Chukwudozie et al. | J Pure Appl Microbiol | 15(1):346-355 | March 2021
Article 6787 | https://doi.org/10.22207/JPAM.15.1.29
Print ISSN: 0973-7510; E-ISSN: 2581-690X
ReseARCh ARtiCle
OPeN ACCess
Oral Administration of Gongronema latifolium Leaf
Extract Modulates Gut Microflora and Blood Glucose
of Induced Diabetic Rats
ikechukwu K. Chukwudozie1, Martina C. Agbo2, Kenneth O. Ugwu1 and
Ifeoma M. Ezeonu1*
Department of Microbiology, University of Nigeria, Nsukka, Nigeria.
Department of Pharmaceutical Microbiology and Biotechnology, University of Nigeria, Nsukka, Nigeria.
1
2
Abstract
Studies have suggested that modulation of gut microbiota is a viable therapeutic possibility for diabetes.
This study evaluated the ability of an edible plant, Gongronema (G.) latifolium Benth (Asclepiadaceae),
to modulate the gut microbiome and reduce blood glucose of alloxan-induced diabetic rats. Thirty (30)
young, male, albino rats were divided into 6 groups of 5 rats each: Group 1 comprised normal rats;
Groups 2 to 4, diabetic rats treated with 200, 400 and 800 mg/Kg body weight of hydro-alcoholic leaf
extract, respectively; Group 5, diabetic rats treated with 0.2 mg/Kg glibenclamide (an anti-diabetic
drug); and Group 6 comprised untreated diabetic rats. Following induction of diabetes with alloxan
injections, the treatments were administered twice daily on a 12-hourly basis by orogastric intubation
for 21 days. Thereafter, faecal samples were collected from the animals and subjected to metagenomic
analysis, to ascertain the composition and relative abundance of the gut microbiota. There were five
dominant bacterial phyla in the rat gut: Firmicutes, Bacteroidetes, Actinobacteria, Spirochaetea and
Proteobacteria. Induction of diabetes resulted in observable dysbiosis in the rats. However, treatment
of the diabetic rats with G. latifolium extract, ameliorated the state of dysbiosis and resulted in
significant increase in species like Lactobacillus (L.) johnsonii, L. reuteri and Prevotella corpri, which
are associated with improved glucose metabolism. The plant extract produced the best result at the
dose of 400 mg/Kg. The results from this study show that G. latifolium may be used as a therapeutic
option for restoration of the microbiome in diabetic patients.
Keywords: Diabetes, Gongronema latifolium, dysbiosis, microbiome, hyperglycaemia, gut flora
*Correspondence: ifeoma.ezeonu@unn.edu.ng; +234 803 795 4649
(Received: November 23, 2020; accepted: January 23, 2021)
Citation: Chukwudozie IK, Agbo MC, Ugwu KO, Ezeonu IM. Oral Administration of Gongronema latifolium Leaf Extract Modulates
Gut Microflora and Blood Glucose of Induced Diabetic Rats. J Pure Appl Microbiol. 2021;15(1):346-355. doi:10.22207/
JPAM.15.1.29
© The Author(s) 2021. Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License which
permits unrestricted use, sharing, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and
the source, provide a link to the Creative Commons license, and indicate if changes were made.
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InTRODUCTIOn
The role of the microbiome, particularly
the gut microbiome, in health cannot be
overemphasized. Studies have shown that the
microbes of the gut microbiome impact the host
physiology, through the gut-brain axis 1,2. The
normal microbial community in the gut contributes
to host nutrient metabolism, xenobiotic and drug
metabolism, maintenance of structural integrity
of the gut mucosal barrier, immunomodulation,
protection against pathogens and production of
various bioactive compounds, thereby leading to
overall improvement of host health3,4. On the other
hand, an imbalance of this microbial community
may result in any of various diseases, including
metabolic diseases such as obesity and diabetes.
Recent studies have also shown that fecal therapy,
probiotics, prebiotics and symbiotics may be new
approaches to the management of diabetes,
through modulation of the gut flora1,4.
