Evaluation of Antidiabetic and Antioxidant Activities of Fruit Pulp Extracts of Cucurbita moschata Duchesne and Cucurbita maxima Duchesne

Objective To evaluate and compare the antidiabetic and antioxidant activities of fruit pulp extracts from Cucurbita moschata (PCMOS) and Cucurbita maxima (PCMAX). Methods The antidiabetic activity was carried out in vivo by orally and daily giving the extracts at a dose of 500 mg/kg·b.w. to the streptozotocin-induced diabetic male albino Wistar rats for six weeks. After the period of administration, blood glucose levels, body weight, serum insulin, morphology of islets of Langerhans, biochemical parameters, and haematological values of the rats were determined. Meanwhile, the antioxidant activity was carried out in vitro by determination of total phenolic and flavonoid contents, DPPH radical scavenging activity, and ferric reducing antioxidant power. Results PCMAX significantly (p < 0.05) reduced blood glucose levels but increased the body weight, serum insulin levels, size and number of islets of Langerhans, and β-cell number of the treated diabetic rats more than PCMOS did. However, they did not alter biochemical parameters and haematological values of the treated diabetic rats. PCMAX possessed total phenolic and flavonoid contents and showed DPPH scavenging and FRAP reducing antioxidant power more significantly (p < 0.05) than PCMOS. Conclusions According to the obtained results, it is indicated that PCMOS and PCMAX possess antidiabetic and antioxidant activities. PCMAX possesses more potent antidiabetic and antioxidant activities than PCMOS. These are probably due to PCMAX providing polysaccharide and total phenolic and flavonoid contents more than PCMOS.


Introduction
Diabetes mellitus (DM) is a severe metabolic disease that signifcantly impacts the health, quality of life, and life expectancy of patients, as well as the healthcare system [1]. It is a chronic carbohydrate, fat, and protein metabolism disorder characterized by high blood glucose levels resulting from the absence of insulin or insulin resistance [2,3]. DM can cause substantial morbidity, mortality, and long-term complications [4]. Te prevalence of DM will increase to 370 million or more by 2030 [5]. Tere is an urgent need for therapeutic agents to treat DM with fewer side efects. Synthetic antidiabetic agents often possess serious side effects. As the availability of antidiabetic agents in developing countries is limited, alternative approaches for treating diabetes using suitable antidiabetic agents from food sources are therefore being examined. Food has been documented to have antidiabetic properties, including cucurbits in the Cucurbitaceae family [6]. Pumpkin, a vegetable, belongs to the Cucurbitaceae. Tis family comprises about 130 genera with 800 species and can be cultivated worldwide [7,8]. Pumpkin has been used in traditional systems of medicine. It exhibits various pharmacological actions, such as antidiabetic, anticancer, antihypertension, antioxidant, antiinfammation, antihyperlipidemic, antimicrobial, and immunomodulation [9]. Its fruits are a valuable part of the plant with a high nutritional value [10] and are a good source of polyphenols [11], vitamin A, iron, phosphorus, calcium, and polysaccharides. Most bioactive chemicals are concentrated in its fruits [12].
C. moschata is a potential source of many antioxidant efects, such as carotenoids and polyphenols. Its fruit pulp is rich in many essential human and animal body compounds, such as amino acids, carbohydrates, polysaccharides, vitamins, and minerals [13,14]. Its fruits are also rich in polysaccharides that show strong hypoglycemic and antidiabetic efects [15][16][17][18]. A previous investigation showed that pumpkin is reported to reduce blood glucose in type 2 diabetic patients [19].
C. maxima is traditionally used in Mexico, China, and India for its hypoglycemic efect helpful in controlling blood glucose [20,21]. It has high potential for antidiabetic activity and can decrease high blood glucose levels in critically ill diabetic patients [21]. Its fruit juice, hydroalcoholic extract [20], fruit fesh powder [22], alcoholic seed extract [23], aqueous extract [24], and methanol extract [25,26] significantly decreased hyperglycemia in STZ-induced diabetic rats. Studies in animal and human models revealed that treatment with some cucurbits exhibited hypoglycemic effects and stimulated β-cell regeneration. At least one of the bioactive components which produced these efects was a polysaccharide [18].
Crude polysaccharides from pumpkin showed hypoglycemic activity in alloxan-induced diabetic rats [27]. Moreover, the pumpkin polysaccharide extract gave excellent healing potential in alloxan-induced diabetic male ICR mice [28] and alloxan-induced diabetic rabbits [17]. It is thought that these efects may have been due to the antioxidant nature of the polysaccharide protecting pancreatic β cells [29], resulting in a reduced need for insulin in diabetic patients [30]. Pumpkin has been reported to be a source of antioxidants such as polyphenols and carotenoids [31], acidic polysaccharide extracted from pumpkin [32], watersoluble polysaccharide fraction from fruits of C. maxima [33], fractions of water-soluble polysaccharide from the fruit of pumpkin [29], methanol extract from aerial parts of C. maxima [25], mature fruits of C. moschata [34], methanolic and aqueous extracts of C. moschata fruits [35], methanolic extract of leaves of C. maxima [10], ethanol extracts of C. moschata and C. maxima [36], leaf extract of C. moschata [37], C. moschata four [38], and fesh of C. maxima [39].
To elucidate the underlying mechanisms that could lead to the antidiabetic and antioxidant activities of the pumpkin, the present study was therefore undertaken to investigate the antidiabetic activity of extracts from the fruit pulp of C. moschata and C. maxima in STZ-induced diabetic rats and the antioxidant activity by DPPH scavenging and FRAP assays and evaluate the total phenolic and favonoid contents. Te results might help identify novel and relevant natural resources for the treatment of diabetes.

