrum scoparium, Oxalis corniculata, Oxidative Stress امللخــص:إن اســتخدام النبــااتت لألغــراض الطبيــة لــه اتريــخ عريــق يف مجيــع أحنــاء العــامل، اال ان هنــاك نقــص يف األحبــاث الــي حتــدد أتثــر النبــااتت الربيــة العمانيــة الصاحلــة لــألكل ضــد مــرض الســكري. يتســبب اإلجهــاد التأكســدي يف تغــرات فيزيولوجيــة مرتبطــة مبــرض الســكري، وتعتــرب مضــادات األكســدة الطبيعيــة مــن التدخــات الفعالــة لتخفيــف درجــة األكســدة الناجتــة عــن مــرض الســكري وابلتــايل التحكــم بــه. هدفــت هــذه الدراســة إىل تقييــم خصائــص مضــادات األكســدة الثنــن مــن النبــااتت الربيــة العمانيــة الصاحلــة لــألكل وفعاليتهــا لضبــط مــرض الســكري، وهــي الســيداف Pteropyrum scoparium واحلُمَّْيــض Oxalis corniculata يف اجلــرذان املصابة بداء السكري اثر حقنها مبركب السرتبتوزوتوسن )STZ(. ولقــــد اشــــتملت التجربــــة علــــى سبعة وثاثن ذكرا مــــن جرذان ســــالة ســــرباغ داويل ، بوزن 250- 300 جــرام ، مقســمة كاأليت: اجملموعــــة الضابطــــة )9 جــرذان ( و اجملموعــــة املصابــة مبــرض الســكري بعــد حقنهــا مبركــب STZ )7 جــرذان ( بينمــــا تلقــــت اجملموعــــات الثاثــة األخــرى )7 جــرذان / جمموعــة( مســــتخلصات أوراق الســيداف أو احلميضــة أو خليطهمــا بعــد حقنهــم مبركــب STZ . اســــتمرت التجربــــة ملــــدة 8 أســابيع و بعدها مت التضحية ابجلرذان و مت قياس مستوى اجللوكوز يف الدم ؛ كما مت تقييم مؤشرات اإلجهاد التأكسدي يف أنسجة البنكرايس جلميع اجلرذان . وقد أظهــرت نتائــج هــــذه الدراســــة زايدة ملحوظة يف نســبة جلوكوز الدم يف اجلرذان املصابة مبرض الســكري و كذلك نقص حاد يف مســتوى مركب اجللواتثيون ) GSH( و القدرة اخللوية اإلمجاليــة املضــادة لألكســدة )TAC( وكذلــك أظهــر الفحــص النســيجي ألنســجة البنكــرايس أن حقــن اجلــرذان مبركــب STZ أدى إىل تغــرات مرضيــة مرتبطــة مبــرض الســكري يف أنســجة البنكــرايس جلميــع جمموعــات داء الســكري. ومــن جانــب اخــر، أظهــر كأل مــن الســيداف واحلُمَّْيــض علــى حــدى أتثـيـــراً خافضــا جللوكــوز الــدم دون أتثر على اإلجهاد التأكســــدي املرتبــــط مبرض الســكري، إال أن خليط هذه النبااتت مل يظهر أي أتثر آتزري ســواء على مســتوى جلوكوز الدم أو االجهاد التاكســدي. الكلمات املفتاحية: مرض السكري ، اإلجهاد التأكسدي ، النبااتت الربية العمانية )السيداف و احلُمَّْيض(. 57Research Article Al-Qalhati, Waly, Al-Subhi, Al-Attabi modern medicine throughout the world (World Health Organization, 2009). According to the World Health Or- ganization, almost 80% of the people in the world used medicinal plants for their primary health care (World Health Organization, 2009). There are many natural products that have been isolated from plants such as fla- vonoids, phenolics, curcuminoids, tannins, coumarins, xanthones, terpenoids, and lignans (Jeong et al., 2004). In addition, synthetic antioxidants like butylated hy- droxytoluene (BHT), tert-butylhydroquinone (TBHQ), and butylated hydroxyanisole (BHA) are manufactured chemically and used in the food industry because they are more effective and cheaper than natural antioxidants (Lourenco et al., 2019). But, the use of synthetic anti- oxidants as food additives has raised some concerns re- lated to their potential health problems and toxicity as TBHQ, BHA and BHT might be carcinogenic and had been banned in several western countries (Lourenco et al., 2019). Therefore, there is a lot of potential commer- cial use of natural antioxidants from plant extracts as an alternative for artificial synthetic ones. There are numerous edible indigenous plant species in the Gulf Region, but there are limited studies about the health aspects of these plants in the daily food sup- ply chain (Al-Attabi et al., 2015). Oxalis corniculata is a cosmopolitan weed spreading with a slim stem covered with rounded tipped hairs (Brown, 1989). It is commonly known as “sour grass” (Pickering et al., 2008). It grows in shady moist places and traditionally, was used for treat- ing wounds and certain diseases (Pickering et al., 2008). Pteropyrum scoparium grows mainly in February af- ter the rainy season in December. It is used in the tradi- tional food in which it is mixed with dried anchovies. The leaves were used medicinally