The term diabetes describes a group
of metabolic disorders that are characterized by
hyperglycaemia in the absence of treatment. Two
major types of diabetes are known, type 1 diabetes
(T1DM) and type 2 diabetes (T2DM); generally
distinguished by the underlying mechanism,
which are inadequate production of insulin and
inadequate sensitivity of cells to insulin action,
respectively. New classifications have been
developed by the World Health Organization,
recently, but while the therapeutic approach
may differ for these types of diabetes, dietary
management remains essential for all types5.
Increasingly, diabetes management is
involving non-conventional drugs. It is estimated
that 25 to 57% of people with diabetes have at one
time or another resorted to complementary and
alternative medicine, including medicinal plants6.
The use of plants in the treatment of diseases
dates back to the early history of man and recent
times are witnessing resurgence in the use of plant
products as an alternative to modern medicine;
due to increasing health care costs, inadequate
health care facilities, religious beliefs, adverse drug
reactions and problems of drug resistance, among
others7,8. Some clinical and laboratory studies,
carried out in different parts of the world, on a
variety of herbs, spices and vitamins, evaluated
their effectiveness in diabetes therapy and some
of these products were found promising6,9,10.
Journal of Pure and Applied Microbiology
In Nigeria, various plants and plant
products are claimed to be useful in managing
diabetes. One such plant is G. latifolium, known
as amaranth in English and utazi among the Ibos
of eastern Nigeria. The plant belongs to the family
Asclepiadaceae. It is a climbing shrub that grows
up to 5 m long and the leaves are used either as
vegetable or spice. In ethnomedicine and folkloric
use, individuals having diabetes or elevated blood
glucose chew the bitter leaves of the plant or use
them as a salad in meals, often in an unregulated
manner, or as much as the individual can stand
the bitter taste. Sometimes, the leaves are used
in conjunction with conventional drugs, raising
questions about the true anti-diabetic effect of
the plant. However, in a study by Akah et al.11 leaf
extracts of the plant were found to reduce the
blood glucose of alloxan-induced diabetic rats in a
dose dependent manner, validating the traditional
medicine claims.
Although this plant and some other
medicinal plants are claimed to have antidiabetic
action, their exact mechanisms of action and
effects on the microbiome have not been studied,
particularly as it has been suggested that the
body’s microbiota plays a strong role in glucose
metabolism. This study therefore aimed at
evaluating the modulatory effect of G. latifolium
extract on the gut microflora and blood glucose of
induced diabetic rats.
METHODOLOGy
Collection and processing of plant materials
Fresh leaves of G. latifolium were
purchased from traditional dealers at a local
market in Nsukka, southeastern Nigeria. Nsukka
is located at longitudes 7° 13 00 – 7° 35 30 and
latitudes 6° 43 30 – 7° 00 to the equator. Leaf
samples were immediately taken to the Herbarium
Unit of the Department of Pharmacognosy and
Environmental Medicine, University of Nigeria,
Nsukka, and authenticated by a Plant Taxonomist/
Curator. A voucher specimen was deposited at the
Herbarium for reference purposes (Voucher No.
PCG/UNN/0343). Extraction was carried out by a
modification of the method described by Ezeonu
et al.12 Within 3 hours after purchase, fresh leaves
were washed with clean tap water and air dried
under a shade for 7 days. Thereafter, the dried
leaves were pulverized into coarse powder with
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in 24 rats by intraperitoneal injection of the alloxan
solution, at a dose of 150 mg/Kg body weight,
following a 12 h fast. The alloxanized animals
were allowed free access to food and water
and monitored daily. Animals with fasting blood
glucose >140 mg/dl for 5 consecutive days were
considered as having developed experimental
diabetes and selected for the study.
Experimental groups and treatments
On the sixth day, following induction, the
rats were divided into 6 different experimental
groups of 5 rats per group by simple randomization.
