Green synthesis of magnesium oxide nanoparticles from Solanum lycopersicum and evaluation of their antidiabetic effect in rats

 Corresponding author: N. John Sushma. Copyright © 2025 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution License 4.0. Green synthesis of magnesium oxide nanoparticles from Solanum lycopersicum and evaluation of their antidiabetic effect in rats Uma Priya L and John Sushma Nannepaga * Department of Biotechnology, Sri Padmavati Mahila Visvavidyalayam, Tirupati, Andhra Pradesh, India. World Journal of Advanced Research and Reviews, 2025, 26(03), 1380-1392 Publication history: Received on 03 April 2025; revised on 11 May 2025; accepted on 13 May 2025 Article DOI: https://doi.org/10.30574/wjarr.2025.26.3.1709 Abstract This study investigates the green synthesis of magnesium oxide nanoparticles (MgO NPs) using Solanum lycopersicum (tomato) extract and evaluates their antidiabetic effect in rats. Diabetic neuropathy (DN) being the common and debilitating complication of diabetes mellitus was therapeutically targeted. The synthesized MgO NPs were characterized using UV-Vis spectrophotometry, phase contrast microscopy, FTIR, SEM-EDS, particle size and zeta potential analyser, and TEM. The antidiabetic neuropathic effect of the Solanum lycopersicum-derived MgO NPs was assessed in streptozotocin-induced diabetic rats by measuring biochemical parameters (blood glucose, HbA1c, and insulin levels), performing histopathological analysis of various brain regions, and conducting behavioral tests to evaluate nociception and motor activity. The results indicate the successful green synthesis of MgO NPs from Solanum lycopersicum and demonstrate their potential to ameliorate diabetic neuropathy in rats, suggesting a promising antidiabetic effect. Keywords: Green Synthesis; Magnesium Oxide Nanoparticles (MgO NPs); Solanum lycopersicum; Antidiabetic Activity; Streptozotocin-Induced Diabetes 1. Introduction Diabetes mellitus, particularly type 2 diabetes mellitus (T2DM), is a growing global health concern characterized by chronic hyperglycemia resulting from impaired insulin secretion, insulin resistance, or both. Persistent high blood glucose levels can lead to long-term damage to various organs, including the heart, kidneys, eyes, and blood vessels [1]. Despite the availability of numerous synthetic antidiabetic drugs, many suffer from limitations such as poor bioavailability, adverse side effects, high cost, and the need for long-term administration. As a result, there is increasing interest in alternative, safer, and more effective therapeutic strategies, including those derived from nanotechnology and medicinal plants [2]. Nanoparticles (NPs) have shown tremendous potential in the treatment of metabolic disorders due to their unique physicochemical properties, including high surface area-to-volume ratio, enhanced cellular uptake, and controlled drug release [3]. Among them, magnesium oxide nanoparticles (MgO NPs) have attracted attention for their bioactivity, biocompatibility, and antioxidant potential. Magnesium plays a vital role in insulin action, glucose metabolism, and enzymatic reactions related to energy production [4]. Notably, magnesium deficiency is commonly observed in individuals with type 2 diabetes and is linked to increased insulin resistance and poor glycemic control. Conventional chemical synthesis of nanoparticles, however, often involves toxic reagents and harsh conditions that pose environmental and biological risks. To address these challenges, green synthesis methods utilizing plant extracts have emerged as eco-friendly and sustainable alternatives. World Journal of Advanced Research and Reviews, 2025, 26(03), 1380-1392 1381 Plant-based synthesis offers several advantages, including mild reaction conditions, low cost, and the incorporation of phytochemicals that can enhance the biological functionality of nanoparticles. Solanum lycopersicum (tomato) is rich in bioactive compounds such as lycopene, flavonoids, and phenolic acids, which possess well-documented antioxidant, anti-inflammatory, and antidiabetic properties [5]. These phytochemicals can act as natural reducing and stabilizing agents in the green synthesis of nanoparticles while also contributing to their therapeutic activity. The present study focuses on the green synthesis and characterization of magnesium oxide nanoparticles using Solanum lycopersicum extract and evaluates their potential antidiabetic effect in streptozotocin-induced diabetic rats. This investigation aims to explore a novel, plant-based nanotherapeutic approach for the management of diabetes mellitus. 2. Materials and Methods 2.1. Plant and Chemical Materials The Solanum lycopersicum plant was collected from the botanical garden. Chemicals were purchased from Sigma Aldrich. 