for blood purification and the treatment of indigestion (Al-Badi, 2011). Streptozo- tocin (STZ) is a potent diabetic-inducing agent common- ly used in rats; the STZ effect is mediated by oxidative stress in pancreatic cells (Al-Maskari et al., 2012). STZ induces diabetes in experimental animals via a mecha- nism that is mediated by glutathione (GSH) depletion and impairing total antioxidant capacity in pancreatic cells of rats (Al-Maskari et al., 2012). GSH is a tripeptide and acts as a part of the defense system against oxidative stress compounds like reactive oxygen and nitrogen spe- cies (Waly et al., 2015). GSH acts as antioxidants since it is a carrier for the active thiol group, and has a direct an- tioxidant effect through interacting with electrophiles, reactive oxygen, or nitrogen (Waly et al., 2015). Oxida- tive stress in pancreatic tissue is a condition under which GSH and antioxidant enzymes (glutathione peroxidase, superoxide dismutase, and catalase) are not counter- balancing ROS, and subsequently, induce pancreatic cellular damage (Unuofin and Lebelo, 2020; Matough et al., 2012). Oman region is rich in medicinal plants with antioxidant properties, therefore understanding the biological aspects of these plants in relation to oxida- tive-stress mediated diabetes might be considered as an effective dietary intervention in the primary prevention of diabetes. In the current study, we aimed to assess the biochemical significance of two edible Omani indige- nous plants (Pteropyrum scoparium and Oxalis cornic- ulata) using an in vivo experimental model for diabetes. Methods Plants Preparation The two edible Omani wild plants, Pteropyrum scopar- ium and Oxalis corniculata, were freshly collected in October 2014 from two areas, Nizwa and Sur, and were identified by a specialized botanist from the Crop Scienc- es Department at the College of Agricultural and Marine Sciences, Sultan Qaboos University. The leaves of the col- lected plant were separated from the undesirable mate- rials. Then the leaves were washed and rinsed by distilled water and dried by free zone 6-liter benchtop freeze dry system (Labconco, USA) at -40 ºC. The dried leaves were powdered by an electrical grinder (PHILIPS, HR2027). One gram of the dried powder was mixed with 50 mL distilled water. At the end, the mixture was stored in air- tight container at -40 ºC until used for later experiments. Experimental Animals Thirty-seven adult Sprague Dawley male rats weighing approximately 250-300 g were used in this study. Ani- mals were adapted to the animal house conditions for one week before starting the experiment. Animals were housed in standard laboratory room conditions at 23±2 ºC, with a 12 h light/dark cycle, relative humidity of 55±10 % and were maintained with free access to stan- dard diet and tap water. The standard diet was acquired from Oman Flour Mills Company (Muscat, Oman). All the animal procedures were implemented accordingly to the “Guide for the Care and use of Laboratory Animals” published by the National Institutes of Health. An eth- ical approval from University Animal Research Ethics Committee was obtained (SQU/AEC/2010-11). Experimental Design and Diabetes Induction The thirty seven rats were randomly allocated into five groups as follow: Non-diabetic control rats (n=9) that fed standard diet, Diabetic control rats (n=7) that were injected with STZ and fed standard diet, Diabetic rats (n=7) that were injected with STZ and fed standard diet and an oral dose of Pteropyrum scoparium extract (5 ml/week), Diabetic rats (n=7) that were injected with STZ and fed standard diet and an oral dose of Oxalis corniculata extract (5 ml/week), Diabetic rats (n=7) that were injected with STZ and fed standard diet and an oral dose of a mixture of the extracts of both plants (10 ml/ week). The oral dose supplementations were carried out in the same day and time on weekly basis for all groups. The experiment was carried out for 8 weeks. Through- out the experimental period, all rats were weighed once a 58 SQU Journal