Plant Materials.
Fresh mature fruits of C. moschata purchased from local gardens in Yasothon Province and C. maxima from a local market in Khon Kaen Province, Northeastern Tailand, were used in this study. Te pumpkin fruit specimens were identifed and authenticated by a botanist in the Department of Biology, Faculty of Science, Mahasarakham University, Tailand. Voucher plant specimens (MSU-SAMOS and MSU-SAMAX) have been deposited at the same department.

Preparation of Extracts.
Te plant fruits were washed, and the fruit pulp was cut into small pieces, dried in a hot air oven at 50°C. Te dried samples were powdered using an electric grinder. Te plant powder was extracted according to the procedure by Quanhong et al. [29] with slight modifcations. Te plant powder was separately suspended in distilled water at a ratio of 1 g powder:20 mL of distilled water, stirred in a water bath at 45°C for 16 h, and cooled and centrifuged at 4,800 rpm for 25 min. Te supernatant was collected, concentrated to a quarter of the original volume by evaporating under reduced pressure at 45°C, and fltered to remove any residues. Tree volumes of 95% ethanol were added to the fltrate to induce precipitation. Te precipitated preparations were centrifuged at 4,800 rpm for 25 min. Te pellet was collected, washed with ethanol, and freezedried. Each preparation was dissolved in distilled water (1 g/50 mL), dialysed against distilled water at 4°C for 72 h, and then freeze-dried. Te yields of extracts from C. moschata (PCMOS) and C. maxima (PCMAX) were 1.15 and 1.10% DW, respectively. Because the active ingredient found in pumpkin has been reported to be polysaccharide [15], the PCMOS and PCMAX extracts were assayed for polysaccharides using the phenol-sulfuric acid method. A 2 mL aliquot of the extract suspension was mixed with 1 mL of 5% aqueous solution of phenol in a test tube. Five mL of concentrated sulfuric acid was added rapidly to the mixture. After allowing it to stand for 10 min, the mixture was mixed thoroughly using a vortex mixer for 30 s and placed for 20 min in a water bath at room temperature (27°C) for colour development. Light absorption at 490 nm was recorded with a spectrophotometer. Te percentage polysaccharide in PCMOS and PCMAX was calculated and found to be 33.41 and 36.99%, respectively.

Experimental Animals.
Male albino Wistar rats (200-250 g body weight) from the Laboratory Animal Centre, Suranaree University of Technology, Tailand, were used to assess antidiabetic activity. Te rats were housed at room temperature (23 ± 2°C) and relative humidity (50-55%), and exposed to a 12 h day-night cycle, and fed with a standard commercial pellet diet and water ad libitum. Animals were maintained in accordance with the guidelines of the Committee Care and Use of Laboratory Animal Resource, National Research Council Tailand, and the advice of the Institutional Animal Care and Use Committee, Mahasarakham University, Tailand, with approval number IACUC/MSU 0020/2017.