Group 1 served as normal control and comprised
5 uninduced rats. Groups 2, 3 and 4, received
treatments of 200, 400 and 800 mg/Kg body
weight of the hydro-alcoholic G. latifolium extract,
respectively. The doses were fixed as previously
described by Akah et al.11 Group 5 was treated
with standard antidiabetic drug (glibenclamide)
given at 0.2 mg/Kg body weight, while Group 6
comprised untreated diabetic rats. The treatments
were administered twice daily on a 12-hourly basis
by orogastric intubation for 21 days.
Measurement of blood glucose
The animals were allowed to fast for
about 12 h. Blood samples were obtained from the
tail veins of the rats and tested for fasting blood
glucose level, using an Oncall Glucometer (ACON
Laboratories Inc, USA). Measurements were taken
at 3-day intervals until the end of treatment and
every week, for three weeks after termination of
treatment.
Microbiome analysis
Faecal samples were collected at the
end of the treatment period. All samples were
collected directly from the animals’ rectum
into sterile vials, containing DNA/RNA shield
transport and storage medium (Zymo Research
Corp, CA, USA). Samples were stored at 4 0C
until courier-dispatch to CosmosID®, Rockville,
MD. DNA extraction, shotgun DNA sequencing
and metagenomic analysis were carried out on
each sample to ascertain the composition and
relative abundance of bacteria, viruses and fungal
species in individual faecal samples. DNA from
the faecal samples was isolated using the Zymo
Miniprep Kit (Zymo Research Corp.), according to
the manufacturer’s protocol. DNA libraries were
prepared using the Illumina Nextera XT library
preparation kit, according to the manufacturer’s
an electric blender. A hydro-alcoholic extract was
prepared by soaking 250 g portion of powder in
1 L of 30% (v/v) ethanol (Sigma-Aldrich, St. Louis
USA) for 48 h, with intermittent stirring and then
filtered through Whatman No. 1 filter paper. The
resulting filtrate was evaporated to a sticky paste
under a constant stream of cool air for 48 h and
stored at 4°C until required for use. The hydroalcoholic preparation was chosen over 100%
aqueous extraction, because it was less prone
to contamination in preliminary studies. The
extraction yield was calculated using the formula:
Percentage yield (%) =
Weight of Extract
Weight of pulverized
plant material
(g) X100
The percentage yield was approximately 4.2%.
experimental animals
A total of 30 young, male albino rats,
weighing between 160-190 g (average weight 172
+ 14g), were obtained from the animal house of
the Faculty of Veterinary Medicine, University of
Nigeria, Nsukka. Male rats were chosen because
they are believed to be more physiologically stable
and less subject to hormonal fluctuations that may
affect results. The animals were housed in wellventilated cages in the animal house and allowed
free access to feed (Vital Feed, Nig. Ltd) and clean
water. The animals were handled with humane
care according to NIH guidelines for use and care
of laboratory animals12. Ethical approval for this
study was also obtained from the University of
Nigeria Faculty of Veterinary Medicine Animal
Care and Use Committee (approval number:
FVM-UNN-IACUC-2020-1059). The guidelines
set out by the University of Nigeria Faculty of
Veterinary Medicine Ethics Committee for Medical
and Scientific Research (MSR) which among
others include good, clean and hygienic housing,
provision of clean water and humane handling of
animals during sample collections were strictly
followed in the experiment.
Induction of diabetes
This was done as described by11,14. A stock
solution of alloxan was prepared by dissolving
4.5 g alloxan monohydrate (Sigma-Aldrich, USA)
in 30 ml of sterile distilled water to give a stock
concentration of 150 mg/ml. Diabetes was induced
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protocol, while Library quantity and quality was
assessed with Qubit (ThermoFisher Scientific, USA)
and Tapestation (Agilent Technologies, CA, USA).
Libraries were then sequenced on Illumina HiSeq
platform 2x150 bp. Unassembled sequencing reads
were directly analyzed by CosmosID bioinformatics
platform (CosmosID Inc., Rockville, MD).
Euthanasia of experimental animals
All 5 untreated diabetic rats in group 6,
died shortly after the 21-day test period. The rats in
the other groups were monitored for an additional
21 days for stability of the blood glucose levels.