of Agricultural and Marine Sciences, 2021, Volume 26, Issue 2 Anti-diabetic Potential Properties of Two Edible Omani Wild Plants (Pteropyrum scoparium and Oxalis corniculata) week, using a laboratory scale (Electronic Balance kern; PCB 6000-0) to the nearest gram. The allocated diabetic groups were injected with a single intra peritoneal injec- tion of STZ (50 mg/ kg body weight) while the non-dia- betic group received a single intra peritoneal injection of 0.1 M citrate buffer solution. STZ was purchased from Sigma-Aldrich Chemical Company (product number S0130), and dissolved in a freshly prepared 0.1 M citrate buffer (pH 4.5). Diabetes was confirmed after three days of the STZ injection by measuring blood glucose. Brief- ly, the diabetic rats were fasted overnight and the distal part of each rat’s tail was lightly snipped; the first blood drop was discarded and the second drop was absorbed by a test strip inserted in a portable glucose meter (One Touch II; Johnson & Johnson, Milpitas, CA, USA).The blood glucose level for all rats in the diabetic groups was ≥ 200 mg/dl. Animals Sacrifice and Pancreatic Tissue Homogenization After eight weeks of the experiment, all rats were fasted overnight and blood samples were taken from the tails to measure blood glucose level. Then all rats were anesthe- tized with a lethal dose of a mixture of ketamine (1 mg), xylazine (5 mg) and acepromazine (0.2 mg). The pancre- as was dissected and removed. Small pieces of the pan- creatic tissues were placed in 10% of formalin for histo- pathological examination. The rest of pancreas samples (2 g) were homogenized in 0.1 M phosphate buffer and centrifuged at 4000 rpm at 4°C for 5 minutes. The re- sulting supernatants were used for protein content mea- surement using the Lowry’s method (Lowry et al., 1951) and for biochemical measurements of glutathione and total antioxidant capacity. Biochemical Measurements The Glutathione (GSH) was measured using the GSH assay kit from Biovision Company (kit number; K251). The assay uses a dye that forms an adduct with glutathi- one which is monochlorobimane (MCB). The unbound MCB is mainly non fluorescent, while the dye fluoresces blue when bound to glutathione. This reaction is cata- lyzed by glutathione S-transferase. The assay identifies both reduced and oxidized glutathione. Total antioxidants capacity (TAC) was estimated using assay kit from Biovison Company (kit number; K274), which can measure both the small molecule an- tioxidants and proteins or small molecules alone in the presence of protein Mask. Cu²+ ion is converted to Cu+ by both small molecule and protein. The Protein Mask prevents Cu²+ reduction by protein, enabling the analy- sis of only the small molecule antioxidants. The reduced Cu+ ion is chelated with a colorimetric probe giving a broad absorbance peak around 570 nm, relative to the total antioxidant capacity. Histopathological Examination Pancreatic tissues saved in 10% formalin at room tem- perature were used to study their histological structures. The fixed specimens were dehydrated in graded ethanol, cleared in xylene and embedded in paraffin wax. Tissue blocks were sectioned into 10 μm thickness using rotary microtome (Thermo Scientific STP120, Thermo Fisher Scientific UK Ltd.). The sections were stained by hema- toxylin and eosin (H&E) to examine the pancreatic tissues under conventional light microscope by a pathologist. Statistical Analysis The statistical analysis was performed using one-way analysis of variance (ANOVA) followed by Tukey’s test using GraphPad Prism (version 5.03; GraphPad Soft- ware Inc. San Diego, CA). P<0.05 is considered as statis- tically significant. The results are expressed as means ± Standard Error of Means (SEM). Results Final Body Weight The effect of the treatment with Pteropyrum scoparium, Oxalis corniculata or their mixture on body weight in all groups is presented in Figure 1. The results exhibited that the diabetic control group showed a significant reduc- tion in the final body weight as compared to the