Hindawi
Evidence-Based Complementary and Alternative Medicine
Volume 2017, Article ID 8128125, 8 pages
https://doi.org/10.1155/2017/8128125
Research Article
Antidyslipidemic, Anti-Inflammatory, and Antioxidant Activities
of Aqueous Leaf Extract of Dioscoreophyllum cumminsii (Stapf)
Diels in High-Fat Diet-Fed Rats
O. B. Ibitoye,1 U. M. Ghali,1 J. B. Adekunle,1 J. N. Uwazie,2 and T. O. Ajiboye3
1
Antioxidants, Redox Biology and Toxicology Research Laboratory, Department of Biological Sciences,
Al-Hikmah University, Ilorin, Nigeria
2
Department of Biochemistry, University of Ilorin, Ilorin, Nigeria
3
Antioxidants, Redox Biology and Toxicology Research Group, Department of Medical Biochemistry, College of Health Sciences,
Nile University of Nigeria, Federal Capital Territory, Nigeria
Correspondence should be addressed to T. O. Ajiboye; ajiboyeyong@yahoo.com
Received 14 May 2017; Revised 2 August 2017; Accepted 20 September 2017; Published 23 October 2017
Academic Editor: Andrea Maxia
Copyright © 2017 O. B. Ibitoye et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Dioscoreophyllum cumminsii (Stapf) Diels leaves are widely used in the treatment of diabetes, obesity, and cardiovascular
related complications in Nigeria. This study investigates the anti-inflammatory and antiobesity effect of aqueous extract of
Dioscoreophyllum cumminsii leaves in high-fat diet- (HFD-) induced obese rats. HFD-fed rats were given 100, 200, and 400 mgkg−1
body weight of aqueous extract of Dioscoreophyllum cumminsii leaves for 4 weeks starting from 9th week of HFD treatment. D.
cumminsii leaves aqueous extract reversed HFD-mediated decrease in the activities of superoxide dismutase, catalase, glutathione
peroxidase, glutathione reductase, and glucose 6-phosphate dehydrogenase. Moreover, HFD-mediated elevation in the levels of
conjugated dienes, lipid hydroperoxides, malondialdehyde, protein carbonyl, and DNA fragmentation in rats liver was lowered.
HFD-mediated alterations in serum total cholesterol, triacylglycerol, high-density lipoprotein cholesterol, low-density lipoprotein
cholesterol, and very low-density lipoprotein cholesterol were significantly reversed by the extract. The treatment of HFD-fed rats
reduced the levels of insulin, leptin, protein carbonyl, fragmented DNA, and tumour necrosis factor-𝛼 and interleukin- (IL-) 6
and IL- 8 and increased the adiponectin level. This study showed that aqueous extract of Dioscoreophyllum cumminsii leaves has
potential antiobesity and anti-inflammatory effects through modulation of obesity-induced inflammation, oxidative stress, and
obesity-related disorder in HFD-induced obese rats.
1. Introduction
Obesity, excessive visceral accumulation and distribution,
is a risk factor in atherosclerosis, cancer, diabetes (type 2),
dyslipidemia, and metabolic syndrome [1]. Indeed, its rising
prevalence which continues to be a global challenge is associated with high-fat, caloric-dense diets, sedentary life styles,
increased urbanization, and psychosocial stress (McLaren,
2007). Adiposity in high-fat consumption has been demonstrated in epidemiological and experimental studies [2, 3] and
is associated with adipose tissue inflammation, endoplasmic
reticulum stress of adipocyte, and necrosis-like cell death
[4]. World Health Organization (WHO) estimated that there
are more than 1.1 billion adults overweight in the world
and about 115 million individuals suffering from obesityrelated problems in low-income and middle-income populations [5]. Drugs including phentermine, fluoxetine, orlistat,
sibutramine, and rimonabant are used for the treatment of
obesity. However, associated side effects are not limited to
nausea, dizziness, insomnia, diarrhea, dyspepsia, and constipation. Thus, there are growing demands for plant derived
foods and compounds to manage and treat ailments such as
metabolic syndrome, obesity, and diabetes [6]. Indeed, antidiabetic activity and capability of Dioscoreophyllum cumminsii
leaves have been validated [7, 8]. In furtherance of these,
the therapeutic importance of Dioscoreophyllum cumminsii
leaves in obesity and associated complications was investigated.
