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In Vitro Glucose Entrapment and Alpha-Glucosidase Inhibition of Mucilaginous Substances from Selected Thai Medicinal Plants

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As a continuous searching for anti-diabetic(type II) substances, seven mucilage polysaccharides from selected plants were studied as follow: aerial parts of Basella alba Linn., fruits of Hibiscus esculentus Linn., leaves of Litsea glutinosa (Lour.) C.B. Robinson, seeds of Ocimum canum Sims., seeds of Plantago ovata Forssk., fruits of Scaphium scaphigerum G. Don. and seeds of Trigonella foenum-graecum Linn. The bioactive properties for entrapping glucose, inhibiting enzyme alpha-glucosidase and free radical scavenger were in vitro studied compared to glucomannan. The physical characteristics for water holding capacity and viscosity were determined. The chemical characteristics were assayed for monosaccharide composition using methanolysis, TMS-derivatization and gas chromatography. O. canum mucilage superiorly entrapped glucose compared to glucomannan. This activity was relevant to its highly viscous gelation. S. scaphigerum showed another property of alpha-glucosidase inhibition. S. scaphigerum mucilage (0.5%) inhibited the enzyme activity by 82.6%, compared to 1-Deoxynorjirimycin (by 47.6%). Most mucilages, except O. canum and P. ovata, showed DPPH scavenging activity higher than glucomannan. Galacturonic acid was found in 3 from 7 mucilages namely B. alba, P. ovata and S. scaphigerum. Whereas rhamnose was common sugar found in all seven mucilages. Monosaccharide components of these mucilages were compared to the results from the previous reports.
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Sci Pharm
Research article Open Access
In Vitro
Glucose Entrapment and Alpha-
Glucosidase Inhibition of Mucilaginous
Substances from Selected Thai Medicinal Plants
Chanida PALANUVEJ 1, Sanya HOKPUTSA 2,
1 College of Public Health Sciences, Chulalongkorn University, Bangkok 10330, Thailand
2 Research and Development Institute, Government Pharmaceutical Organization, Bangkok 10400, Thailand
3 Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
* Corresponding author. E-mail: (N. Ruangrungsi)
Sci Pharm. 2009; 77: 837–849 doi:10.3797/scipharm.0907-17
Published: October 10th 2009 Received: July 25th 2009
Accepted: October 9th 2009
This article is available from:
© Palanuvej et al.; licensee Österreichische Apotheker-Verlagsgesellschaft m. b. H., Vienna, Austria.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License
(, which permits unrestricted use, distribution, and reproduction
in any medium, provided the original work is properly cited.
As a continuous searching for anti-diabetic(type II) substances, seven mucilage
polysaccharides from selected plants were studied as follow: aerial parts of
Basella alba Linn., fruits of Hibiscus esculentus Linn., leaves of Litsea glutinosa
(Lour.) C.B. Robinson, seeds of Ocimum canum Sims., seeds of Plantago ovata
Forssk., fruits of Scaphium scaphigerum G. Don. and seeds of Trigonella
foenum-graecum Linn. The bioactive properties for entrapping glucose,
inhibiting enzyme alpha-glucosidase and free radical scavenger were in vitro
studied compared to glucomannan. The physical characteristics for water
holding capacity and viscosity were determined. The chemical characteristics
were assayed for monosaccharide composition using methanolysis, TMS-
derivatization and gas chromatography. O. canum mucilage superiorly
entrapped glucose compared to glucomannan. This activity was relevant to its
highly viscous gelation. S. scaphigerum showed another property of alpha-
glucosidase inhibition. S. scaphigerum mucilage (0.5%) inhibited the enzyme
activity by 82.6%, compared to 1-Deoxynorjirimycin (by 47.6%). Most mucilages,
except O. canum and P. ovata, showed DPPH scavenging activity higher than
glucomannan. Galacturonic acid was found in 3 from 7 mucilages namely B.
alba, P. ovata and S. scaphigerum. Whereas rhamnose was common sugar
found in all seven mucilages. Monosaccharide components of these mucilages
were compared to the results from the previous reports.
838 C. Palanuvej et al.:
Sci Pharm. 2009; 77; 837–849.
Mucilage • Polysaccharide • Anti-diabetic potential • Free radical scavenger •
Physicochemical property
Type 2 diabetes comprises 90% of people with diabetes around the world and is one of the
major public health challenges of the 21st century. The number of cases worldwide in
2000 is estimated to be about 171 million and is projected to rise to 366 million in 2030.
The World Health Organization (WHO) projects that without urgent action, diabetes-related
deaths will increase by more than 50% in the next 10 years. Especially in upper-middle
income countries, diabetes deaths are projected to increase by over 80% between 2006
and 2015 [1]. This circumstance results that the demand for medical care in type 2
diabetes will continue to increase. The substantial care and cost are due to the
management of complications of the disease at both the starting point and the degree of
deterioration over time. Macrovascular complications (ischemic heart disease, peripheral
vascular disease, and cerebrovascular disease) has been estimated to be the largest cost
component followed by microvascular complications (nephropathy, neuropathy and
retinopathy) [2]. Endothelial dysfunction is considered to be an integral component of
vascular diseases. Impaired endothelial function induces vasoconstriction, inflammatory
and proliferative changes in the arterial wall and promotes atherosclerotic lesion growth.