Induction of Diabetes.
Te overnight fasting rats were induced to be diabetic by a single intraperitoneal injection of 65 mg/kg·b.w. streptozotocin (STZ, Sigma Chemicals, St.
After STZ injection, the rats were provided with 2% sucrose in drinking water for 48 h to alleviate discomfort after initiating the hypoglycemic phase. After 3 days of diabetic induction, fasting blood glucose (FBG) of each rat was assessed by using a glucometer (Accu-Check, Roche, Manheim, Germany). Te rats with FBG at or above 126 mg/dL were considered to be diabetic and employed in the study [40].

Experimental Design.
A total of 30 rats, 6 normal rats and 24 diabetic rats, were used. Te rats were divided into fve groups with six rats in each. Group I: normal rats were treated with 0.5% Tween 80 (normal controls). Group II: diabetic rats were treated with 0.5% Tween 80 (diabetic controls). Groups III, IV, and V: diabetic rats were treated with PCMOS 500 mg/kg·b.w., PCMAX 500 mg/kg·b.w., and glibenclamide 0.5 mg/kg·b.w., respectively. PCMOS and PCMAX were suspended in 0.5% Tween 80 and administered orally to the rats using an orogastric tube. Te volume of administration was 10 mL/kg·b.w [41]. Te oral administration of PCMOS, PCMAX, and the standard drug, glibenclamide, was carried out once a day for a period of six weeks. Body weight, fasting blood glucose, haematological values, serum insulin levels, biochemical parameters for lipid profles, renal and hepatic functions, and pancreatic histological observation of the rats were determined.

Determination of Body Weight and Fasting Blood Glucose.
Before the commencement of the experiments, body weight and fasting blood glucose levels of all rats were monitored. After the administration of PCMOS, PCMAX, and glibenclamide, the body weight and fasting blood glucose levels were measured weekly for 6 weeks. Te fasting blood glucose level was evaluated from a drop of fasting blood drawn by the tail prick method using a glucometer (Accu-Check, Roche, Manheim, Germany).

Determination of Haematological Values.
At the end of the experiments, the rats were made to fast overnight and were sacrifced under ether anesthesia. Blood samples were collected from the rat hearts by cardiac puncture and heparinized. Te heparinized blood was used for the determination of haematological values, including white blood cells (WBCs), red blood cells (RBCs), hemoglobin (Hb), hematocrit (Hct), neutrophils (Neu), lymphocytes (Lym), monocytes (Mono), and platelets (Plt) by using an automatic blood chemical analyzer (BT 2000 plus, Germany).

Determination of Serum Insulin Levels.
Te blood sample collected from each rat heart was centrifuged to separate blood serum. Te insulin levels in the serum were determined using a radio immune assay kit (MP Biomedicals; Orangeburg, NY, USA) and detected using an automatic gamma counter (Wallac 1470 Wizard; Perkin Elmer Instrument;Überlingen, Germany).

Histological Observation.
After scarifcation, the rat pancreas was removed immediately and prepared for histological observation. Te pancreas was washed with normal saline, fxed in 10% formaldehyde, embedded in parafn, and sectioned using a rotary microtome. Slides of the sections of approximately 5 microns were routinely stained with hematoxylin and eosin (H&E) and were qualitatively (morphological) and quantitatively (morphometric) analyzed according to Berraaouan et al. [42] with some modifcations.

Determination of Antioxidant Activity.
Te antioxidant activity of PCMOS and PCMAX was determined by using the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay and ferric reducing antioxidant power (FRAP) assay. As antioxidant potential of many plants is mainly due to phenolic components, total phenolic and favonoid contents in PCMOS and PCMAX were also investigated.