2
Dioscoreophyllum cumminsii, a tropical rainforest vine,
family Menispermaceae, is known as serendipity berry,
(Omu-aja) Yoruba, and Okazi (Igbo) [9]. It is widely distributed in Guinea-Bissau, Sierra Leone, Liberia, Nigeria,
Benin, and Congo. Monellin, a content of the fruit, is 3000
times sweeter than sugar [10]. Alkaloids, anthraquinones, cardiac glycosides, flavonoids, phlobatannins, saponins, and tannins are reported phytochemicals in Dioscoreophyllum cumminsii leaves [11]. Leaves of this plant are used in the treatment of diarrhea, dysentery, and uterine haemorrhages [11].
Recently, we reported in different models that magnoflorine,
jatrorrhizine, and columbamine are responsible for the
antidiabetic and protective importance in metabolic syndrome model [7, 8]. As diabetes and metabolic syndrome
could result from obesity, we evaluated the effect of aqueous
leaf extract of Dioscoreophyllum cumminsii on HFD-induced
dyslipidemia, inflammation, and oxidative stress.
2. Materials and Methods
2.1. Experimental Animals. Thirty-five male albino rats (Rattus norvegicus) of Wistar strain (141.24±0.32 g) were obtained
from the Animal House of Veterinary Physiology, Biochemistry and Pharmacology, University of Ibadan, Nigeria. Rats,
kept in clean plastic cages, were placed in well-ventilated
house conditions and supplied with feed (Capefeed Ltd.,
Osogbo, Nigeria) and water ad libitum.
2.2. Plant Material and Authentication. Dioscoreophyllum
cumminsii leaves were collected from Oja Titun, Ilorin, Nigeria. They were authenticated and deposited in the herbarium
of Department of Plant Biology, University of Ilorin, Ilorin,
Nigeria (UIH 001/1082).
2.3. Chemical Reagents and Assay Kits. Disodium salt, hexahydrate and guanidine hydrochloride, ultrapure water, 5,5dithiobis-2-nitrobenzoic acid (DNTB), and trichloroacetic
acid were purchased from Research Organics, 4353 East
49th Street, Cleveland, Ohio 44125; superoxide dismutase,
glutathione peroxidase, glutathione reductase, glucose-6phosphate dehydrogenase, catalase, total cholesterol, triglyceride, and HDL-cholesterol assay kits were purchased from
Randox Laboratories Co., Antrim, UK. Adiponectin, insulin,
and leptin (enzyme immunoassay kits) were products of
Sigma-Aldrich Inc., St. Louis, USA. All other reagents used
were products of Sigma-Aldrich Inc., St. Louis, USA.
2.4. Preparation of Plant Extract. Dioscoreophyllum cumminsii leaves were washed clean with distilled water, airdried, and pulverized using domestic blender. Pulverized
leaves (200 g) were extracted in distilled water (1 L) for
48 h, filtered, and concentrated on water bath. The extract
yield (26.60 g) was reconstituted to 100, 200, and 400 mg/kg
body weight doses. We reported magnoflorine (1.97 mg/g),
jatrorrhizine (1.35 mg/g), and columbamine (2.12 mg/g) as
the antidiabetic and antidyslipidemic agents in aqueous leaf
extract of Dioscoreophyllum cumminsii [7]. The extract was
refrigerated all through the experimental period to avoid
microbial contamination and maintain its composition.
Evidence-Based Complementary and Alternative Medicine
Table 1: Feed composition and formulation.