Prevention or normalization of endothelial function, contributes to the prevention of
vascular lesion progression or destabilization [3]. Hyperglycemia has been proposed to be
a crucial factor inducing endothelial dysfunction. High concentration of blood glucose as
well as high glucose fluctuation during postprandial period correlates with the increase in
reactive oxygen species or oxidative stress. Reactive oxygen species mediates the
activation of the imbalance in vasoregulating factors (vasodilators and vasoconstrictors)
then affects endothelial homeostasis and triggers atherogenic changes, including
increases in low-density lipoprotein oxidation, sympathetic tone, vasoconstriction, and
thrombogenicity [4]. Accordingly, glucose control is an important goal to diminish the risk of
long term health complications of type 2 diabetes. In addition to glycated haemoglobin and
fasting plasma glucose, postprandial glucose is recently recommended as essential target
for diabetes management [5]. Alpha-glucosidase inhibition is one of the powerful
interventions. Alpha-glucosidase is intestinal enzyme which catalyzes the degradation of
diet polysaccharides to absorbable monosaccharide. Natural or synthetic glucosidase
inhibitors are of therapeutic interest to delay postprandial hyperglycemia in type 2
diabetes. Amongst these, saccharide derivatives, for example Acarbose and Miglitol, have
been approvable for anti-diabetic drugs [6]. Non-starch polysaccharides designated as
soluble dietary fibers are also useful functional foods according to their association with
the reduced risks of diabetes and cardiovascular diseases [7]. The viscous characteristics
due to excellent water-holding and gel-forming capabilities have been proposed as an
important mechanistic factor to delay gastric emptying and delay absorption of glucose in
gastrointestinal tract [8]. Plant mucilage has been credited as one of plant chemical
constituents showing hypoglycemic activity [9, 10]. This study investigated in vitro
properties for anti type 2 diabetic potential among selected mucilaginous plants compared
to a well known soluble dietary fiber, glucomannan. Some physico-chemical characteristics
of these mucilages were also characterized.
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Sci Pharm. 2009; 77; 837–849.
Results and Discussion
Mucilage extraction
Seven mucilaginous plants were studied as follow: aerial parts of Basella alba Linn.
(Basellaceae), fruits of Hibiscus esculentus Linn. (Malvaceae), leaves of Litsea glutinosa
(Lour.) C.B. Robinson (Lauraceae), seeds of Ocimum canum Sims. (Labiatae), seeds of
Plantago ovata Forssk. (Plantaginaceae), fruits of Scaphium scaphigerum G. Don.
(Sterculiaceae) and seeds of Trigonella foenum-graecum Linn. (Papilionaceae). The
mucilages from selected plants yielded range from 3.5% to 23.0% as shown in table 1.
Tab. 1. Mucilage polysaccharides from selected plants
Plants Used parts % Yield
Basella alba Linn. aerial parts 3.5
Hibiscus esculentus L. fruits 5.6
Litsea glutinosa Lour. leaves 12.0
Ocimum canum Sims. seeds 17.6
Plantago ovata Forssk. seeds 19.0
Scaphium scaphigerum G. Don. fruits 23.0
Trigonella foenum-graecum L. seeds 15.0
In vitro property of entrapping glucose
Dialysis tubing technique is a simple model to evaluate the potential of soluble dietary
fibers to additionally retard the diffusion and movement of glucose in the intestinal tract
[11]. Movement in this system is not by the true diffusion but is assisted by the convective
activity of intestinal contractions [12]. The entrapment ability of mucilage gel resulted in
decreasing of glucose diffusion into the external solution. The retardation of the nutrient
flow into the external medium is an indication of the modulating effect of that fiber on
glucose absorption in the jejunum [11]. From the studied model, all mucilages showed
concentration response (0.5, 1.0 and 2.0%w/v) on glucose entrapment activity. The
percentage of glucose releasing from 2% mucilage suspension were 61.6, 70.8, 71.7,
80.6, 83.4, 85.8 and 92.8 % for O. canum, P. ovata, T. foenum-graecum, L. glutinosa, H.
esculentus, B. alba and S. scaphigerum respectively. Glucomannan showed 65.4% of
glucose releasing at the same concentration (Figure 1). Glucomannan seems to be the
most impressive natural fiber with increasing importance in the biomedical and
pharmaceutical fields. It has been found to decrease the serum glucose levels and also
the postprandial insulin flow which aiding diabetic control [13]. Psyllium seeds from P.
ovata and fenugreek seeds from T. foenum-graecum are also reported as an adjunct to
dietary therapy in patients with type II diabetes, to reduce glucose and glycosylated
hemoglobin [14, 15]. Figure 1 showed that the retardation effect on glucose movement of
the mucilages from P. ovata and T. foenum-graecum were lower degree than
glucomannan. Whilst O. canum mucilage of all concentration superiorly entrapped glucose
compared to glucomannan. There have been previous studies of hypoglycemic effect of O.
canum but from leaves extract [16].