Thereafter, the rats were sacrificed by cervical
dislocation. Liver tissues from each experimental
group were harvested and frozen for further
studies. The euthanasia and harvest of organs
were carried out by qualified veterinarians from
the Faculty of Veterinary Medicine, University of
Nigeria, Nsukka.
Statistical analysis
Data obtained were subjected to oneway Analysis of Variance (ANOVA), using IBM
SPSS Statistics software version 23. Values were
expressed as mean + SEM. Significance was
accepted at p ≤ 0.05.
Results
Effect of treatments on gut flora
Although metagenomic analysis of the
animals’ faecal samples provided information
about the relative abundance of bacteria,
fungi, protists and viruses in the samples,
this study focused only on the gut bacteria.
Metagenomic analyses of faecal samples of the
experimental animals revealed the presence of
bacteria from 5 major phyla, namely: Firmicutes,
Bacteroidetes, Actinobacteria, Spirochaetae and
Proteobacteria. In normal, non-diabetic rats, the
relative abundance of the different phyla was:
61%, 24%, 6%, 7% and 2%, respectively. In diabetic
rats, however, there was reduction in abundance
of all phyla, except Actinobacteria, which increased
more than three-fold. The relative abundance of
the phyla in diabetic rats was 57%, 19%, 20%, 0.4%
and 2%, respectively. All treatment groups showed
a reduction in relative abundance of phylum
Fig. 1. Relative abundance of bacterial phyla in faecal samples from normal, diabetic and treated rats. Diabetic rats
showed significant increase in Phylum Actinobacteria with decrease in all other phyla, while all treatment groups
showed reduction in Phylum Spirochaetae.
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Stages
350
Baseline
After
induction
Day 3
Day 6
Day 9
Day 12
Day 15
Day 18
Day 21
1 week after
treatment
2 weeks after
treatment
3 weeks after
treatment
Normal rats
Diabetic Rats
Rats treated with
200 mg/kg bw G.l
Rats treated with
400 mg/kg bw G.l
Rats treated with
800 mg/kg bw G.l
Rats treated with
(Glibenclamide)
76.33 ± 10.02ab
94.00 ± 8.72a
88.00 ± 2.00b
310.33 ± 43.89b
68.33 ± 7.64a
217.67 ± 140.01ab
87.67 ± 1.53b
320.00 ± 121.51b
91.67 ± 10.69b
254.00 ± 72.13ab
84.00 ± 14.00ab
330.33 ± 69.97b
88.67 ± 7.57a
89.67 ± 7.51a
93.33 ± 6.43a
89.67 ± 4.51a
63.67 ± 7.37a
65.00 ± 7.81a
80.67 ± 7.02a
85.33 ± 5.69ab
446.67 ± 46.15d
483.00 ± 73.82c
412.67 ± 44.12b
514.00 ± 41.76b
442.33 ± 69.50b
378.33 ± 96.72b
552.00 ± 56.32b
- (animals dead)
352.00 ± 112.80cd
110.67 ± 29.28ab
150.67 ± 61.49a
130.67 ± 42.58a
107.00 ± 42.04a
105.33 ± 37.75a
94.33 ± 21.78a
89.00 ± 6.56b
272.00 ± 26.15bc
121.67 ± 15.50ab
137.33 ± 41.55a
107.33 ± 37.22a
92.67 ± 28.02a
93.00 ± 7.94a
88.00 ± 5.29a
85.00 ± 9.54ab
324.00 ± 57.24bc
175.67 ± 33.29b
132.00 ± 57.82a
99.00 ± 16.46a
94.67 ± 6.43a
82.67 ± 7.57a
64.00 ± 5.29a
72.67 ± 7.02a
231.00 ± 35.37b
90.00 ± 6.00a
82.33 ± 10.02a
86.00 ± 2.00a
90.33 ± 1.53a
72.67 ± 7.02a
66.67 ± 13.32a
84.00 ± 7.21ab
82.33 ± 7.37a
- (animals dead)
87.33 ± 8.51a
82.67 ± 5.51a
82.33 ± 9.51a
84.00 ± 6.00a
81.33 ± 4.16a
- (animals dead)
97.67 ± 3.51c
80.67 ± 5.86a
90.00 ± 2.00b
84.00 ± 2.00ab
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Mean values with different alphabets as superscripts in a row differ significantly (p ≤ 0.05)
Mean values with different numbers as superscripts for a parameter in a column differ significantly (p ≤ 0.05)
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Journal of Pure and Applied Microbiology
Table 1. Fasting blood sugar levels in rats before and after treatment with different concentrations Gongronema latifolium leaf extract
Chukwudozie et al. | J Pure Appl Microbiol | 15(1):346-355 | March 2021 | https://doi.org/10.22207/JPAM.15.1.29
Spirochaetae. There was no significant difference
between normal rats and the treatment groups in
the other phyla (Fig. 1).