Feed component
Corn starch
Casilan 90∗
Lard
Cholesterol
Sucrose
Rice husk
DL-methionine
Lysine
Vitamin mix∗∗
Mineral mix∗∗∗
Control diet (g/kg)
506
250
40
0
100
40
4
10
10
40
High-fat diet (g/kg)
396
250
140
10
100
40
4
10
10
40
∗
Casilan 90 (g 100 g−1 ), energy (1572 kg 100 g−1 ), protein (90 g), carbohydrate (0.3 g), fat (1.0 g), fibre (trace), sodium (0.03 mg), and calcium
(1400 mg). ∗∗ Vitamin mix (per kg of diet): thiamine hydrochloride (6 mg),
pyridoxine hydrochloride (7 mg), nicotine acid (30 mg), calcium pantothenate (16 mg), folic acid (2 mg), biotin (0.2 mg), Cyanocobalamin (0.01 mg),
retinol palmitate (4000 IU), cholecalciferol (100 IU), 𝛼-tocopherol acetate
(50 IU), menadione (0.05 mg), and choline chloride (2 g). ∗∗∗ Mineral mix
(g kg−1 ): CoCl2 ⋅6H2 O (0.001), CuSO4 ⋅5H2 O (0.079), MnSO4 ⋅7H2 O (0.178),
KI (0.033), NaCl (3.573), ZnCO3 (1.60), CaSO4 (11.61), MgSO4 ⋅7H2 O (2.292),
K2 HPO4 (10.559), and FeSO4 ⋅7H2 O (1.075).
2.5. Feed Composition and Formulation. HFD with composition presented in Table 1 was used for the study and
formulated as described by Ajiboye et al. [12].
2.6. Animal Grouping and Treatments. Rats (35) were randomized into seven groups (A–G) of five rats each. All rats
received HFD for 12 weeks except rats in groups A and C
fed with control diet. In addition, rats in groups C–F were
gavaged with 400, 100, 200, and 400 mg/kg BW of aqueous
extract of D. cumminsii, respectively, for 4 weeks starting from
9th week of diet treatments. Group A rats, which served as
control, were gavaged with distilled water (1 mL), while group
G rats received 400 mg/kg BW metformin [8], reference
drug, for 4 weeks starting from 9th week. This study was
approved by Al-Hikmah University Ethical Committee on
the use of laboratory animals (HUI/ECULA/014/009) and all
treatments were done in accordance with the Guidelines of
National Research Council’s Guide for the Care and Use of
Laboratory Animals [13].
2.7. Preparation of Serum and Tissue Homogenate. Rats were
anaesthetized with diethyl ether and sacrificed 24 h after the
last day of the experimental period. Blood collected from the
jugular vein was allowed to clot for 15 min and centrifuged
for 5 min at 500𝑔 for serum collection. Liver was excised
and homogenized in sucrose-Tris buffer (0.25 mol/L sucrose,
10 mmol/L Tris-HCl, pH 7.4).
2.8. Biochemical Assays
2.8.1. Blood Insulin, Adipokines, and Cytokines. Adiponectin,
insulin, leptin, tumour necrosis factor-𝛼, interleukin-6, and
interleukin-8 were determined as described in manufacturer’s
assay kit manual.
Evidence-Based Complementary and Alternative Medicine
3
Table 2: Insulin, leptin, and adiponectin levels of HFD-fed rats following oral administration of aqueous leaf extract of Dioscoreophyllum
cumminsii.
Group
Control
HFD
400 mg/kg body weight of extract
HFD + 100 mg/kg body weight extract
HFD + 200 mg/kg body weight extract
HFD + 400 mg/kg body weight extract
HFD + 400 mg/kg body weight metformin
Insulin (IU/L)
0.61 ± 0.09a
2.43 ± 0.12e
0.67 ± 0.07a
2.01 ± 0.24d
1.71 ± 0.13c
1.00 ± 0.08b
1.65 ± 0.11c
Leptin (ng/mL)
1.81 ± 0.04b
3.89 ± 0.03e
1.65 ± 0.03a
3.04 ± 0.25d
2.82 ± 0.16c
1.83 ± 0.10b
2.72 ± 0.91c
Adiponectin (mg/mL)
42.21 ± 2.10d
20.65 ± 1.23a
41.02 ± 1.62d
23.89 ± 1.05a
28.72 ± 0.96b
36.01 ± 0.58c
35.98 ± 0.73c
Values are mean ± SEM of five determinations and are considered statistically significant at 𝑝 < 0.05. HFD: high-fat diet. Values with different alphabetical
superscript are significantly different (𝑝 < 0.05).