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In vitro property of alpha-glucosidase inhibition
The effect of selected mucilages against α-glucosidase was evaluated. At the
concentration of 0.5% mucilage, S. scaphigerum, L. glutinosa, H. esculentus, O. canum, T.
foenum-graecum, P. ovata, B. alba and glucomannan showed the inhibitory percentage of
82.6, 41.0, 37.6, 32.8, 30.6, 27.0, 25.0 and 19.7 % respectively. Whereas, 1-Deoxy-
norjirimycin at the same concentration showed the inhibition of 47.6% (Figure 2). S.
scaphigerum mucilage was further investigated and found that the concentration for 50%
inhibition of α-glucosidase activity (IC50) was 0.17% (Figure 3). S. scaphigerum or Malva
nut tree is mostly found in the East of Thailand. The gel made from malva nuts is used as
ingredients in dishes and beverages. Malva nut drink is traditionally used to relief coughing
and sore throats. The previous study in type 2 diabetic patients reported that after the
intake of malva nut drink, fasting plasma glucose and glycosylated hemoglobin decreased
significantly [17]. The present study showed a possible mechanism in alpha-glucosidase
DPPH radical-scavenging activity
Tab. 2. DPPH scavenging activity as IC50 among mucilage polysaccharides from
selected plants
Mucilages IC50 (mg/ml) Mucilages IC50 (mg/ml)
B. alba 2.00 S. scaphigerum 0.61
H. esculentus 0.70 T. foenum-graecum 1.52
L. glutinosa 0.49
O. canum >10 Glucomannan 4.15
P. ovata >10 Ascorbic acid 0.02
a mean of 3 runs
glucose releasing
Fig. 1. Percentages of glucose releasing from 0.5, 1, 2% mucilage containing 2% glucose
after 2 hr dialysis (n=4). The significance of differences from the control (0%
mucilage, 99.8±0.9%) was determined by ANOVA followed by Dunnett’s test
(*p<0.01, **p<0.05).
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Fig. 2. Percentage of alpha-glucosidase inhibition by 0.5% mucilage (n = 3).
# %inhibition was not significantly different from control (Deoxynorjirimycin)
(p>0.05); * %inhibition was significantly higher from control (p<0.05);
* %inhibition was significantly lower than control (p<0.05) (determined by
ANOVA followed by Dunnett’s test).
Concentration (%)
Fig. 3. Percentage of alpha-glucosidase inhibition from various concentration of S.
scaphigerum mucilage
Endothelial dysfunction is a key factor in all stages of atherosclerosis development. This
term refers to an imbalance in the production of vasodilators at the circumstance of high
concentrations of reactive oxygen species or oxidative stress [4]. Scavenging of the stable
free radical diphenylpicrylhydrazyl (DPPH) is the basis of a common antioxidant assay.
There have been widely different protocols which differed in the conditions (i.e. pH,
inhibition (%)
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solvents, wavelength of measurement), yielding different results. In the present study, the
polysaccharide samples were incubated with 100 µM DPPH in methanol for 30 min using
ascorbic acid as standard antioxidant. The number of DPPH reduced by one molecule of
ascorbic acid (antioxidant stoichiometry) was 2.5 which was higher than the theoretic value
of 2.0 but close to the previous experiments [18, 19]. Table 2 demonstrated the
scavenging activity of the polysaccharide samples on the DPPH radical. Except for O.
canum and P. ovata, other mucilages showed scavenging activities higher than
glucomannan. Especially the mucilages of L. glutinosa, S. scaphigerum and H. esculentus
had IC50 less than 1 mg/ml. Although the abilities were lower than that of ascorbic acid,
these mucilages counteracted with DPPH as strongly as Ganoderma polysaccharides
(IC50 between 3–13 mg/ml) [20].
Swelling measurements and viscosity
There are a series of physical interactions in the gastrointestinal tract which affect
absorption, as follow: diffusion of nutrients from the bulk solution to the intestinal epithelia,
the rate of removal of waters of hydration from a complex nutrient solvent system, counter
diffusion of nutrients away from the intestinal surface and diffusion of nutrients along the
epithelial surface to an appropriate absorptive site [21]. Water can be held within the
polysaccharide matrix causing considerable swelling and viscous solution or gelation.
Viscous polysaccharide gels may slow absorption by trapping nutrients, digestive enzymes
or bile acids in the matrix and by slowing mixing and diffusion in the intestine [22]. These
physical properties of selected mucilages were studied (Table 3). O. canum and S.
scaphigerum mucilages showed highest values of swelling volume (SV) and water
absorption index (WAI) followed by P. ovata and T. foenum-graecum respectively. Other
mucilages showed the same values of SV and WAI as glucomannan. Viscosity was
determined using falling ball viscosity method. O. canum mucilage had highest viscosity
value even at low concentration (0.5%). Viscous character seemed to be a prominent
factor affected the hypoglycemic potential of O. canum but not S. scaphigerum mucilage.
Tab. 3. Swelling volume (SV), water absorption index (WAI) and viscosity among
mucilage polysaccharides from selected plants
Viscosity (mPa s)
Mucilages SV
(g/g) 0.5% 1.0% 2.0%
glucomannan 23.9 ± 1.9 22.1 ± 1.9 21.1 ± 0.3 143.2 ± 8.9 4582.8 ± 60.3
B. alba 25.7 ± 6.3 15.8 ± 3.0 2.2 ± 0.3 3.5 ± 0.4 7.0 ± 0.4
H. esculentus 22.2 ± 4.6 20.7 ± 4.3 7.7 ± 0.7 17.1 ± 0.9 45.1 ± 2.0
L. glutinosa 27.5 ± 8.5 20.6 ± 4.6 1.8 ± 0.2 5.9 ± 0.6 19.1 ± 2.6
O. canum 115.9 ± 17.3* 111.1 ± 17.1* 581.3 ± 59.1 >5000 >5000
P. ovata 60.4 ± 7.7* 48.3 ± 3.2* 6.2 ± 0.3 18.5 ± 1.1 1575.3 ± 57.5
S. scaphigerum 210.5 ± 4.3* 102.8 ± 1.6* 0 0 0
T. foenum-graecum 38.9 ± 1.0 19.1 ± 1.4 6.7 ± 0.4 29.6 ± 1.9 213.0 ± 17.9
a mean of 3 runs; * the significance of differences of SV and WAI from the control (glucomannan) was
determined by ANOVA followed by Dunnett’s test (p<0.01).