non-di- abetic group, P< 0.05. Diabetic groups treated with Pteropyrum scoparium, Oxalis corniculata or their mix- ture showed an improvement in the final body weight, although the differences were not significant (P> 0.05) Fasting Blood Glucose Levels after Animal’s Sacrifice Figure 2 illustrates the effect of Pteropyrum scoparium, Oxalis corniculata and their mixture on the fasting blood glucose level. STZ injection induced a significant in- crease in fasting blood glucose level of all diabetic groups as compared with the non-diabetic group, P<0.05. Feed- ing diabetic groups with Pteropyrum scoparium, Oxal- is corniculata or their mixture positively ameliorated the elevation of blood glucose level as compared to the diabetic control group, but not significantly (P>0.05). Pancreatic Tissue Antioxidants Markers Table 1 presented the potential effect of Pteropyrum sco- parium, Oxalis corniculata or their mixture on the cel- lular antioxidants markers (GSH and TAC). In all diabet- ic groups (treated and untreated), there was a depletion in the GSH level compared to the non-diabetic control group (P<0.05). There was a significant impairment of TAC level of the diabetic groups treated with the extracts of Pteropyrum scoparium, Oxalis corniculata and their mixture as compared to control non-diabetic group. 59Research Article Al-Qalhati, Waly, Al-Subhi, Al-Attabi Histopathological Examination Figure 3 shows the histological appearance of the pan- creatic islet cells of all experimental groups. The pan- creatic section from the non-diabetic control group showed the normal histological structure of pancreatic cells with increased size and cellularity of the cells (Fig- ure 3.A). On the other hand, microscopic examination of the pancreatic sections of the diabetic control rats revealed decreased size and number of lymphocytes of β-cells of islets of Langerhans (Figure 3.B). Figures 4C-E represents the pancreatic sections of the diabet- ic rats that were treated with Pteropyrum scoparium, Oxalis corniculata and their mixture, respectively. A mild to chronic lymphocytic infiltration is noted be- tween acini in Figure 3.C; cystic dilatation of pancre- atic duct was detected in Figure 3D and a congestion of pancreatic blood vessel was observed in Figure 3E. Discussion There is an increasing effort in searching for plants prod- ucts possessing anti-diabetic activity with fewer side ef- fects. Diabetes is a challenging metabolic disease that affects the population worldwide (Pradeepa et al., 2013). The total number of people with diabetes in the globe is estimated to increase sharply in the future (Abdul Sani et al., 2014). Several treatments were used to cure diabetes mellitus, yet these treatments have limitations and un- desirable effects (Pradeepa et al., 2013). Therefore, there was an increasing effort in searching for plant products possessing anti-diabetic activity with fewer side effects (Habibuddin et al., 2008). The recent scientific studies as the traditional practices believed that the combination of many plants will be more efficient than using a single plant (Ogbonnia et al., 2008). Few studies revealed the effect of Oxalice cornicula- ta in diabetic animal models (Agila, 2012), while there is no study conducted with Pteropyrum scoparuim or the combination of these two plants. The present study has been undertaken to assess the effect of Pteropyrum scoparuim, Oxalice corniculata and their mixture in STZ-induced diabetic model. In the present study, the diabetic control group showed a significant decrease in the final body weight compared with non-diabetic group. The obtained findings were in agreement with a previous reported that the injection of STZ has been related with body weight loss because of the elevation in protein catabolism and muscle wasting. Moreover, the lack of insulin secretion leads to unavailability of carbo- hydrate which is a source of energy resulting in the ob- served body weight loss among the diabetic groups. This finding is consistent with what was reported earlier