2.8.2. Lipid Profile. Serum TC, TAG, and HDLc were determined as described in commercial kits (Randox Laboratories
Ltd., Antrim, UK). LDLc and VLDLc were calculated using
the following expression:
LDLc = 0.2 × TAG
LDLc = TC − (HDLc + VLDLc) .
(1)
Cardiac index (CI), atherogenic index, and coronary artery
index were estimated as described by Kang et al. [14],
Kayamori and Igarashi [15], and Ajiboye et al. [16], respectively.
2.8.3. Antioxidant Enzymes and Oxidative Stress Biomarkers
Superoxide Dismutase. Superoxide dismutase in the liver of
rats was determined as described by Misra and Fridovich [17].
The assay mixture consisted of liver homogenate (0.2 mL),
2.5 mL carbonate buffer (0.05 M, pH 10.2), and freshly prepared 0.3 mM epinephrine (0.3 mL). Increase in absorbance
was monitored at 480 nm every 30 s for 150 s. A unit of
enzyme activity was defined as 50% inhibition of the rate
of autoxidation of epinephrine as determined by change in
absorbance/min at 480 nm.
Catalase. Catalase activity was determined as described by
Beers and Sizer [18]. The assay mixture consisted of 2 mL
phosphate buffer and 30 mM H2 O2 and liver homogenate
(50 𝜇L). Absorbance was read at 240 nm for 1 min and the
activity was calculated using the extinction coefficient of
H2 O2 (43.6 M cm−1 ).
Glutathione Peroxidase and Glutathione Reductase. Activities
of glutathione peroxide and glutathione reductase were determined as described in commercial kits (Randox Laboratories
Ltd., Antrim, UK).
Reduced Glutathione (GSH). Glutathione content of liver
was determined as described by Ellman [19]. Briefly, liver
homogenate (1.0 mL) was mixed with 0.1 mL of 25% trichloroacetic acid (TCA). The mixture was centrifuged at 5,000 ×g
for 10 min to remove precipitate. Supernatant (0.1 mL) was
mixed with 2 mL of 0.6 mM DTNB prepared in 0.2 M sodium
phosphate buffer pH (8.0). Absorbance was read at 412 nm.
Lipid Peroxidation Products. Lipid peroxidation products
were determined as described for conjugated dienes [20],
lipid hydroxide [20], and malondialdehyde [20].
Protein Carbonyl and Fragmented DNA. Protein carbonyl and
fragmented DNA contents of the liver were determined as
described by Levine et al. [21] and Burton [22], respectively.
2.9. Statistical Analysis. All the data were expressed as the
mean ± SEM of five replicates unless stated otherwise. Analysis of variance (ANOVA) followed by Tukey-Kramer test for
difference between means was used to detect any significant
difference between the treatment groups in this study. Statistical evaluation of data was performed with SPSS version
20.0. Differences were considered statistically significant at
𝑝 < 0.05.
3. Results
3.1. Insulin, Leptin, Adiponectin, and Inflammatory Biomarkers. Serum insulin and leptin of HFD-fed rats increased
significantly (𝑝 < 0.05) by 298.36 and 114.92%, respectively,
when compared with the control (Table 2). This increase was
significantly lowered by aqueous leaf extract of Dioscoreophyllum cumminsii (100, 200, and 400 mg/kg BW). Conversely,
HFD-mediated increase in serum adiponectin was significantly attenuated by the extract and compared well with the
reference drug (Table 2).