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Monosaccharide analysis and protein content
The selected mucilages as well as glucomannan were analyzed for the primary structures
of their monosaccharide compositions as shown in Table 4 and 5. Konjac glucomannan in
this study showed the mannose : glucose molar ratio of around 1.6 : 1 which was in the
range reported elsewhere. Galacturonic acid was found in 3 from 7 mucilages namely
B. alba, P. ovata and S. scaphigerum. Whereas rhamnose was common sugar found in all
studied mucilages. Chemical analyses of the mucilages in this study showed some
differing results from the previous reports. This was due to the differences in either plant
origin or methodology of extraction and analysis. Literature reviews of monosaccharide
composition among these mucilages were summarized in Table 6. H. esculentus mucilage
from this study had highest glucose (79%) composition compared to 44% and 5% from the
literatures. L. glutinosa mucilage from the leaves in this study had xylose/ arabinose ratio
differed from the reported barks. P. ovata and T. foenum-graecum mucilages displayed the
typical characters of arabinoxylan and galactomannan respectively. The water extracts of
S. scaphigerum mucilages in this report had similar ratio of monosaccharide with the
alkaline extracts reported elsewhere. B. alba mucilage was firstly revealed the composition
of arabinose, rhamnose, galactose, galacturonic acid and glucose (24:5:41:13:16). Total
protein contents in these crude polysaccharides ranged from 2% in P. ovata to 38% in L.
glutinosa (Table 4).
Tab. 4. Monosaccharide composition and total protein content (µg/mg) among mucilage
polysaccharides from selected plants
Arab Rham Xy Man
glucomannan 493.8 ± 11.6
B. alba 43.5 ± 0.8 10.7 ± 0.1
H. esculentus 27.8 ± 0.6
L. glutinosa 84.1 ± 1.2 6.0 ± 0.2 56.4 ± 0.5 9.7 ± 0.1
O. canum 47.8 ± 1.1 28.0 ± 0.7 98.43 ± 2.5 37.5 ± 1.5
P. ovata 165.2 ± 13.5 52.0 ± 3.4 697.5 ± 1.3
S. scaphigerum 121.7 ± 3.4 155.2 ± 4.8 20.8 ± 0.7
T. foenum-graecum 18.8 ± 0.4 20.4 ± 0.2 310.4 ± 1.2
Gal Galn Glu TPc
glucomannan 309.6 ± 3.6 107.8 ± 0.04
B. alba 88.7 ± 1.0 33.7 ± 1.3 34.6 ± 0.8 235.5 ± 0.04
H. esculentus 46.5 ± 1.4 285.7 ± 1.4 152.7 ± 0.04
L. glutinosa 29.7 ± 0.6 88.9 ± 0.5 375.1 ± 0.01
O. canum 156.2 ± 0.8 66.30 ± 0.2 81.8 ± 0.02
P. ovata 51.7 ± 3.0 20.3 ± 0.02
S. scaphigerum 144.6 ± 0.3 173.4 ± 2.9 21.1 ± 0.2 195.3 ± 0.03
T. foenum-graecum 302.2 ± 1.2 82.2 ± 0.5 209.5 ± 0.01
a mean of 3 runs; b monosaccharides found in these mucilages included arabinose (ara),
rhamnose (rham), xylose (xy), mannose (man), galactose (gal), galacturonic acid (galn) and
glucose (glu). Fucose (fu) and glucuronic acid (glun) were absent; c Total protein.
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Tab. 5. Monosaccharide composition (% mole ratio) among mucilage polysaccharides
from selected plants
Ara Rham Xy Man Gal Galn Glu
glucomannan 61 39
B. alba 24 5 41 13 16
H. esculentus 8 13 79
L. glutinosa 33 2 22 3 10 29
O. canum 12 6 25 8 34 14
P. ovata 18 5 74 4
S. scaphigerum 23 24 4 23 23 3
T. foenum-graecum 3 3 42 41 11
Tab. 6. Monosaccharide composition among mucilage polysaccharides from literatures
glucomannan man : gluc 1.6 : 1 [23]
rham : gal : galn: glu : glun 1 : 2.5 : 1.8 : 0.3 : 0.2 [24]
H. esculentus ara : rham : xyl : man : gal : galn : glu : glun 5 : 3 : 5 : 3 : 17 :
16 : 44 : 7
L. glutinosa ara : xy 3.4 : 1.0 (barks) [26]
O. canum ara : rham : xy : man : gal : glu 1 : 2 : 1 : 2 : 5 : 8 (uronic acids
P. ovata ara : rham : xy : man : gal : glu 20.7 : 1.1 : 50.3 : 1.1 : 4.8 : 2.0 [28]
S. scaphigerum ara :rham : gal 1.1 : 1.0 : 1.0 (%w/w) [29]
ara: rham : man : gal : glu 0.5 : 0.2 : 31.4 : 26.2 : 0.6 [30]
T. foenum-
graecum gal : man 1.00 : 1.02 to 1.00 : 1.14 [31]
The plants bearing mucilage in this study have been well known in Thailand as both edible
and medicinal plants. Mucilagenous typed polysaccharides from these plants were
investigated for the biological activities especially antidiabetic potential. Despite the
limitations of this in vitro study, there seemed to be various mechanisms possibly involved
by mucilages due to their physico-chemical characteristics. The in vitro models could be
beneficial tools for the survey of other potential plant mucilages. Moreover they could
refine the possible and capable research designs prior to the expensive further studies of
either the animal models or the clinical trials.