2.2. Preparation of the Extract Solanum lycopersicum fruits were collected, rinsed with distilled water, peeled, and ground into a fine paste which was filtered through a sterile funnel containing Whatman filter paper No. 1. This extract was stored at 4°C. 2.3. Spectrophotometric Analysis of Synthesized MgO NPs MgO Nanoparticles were synthesized by adding 5 ml of plant extract to 100 ml of MgCl2, following a standardized protocol. Then, 50 ml of NaOH was slowly added, and the mixture was centrifuged at 10,000 rpm. The precipitate was calcined at 100-200 °C, and its absorbance was recorded at a wavelength range of 200 nm – 800 nm using a UV spectrophotometer [4] 2.4. Phase Contrast Microscopy The synthesized nanoparticles were dispersed in water and shaken. A drop of this dispersion was observed with phase contrast microscope. 2.5. Analysis of Functional Groups of Nanoparticles by FTIR 99 mg of dry KBr was homogeneously mixed with 1 mg of MgO nanoparticles to make pellets of 7 mm diameter and 0.5 mm thickness. An FTIR spectrum was obtained on Alpha Bruker FT-IR spectrometer. 2.6. Particle Size and Zeta Potential Analysis The zeta potential and size distribution of MgO nanoparticles were measured with Horiba Nano ZS. 1 mg of nanoparticles was dispersed in 1 ml of ultrapure water. This suspension was ultrasonically agitated for 60 seconds. 2.7. DPPH Assay Samples of different concentrations (5 µg/ml, 10 µg/ml, 15 µg/ml, 20 µg/ml, 25 µg/ml) and ascorbic acid (standard) were prepared. The solution was made up to 3 ml with 0.004% DPPH (in methanol). Absorbance was measured at 517 nm [6]. 2.8. Animal Selection and Grouping Male albino rats, with an average age of 6 months and weight of 120 ± 20 g. They were divided into 3 groups: • Group 1 (control): No treatment given. • Group 2 (induced): Single dose of 40 mg/kg streptozotocin (intraperitoneal) to induce diabetes. • Group 3 (induced + treated): Streptozotocin and MgO NPs (4 mg/kg, intraperitoneal). 2.9. Sampling Protocol In all experimental rats, blood samples were collected from the tail vein. Serum samples (~150 μL) were obtained by centrifugation to analyze blood glucose, insulin, and HbA1c levels. World Journal of Advanced Research and Reviews, 2025, 26(03), 1380-1392 1382 2.10. In vivo Biochemical Determination of Antidiabetic Activity of MgO Nanoparticles Blood glucose was analyzed with a glucometer using blood from the rat's tail. Sampling was timed to maintain consistency, and readings were recorded. HbA1C levels were analyzed using standard ion-exchange HPLC protocol. Insulin levels were analyzed using standard immunoassay. 2.11. Histopathology Cerebrum, cerebellum, medulla oblongata, and hippocampus tissues were harvested and preserved in 10% buffered formalin. They were sectioned (4 μm) after embedding in paraffin wax. Histopathological evaluation was performed using Hematoxylin and Eosin stains and observed under phase contrast microscope. 2.12. Behavioral Tests • Heat hyperalgesic test: Paw withdrawal latency (PWL) of the right hind paw of rats in response to heat was measured using an infrared radiant heat apparatus. Animals were allowed to acclimatize for 5 minutes in the chamber. The plantar surface of the hind paw was exposed to the heat source, and the time taken for paw withdrawal was recorded. Baseline latency was set at 6 s, and a cut-off latency at 20 s [7] • Tail immersion test: Hot allodynia or hyperalgesia was assessed using the tail immersion test at 42-48 °C. 5 cm distal part of the rat’s tail was immersed in a water-filled container maintained at the required temperature. The duration of tail immersion was recorded, with a cut-off time of 20 seconds [8]. • Spontaneous locomotor activity test: Spontaneous motor activity was assessed using a photoactometer test. Rats were placed in an enclosed chamber (30 × 30 × 30 cm) containing 6 photocells. Interruptions of the photocell beams by the rats’ movement were recorded digitally [9]. • Formalin test: The formalin test was used to assess the antinociceptive activity of the drugs. Rats were intraperitoneally administered with NPs. The dorsal surface of the right hind paw was injected with 20 µl of 5% formalin. The total time spent licking or biting the injured paw in the early phase (first 5 min) and the late phase (15 min to 40 min) was recorded using a stopwatch [10] 3. Results 3.1. Spectrophotometric Analysis UV-Vi’s spectrophotometry revealed the synthesis of magnesium oxide nanoparticles. The absorption spectrum displayed a peak range of 223-360 nm, with a maximum peak observed at 314 nm (Fig. 1), confirming the formation of MgO NPs. The calculated band gap energy was 3.94 eV, which is lower than the 7.8 eV band gap energy of bulk MgO. Figure 1 Absorption spectrum of green synthesized MgO NPs