Inflammatory biomarkers, TNF-𝛼, IL-6, and IL-8, increased significantly in the serum of HFD-fed rats in comparison with control rats (Figures 1–3). The extract produced
dose dependent decrease in these biomarkers and compared
well with the reference drug (Figures 1–3). The highest dose
(400 mg/kg BW) of D. cumminsii leaves produced profound
decrease in HFD-mediated increase in serum TNF-𝛼, IL-6,
and IL-8, respectively.
3.2. Lipid Profile. TC, TAG, VLDLc, and LDLc of HFD-fed
rats increased significantly with concomitant decreased
HDLc in comparison with control rats. Administration
of D. cumminsii leaves extract significantly reversed
4
Evidence-Based Complementary and Alternative Medicine
Table 3: Lipid profile HFD-fed rats following oral administration of aqueous leaf extract of Dioscoreophyllum cumminsii.
Group
Total cholesterol
Control
47.21 ± 1.28b
HFD
66.21 ± 1.65d
400 mg/kg body weight of extract
43.11 ± 2.01a
HFD + 100 mg/kg body weight extract
63.24 ± 1.46d
HFD + 200 mg/kg body weight extract
58.67 ± 0.76c
HFD + 400 mg/kg body weight extract
50.04 ± 0.48b
HFD + 400 mg/kg body weight metformin
55.21 ± 0.92c
Triglyceride
52.33 ± 1.14a
80.07 ± 1.86d
51.12 ± 2.70a
76.34 ± 4.11d
71.35 ± 3.19c
62.35 ± 2.30b
64.76 ± 2.05b
VLDL cholesterol
10.04 ± 0.69a
15.68 ± 1.67c
9.76 ± 0.11a
15.37 ± 0.43c
14.99 ± 1.04b
13.77 ± 0.87b
13.92 ± 0.92b
LDL cholesterol
3.63 ± 0.09a
33.21 ± 0.12d
2.12 ± 0.24a
30.04 ± 1.02d
18.54 ± 0.92c
11.64 ± 1.03b
17.65 ± 1.00c
HDL cholesterol
33.77 ± 1.26d
15.06 ± 1.33a
34.29 ± 0.98d
16.78 ± 1.54a
23.11 ± 1.29b
26.45 ± 0.89c
24.68 ± 0.57b
3.3. Antioxidant Enzymes. Activities of antioxidant enzymes,
superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glucose 6-phosphate dehydrogenase,
in the liver of HFD-fed rats decreased significantly (𝑝 <
0.05) when compared to control rats. This decrease was
significantly reversed by aqueous leaf extract of D. cumminsii
in dose dependent manner (Table 4), which compared significantly with metformin treated rats.
3.4. Oxidative Stress Biomarkers. Lipid peroxidation products, conjugated dienes, lipid hydroperoxides, and malondialdehyde, in the liver of HFD-fed rats increased significantly
b
c
d
a
a
d
e
HFD
HFD-mediated alterations in these parameters. Indeed, the
highest dose (400 mg/kg body weight) produced 85.11, 64.04,
51.60, 72.92, and 60.88% reversal of TC, TAG VLDLc, LDLc,
and HDLc, respectively, and compared significantly with
reference drug, metformin (Table 3).
10
9
8
7
6
5
4
3
2
1
0
Control
Figure 1: TNF-𝛼 concentration in the serum of HFD-fed rats following the administration of aqueous Dioscoreophyllum cumminsii
leaves. Values are mean ± SEM of five determinations and are
statistically significant at 𝑝 < 0.05. Bars with different alphabetical
superscript are significantly different at 𝑝 < 0.05. HFD: high-fat diet;
TNF-𝛼: tumour necrosis factor-𝛼.
Figure 2: Serum concentration of IL-8 of HFD-fed rats following
the administration of aqueous extract of Dioscoreophyllum cumminsii leaves. Values are mean ± SEM of five determinations and are
statistically significant at 𝑝 < 0.05. Bars with different alphabetical
superscript are significantly different at 𝑝 < 0.05. HFD: high-fat diet;
IL-8: interleukin-8.