Seven mucilaginous plants were studied as follow: aerial parts of Basella alba Linn.
(Basellaceae), fruits of Hibiscus esculentus Linn. (Malvaceae), leaves of Litsea glutinosa
(Lour.) C.B. Robinson (Lauraceae), seeds of Ocimum canum Sims. (Labiatae), seeds of
Plantago ovata Forssk. (Plantaginaceae), fruits of Scaphium scaphigerum G. Don.
(Sterculiaceae) and seeds of Trigonella foenum-graecum Linn. (Papilionaceae).
Glucomannan flour (the Siam Konjac Co., Ltd.) was used for comparison. Chemicals and
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Sci Pharm. 2009; 77; 837–849.
reagents included p-nitrophenyl-α-D-glucopyranoside and α-glucosidase (EC from
Saccharomyces cerevisiae, 1-Deoxynojirimycin, 1,1-Diphenyl-2-picrylhydrazyl (DPPH),
standard monosaccharides (Sigma Chemical Co. Ltd, St. Louis, MO.); methanolic HCl,
trimethylchlorosilane, hexamethyldisilazane (Supelco, Bellefont, PA); Glucose Liquicolor
kit (Human Gesellschaft für Biochemica und Diagnostica mbH, Germany); Lactated
Ringers Buffer pH 7 (General Hospital Product Public Co., LTD., Thailand), All other
chemicals were analytical grade. Dialysis tubing cellulose membrane (molecular weight cut
off = 12,000 Da) was from Sigma Chemical Co. Ltd, St. Louis, MO. Dialysis tubing cellulose
membrane (molecular weight cut off = 3,500 Da) was from Spectrum Medical Industries,
Inc., Los Angeles, CA.
Mucilage extraction
The mucilage were extracted from the specified plant parts with warm water and
concentrated by lyophilization. The lyophilized samples were re-dissolved in water,
precipitated twice with 2 volume of 80% ethanol and dialyzed against distilled water in a
dialysis tubing cellulose membrane (molecular weight cut off = 3,500 Da). The samples
were lyophilized, ground and kept in refrigerator for further studies.
In vitro property of entrapping glucose
The mucilage and glucomannan were dissolved in Ringers buffer. Glucose was added to
make the final concentration of 2% glucose and 0, 0.5, 1 and 2 % w/v polysaccharide gel.
Four milliliter of each concentration was dialysed against 60 ml of Ringers buffer in a
dialysis tubing cellulose membrane (molecular weight cut off = 12,000 Da) for 2 hours
under rotationally shaking at 150 rpm. The released glucose was determined by glucose
oxidase - phenyl ampyrone (GOD-PAP) colorimetric method using Glucose Liquicolor kit
according to manufacturer's instructions.
In vitro property of alpha-glucosidase inhibition
Alpha-glucosidase activity was assayed using 0.1M sodium phosphate buffer at pH 6.9,
and 1 mM p-nitrophenyl-α-D-glucopyranoside was used as a substrate [32]. The
concentration of α-glucosidase was 1 U/mL in each experiment. The enzyme (4 μl) was
incubated in the absence or presence of various concentrations of tested polysaccharides
at 37 °C. The preincubation time was specified at 10 min and the substrate (95 μL) was
added to the mixture. The reaction was carried out at 37 °C for 20 min, and then 100 μL of
1M Na2CO3 was added to terminate the reaction. Enzymatic activity was quantified by
measuring the absorbance of p-nitrophenol at 405 nm. One unit of α-glucosidase is
defined as the amount of enzyme liberating 1.0 μmol of p-nitrophenol per minute under the
conditions specified. 1-Deoxynojirimycin was used as the positive control.
DPPH radical-scavenging activity
The potential antioxidant activity of polysaccharide samples was determined on the basis
of the scavenging activity of the stable DPPH free radical [33]. Various concentrations
of polysaccharides samples (0.5 ml) were added to 1.5 mL of a 0.004% methanolic
solution of DPPH. Absorbance at 517 nm was determined after 30 min, and the percent
scavenging activity was calculated by the following formula:
Scavenging effect (%) = (1 Asample/Acontrol) x 100
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Where Acontrol is the absorbance of control (DPPH solution plus water), Asample is the test
sample (DPPH solution plus test sample or positive control) and the percent inhibition
activity was calculated. IC50 values denote the concentration of sample required to
scavenge 50% DPPH free radicals.
Swelling measurements and viscosity
Swelling volume (SV) and water absorption index (WAI) were determined from the ratio of
the volume and weight of swollen gel to the dry weight of sample respectively [34,35]. A
0.050 g ground sample (<60 mesh) was suspended in 25 ml of water in a 25-ml graduated
cylinder for 2 hours. The volume of swollen gel was measured. The supernatant liquid was
removed, the swollen gel was weighed and SV and WAI were calculated. Viscosities at
various concentrations were measured with a falling ball viscometer (HAAKE Mess-Technik
GmbH u. Co, Germany) at 20 °C.