At the species level, significant (P <
0.05) differences were observed in the relative
abundance of individual bacterial species within
the phyla. Major bacterial species identified in
the normal rat samples included: Lactobacillus
murinus, L. acidophilus, L. johnsonii, Prevotella
copri, L. leuteri, Bacteroides (B.) sartorii, B.
uniformis, Weisella confusa, Clostridiales, and
Brevibacterium linens among others. These
ten bacterial species accounted for more than
50% of the total bacteria, with L. murinus and
L. acidophilus being the most dominant (Fig. 2a
and 3a). In diabetic rats, however, there was a
noticeable disruption in both the diversity and
abundance of the flora. Most of the core bacteria
reduced in relative abundance, while other species
such as Brevibacterium spp, Brachybacterium
spp, Corynebacterium variable, Desulfovibrio,
Lactobacillus amylovorous etc., previously present
in relatively lower abundance, increased in
abundance (Fig. 2b and 3b). In rats treated with
glibenclamide and G. latifolium hydro-alcoholic
extract, the diversity of the bacterial flora was
restored (Fig. 2c – 2f). However, differences were
observed in the relative abundance of the bacteria
in different treatment groups. Rats treated with
moderate (400 mg/Kg body weight) and high dose
(800 mg/Kg body weight) of G. latifolium extract
showed enrichment of L. johnsonii and Prevotella
copri, with a reduction in the other species (Fig.
2d and 2e). A more balanced mix was observed at
400 mg/Kg bw (Fig. 2d and 3c).
Effect of treatments on blood glucose levels
Intraperitoneal injection of alloxan
monohydrate to rats caused elevated blood
glucose levels (diabetes) in the rats, with blood
glucose levels rising from baseline levels of about
85 mg/dl in normal rats to about 350 mg/dl in
alloxan-treated rats. Administration of G. latifolium
extract to the diabetic rats over a period of 21 days
effectively reduced the blood glucose levels in a
dose dependent manner (Table 1). Moreover, the
effect was lasting, as the treated rats maintained
normal blood glucose levels up to three weeks
after treatment was terminated. The best antidiabetic effect was observed with the dose of 400
mg/Kg body weight. All the 5 untreated diabetic
rats in group 6, died shortly after the 21 days
experimental period.
Fig. 2. Relative abundance of major bacterial species in the colonic flora of rat groups: (a) normal rats (b) untreated
diabetic rats (c) rats treated with 200 mg/Kg bw G. latifolium (d) rats treated with 400 mg/Kg bw G. latifolium (e)
rats treated with 800 mg/Kg bw G. latifolium (f) rats treated with glibenclamide. Note significant disruption of
composition of flora of diabetic rats compared with groups treated with G. latifolium, in which there was increase
in species associated with improved glucose metabolism. Dosage of 400 mg/Kg bw produced the best results.
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DISCUSSIOn
The gastrointestinal tract of vertebrates
is a delicately balanced ecosystem, containing
a variety of microbial species that interact with
the host and with each other. These microbial
species co-exist in a delicate balance, which when
disrupted – a condition known as dysbiosis – often
has negative consequences for the host’s health.