IL-6 concentration (pg/mL)
HFD + 400 mg/kg
BW metformin
HFD + 400 mg/kg
BW D. cumminsii
HFD + 200 mg/kg
BW D. cumminsii
HFD + 100 mg/kg
BW D. cumminsii
400 mg/kg
BW
D. cumminsii
HFD
Control
0
HFD + 400 mg/kg
BW metformin
a
HFD + 400 mg/kg
BW metformin
a
5
a
a
0
HFD + 400 mg/kg
BW D. cumminsii
10
5
HFD + 400 mg/kg
BW D. cumminsii
f
15
e
10
HFD + 200 mg/kg
BW D. cumminsii
20
15
HFD + 200 mg/kg
BW D. cumminsii
e
25
d
d
20
HFD + 100 mg/kg
BW D. cumminsii
d
30
25
HFD + 100 mg/kg
BW D. cumminsii
c
35
c
30
400 mg/kg
BW
D. cumminsii
40
b
35
Control
TNF- concentration (pg/mL)
45
40
400 mg/kg
BW
D. cumminsii
b
HFD
50
Concentration of IL-8 (pg/mL)
Values are mean ± SEM of five determinations and are considered statistically significant at 𝑝 < 0.05. VLDL cholesterol: very-low density lipoprotein cholesterol;
HDL cholesterol: high-density lipoprotein cholesterol; LDL cholesterol: low-density lipoprotein cholesterol, HFD; high-fat diet. Concentrations of lipid profile
parameters are expressed as mg/dL. Values with different alphabetical superscript are significantly different (𝑝 < 0.05).
Figure 3: Serum concentration of IL-6 of HFD-fed rats following
the administration of aqueous extract of Dioscoreophyllum cumminsii leaves. Values are mean ± SEM of five determinations and are
statistically significant at 𝑝 < 0.05. Bars with different alphabetical
superscript are significantly different at 𝑝 < 0.05. HFD: high-fat diet;
IL-6: interleukin-6.
Evidence-Based Complementary and Alternative Medicine
5
Table 4: Specific activities of antioxidant enzymes in the liver of HFD-fed rats following the administration of aqueous extract of D. cumminsii
leaves to high-fat diet-fed rats.
Group
Control
HFD
400 mg/kg body weight of extract
HFD + 100 mg/kg body weight extract
HFD + 200 mg/kg body weight extract
HFD + 400 mg/kg body weight extract
HFD + 400 mg/kg body weight metformin
SOD
44.03 ± 2.01d
27.54 ± 3.12a
48.76 ± 1.11e
33.24 ± 1.78b
37.65 ± 0.99c
40.19 ± 2.03c
41.07 ± 1.02c
Catalase
32.03 ± 0.16e
14.21 ± 0.32a
38.23 ± 1.23f
17.65 ± 2.19b
23.15 ± 0.75c
27.24 ± 1.14d
24.01 ± 1.23c
GSH-Px
78.21 ± 0.97f
26.26 ± 1.34a
83.51 ± 1.26
42.08 ± 2.10b
53.15 ± 2.31c
67.22 ± 1.01d
72.92 ± 2.22e
GSH-Red
33.33 ± 1.41d
13.18 ± 1.56a
34.10 ± 1.23d
13.27 ± 1.34a
17.37 ± 1.39b
21.23 ± 0.64c
20.05 ± 0.68c
Glucose-6-PD
23.71 ± 2.01d
9.75 ± 1.98a
24.21 ± 1.65d
13.45 ± 1.89b
18.76 ± 3.41c
7.02 ± 0.26a
8.22 ± 0.93a
Values are mean ± SEM of five determinations and are considered statistically significant at 𝑝 < 0.05. SOD: superoxide dismutase; GSH-Px: glutathione
peroxidase; GSH-Red: glutathione reductase; Glc 6-PD: glucose 6-phosphate dehydrogenase; HFD: high-fat diet. Enzyme activities are expressed as
nmol/min/mg protein. Values with different alphabetical superscript are significantly different (𝑝 < 0.05).