Monosaccharide analysis and protein content
The polysaccharide samples (1 mg) were subjected to methanolysis with 4 M methanolic
HCl at 80°C for 24 h. Mannitol was added as an internal standard. The samples were dried
with nitrogen, methanol was added and the samples were dried again. This washing was
repeated twice [36]. Prior to gas chromatographic analysis, the samples were
trimethylsilylated using trimethylchlorosilane : hexamethyldisilazane : Pyridine 1:2:5 (0.4
ml) at room temperature for 30 min. Instrumentation was performed on a Finnigan Trace
GC Ultra with DSQ MS detector and a split–splitless injector. The column was a ZB-5
fused silica capillary column (30 m × 0.25 mm i.d.) with film thickness 0.25 μm. Helium
was used as carrier gas at a flow rate of 1.0 ml/min. The injector and detector temperature
were 260 and 300°C respectively. The column temperature was initially 140°C, then an
increase of 1°C/min to 170°C and followed by 6°C/min to 250°C. The protein contents of
the samples were determined by Lowry method using bovine serum albumin as protein
Statistical analysis
The significance of differences between the mean values was determined by analysis of
variance (ANOVA), followed by Dunnett’s test, and a p value of less than 0.05 was
considered statistically significant.
C.P. wishes to thank the Thailand Research Fund through the Royal Golden Jubilee Ph.D.
Program and Chulalongkorn University Graduate School Thesis Grant for financial
supports. The authors also express their gratitude to the Siam Konjac Co., Ltd. for
standard glucomannan.
Authors’ Statement
Competing Interests
The authors declare no conflict of interest.
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... Basellasaponins A, B, C, D, β-sitosterol, stigmasterol glucoside, β-vulgaroside I, syringic acid, lupeol, kaempferol, ferulic acid, rutin, betacyanin and acacetin are some of the bioactive compounds reportedly isolated from B. alba aerial parts [14,[18][19][20][21]. Furthermore, an acidic polysaccharide (pH 5.3-5.4) with arabinose, rhamnose, galactose, galacturonic acid and glucose as major repeating exhibited slow swelling capacity, strong suspending ability and high viscosity resulting in considerable glucose entrapment ability and αglucosidase inhibitory activity in vitro [22][23][24]. Apart from their prospective applications in the nutraceutical industry as thickening, suspending, binding, and gelling agents, these complex polysaccharides have shown significant antidiabetic efficacy in animal studies [25][26][27]. However, the mechanism of its antidiabetic action has not been studied. ...
... As a consequence, it is reasonable to believe that the polysaccharides molecules interfere with glucose movement by physically adsorbing or entrapping glucose molecules within the fiber matrix [30], with the effect being directly proportional to the level of viscosity given by the gelforming polysaccharides of B. alba. These findings are consistent with a previous study in which mucilage extracted from B. alba demonstrated significant glucose entrapment ability in vitro [24]. These results are also consistent with an earlier study in which juice produced from B. abla leaves decreased both starch and glucose-induced post-prandial glycemic load in normoglycemic rats [40]. ...
... The mucilage, isolated from the leaves of L. glutinosa, exhibit anti-diabetic (type II) and antioxidant property (Palanuvej et al., 2009). Although a relatively recent report revealed that L. glutinosa leaves have antidiarrheal properties, scientific proof of the same for the bark has not yet been discovered. ...
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The work is about the antidiarrheal potential of pyrazole ring containing compounds of Litsea glutinosa
... The chicken stew had the lowest glucosidase inhibition of 2.13%. Previous study also suggested psyllium mucilage could delay α-glucosidase activity and entrap glucose in vitroand in vivo (Palanuvej, 2009;Gibb et al., 2015), but this mechanism has not been explored. Overall, it can be concluded that husk-20% inulin emulsion gel incorporation in food product will beneficially delay α-glucosidase activity. ...
The aim of this paper was to investigate effects of inulin and ultrasonic homogenization on particle size distribution and microstructure of oil-in-water emulsion gels stabilized by psyllium husk were investigated. The emulsion gel was assessed their utility in meat puree prepared for people with dysphagia. The results showed that increasing inulin percentage resulted in reduced particle size and improved emulsion stability with the optimum at 20% w/w inclusion. Ultrasonic homogenization further enhanced the emulsion stability by reducing the size of emulsion droplet and improving encapsulation of emulsion droplet. Increasing inulin concentrations in the emulsion gels added into purees also corresponded with decreasing total expressible fluid (TEF). The stability of puree against the action of carbohydrate-hydrolyzing enzymes (α-amylase and α-glucosidase) was improved with the addition of emulsion gels. Therefore, these developed emulsion gels could be beneficial in formulating modified-texture food prepare for people with dysphagia.
... The alpha glucosidase inhibitory activity was determined using the (Palanuvej et al. 2009) technique. Yeast alpha glucosidase was dissolved at 0.1U/ml in 100mM phosphate buffer, pH 7.0, including 2000 mg/l bovine serum albumin and 200 mg/ml sodium azide as an enzyme source. ...
