The Antioxidative Role of Natural Compounds from a Green Coconut Mesocarp Undeniably Contributes to Control Diabetic Complications as Evidenced by the Associated Genes and Biochemical Indexes

Abstract

The purpose of this study was to look into the effects of green coconut mesocarp juice extract (CMJE) on diabetes-related problems in streptozotocin- (STZ-) induced type 2 diabetes, as well as the antioxidative functions of its natural compounds in regulating the associated genes and biochemical markers. CMJE's antioxidative properties were evaluated by the standard antioxidant assays of 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide radical, nitric oxide, and ferrous ions along with the total phenolic and flavonoids content. The α-amylase inhibitory effect was measured by an established method. The antidiabetic effect of CMJE was assayed by fructose-fed STZ-induced diabetic models in albino rats. The obtained results were verified by bioinformatics-based network pharmacological tools: STITCH, STRING, GSEA, and Cytoscape plugin cytoHubba bioinformatics tools. The results showed that GC-MS-characterized compounds from CMJE displayed a very promising antioxidative potential. In an animal model study, CMJE significantly (P < 0.05) decreased blood glucose, serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatinine, uric acid, and lipid levels and increased glucose tolerance as well as glucose homeostasis (HOMA-IR and HOMA-b scores). The animal's body weights and relative organ weights were found to be partially restored. Tissue architectures of the pancreas and the kidney were remarkably improved by low doses of CMJE. Compound-protein interactions showed that thymine, catechol, and 5-hydroxymethylfurfural of CMJE interacted with 84 target proteins. Of the top 15 proteins found by Cytoscape 3.6.1, 8, CAT and OGG1 (downregulated) and CASP3, COMT, CYP1B1, DPYD, NQO1, and PTGS1 (upregulated), were dysregulated in diabetes-related kidney disease. The data demonstrate the highly prospective use of CMJE in the regulation of tubulointerstitial tissues of patients with diabetic nephropathy.

Figure 1

Effect of CMJE on scavenging capacities in DPPH (2,2-diphenyl 1-picrylhydrazyl) radical scavenging, SO (superoxide) scavenging, ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) radical scavenging, NO (nitric oxide) scavenging, and IC (iron-chelating) assays. All values were presented as means ± SD (triplicate). Data were analyzed by one-way ANOVA (analysis of variance) using the SPSS (Statistical Package for Social Science) software followed by Tukey's post hoc test.

Figure 2

Effects of CMJE on the α-amylase inhibitory activity. Acarbose was used as the reference standard. Data are presented as means ± SD (triplicate). All data were analyzed by one-way ANOVA (analysis of variance) using the statistical software SPSS (Statistical Package for Social Science, version 20.0) followed by Tukey's post hoc test. Superscript letters (a, b) over the graphical bars indicate the statistical difference between inhibitory effect of CMJE and acarbose.

Figure 3

Effects of CMJE extracts on body weight (a) and weekly blood glucose levels (b) of treated animals. Data are expressed as means ± SD (n = 6). All data were analyzed by one-way ANOVA (analysis of variance). Significance was confirmed at P < 0.05. Alphabets (a–c) over the line graphs indicate the statistical differences among the groups.

Figure 4

Effects of CMJE on oral glucose tolerance (OGT) at the third week of intervention. Data are expressed as means ± SD (n = 6). All data were analyzed by one-way ANOVA (analysis of variance) using the statistical software SPSS (Statistical Package for Social Science, version 20.0) followed by Tukey's post hoc test. Data significance was confirmed at P ≤ 0.05.

Figure 5

Effects of CMJE on serum cholesterol and triglyceride levels of treated animals. Data are expressed as means ± SD (n = 6). All data were analyzed by one-way ANOVA (analysis of variance) using the statistical software SPSS (Statistical Package for Social Science, version 20.0) followed by Tukey's post hoc test for significance at P ≤ 0.05. Superscript letters (a, b) on the bar graph represent the values that are significantly different compared to each other at least at the intervention period.

Figure 6

Histopathological examination by hematoxylin and eosin staining of pancreatic (a) and kidney (b) tissues after the intervention (microscopic resolution: 10 × 40). Light microscopies of pancreatic sections stained with PAS and counterstained with hematoxylin are shown. NC, DC, CMJE50, CMJE100, and CMJE200 stand for normal control (diabetic control, coconut mesocarp juice extract 50 mg/kg bw, coconut mesocarp juice extract 100 mg/kg bw, and coconut mesocarp juice extract 200 mg/kg bw).

Figure 7

GC-MS spectra of CMJE obtained from the mass spectrometer-electron impact ionization (EI) method (GC-MS TQ 8040, Shimadzu Corporation, Kyoto, Japan) coupled with a gas chromatograph (GC-17A, Shimadzu Corporation, Kyoto, Japan). A fused silica capillary column with inlet temperature 260°C and oven temperature 70°C (0 min) was programmed. The mass range was set in the range of 50-550 m/z.

Figure 8

The protein-protein interaction (PPI) network of the 75 target proteins.

Figure 9

Dysregulation of hub targets (mRNA expression levels) in diabetic human kidney tubuli, when compared with control tubuli. FC: fold change, DKDT: diabetic kidney disease tubuli, control: control tubuli, ^∗P < 0.05, ^∗∗P < 0.01, and ^∗∗∗P < 0.001.