DPPH Free Radical Scavenging Assay.
Te antioxidant activity of PCMOS and PCMAX using the DPPH assay was assessed according to the method by Nakornriab and Krasaetep [43] with suitable modifcations. PCMOS and ECMAX at the concentrations of 0.1, 0.2, 0.4, 0.6, 0.8, and 1 mg/mL were mixed with 3.0 mL of 0.1 mM DPPH solution. Te mixture was shaken and incubated at 37°C for 30 min in the dark. Absorbance at 517 nm was recorded using a spectrophotometer. Ascorbic acid was used as a reference reagent. Te DPPH radical scavenging assay was carried out with three replicates. Percentage inhibition of DPPH radicals was calculated using the following equation: % inhibition � 1 − absorbance of the solution with extracts absorbance of the solution without extracts × 100.
Te Scientifc World Journal IC 50 of PCMOS, PCMAX, and ascorbic acid was estimated from plots of % inhibition vs. concentration.

Ferric Reducing Antioxidant Power (FRAP) Assay.
Te FRAP assay was performed using a modifed method described by Zolfaghari et al. [44]. PCMOS or PCMAX solution (100 µL of 10 mg/mL) was mixed with 3 mL of FRAP solution (300 mM acetate bufer, pH 3.6, 10 mM/L TPTZ in 40 mM/L HCl, and 20 mM/L FeCl 3 anhydrous). Te working FRAP reagent was prepared freshly by mixing acetate bufer, TPTZ solution, and FeCl 3 anhydrous in the ratio of 10 : 1 : 1. Te prepared FRAP solution was incubated at 37°C for 4 min. Te absorbance was then measured at 593 nm using a UV-visible spectrophotometer. Te results were expressed as millimolar ferrous sulphate per gram of dry weight (mM Fe (II)/g DW).

Determination of Total Phenolic Content.
Te total phenolic content in PCMOS and PCMAX was determined calorimetrically using the Folin-Ciocalteu reagent according to the modifed method by Bonoli et al. [45]. 50 µL of the extracts (10 mg/mL) was mixed with 1.5 mL of the 10% Folin-Ciocalteu reagent (diluted 10 fold with distilled water). Te mixed solution was incubated at room temperature for 15 min, and then, 1.5 mL of 10% (w/v) sodium carbonate solution was added. Te mixture was shaken and incubated again at room temperature for 15 min. Gallic acid was used as a standard agent. Te absorbance of all samples was measured at 750 nm using a UV-visible spectrophotometer. Total phenolic content was calculated by comparison to a gallic acid standard curve and expressed as mg gallic acid equivalent/g (mg GAE)/g.

Determination of Total Flavonoid Content.
Te amount of total favonoid content of PCMOS and PCMAX was determined according to the modifed method by Prasad et al. [46]. PCMOS or PCMAX (250 µL of 10 mg/mL) was mixed with 1.25 mL of deionized water and 75 µL of 5% sodium nitrite (NaNO 2 ) solution and allowed to stand for 5 min at room temperature. Aluminium chloride (AlCl 3 ) (150 µL of 10% solution) was added to the mixture and allowed to react for 6 min at room temperature. Ten, 500 µL of 1 M sodium hydroxide (NaOH) and 775 µL of distilled water were added to the mixture. Te absorbance of all samples was immediately measured at 510 nm using a UVvisible spectrophotometer. Te samples were assayed in triplicate. Te amount of total favonoid content was calculated using a catechin calibration curve and expressed in mgCE/g.

2.
14. Data Analysis. Data were expressed as the mean-± standard error of mean (SEM). Te signifcant diference in data between diferent groups was compared using oneway analysis of variance (ANOVA) followed by Duncan's test. p < 0.05 was considered to indicate a signifcant diference.

Determination of Antidiabetic Activity.
Te results of body weight, haematological values, blood glucose levels, serum insulin levels, number of β cells, size of islets of Langerhans, biochemical parameters including lipid profles, and renal and hepatic function parameters of normal controls, diabetic controls, and diabetic rats treated with PCMOS, PCMAX, and glibenclamide are presented in Tables 1-4 and Figure 1, respectively.

Body Weight.
At the initial stage, the body weight of the rats was not diferent. However, at the end of the experiments, the body weight of the diabetic controls decreased signifcantly (p < 0.05) when compared to that of the normal controls (301.56 ± 11.12 vs. 361.33 ± 10.95 g). It increased signifcantly (p < 0.05) in the diabetic rats treated with PCMOS (354.16 ± 7.44 g) and PCMAX (359.66 ± 7.74 g) compared to that in the diabetic controls and in the diabetic rats treated with glibenclamide (354.16 ± 8.96 g).