recorded in UV-vis spectrophotometer showing broad peak at 314 nm with low band gap energy World Journal of Advanced Research and Reviews, 2025, 26(03), 1380-1392 1383 3.2. Phase Contrast Microscopy Phase contrast microscopy was used for preliminary characterization. Observation at 40X magnification showed the presence of distinct particles, indicating the successful formation of nanoparticles (Fig. 2) Figure 2 Green synthesized MgO nanoparticles observed at 40X through Phase Contrast Microscope 3.3. FTIR Analysis FTIR spectroscopy identified the functional groups present in the synthesized nanoparticles. The spectrum showed peaks at 447.22 cm-1, 1495.90 cm-1, and 3405.61 cm-1 (Fig. 3). Figure 3 FTIR spectra of green synthesized MgO NPs showing peak at 447.22 cm-1 indicating Mg-O vibration The peak at 447.22 cm-1 is characteristic of Mg-O stretching vibrations, confirming the formation of MgO. The peaks at 1495.90 cm-1 indicate asymmetrical and symmetrical stretching vibrations of carbonate, and the peak at 3405.61 cm1 suggests the presence of -OH stretching. World Journal of Advanced Research and Reviews, 2025, 26(03), 1380-1392 1384 3.4. SEM-EDS Analysis SEM-EDS analysis provided information on the elemental composition of the synthesized nanoparticles. The analysis revealed the presence of 36.21% Mg (wt %), along with 54.47% O, 6.83% Na and 2.49% S (Fig. 4). Figure 4 Visualization of green synthesized MgO NPs by SEMEDS with 36.21% Mg (wt%) 3.5. Particle Size and Zeta Potential Analysis Particle size analysis determined the mean particle size to be 144.1 nm, confirming the synthesis of nanoparticles (Fig. 5). Figure 5 Graphical representation of the mean particle size of green synthesized MgO NPs at 144.1nm World Journal of Advanced Research and Reviews, 2025, 26(03), 1380-1392 1385 Zeta potential measurement indicated a value of -19.1 mV (Fig. 6), suggesting the formation of stable particles with minimal agglomeration. Figure 6 Graphical representation of the zeta potential of green synthesized MgO NPs at -1.9 mv 3.6. TEM Analysis TEM analysis was used to visualize the size and shape of the nanoparticles at higher magnification. The SAED pattern revealed the polycrystalline nature of the synthesized particles, showing elongated spike-shaped structures with aggregation at the 50 nm scale (Fig. 7). World Journal of Advanced Research and Reviews, 2025, 26(03), 1380-1392 1386 Figure 7 Visualization of green synthesized MgO NPs by TEM SAED 3.7. DPPH Assay The antioxidant activity of the synthesized nanoparticles was evaluated using the DPPH assay. The nanoparticles exhibited 20.19% inhibition at 100 µg/ml when compared with the standard ascorbic acid (Fig. 8). Figure 8 In vitro antioxidant activity of the green synthesized MgO nanoparticles by DPPH assay 3.8. Biochemical Analysis of Antidiabetic Activity In vivo assessment of antidiabetic activity in rats showed significant changes in glucose, HbA1C, and insulin levels. Glucose levels in diabetic neuropathy-induced rats increased to 228.571%, HbA1C levels increased to 239.757%, and insulin levels increased to 1559.34%. Following treatment with MgO nanoparticles, glucose levels decreased to 161.905%, HbA1C levels decreased to 116.146%, and insulin levels decreased to 158.842% (Fig. 9, Table 1). World Journal of Advanced Research and Reviews, 2025, 26(03), 1380-1392 1387 Figure 9 Biochemical analysis of antidiabetic activity of green synthesized MgO NPs Table 1 The comparative analysis of HbA1c levels, glucose levels, and insulin levels across three experimental groups Levels of HbA1c S.No Samples Mean % SD tTEST 1 Control 5.76 100 0.02309 2 Induced 13.81 239.757 0.28868 0.01818 3 Induced + Treated (mg/ml) 6.69 116.146 0.34641 0.21097 Levels of glucose S.No Samples Mean % SD tTEST 1 Control 73.5 100 2.88675 2 Induced 168 228.571 5.7735 0.05042 3 Induced + Treated (mg/ml) 119 161.905 3.4641 0.07658 Levels of insulin S.No Samples Mean % SD tTEST 1 Control 573.8 100 5.7735 2 Induced 8947.5 1559.34 59.4671 0.00354 3 Induced + Treated (mg/ml) 911.435 158.842 3.49297 0.01513 World Journal of Advanced Research and Reviews, 2025, 26(03), 1380-1392 1388 3.9. Histopathology Histopathological examination of the cerebrum, cerebellum, medulla oblongata, and hippocampus of streptozotocininduced rats revealed visible lesions. In contrast, nanoparticle-treated rats showed restoration of normal tissue structure (Figs. 10-13). Figure 10 Photomicrograph showing – (1) Control, (2) Streptozotocin induced, (3) MgO NPs treated cerebral cortex of albino rats Figure 11 Photomicrograph showing – (1) Control, (2) Streptozotocin induced, (3) MgO NPs treated cerebellum of albino rats Figure 12 Photomicrograph showing – (1) Control, (2) Streptozotocin induced, (3) MgO NPs treated medulla oblongata of albino rats