that administration of 50 mg /kg of STZ resulted in a signif- icant reduction in the body weight of diabetic animals (Suresh et al., 2017; Waly et al., 2015). There were no previous studies to verify the effect of supplementation with Pteropyrum scoparium, Oxalis corniculata or their mixture on the body weight of STZ-diabetic rats. Our results showed an improvement trend in the final body weight of all three treated diabetic groups compared to the untreated diabetic control group. However, the ob- tained results were not significant and this may be due to the size of the dose used which might have not been enough to relief the weight loss resulting from the dia- betes insult. In our study, STZ-induced diabetic control rats showed a significantly elevation in the fasting blood glu- cose level when compared with the control non diabet- ic group, P<0.05. A similar result was reported earlier which stated that STZ in a dose of 50 mg/kg induced di- abetes in the experimental animals (Suresh et al., 2017). Diabetes mellitus is characterized by a disturbance of glucose homeostasis and adversely affects carbohy- drates, fat, and protein metabolism due to lack of insu- Figure 1. Final body weight in the rat groups aAll the diabetic groups had significantly lower body weight than the non-diabetic group, P< 0.05. 60 SQU Journal of Agricultural and Marine Sciences, 2021, Volume 26, Issue 2 Anti-diabetic Potential Properties of Two Edible Omani Wild Plants (Pteropyrum scoparium and Oxalis corniculata) lin (Waly et al., 2015). The increase in the blood glucose level is attributed to the cytotoxic effect of STZ on pan- creatic cells (Waly et al., 2015). In addition, STZ leads to destruction of β-cells of Islets of Langerhans and mal- functioning of the pancreas resulting in the blood glucose elevation (Sung et al., 2019; Agila and Kavitha, 2012). Furthermore, our study revealed amelioration in the fasting blood glucose levels of all the treated diabetic groups. In contrast to our findings with respect to Ox- alis corniculata, it was demonstrated that a single daily oral administration of an aqueous extract of Oxalis cor- niculata (100 mg/kg body weight) caused a significant reduction in the blood glucose in Alloxan-induced di- abetic mice when treated for a period of ten days (do Prado et al., 2020). The results observed in our study are based on a different dose and feeding duration. On the other hand, there were no studies to compare the results obtained from treating diabetic animals with Pteropyrum scoparium or the mixture of two plants. Long term of untreated hyperglycemia in diabetes is as- Figure 2. Fasting blood glucose measurements in the rat groups. All the diabetic groups treated with Pteropyrum scopari- um, Oxalis corniculata or their mixture positively ameliorated the elevation of blood glucose level as compared to diabetic control group, but not significantly, P>0.05 a, bSimilar superscripts are not significantly different. Figure 3. Histopathological examination of the pancreatic tissues of rat groups (H&E stain x 400). Section A: pancre- atic tissue of the non-diabetic group consisting of acini; ducts and islets of Langerhans with no evidence of inflammation and necrosis. Section B: pancreatic tissue of the diabetic group; the islets are small (atrophic) and a few lymphocytes (black arrow) are noted. Section C: Diabetic + Pteropyrum scoparium; occasional islets show moderate chronic inflammatory cells infiltrate (black arrow) and necrosis (red arrow) with mild lymphocytic infiltration noted between acini (black arrow). Section D: Diabetic + Oxalis corniculata; show dilated and congested blood vessels (black arrow). Section E: Diabetic + Pteropyrum scoparium & Oxalis corniculata; show moderate number of lymphocytes (black arrow), occasional single cell necrosis (red arrow) and dilated ducts (large black arrow). No improvement in the STZ-mediated pathological effects were seen in any of the three treated groups. 