Studies have established a strong link between
the gut microbiome and metabolic diseases such
as diabetes and suggested that these diseases
may be managed through modulation of the gut
flora4,15-18. This study was conducted to evaluate
the modulatory effect of an edible plant, G.
latifolium, claimed to have anti-diabetic activity
in traditional medicine, on the gut flora of druginduced diabetic rats.
A previous study had evaluated and
reported the antidiabetic activities of aqueous and
methanolic extracts of G. latifolium11. This study
focused mainly on the effects of a hydro-alcoholic
(30% ethanol) preparation of the leaves of the
plant on the gut microbiome of diabetic rats.
In this study, metagenomic analyses
of faecal samples of normal rats showed the
presence of bacteria, fungi, viruses, protists as well
as various resistance genes and virulence factors
within the rat gut. The study however focused
on only the bacteria. Five major phyla of bacteria
were identified in normal non-diabetic rats, in the
order - Firmicutes > Bacteroidetes > Spirochaetae
> Actinobacteria > Proteobacteria. The Firmicutes
and Bacteroidetes accounted for more than 80%
of all the bacteria; having 61% and 24% relative
abundance, respectively. This is consistent with
the reports of Clarke et al.19 and Li et al.20 that
the Firmicutes and Bacteroidetes are the most
predominant phyla in the rat gut. However, this
Fig. 3. Dominant bacterial species in the colonic flora of (a) normal rat, (b) untreated diabetic rat and (c) rat treated
with 400 mg/Kg bw G. latifolium. Note depletion of the normally dominant species in diabetic rat and proliferation
of other species (dysbiosis). Note also, restoration and improvement with G. latifolium treatment.
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order was altered in diabetic rats, with significant
decreases in relative abundance of bacteria in
three of the phyla (Firmicutes, Bacteroidetes and
Spirochaetae), in favour of Actinobacteria, which
became the second most abundant phylum (Fig.
1).
In healthy animals, gut bacteria comprise
a great diversity of bacterial species, including
beneficial or friendly bacteria and potentially
harmful bacteria. The friendly bacteria keep a check
on the abundance of harmful organisms, through a
variety of mechanisms, including lowering of pH,
production of inhibitory substances, competitive
exclusion of receptors and nutrients among
others. A depletion of the protective friendly
bacteria, by any mechanism, including antibiotic
use or disease, affects this protective shield and
creates opportunity for overgrowth of the harmful
bacteria, a condition known as dysbiosis. Dysbiosis,
in turn, has various negative consequences for the
host, depending on the organisms that eventually
dominate. In this study, some bacterial species
were identified as major bacteria in the normal
rat gut, based on recurrence in different rats
and their relative abundance. These include: L.
murinus, L. acidophilus, L. johnsonii, Prevotella
copri, L. leuteri, B. sartorii, B. uniformis, Weisella
confusa, Clostridiales, and Brevibacterium linens;
mostly of the Firmicutes and Bacteroidetes phyla.
The relative abundance of these bacteria was
therefore compared in untreated diabetic rats
versus rats treated with G. latifolium leaf extract
and standard anti-diabetic drug (glibenclamide).
The results showed that induction of diabetes
in the rats caused a significant disruption of the
gut bacterial flora as L. acidophilus became the
most abundant organism (11.01% + 2.00%) in
the diabetic animals, followed by Brevibacterium
linens (5.28% + 2.96%), with appearance of species
such as Brachybacterium paralongomeratum,
Corynebacterium variable, Brevibacterium sp
VCM10, L. amylovorus, L. plantarum and L.
coleohominis; while L. murinus, L. johnsonii,
L. reuteri and Prevotella copri decreased in
abundance (Fig. 1b and 2b). Induction of diabetes
in the rats, thus resulted in dysbiosis, with
members of the Actinobacteria replacing some of
the core bacteria and becoming the predominant
flora. This observation is in agreement with one
study suggesting that there is disturbance of
Journal of Pure and Applied Microbiology
microflora with onset of diabetes21. Many studies
in both animal models and humans have shown
that there are indeed differences in the microflora
of diabetic and non-diabetic individuals4,15,18,22,
but while most of these studies suggest that
the composition of the flora may predispose the
host towards development of diabetes (that is,
composition as the cause and diabetes as effect),
the results in this study show clearly that diabetes
can be the cause of dysbiosis. The association
between dysbiosis and diabetes can therefore be
likened to a vicious cycle; dysbiosis predisposes
towards development of diabetes and diabetes in
turn, causes dysbiosis, in which there is increased
abundance of opportunistic pathogens.