Fasting Blood Glucose Levels.
At the initial stage, fasting blood glucose of the diabetic rats was signifcantly higher (p < 0.05) than that of the normal controls. At the end of the experiments, the fasting blood glucose level of the diabetic controls (186.66 ± 15.70 mg/dL) increased signifcantly (p < 0.05) compared to that in the normal controls (83.07 ± 11.47 mg/dl). In contrast, it reduced signifcantly (p < 0.05) in the diabetic rats treated with PCMOS (102.16 ± 11.20 mg/dl) and PCMAX (96.00 ± 13.05 mg/dl) compared to that in the diabetic controls, but it was not diferent from that in the diabetic rats treated with glibenclamide (96.66 ± 12.32 mg/dL).

Serum Insulin Level.
Te serum insulin level of the diabetic controls (12.14 ± 0.34 µIU/mL) decreased signifcantly (p < 0.05) compared with that of the normal controls (23.88 ± 1.38 µIU/mL). In contrast, it increased signifcantly (p < 0.05) in the diabetic rats treated with PCMAX (16.64 ± 3.20 µIU/mL) and increased slightly in the diabetic rats treated with PCMOS (13.00 ± 0.20 µIU/mL). However, it was less than that in the diabetic rats treated with glibenclamide (24.80 ± 0.50 µIU/ml) which was close to that in the normal controls.
3.6.1. Renal Function. TP in the diabetic controls decreased signifcantly (p < 0.05) compared to that in the normal controls. In contrast, it increased signifcantly (p < 0.05) in the diabetic rats treated with PCMOS, PCMAX, and glibenclamide and was similar to that in the normal controls. However, BUN and creatinine in the diabetic controls and diabetic rats treated with PCMOS, PCMAX, and glibenclamide were not diferent and were not diferent from those in the normal controls.

Hepatic Function.
AST in the diabetic controls increased signifcantly (p < 0.05) compared to that in the normal controls. However, it decreased signifcantly (p < 0.05) in the diabetic rats treated with PCMOS, PCMAX, and glibenclamide and was not diferent from that in the normal controls. Changes in ALT were not found among diferent groups of rats. ALP in the diabetic controls increased signifcantly (p < 0.05) but decreased signifcantly (p < 0.05) in the diabetic rats treated with PCMOS, PCMAX, and glibenclamide compared to that in the diabetic controls. Interestingly, ALP in the diabetic rats treated with PCMOS, PCMAX, and glibenclamide was comparable to that in the normal controls.

Histological Observation.
Histological observations revealed that the pancreatic tissues of the diabetic controls experienced morphological changes with injury and death of pancreatic β cells leading to a decrease in the size of islets of Langerhans (143.74 ± 2.11µ; Figure 1(b)) and the number of β cells (84.06 ± 2.02 cells/unit; Table 3) compared with the normal controls (222.03 ± 2.71µ; Figure 1(a) and 190.37 ± 7.84 cells/unit; Table 3). Surprisingly, PCMOS and PCMAX attenuated diabetes-induced pancreatic morphological changes by signifcantly increasing (p < 0.05) the size of islets of Langerhans and the number of β cells in the diabetic rats treated with PCMOS (210.46 ± 4.05µ; Figure 1(c) and 134.02 ± 4.11 cells/unit; Table 3) and in the diabetic rats treated with PCMAX (214.27 ± 4.49µ; Figure 1(d) and 162.34 ± 3.72 cells/unit; Table 3). However, they were not diferent from those in the diabetic rats treated with glibenclamide (209.80 ± 3.46µ; Figure 1(e) and 158.25 ± 9.11 cells/unit).

Determination of Antioxidant Activity.
Te results of the determination of antioxidant activity of PCMOS and PCMAX are presented in Table 5. Te DPPH assay revealed that PCMOS exhibited a scavenging DPPH radical less potent than PCMAX did with EC50 of 13.69 ± 0.45 vs. 8.03 ± 0.95 µg/mL, respectively. However, PCMOS and PCMAX possessed a relatively low antioxidant activity compared to ascorbic acid (0.01 ± 0.02 µg/mL); while using the FRAP assay, it was demonstrated that PCMOS exhibited less antioxidant activity by reducing Fe 2+ than ECMAX did with 31.23 ± 3.15 vs. 42.67 ± 0.77 mMFe 2+ /g, respectively. PCMOS and PCMAX exhibited antioxidant activity as measured by the DPPH and FRAP assay in a concentrationdependent manner. PCMOS showed less TPC and TFC values than PCMAX with values of 5.27 ± 0.31 vs. 11.22 ± 0.19 mgGAE/g and 20.81 ± 0.09 vs. 55.08 ± 2.21 mgCE/g, respectively.