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The in vitro antidiabetic efficacy of ethanolic extract Boerhavia diffusa (B.diffusa) synthesized silver nanoparticles (AgNPs) was investigated by inhibition of α-amylase, α-glucosidase, protein glycation assay, non-enzymatic glycosylation of hemoglobin, glucose uptake by yeast cells and glucose diffusion at varying concentrations (10 to 100µg/ml). The alpha-amylase assay shows that the acarbose (standard) and B. diffusa had IC50 values of 46.2 µg/ml and 55.4 µg/ml, whereas alpha-glucosidase inhibitory activity was found to be 63.4 µg/ml and 93.0 µg/ml respectively. Further, non-enzymatic glycosylation analysis showed IC50 value of metformin (standard) as 28.6 µg/ml and B. diffusa as 63.9 µg/ml. The protein glycation activity was inhibited in non-enzymatic glycosylation of hemoglobin. The glycosylation was induced using pioglitazone (standard) which gives IC50 value of 616.4 µg/ml by which B. diffusa showed 756.3 µg/ml. The uptake of glucose by yeast cells was analyzed and the result shows that the glucose concentration increased steadily from 5mM to 25mM (maximum absorption) of both metronidazole (standard) and B. diffusa . From 30 to 180 minutes, the glucose diffusion experiment revealed that the concentration of the metformin and B. diffusa extract was positively correlated with the time. The ethanolic extract of synthesized AgNPs and the reference medication employed in all experiments both benefit their curative potential for the treatment of insulin resistance. The generated silver nanoparticles can be used for industrial and therapeutic purposes and can be released into the environment without harm. More in vivo study can be reviewed, however the green synthesized ethanolic extract of B. diffusa exhibits promising affect for the treatment of diabetes mellitus.
... The seeds consist of proteins that have prominence in ancient ayurvedic medicine (Khan et al. 2018). Palanuvej et al. (2009) reported that fenugreek (T. foenum graecum) seeds consist of mannose and galactose molar ratio (Mathur 2011). ...
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Coagulation is an essential and easy process to treat water and wastewater and also to adopt for point of use solutions. Coagulants have played a significant role in providing safe and potable water. Nevertheless, the ill effects of chemical coagulants, such as health effects and substantial sludge quantities, cannot be ignored. Under given conditions, the search for alternative coagulants has been the need of the hour, and researchers have presented those natural coagulants are promising alternatives. The exploration and evaluation of plant-based coagulants have shown that these are fit to substitute chemical coagulants sustainably. Previous studies have presented the efficacy of various coagulants but could not fill in the gap existing in terms of a cumulative database of natural coagulants. In these lines, the focus of the current review is to present the history of natural coagulants, the science involved and studies carried out to evaluate them at different levels. Furthermore, a cumulative database of 57 natural coagulants with their efficacy in removing impurities from raw water is presented.
Diabetes mellitus is a globally metabolic endocrine syndrome marked by a deficiency of insulin secretion (type-1 DM) or glucose intolerance arising from insulin response impairment (type-2 DM) leading to abnormal glucose metabolism. With an increasing interest in natural dietary components for diabetes management, the identification of novel agents witnessed major discoveries. Plant-derived mucilage, pectin, and inulin are important non-starch polysaccharides that exhibit effective antidiabetic properties often termed soluble dietary fiber (SDF). SDF affects sugar metabolism through multiple mechanisms affecting glucose absorption and diffusion, modulation of carbohydrate metabolizing enzymes (α-amylase and α-glucosidase), ameliorating β-pancreatic cell dysfunction, and improving insulin release or sensitivity. Certain SDFs inhibit dipeptidyl peptidase-4 and influence the expression levels of genes related to glucose metabolism. This review is designed to discuss holistically and critically the antidiabetic effects of major SDF and their underlying mechanisms of action. This review should aid drug discovery approaches in developing novel natural antidiabetic drugs from SDF.
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3'3-Diindolylmethane (DIM) is a compound derived from the digestion of indole-3-carbinol, found in Cruciferous vegetables (Broccoli, Cabbage, Cauliflower,) promote Estrogen metabolism in females. It has been known to help in the reduction of heavy blood flow during menstruation especially in females with fibroids. Dim-plus a herbal supplement contains Vitamin E, DIM, Phosphatidylcholine, Spinach, Cabbage, and Broccoli powder. The purpose of this research is to extract and identify the compounds present in Broccoli, Spinach and Cabbage obtained in local markets in Lagos, Nigeria and compare it with the reference standard DIM-plus. Identification of compounds qualitatively by TLC showed different Rf values which were compared with the reference to identify compounds with similar Rf values. The extract was also subjected to HPLC analysis to confirm the presence of DIM in the Cruciferous vegetables using Dim-plus as standard. Based on the TLC and HPLC analysis it was discovered that the common peak which the crude extracts of the vegetables has is DIM. Thus, the vegetable extracts have Diindolylmethane.