Table 5: Levels of malondialdehyde, conjugated dienes, and lipid hydroperoxides in the liver of HFD-fed rats following the administration
of aqueous extract of D. cumminsii leaves.
Group
Control
HFD
400 mg/kg body weight of extract
HFD + 100 mg/kg body weight extract
HFD + 200 mg/kg body weight extract
HFD + 400 mg/kg body weight extract
HFD + 400 mg/kg body weight metformin
Malondialdehyde
3.84 ± 0.37a
27.21 ± 0.45d
3.62 ± 0.54a
16.82 ± 1.79c
12.05 ± 1.06c
7.45 ± 1.92b
7.53 ± 1.63b
Conjugated dienes
23.89 ± 2.33b
75.21 ± 3.07f
18.05 ± 0.29a
38.24 ± 0.98e
27.01 ± 1.34c
27.23 ± 1.65c
30.61 ± 1.53d
Lipid hydroperoxides
18.07 ± 0.62b
64.62 ± 3.27g
10.12 ± 1.24a
38.76 ± 0.43f
33.21 ± 2.22e
25.32 ± 1.86c
28.22 ± 0.37d
20
c
15
d
10
e
5
f
a
a
HFD + 400 mg/kg
BW metformin
HFD + 400 mg/kg
BW D. cumminsii
HFD + 200 mg/kg
BW D. cumminsii
HFD + 100 mg/kg
BW D. cumminsii
0
400 mg/kg
BW
D. cumminsii
Demands for health promoting/maintenance foods have led
to increase in investigations into the bioactive constituents
(phenolic acids, polyphenols, and micro- and macronutrients) conferring the medicinal properties [6]. Although
studies have documented the usefulness of D. cumminsii
leaves in the management of diabetes and high-fructoseinduced metabolic syndrome, no study has evaluated the
effect on HFD-induced obesity. This study thus presents the
antidyslipidemic, anti-inflammatory, and antioxidant activities of aqueous leaf extract of Dioscoreophyllum cumminsii
(Stapf) Diels in HFD-fed rats.
Leptin, adiponectin, and insulin are indicators of body
mass fats and energy imbalance and are present in obesity
[23, 24]. The increase in serum leptin and insulin of HFD-fed
rats is in consonance with previous studies [25–27]. Reversal
of HFD-mediated increase in leptin and insulin by the
b
HFD
4. Discussion
25
Control
by 608.59, 214.82, and 257.61% when compared to control
rats. Administration of aqueous leaf extract of D. cumminsii
significantly lowered HFD-mediated increase in levels of conjugated dienes, malondialdehyde, and lipid hydroperoxides
when compared to the control rats (Table 5). Similar reduction was observed for HFD-fed rats treated with metformin.
Also, protein carbonyl, product of protein oxidation, and
fragmented DNA of HFD-fed rats were lowered by extract
administration (Figures 4 and 5).
Protein carbonyl level (nmol/mg protein)
Values are mean ± SEM of ten determinations and are considered statistically significant at 𝑝 < 0.05. HFD: high-fat diet. Conjugated dienes, lipid
hydroperoxides, malondialdehyde, and protein carbonyl are expressed as nmol/mg protein. Values with different alphabetical superscript are significantly
different (𝑝 < 0.05).