. Discussion
Streptozotocin (STZ) is one of the most commonly used substances to induce diabetes in rats. STZ selectively destroys pancreatic insulin-secreting β cells causing diabetes similar to type 2 diabetes in humans according to [23], and induction of diabetes with STZ was associated with the characteristic loss of body weight due to increased muscle wasting and loss of tissue proteins because protein and fat are broken down to provide energy instead of blood glucose [47]; therefore, the body weight in the STZ-induced diabetic rats (diabetic controls) in the present study decreased signifcantly. Te results are consistent with the report by Baldi et al. who found that a pumpkin concentrate caused a signifcant decrease in body weight in diabetic control rats [48]. Oral administration of PCMOS and PCMAX at a dose of 500 mg/kg to the rats once a day for six weeks increased the body weight of the PCMOS and PCMAX-treated diabetic Values are expressed as means ± S.E.M, n � 6 rats in each group. Tere was no signifcant diference between means that have the same alphabetical superscript letter in the same column (p < 0.05). Statistical analysis was carried out using one-way ANOVA followed by Duncan's test. DM � diabetic rats; Glib � glibenclamide.  Values are expressed as means ± S.E.M, n � 6 rats in each group. Tere was a signifcant diference between means that have the diferent superscript letters in the same row (p < 0.05). Statistical analysis was carried out using one-way ANOVA followed by Duncan's test. DM � diabetic rats; Glib � glibenclamide; FBG � fasting blood glucose. Values are expressed as means ± S.E.M, n � 6 rats in each group. Tere was a signifcant diference between means that have the diferent superscript letters in the same row (p < 0.05). Statistical analysis was carried out using one-way ANOVA followed by Duncan's test. DM � diabetic rats; Glib � glibenclamide; TG � triglyceride; CHO � cholesterol; LDL � low-density lipoprotein; HDL � high-density lipoprotein; TP � total protein; BUN � blood urea nitrogen; Crea � creatinine; AST �aspartate aminotransferase; ALT �alanine aminotransferase; ALP � alkaline phosphatase.  Te Scientifc World Journal rats because the characteristics of PCMOS and PCMAX were consistent with the pumpkin concentrate preparation, which increased the body weight of diabetic rats [23], and a watersoluble polysaccharide from pumpkin signifcantly increased the body weight of diabetic rabbits [17]. Te action of PCMOS and PCMAX to increase the body weight of diabetic rats is probably due to their hypoglycemic property, which increases the utilization of blood glucose and, in turn, prevents the breakdown of fat and protein to provide energy. STZ causes the destruction of the pancreatic insulinsecretingβ cells, which reduces insulin and, in turn, results in a rise in blood glucose concentration, i.e., hyperglycemia [49]; the extracts, especially PCMAX, signifcantly decreased the blood glucose levels in the diabetic rats. Tis indicates that PCMAX contains a hypoglycemic agent which is responsible for lowering blood glucose levels. Te blood glucose level of the diabetic control rats was still high during the experimentation for six weeks. However, the haematological values except for the platelet in the diabetic control rats and diabetic rats treated with PCMOS and PCMAX did not alter compared to those in the normal controls. Tis indicates that PCMOS and PCMAX produce nontoxicity as judged by haematological values. Serum insulin levels were found to be increased in the diabetic rats treated with PCMOS and PCMAX. Tis result is in agreement with results for the alcoholic seed extract of C. maxima which   Te Scientifc World Journal signifcantly reduced the elevated fasting blood glucose level by increasing the pancreatic secretion of insulin from β cells of islets of Langerhans in STZ-induced diabetic albino Wistar rats [23]. Lipid profles, including total cholesterol (TC), triglycerides (TGs), and low-density lipoprotein (LDL), increased signifcantly. In contrast, the high-density lipoprotein (HDL) decreased signifcantly in the diabetic controls [50,51]. In the present study, oral administration of PCMOS and PCMAX at a dose of 500 mg/kg to the diabetic rats once a day for six weeks signifcantly decreased TC, TG, and LDL levels but increased HDL levels in the treated diabetic rats. In agreement with the present data, there have been reports that