Natural dipeptidyl peptidase-IV inhibitor mangiferin mitigates diabetes- and metabolic syndrome-induced changes in experimental rats

Figures & data

Figure 1 DPP-IV in vitro activity of mangiferin and standard synthetic DPP-IV inhibitor (vildagliptin and sitagliptin).

Note: Error bars are presented as SD.
Abbreviations: DPP-IV, dipeptidyl peptidase-IV; MNG, mangiferin; VIL, vildagliptin; SIT, sitagliptin; SD, standard deviation.

Table 1 Anthropometric and lipid profile parameters in various experimental groups

SN	Variable	NC	HF-DC	MET	VIL	MNG
1	AC/TC ratio	1.06	1.06	1.06	1.07	1.06
2	TCh (mg/dL)	64±12	316±34	105±13***	98±8***	85±17***,$
3	TG (mg/dL)	74±17	364±33	141±18***	130±16***	85±17***,$
4	HDL (mg/dL)	32±2	25±2	35±2**	38±3**	40±3***,$,©
5	LDL (mg/dL)	17±1	62±15	34±3.16**	32.42±2.94**	25.08±2.28**,$
6	Atherogenic index	0.9±0.2	12±2	2±0.4**	1.6±0.5**	1.3±0.5**,$

Notes: NC (n=8), HF-DC (n=7), MET (n=8), VIL (n=8), and MNG (n=7). Values are expressed as mean ± SD.

*** P<0.001.

** P<0.01 vs HF-DC.

$ P<0.05 vs MET.

© P<0.05 vs VIL. P value obtained from anova.

Abbreviations: AC/TC, abdominal circumference/thoracic circumference; NC, normal control; HF-DC, high-fat diabetic control; MET, metformin; VIL, vildagliptin; MNG, mangiferin; HDL, high-density lipoprotein; LDL, low-density lipoprotein; TG, triglyceride; TCh, total cholestrol.

Figure 2 Percentage of change in body weight NC (n=8), HF-DC (n=7), MET (n=8), VIL (n=8), and MNG (n=7).

Notes: Values are expressed as mean ± SD. *P<0.05. **P<0.01 vs HF-DC. ^$P<0.05 vs MET.
Abbreviations: NC, normal control; HF-DC, high-fat diabetic control; MET, metformin; VIL, vildagliptin; MNG, mangiferin.

Figure 3 Time course changes in blood glucose of NC (n=8), HF-DC (n=7), MET (n=8), VIL (n=8), and MNG (n=7).

Notes: Values are expressed as mean ± SD. ***P<0.01 vs HF-DC. ^$P<0.05 vs MET. ^@P<0.05 vs VIL.
Abbreviations: NC, normal control; HF-DC, high-fat diabetic control; MET, metformin; VIL, vildagliptin; MNG, mangiferin.

Figure 4 The HbA1c level at tenth week of NC (n=8), HF-DC (n=7), MET (n=8), VIL (n=8), and MNG (n=7).

Notes: Values are expressed as mean ± SD. **P<0.01, *P<0.05 vs HF-DC.
Abbreviations: NC, normal control; HF-DC, high-fat diabetic control; MET, metformin; VIL, vildagliptin; MNG, mangiferin.

Table 2 Assessment of insulin, C-peptide, DPP-IV pathway, inflammatory, and oxidant variables in various experimental groups

SN	Name of parameter	Insulin (µU/ml)	C-peptide (ng/ml)	HOMA-IR	HOMA-β	Serum DPP-IV (λU/mL)	hs-CRP (mg/dL)	MDA (nmol/mL)
1	NC	6±0.6	0.07±0.02	1.57	66.6	4.76±0.43	0.86±0.07	1.84±0.08
2	HF-DC	2.93±1.11	0.05±0.03	2.17	5.9	44.53±4.5	2.2±0.5	6.07±0.66
3	MET	4.33±1.2**	0.07±0.02	1.64	17.2*	28.45±2.9**	1.68±0.31*	4.25±0.43*
4	VIL	4.73±0.31**	0.06±0.03	1.79	18.37*	12.32±1.02***,$	0.94±0.16*	4.09±0.46*
5	MNG	4.13±0.4**	0.07±0.01	1.6	17.08*	15.26±1.8***,$	1.01±0.24*	3.31±0.21**

Notes: NC (n=8), HF-DC (n=7), MET (n=8), VIL (n=8), and MNG (n=7). Values are expressed as mean ± SD.

* significant P<0.05,

** P<0.01,

*** P<0.001 vs HF-DC.

$ P<0.05 vs MET.

Abbreviations: DPP-IV, dipeptidyl peptidase-IV; HOMA-β, homeostasis model assessment-β; HOMA-IR, homeostasis model assessment of insulin resistance; hs-CRP, high-sensitivity C-reactive protein; MDA, malondialdehyde; NC, normal control; HF-DC, high-fat diabetic control; MET, metformin; VIL, vildagliptin; MNG, mangiferin; SN, serial number; λU/mL, micro unit/ml.

Figure 5 Time course changes in CPK-MB NC (n=8), HF-DC (n=7), MET (n=8), VIL (n=8), and MNG (n=7).

Notes: Values are expressed as mean ± SD. ***P<0.001 vs HF-DC. ^@P<0.05 vs VIL.
Abbreviations: CPK-MB, creatine phosphokinase MB; NC, normal control; HF-DC, high-fat diabetic control; MET, metformin; VIL, vildagliptin; MNG, mangiferin.