Figure 4: Protein carbonyl level in the liver of HFD-fed rats
following the administration of aqueous extract of Dioscoreophyllum
cumminsii leaves. Values are mean ± SEM of five determinations
and are statistically significant at 𝑝 < 0.05. Bars with different
alphabetical superscript are significantly different at 𝑝 < 0.05. HFD:
high-fat diet.
extract suggests inhibition of lipogenesis and stimulation of
lipolysis and reduction of intracellular lipid levels in skeletal
6
Evidence-Based Complementary and Alternative Medicine
b
70
60
50
c
40
20
10
a
e
e
HFD + 400 mg/kg
BW metformin
d
30
HFD + 400 mg/kg
BW D. cumminsii
Fragmented DNA (%)
80
a
HFD + 200 mg/kg
BW D. cumminsii
HFD + 100 mg/kg
BW D. cumminsii
400 mg/kg
BW
D. cumminsii
HFD
Control
0
Figure 5: Fragmented DNA (%) in the liver of HFD-fed rats
following the administration of Dioscoreophyllum cumminsii leaves.
Values are mean ± SEM of five determinations and are statistically
significant at 𝑝 < 0.05. Bars with different alphabetical superscript
are significantly different at 𝑝 < 0.05. HFD: high-fat diet.
muscle, liver, and pancreatic 𝛽-cells, leading to improved
insulin sensitivity [24] and decreased lipid accumulation in
adipocytes [28].
Previous studies have demonstrated decrease in adiponectin level in HFD-fed rats and have implicated its
involvement in diseases presenting obesity [24]. This could
be associated with insulin resistance and hyperinsulinemia
[29]. The reversal of HFD-mediated decrease in adiponectin
by aqueous leaf extract of Dioscoreophyllum cumminsii could
have resulted from improved insulin sensitivity, as evident
in this study, leading to decreased flow of free fatty acids
and stimulating glucose utilization and fatty acid oxidation
[30]. In addition, this may protect cardiovascular system and
reduce incidence of myocardial infarction [29].
Elevated levels of TC, TG, VLDLc, and LDLc with concomitant reduction in HDLc characterize the dyslipidemic
changes reported for HFD [12, 31]. Indeed, TC, TG, VLDLc,
LDLc, and HDLc indicate disordered lipid metabolism
and predisposition to cardiovascular disease [12, 31, 32].
These alterations could predispose the risk of developing
atherosclerosis and cardiovascular diseases [33], while reduction in HDL cholesterol could intensify the development of
atherosclerosis and cardiovascular diseases. Indeed, studies
have demonstrated the importance of aqueous leaf extract of
Dioscoreophyllum cumminsii in the regulation of dyslipidemia
in diabetic and metabolic HFD-fed rats [7, 8]. Thus, the
reversal of HFD-fed rats mediated alterations in lipid profile
by aqueous leaf extract of D. cumminsii suggests antidyslipidemic activity of the extract.
Oxidative stress associated with consumption of HFD
results from overwhelmed antioxidant enzymes, which act
in concerted manner to detoxify reactive oxygen species
[34]. The decreased antioxidant enzymes observed in this
study have been documented in HFD-fed rats [12, 32, 35,
36]. Reversal of HFD-mediated decrease in these enzymes
suggests antioxidant activity of the extract, although, in a
different animal model, antioxidant activities of D. cumminsii
have been reported [7, 8].
Lipid peroxidation, protein oxidation, and DNA fragmentation are consequential effects of overwhelmed antioxidant defense system. Elevated levels of lipid peroxidation
products, CD, LH, and MDA, in this study are in accordance
with previous studies [12, 32, 37, 38]. This may lead to disorganization and functional loss of membrane [39]. Similar
increased protein carbonyl and fragmented DNA, associated
with HFD consumption [40–43], indicate oxidative stressed
rats. The capability of D. cumminsii to reverse the increase in
oxidative stress biomarkers further provided the antioxidant
capability of the extract.
5. Conclusion
Arising from the data obtained from this study, it is evident
from the reversal of HFD-mediated alterations in proinflammatory cytokines, metabolic hormones, and antioxidant
enzymes that aqueous leaf extract of Dioscoreophyllum cumminsii leaves possesses antioxidants, antidyslipidemic, and
anti-inflammatory properties.
Conflicts of Interest
The authors declare no potential conflicts of interest with
respect to the research, authorship, and/or publication of this
article.
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