61Research Article Al-Qalhati, Waly, Al-Subhi, Al-Attabi sociated with oxidative stress generating from glucose autoxidation, protein glycation and glycoxidation lead- ing to tissue injury and damage (do Prado et al., 2020). Induction of STZ generates H2O2 and increased the production of free radicals in vitro as well as in vivo in- creasing the oxidative stress level (Balaji et al., 2020). Those reactive free radical species generated by STZ contribute to DNA fragmentation and induce other damaging changes in the cells. The formation of superoxide anions could be a result of STZ action or/ and an increased activity of xanthine oxidase on mito- chondria (Hassanzadeh et al., 2019). Thus high blood glucose level induces a damage to the body by many mechanisms that lastly leads to cellular stress (Jakus, 2000). In the present study, STZ-induced diabetic rats showed a depletion trend in the glutathione level. Sim- ilar results were observed in the three treated diabetic groups. Such a finding could be due to hyperglycemia which causes osmotic stress to cells by increasing the movement of glucose through polyol pathway and the production of sorbitol that consumes dihydronicotine amide adenine dinucleotide phosphate causing deple- tion in intracellular glutathione (Pradeepa et al., 2014). It was reported that the best solvents of extracting the flavonoid from Oxalis corniculata are the polar solvents such as methanol and water (Al Qalhati, 2016). Moreover, the polar solvents like the ethanolic extract of Pteropy- rum scoparium showed better free radical scavenging ac- tivity indicating that the Pteropyrum scoparium is a rich source of some antioxidants constituents like epicate- chin-3-O-gallate (Al Qalhati, 2016). In the present study the plants extracts were aqueous-based, and the results obtained in our study showed a significant impairment of total antioxidants capacity in the three treated groups. STZ as a diabetic insult is causing specific cytotox- icity to β-cells of the pancreas (Waly et al., 2015). It generates high level of free radicals causing DNA frag- mentation of ß cells and cells necrosis which leads to decreasing the level of insulin and increasing the blood glucose level (Suresh et al., 2017). The microscopic ex- amination of the pancreatic tissue of the diabetic control group is in conformity with what was reported earlier that atrophy of β-cells of islets of Langerhans, necrosis along with cystic dilatation of pancreatic duct, reduc- tion in cells size, decrease cellularity, and congestion of pancreatic blood vessels (Kakkar et al., 1998). These changes in pancreatic cells can be attributed to the STZ cytotoxicity causing a destruction of β-cells of the pan- creas (Khattab et al., 2013). Also, this effect may be ex- plained by generation of H2O2 in the pancreatic β-cells by induction of STZ causing DNA fragmentation. In addition, the hyperglycemia stimulates the production of free radicals causing cell dysfunction and damaging the pancreatic cells (Singab et al., 2014). The microscop- ic examination of the pancreatic tissues of the treated diabetic groups showed no histopathological changes indicating that treatment with Pteropyrum scopari- um, Oxalis corniculata or their mixture have any ef- fect on the pancreatic tissues. This may be due to the increase in the oxidative stress (Srikanth et al., 2012). Conclusion In conclusion, our study demonstrated that STZ induced diabetes and oxidative stress in the experimental rat model. In addition, it indicated that Pteropyrum scopar- ium, Oxalis corniculata, and their mixture improved the STZ-induced hyperglycemia and the final body weight but not significantly. Neither the two plants nor their mixture has an effect on the cellular antioxidant markers or the histopathological changes in pancreatic tissues. There was no significant synergistic effect of the two plants (Pteropyrum scoparium and Oxalis corniculata) on STZ-induced diabetes and oxidative stress. Further research is needed to investigate the dose and time-de- pendent attributes of Pteropyrum scoparium and/or Ox- alis corniculata in relation to