the lipid profles were changed to decrease total cholesterol, triglycerides, and LDL and increase HDL levels in the diabetic rats treated with pumpkin (C. maxima) at a dose of 400 mg/kg [52], and the administration of the pumpkin polysaccharide signifcantly lowered TC and TG in diabetic rabbits [17]. Tese results may be associated with the possible protective efect of the extract (mainly polysaccharides) on pancreatic β cells. In addition, these efects may be due to the low activity of cholesterol biosynthetic enzymes or the insignifcant level of lipolysis under the control of insulin [53]. Moreover, in pumpkin seeds, unsaturated fatty acids, such as oleic acid and linoleic acid, can reduce cholesterol levels in rats [54]. Tese activities of PCMOS and PCMAX probably involve inhibiting the absorption of bile acids and cholesterol and enhancing the activity of LDL receptors [55].
PCMOS and PCMAX recovered TP and showed no efects on BUN as BUN in the diabetic controls, diabetic rats treated with PCMOS, PCMAX, and glibenclamide, and normal controls was not diferent. Tese results indicate the nontoxicity of PCMOS and PCMAX in renal function.
AST and ALP increased in the diabetic controls, but they decreased in the diabetic rats treated with PCMOS and PCMAX, and the levels were close to those in the normal controls. In addition, ALT in all rats was not diferent. Tese results indicate that PCMOS and PCMAX can improve the pathological hepatic function resulting from STZ-induced diabetes.
In the present study, histological observation revealed a diference in the mean diameter and the number of Langerhans islets and the number of pancreatic β cells between the diabetic controls and the normal controls. Decreasing the size of islets of Langerhans and the number of pancreatic β cells indicated the destruction of pancreatic tissues in diabetic rats. Aboulthana et al. reported that STZ caused infammatory changes in pancreatic islets of diabetic rats. Consequently, this leads to atrophy in islands of the Langerhans cells associated with the vacillation of islet cells [56]. Tis might be due to the destruction of β cells and hence a decrease in pancreatic islets. Tis fnding agrees with that of Sedigheh et al. who stated that histological analysis showed signifcant diferences in the mean diameter and the number of Langerhans islets between the diabetic control group and the standard control group [57]. Te mean diameter of islets in the diabetic group signifcantly decreased compared with that in the normal control group. Pancreatic β cells take up STZ via the GLUT 2 transporter, which leads to β-cell death by DNA fragmentation [58]. Due to the optical microscope images of islets of β cells of experimental animals, this suggests that the oral administration of PCMOS and PCMAX was potentially efective after STZ damage. Te histopathological investigation showed that PCMOS and PCMAX could prevent pancreatic β-cell damage and increase the size and number of islets of Langerhans, leading to an increase in insulin levels. It has been reported that the fruit fesh powder of C. maxima signifcantly improved blood glucose and insulin levels and healed Langerhans islets by increasing the number and size of Langerhans islets in STZinduced diabetic rats, indicating the efects of pumpkin powder on the repair and restoration of pancreatic tissues [22], and the methanol extract of aerial parts of C maxima altered the histological profles of the pancreas of the STZinduced diabetic albino Wistar rats to match those in the normal controls [25] more closely. Te activity of PCMOS and PCMAX was in agreement with that of the methanol extract of C. maxima which attenuated diabetes-induced pancreatic injury in STZ-induced diabetic rats [26]. Administration of antioxidants to diabetic rats signifcantly increased the number of β cells [59]. Antioxidant compounds could increase the number of pancreatic β cells by enhancing the repair and restoration of these cells. Moreover, favonoids could protect DNA from oxidative damage to lessen the problem in β cells [60][61][62].