Table 3 Safety marker in various experimental groups

SN	Variable	NC	HF-DC	MET	VIL	MNG
1	Pancreatic marker pancreatic lipase (U/L)	30.66±2.10	48.26±9.36	36.83±1.50*	44.06±5.44**	33.50±3.33*,@
2	Liver marker SGPT (U/L)	61.25±8.68	99.85±10.38	77.42±7.20**	75.25±6.84**	66.26±8.16*,@
3	Kidney marker creatinine (mg/dL)	0.32±0.07	1.27±0.43	0.51±0.06*	0.58±0.04*	0.35±0.14*,$,@

Notes: NC (n=8), HF-DC (n=7), MET (n=8), VIL (n=8), and MNG (n=7). Values are expressed as mean ± SD.

* P<0.05,

** P<0.01 vs HF-DC.

$ P<0.05 vs MET.

@ P<0.05 vs VIL. P value obtained from anova.

Abbreviations: NC, normal control; HF-DC, high-fat diabetic control; MET, metformin; VIL, vildagliptin; MNG, mangiferin; HDL, high-density lipoprotein; LDL, low-density lipoprotein; SN, serial number; SGPT, serum glutamate pyruvate transminase.

Figure 6 Histopathological section of myocardium.

Notes: (A) Photomicrograph of heart of NC group rat heart revealed the noninfracted architecture of myocardium. (B) HF-DC group rat heart shows fatty infiltration in myocardial cells, hemorrhage, marked edema, congested blood vessels, and inflammation. (C) In the MET group rats, occasional focal myofiber loss and the degree of edema, inflammation, and necrosis were less compared to the HF-DC. (D) In the VIL group rats, the degree of edema and inflammation were found but less. (E) In the MNG group rats, edema, inflammation, and necrosis were less. Magnification 40×.
Abbreviations: NC, normal control; HF-DC, high-fat diabetic control; MET, metformin; VIL, vildagliptin; MNG, mangiferin.

Figure 7 Histopathological section of pancreas.

Notes: (A) Photomicrograph of pancreas sections of NC rats shows an organized pattern and shows normal architecture pancreas. (B) The pancreas of HF-DC group rat shows severe degenerative changes in the pancreatic islets, damaged islets of Langerhans, reduced beta cell mass, and the atrophy of beta cells. (C) In the MET group rats, pancreas shows less inflammatory infiltration and hemorrhage compared to HF-DC group. (D) In the VIL treatment group rats, pancreas shows fibrosis, less inflammatory infiltration, and hemorrhage. (E) In the MNG group rats, pancreas shows improve beta cell mass less fibrosis, less inflammatory infiltration, and no hemorrhage. Magnification 40×.
Abbreviations: NC, normal control; HF-DC, high-fat diabetic control; MET, metformin; VIL, vildagliptin; MNG, mangiferin.

Figure 8 Histopathological section of liver.

Notes: (A) Photomicrograph of liver sections of NC rats shows normal architecture of liver. (B) In contrast, the liver of HF-DC group rat shows fatty liver, moderate fatty degeneration, ballooning of cell, inflammatory infiltration more, and congestion of blood vessels in the central vein. (C) In the MET group rats, liver shows less fatty degeneration, inflammatory infiltration, congestion of blood vessels, fibrosis, edema, and necrosis. (D) In the VIL group rats, liver shows less fatty degeneration, inflammatory infiltration, edema, and necrosis. (E) In the MNG group rats, liver shows less inflammatory infiltration, edema, and normal structure of central vein, peripheral vein, and no congestion of sinosoides. Magnification 40×.
Abbreviations: NC, normal control; HF-DC, high-fat diabetic control; MET, metformin; VIL, vildagliptin; MNG, mangiferin.

Figure 9 Histopathological section of kidney.

Notes: (A) Photomicrograph of kidney sections of NC rats shows normal structure of the kidney. (B) HF-DC group rats demonstrated congestion of glomerular blood vessels, tubular necrosis, inflammation, and cloudy degeneration. (C) In MET group, kidney shows congestion of glomerular blood vessels, less hemorrhage, less tubular necrosis, inflammation, and focal area compared to HF-DC group. (D) In VIL group, kidney shows congestion of glomerular blood vessels, inflammation, and focal area. (E) In MNG group, kidney shows no congestion of glomerular blood vessels, less tubular necrosis, and inflammation. Magnification 40×.
Abbreviations: NC, normal control; HF-DC, high-fat diabetic control; MET, metformin; VIL, vildagliptin; MNG, mangiferin.

Table 4 Immnunohistochemistry (IHC) of pancreas for localization of insulin

SN	Groups of rats	IHC – finding for insulin
1	NC	>85% positivity is noted within parenchymal cells
2	HF-DC	<10% positivity is noted within parenchymal cells
3	MET	10%–12% positivity is noted within parenchymal cells
4	VIL	15%–20% positivity is noted within parenchymal cells
5	MNG	25%–30% positivity is noted within parenchymal cells

Abbreviations: NC, normal control; HF-DC, high-fat diabetic control; MET, metformin; VIL, vildagliptin; MNG, mangiferin; SN, serial number.

Figure 10 Immunohistochemistry of pancreas.

Notes: Immunohistochemical localization of insulin. (A) Immunohistochemistry of NC group pancreas showed increased localization of insulin. (B) The HF-DC group showed decreased localization of insulin and hence loss of beta cell functions. (C) The MET group pancreas showed increased localization of insulin compared to HF-DC group. (D) The VIL group pancreas showed increased localization of insulin compared to HF-DC group. (E) The MNG group pancreas showed marked increased localization of insulin compared to standard groups. Magnification 40×.
Abbreviations: NC, normal control; HF-DC, high-fat diabetic control; MET, metformin; VIL, vildagliptin; MNG, mangiferin.