diabetes. Table 1. . Biochemical measurements of glutathione (GSH) and total antioxidant capacity (TAC) in the rat groups. Antioxidant Marker Group GSH (ng/mg protein) TAC (ng/mg protein) Non-diabetic 1.24 ±0.17 251.16 ±64.11 Diabetic *0.89 ± 0.24 *143.71 ± 34.15 Diabetic + Pteropyrum scoparium 0.70 ± 0.16 82.23 ± 20.41 Diabetic + Oxalis corniculata 0.75 ± 0.13 73.4 ± 11.13 Diabetic + Pteropyrum scoparium & Oxalis corniculata 0.72 ± 0.09 68.10 ± 5.44 *Significantly lower than non-diabetic group, P< 0.05. In all diabetic treated and non-treated groups there was depletion in the GSH level compared to the control non-diabetic group but this depletion was not significant P>0.05. Meanwhile, a significant impairment of TAC level of diabetic groups treated with Pteropy- rum scoparium, Oxalis corniculata or their mixture was observed as compared to control non-diabetic group. 62 SQU Journal of Agricultural and Marine Sciences, 2021, Volume 26, Issue 2 Anti-diabetic Potential Properties of Two Edible Omani Wild Plants (Pteropyrum scoparium and Oxalis corniculata) References Abdul Sani NF, Belani LK, Pui Sin C, Abdul Rahman SNA, Das S, Zar Chi T,Yusof YAM. (2014). Effect of the combination of gelam honey and ginger on ox- idative stress and metabolic profile in streptozoto- cin-induced diabetic Sprague-Dawley rats. Biomed Research International 2014:1-9. Agila K. (2012). Antidiabetic, antihyperlipidaemic and antioxidant activity of Oxalis corniculata in alloxan induced diabetic mice. Journal of Natural Sciences Research 2(7): 9-17. Al Qalhati I. 2016. Anti-diabetic Effect of Pteropyrum scoparium, Oxalis corniculata and Their Mixture in Rats, M. Sc. Thesis, Sultan Qaboos University, Oman. Al-Attabi Z, AlMamri R, Al AbdAslam K. (2015). Antiox- idant potential properties of three Wild Omani plants against hydrogen peroxide-induced oxidative stress. Canadian Journal of Clinical Nutrition 3(2): 16-22. Al-Maskari MY, Waly MI, Ali A, Al-Shuaibi YS, Ouh- tit A. (2012). Folate and vitamin B12 deficiency and hyperhomocysteinemia promote oxidative stress in adult type 2 diabetes. Nutrition 28: 23-26. Balaji P, Madhanraj R, Rameshkumar K, Veeramanikan- dan V, Eyini M, Arun A, Thulasinathan B, Al Farraj DA, Elshikh MS, Alokda AM, Mahmoud AH, Tack JC, Kim HJ. (2020). Evaluation of antidiabetic activity of Pleurotus pulmonarius against streptozotocin-nic- otinamide induced diabetic wistar albino rats. Saudi Journal of Biological Science 27(3): 913-924. Brown CE. (1989). Medicinal and Other Uses of North American Plants: A Historical Survey with Special Reference to the Eastern Indian Tribes. Dover Publi- cations Inc., pp 1-510. do Prado FC, Vieira WF, Fernandes de Magalhaes S, Bonet IJM, Tambeli CH, Parada CA. (2020). The onset speed of hyperglycemia is important to the development of neuropathic hyperalgesia in strep- tozotocin-induced diabetic rats. European Journal of Neuroscience 52: 3642-3651. Habibuddin M, Daghriri HA, Humaira T, Al Qahtani MS, Hefzi AAH. (2008). Antidiabetic effect of alco- holic extract of Caralluma sinaica L. on streptozoto- cin-induced diabetic rabbits. Journal of Ethnophar- macology 117(2): 215-220. Hassanzadeh KN, Kim EY, Dryer SE. (2019). TRPC6 inac- tivation does not protect against diabetic kidney dis- ease in streptozotocin (STZ)-treated Sprague-Daw- ley rats. FASEB Bioadvances 1(12):773-782. Jakus V. (2000). The role of free radicals, oxidative stress and antioxidant systems in diabetic vascular disease. Bratislavske Lekarske Listy 101(10): 541-551. Jeong SM, Kim SY, Kim DR, Jo SC, Nam KC, Ahn DU, Lee SC. (2004). Effect of heat treatment on the anti- oxidant activity of extracts from citrus peels. Journal of Agricultural Food Chemistry 52(11): 3389-93. Kakkar R, Mantha SV, Radhi J, Prasad K, Kalra J. (1998). Increased oxidative stress in rat liver and pancreas during progression of streptozotocin-induced diabe- tes. Clinical Science 94(6): 623-632. Khattab HA, Al-Amoudi NS, Al-Faleh A. (2013). Effect of Ginger, Curcumin and Their Mixture on Blood Glucose and Lipids in Diabetic