According to these fndings, (1) the phytochemical investigation of pumpkins reveals the presence of polysaccharides [15], (2) chemicals from pumpkin fruit pulp that are hypoglycemic include polysaccharides [63], (3) polysaccharides cause a signifcant decrease in the blood glucose of STZ-induced diabetic rats [64], (4) powdered pumpkin has hypoglycemic activity in alloxan-induced diabetic rats [58], which is due to polysaccharide components [15,28,58,65], (5) protein-bound polysaccharides from the fruit of pumpkin (C. moschata) could decrease blood glucose levels [29], and (6) the polysaccharide is the main chemical in extracts, with 33.41% in PCMOS and 36.99% in PCMAX. Tese suggest that the hypoglycemic activity of PCMOS and PCMAX could be partly due to polysaccharide content. Previous studies using high-performance liquid chromatography (HPLC) analysis found the content of free sugars and polysaccharides in C. maxima fruits [66]. In addition, C. moschata polysaccharide possessed signifcant cytoprotective efects on diabetes and antioxidative activity [32], favonoid extracted from Cucurbitaceae possessed hypoglycemic activity in diabetic rats [67], and oral administration of pumpkin seed extracts produced a signifcant antidiabetic efect in controlling the blood glucose level, possibly due to favonoids [22]. Tus, the extracts were signifcantly antidiabetic, and the antioxidant efect correlates with the presence of the components mentioned.
Based on the presence of total phenolic (TPC) and total favonoid (TFC) content in PCMOS and PCMAX, PCMOS and PCMAX exhibited signifcant antidiabetic activity, almost the same as glibenclamide, an antidiabetic drug; the mechanism of action on antidiabetic activity of PCMOS and Te Scientifc World Journal PCMAX may be due to the polysaccharide, phenolic, and favonoid content improving STZ-induced damage to pancreatic islets of Langerhans and stimulated serum insulin secretion from pancreatic β cells resulting in a reduction of blood glucose.
Te DPPH scavenging and ferric reducing activity assay revealed the antioxidant activity of PCMOS and PCMAX, and PCMOS exhibited less potent antioxidant activity than PCMAX. However, they showed a relatively low activity compared to ascorbic acid, a reference agent. Because phenolic and favonoid compounds are responsible for antioxidant activity in plants [68], the phenolic compound present in plants possesses hydroxyl groups with radical scavenging activity; antioxidants, in interaction with DPPH, either transfer an electron or a hydrogen atom to DPPH [69]. Te methanol extract from aerial parts of C. maxima exhibits potent antioxidant activity with free radical scavenging activity equivalent to BHT, and the antioxidant property may be due to phenolic and favonoid contents [25]. Terefore, the antioxidant activity of PCMOS and PCMAX in the present study was partly due to total phenolic and favonoid contents. Nevertheless, the factors which involve the antioxidant efect of C. moschata showed high genetic variability for synthesising phenolic compounds, carotenoids, and antioxidant activity [70]. While the ABTS radical scavenging activity of pumpkin tended to increase according to the level of pumpkin leaf powder [71], the fruit acetone extract has an antioxidant efect of being higher in C. maxima lines than in C. moschata lines [14], and the antioxidant activity is more afected by the type of cultivar than by the pumpkin species [13]. Furthermore, numerous studies have shown that administering antioxidants to diabetic rats increases the number of β cells [42,59]. Terefore, the pancreatic protective efect and its hypoglycemic properties should be attributable, in part, to the antioxidant activity of these two fruit pulps [22].

Conclusions
Te fruit pulp extracts from C. moschata (PCMOS) and C. maxima (PCMAX) exhibit both antidiabetic activity in STZ-induced diabetic rats and antioxidant activity. Te extracts display the antidiabetic activity by increasing the β-cell number and size of islets of Langerhans which lead to reducing blood glucose levels in the treated diabetic rats. Tey exert the antioxidant activity by DPPH scavenging and ferric reducing activity. PCMAX exhibits more potent activities than PCMOS which may result from PCMAX giving more polysaccharides and total phenolic and favonoid contents. In the present study, a single dose (500 mg/kg·b.w.) of the extracts was used for the antidiabetic activity assessment. In further studies, various doses of the extracts should be employed to determine whether the activity is in a dose-dependent manner.

Data Availability
Te data that support the fndings of this study are available from the corresponding author upon request.

Conflicts of Interest
Te authors declare that they have no conficts of interest.