The condition was however ameliorated
by treatment of the rats with G. latifolium leaf
extract and glibenclamide, in this study. At all three
test doses of G. latifolium, as with glibenclamide,
there was noticeable restoration of the microflora
as compared with that of untreated diabetic
rats (Fig. 2 and 3). Moreover, the treatments
produced increases in relative abundance of
species like Prevotalla copri and L. johnsonii,
which are associated with improved glucose
metabolism3,23,24. The best results were observed
with G. latifolium extract at the dosage of 400
mg/Kg body weight. An interesting observation in
this study was the fact that although there were
no overt changes in ratios of the different phyla
between the animal groups, the changes were
observed in relative abundance of species and
strains within the phyla. As seen in Fig. 1, besides
the dramatic increase in abundance of the phylum
Actinobacteria in diabetic rats, the Firmicutes and
Bacteroidetes remained the predominant phyla in
most other groups. However, a look at the strain
level showed that there were significant changes
in abundance of individual species (Fig. 3). These
findings suggest that studies to evaluate changes
in the microbiome should ideally be at the strain
level and not at the phylum level.
Tracking of the fasting blood glucose of
the rats over a six-week period showed that G.
latifolium leaf extract also effectively normalized
the blood glucose levels of the diabetic rats and
the effect was sustained for up to three weeks
following cessation of treatment. This finding is
consistent with previous reports that G. latifolium
has anti-diabetic activity11. The best result was
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DATA AvAILABILITy
The metagenomic data are available on
the CosmosID® portal, http://app.cosmosid.com
Other data generated are included in this
manuscript.
again observed at the dose of 400 mg/Kg body
weight. Although the dose of 800 mg/Kg produced
equally good blood glucose results, in terms of
effect on microbiome, this high dose appeared
to cause an over-enrichment of only one or two
bacterial species, while causing an overt reduction
in some core bacterial flora, including L. murinus,
L. johnsonii, L. leuteri, B. sartorii and Weisella
confusa. This finding suggests that treatments
aimed at modulating the microbiome may be
better at moderate rather than high doses, even
if the treatment agent is non-toxic.
ethiCs stAtemeNt
The animals were handled with humane
care according to NIH guidelines for use and
care of laboratory animals. The protocol was
also reviewed and approved by the University of
Nigeria Faculty of Veterinary Medicine Animal Care
and Use Committee (approval number: FVM-UNNIACUC-2020-1059).
CONClusiON
The results from this study show that
hydro-alcoholic leaf extracts of G. latifolium,
administered at moderate doses, can effectively
control diabetes through modulation of the gut
microbiome and provides support for management
of metabolic diseases through modulation of the
microbiome.
REFEREnCES
1.
2.
ACKnOwLEDGMEnTS
The authors wish to thank Dr. Remigius
Onoja and Mr. Anthony Agbo of the Faculty of
Veterinary Medicine, University of Nigeria, Nsukka,
for their assistance in the handling and care of the
experimental animals.
3.
4.
COnFLICT OF InTEREST
The authors declare that there is no
conflict of interest.
5.
6.
AUTHORS' COnTRIBUTIOn
EIM conceptualized, organized and
supervised the research work. She also prepared
the final versions of the manuscript.
CIK carried out the experiments and
prepared the first draft of the manuscript.
AMC assisted with the genomic DNA
extractions and some other molecular aspects
of the research. She also assisted in sample
collection.
UKO assisted with measurements of
blood glucose and other hematological parameters
during the project. He also reviewed the initial
draft of the manuscript.
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FUnDInG
None.
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