Rats. Life Science Journal 10(4): 428-442. Krishnaiah D, Sarbatly D, Nithyanandam R. (2011). A review of the antioxidant potential of medicinal plant species. Food and Bioproducts Processing 89(3): 217-233. Lourenço SC, Moldao-Martins M, Alves VD. (2019). Antioxidants of Natural Plant Origins: From Sourc- es to Food Industry Applications. Molecules 24(22): 1-25 (Article 4132). Lowry OH, Rosebrough NJ, Farr AL, Randall RJ. (1951). Protein measurement with the Folin phenol reagent. Journal of Biological Chemistry 193: 265-275. Matough FA, Budin SB, Hamid ZA, Alwahaibi N, Mo- hamed J. (2012). The role of oxidative stress and an- tioxidants in diabetic complications. Sultan Qaboos University Medical Journal 12(1): 5-18. Al-Badi MSM. (2011). Oligomeric pronthocyandins from Petropyrum scoparium and their antioxidant proper- ties. Sultan Qaboos University, M. Sc. Thesis, Oman. Ogbonnia SO, Odimegwu JI, Enwuru VN. (2008). Evalu- ation of hypoglycaemic and hypolipidaemic effects of aqueous ethanolic extracts of Treculia africana Dec- ne and Bryophyllum pinnatum, Lam and their mix- ture on streptozotocin (STZ)-induced diabetic rats. African Journal of Biotechnology 7(15): 2535-2539. Petrovska BB. (2012). Historical review of medicinal plants’ usage. Pharmacognosy Reviews 6(11): 1-5. Pickering H, Patzelt A. (2008). Field guide to the wild plants of Oman: Royal Botanic Gardens, Oman. Pradeepa S, Subramanian S, Kaviyarasan V. (2013). Biochemical evaluation of antidiabetic properties of Pithecellobium dulce fruits studied in streptozoto- cin induced experimental diabetic rats. International Journal of Herbal Medicine 1(4): 21-28. Pradeepa S, Subramanian S, Kaviyarasan V. (2014). Antioxidant role of Pithecellobium dulce fruit pulp extract in ameliorating hyperglycemia induced oxi- dative stress studied in streptozotocin induced exper- imental diabetic rats. Journal of Pharmacy Research 8(3): 377-384. Qihui L, Shuntian D, Xin Z, Xiaoxia Y, Zhongpei C. (2020). Protection of curcumin against streptozo- cin-induced pancreatic cell destruction in T2D rats. Planta Medica 86(2): 113-120. 63Research Article Al-Qalhati, Waly, Al-Subhi, Al-Attabi Singab AN, Youssef FS, Ashour ML. (2014). Medicinal plants with potential antidiabetic activity and their assessment. Med Aromat Plants 3(1): 151-156. Srikanth M, Swetha T, Veeresh B. (2012). Phytochem- istry and pharmacology of Oxalis corniculata Linn. International Journal of Pharmaceutical Sciences and Research 3(11): 1-12. Sung Y, Jeong J, Kang RJ, Choi M, Park S, Kwon W, Lee J, Jang S, Park SJ, Kim SH, Yi J, Choi SK, Lee MH, Liu K, Dong Z, Ryoo ZY, Kim MO. (2019). Lin28a expression protects against streptozotocin-induced β-cell destruction and prevents diabetes in mice. Cell Biochemisty and Function 37(3):139-147. Suresh S, Waly MI, Rahman MS, Guizani N, Al-Kindi MAB, Al-Issaei HKA, Al-Maskari SNM, Al-Ruqa- ishi BRS, Al-Salami A. Broccoli (Brassica oleracea). (2017). Reduces oxidative damage to pancreatic tissue and combats hyperglycaemia in diabetic rats. Preven- tive Nutrition and Food Science 22(4): 277-284. Tripathi BK, Srivastava AK. (2006). Diabetes mellitus: Complications and therapeutics. Medical Science Monitor 12(7): RA130-147. Unuofin JO, Lebelo SL. (2020). Antioxidant effects and mechanisms of medicinal plants and their bioactive compounds for the prevention and treatment of type 2 diabetes: An Updated Review. Oxidative Medicine Cellular Longevity 2020: 1-36 (Article 1356893). Waly MI, Ali A, Essa MM, Al-Shuaibi Y, Al-Farsi YM. (2010). The global burden of type 2 diabetes: A re- view. International Journal of Biological Medical Re- search 1(4): 326-329. Waly MI, Guizani N, Suresh S, Rahman MS. (2015). Ginger extract attenuates preliminary steps of strep- tozotocin-mediated oxidative stress in diabetic rats. International Journal of Nutrition, Pharmacology, Neurological Diseases 5: 151-158. World Health Organization. (2009). The Use of Herbal Medicines in Primary Health Care, Technical report, 2009, pp1-66. https://apps.who.int (accessed 2 Janu- ary 2020).