This research investigated the effect of organic extracts from Litsea glutinosa (Lour.) C. B. Rob bark and its five heterocyclic compounds on induced diarrheal models. The bark of L. glutinosa was extracted with chloroform, ethyl acetate, and methanol. The resultant extracts were examined for disc-diffusion-guided activity against diarrhea-causing bacteria and chemical-induced anti-diarrheal properties in castor oil- and magnesium sulfate-induced diarrheal models. The effect of the extracts on gastrointestinal motility was tested in activated charcoal meal and barium sulfate milk models. The effects of the extracts on electrolytes (Na+, K+, Cl- and HCO3–), creatinine, triglycerides (TG), C-reactive protein (CRP), and immunoglobulin E (IgE) were assessed in the blood serum of treated animals. From the GC–MS analysis of the L. glutinosa methanol extract, five heterocyclic compounds were selected, and their interactions with target receptors were investigated using molecular docking techniques. The methanol extract (MExLG) showed the highest zone of inhibition for Shigella dysentriae (ZOI, 24 ± 0.9 mm) and E. coli (ZOI, 16.00 ± 1.14 mm), Salmonella paratyphi (18.23 ± 3.06 mm) and Vibrio cholerae (22.10 ± 2.62 mm). For both castor oil- and barium sulfate-induced diarrhea, MExLG achieved the highest levels of diarrheal inhibition 82.5% and 77.33%, respectively. MExLG showed the best in Na+, K+, Cl-, and HCO3– equivalence. Serum creatinine, TG, CRP and IgE levels were significantly (P
Basella alba is a commonly available plant having significant quantity of mucilage present in its leaves and stem. The review focuses on the method of extraction of mucilage, its chemical composition, monosaccharide composition and various chemical and physical properties of mucilage. The rheological properties of B.alba mucilage, exhibiting pseudoplastic flow enable it to be used for formulating artificial human saliva. The B.alba mucilage is found to be used as disintegrating agent, binding agent, suspending agent, matrix former, gelling agent, encapsulating agent and as release retardant in pharmaceutical formulation. The properties of mucilage have been evaluated against standard excipient and confirmed of their adjuvant properties. The mucilage also possesses drag reducing ability due to which it can be used as natural flow improver in pipelines for reducing the frictional pressure drop. The plant is rapidly growing, commonly available and possesses wide additive properties; even then it remains under- utilized as pharmaceutical excipient so its versatility in targeted drug delivery, micro-/nano-drug delivery, tissue engineering and stimuli responsive delivery system is highly desirable. Apart from this, several opportunities of mucilage which are left unexplored is discussed in the review like formation of BioMEMS, formation of microneedles and as theranostic agents. Thus, the review explores various pharmaceutical applications and opportunities of B.alba mucilage to act as smart novel carrier in pharmaceutical formulation.
Okra (Abelmoschus esculentus) has traditionally been used in diabetes treatment. This study investigated the effect of Okra whole fruit on blood glucose level of patients with diabetes mellitus type 2 with concomitant use of oral hypoglycemic agents. In this double‐blind randomized clinical trial, 120 diabetic patients were assigned to okra group (n = 60) and control group (n = 60). The okra group received 1,000 mg of A.esculentus whole fruit capsules orally, every 6 hr for 8 weeks. The control group received placebo capsule in the same manner. The levels of FBS (fasting blood sugar), BS (blood sugar), and Hemoglobin A1C (HgA1c) were measured at baseline and after intervention in both groups. The levels of FBS, BS, and HgA1c were significantly decreased in okra group within the intervention compared to control group (p < .05). Moreover, the numbers to treat (NNT) for FBS, BS, and HgA1C were seven, eight, and seven, respectively. Okra whole fruit supplementation has a promising anti‐hyperglycemic effect in patients with diabetes mellitus type 2 who received oral agents. Diabetic patients could benefit from adjuvant therapy of okra with other medication.
The capsular mucilage of the seeds was extd. in 7% yield. It is partly O-acetylated (OAc, 4.0%) and contains lipids (free 24% and bound 5%). The mucilage is composed of D-glucose, D-galactose, D-mannose, L-arabinose, D-xylose, and L-rhamnose in the approx. ratio 8:5:2:1:1:2 and uronic acids (8.15%). The uronic acids were identified as D-galacturonic and D-mannuronic acids. The mucilage was fractionated into an acid-sol. fraction, which was significantly acetylated (OAc, 6.6%) and rich in uronic acids (34.4%) and pentosans, and an acid-insol. fraction rich in hexosans. The latter on further fractionation with alkali gave a glucomannan with glucose and mannose in the ratio 10:3, and a galactoglucomannan with galactose, glucose, and mannose in the ratio 2:4:1. Thus the mucilage is heterogeneous, contg. at least 3 different polysaccharides, and is comparable to cellulose-contg. seed mucilages and acidic bacterial polysaccharides. [on SciFinder(R)]
Glycoside trimming enzymes are crucially important in a broad range of metabolic pathways, including glycoprotein and glycolipid processing and carbohydrate digestion in the intestinal tract. Amongst the large array of enzymes, glucosidases are postulated to be a powerful therapeutic target since they catalyze the cleavage of glycosidic bonds releasing glucose from the non-reducing end of an oligo- or polysaccharide chain involved in glycoprotein biosynthesis. Glucosidase inhibitors are currently of interest owing to their promising therapeutic potential in the treatment of disorders such as diabetes, human immunodeficiency virus (HIV) infection, metastatic cancer, and lysosomal storage diseases. Glucosidase inhibitors have also been useful in probing biochemical pathways and understanding structure–activity relationship patterns required for mimicking the enzyme transition state. Amongst the various types of glucosidase inhibitors, disaccharides, iminosugars, carbasugars, thiosugars, and non-sugar derivatives have received great attention. This review is aimed at highlighting the main chemical classes of glucosidase inhibitors, as well as their biological activities toward α- and β-glucosidases, but it is not intended to be an exhaustive review on the subject. Inhibition data on the compounds covered in this review are included in a tabular form as an Appendix, where the type of each glucosidase associated with a specific inhibitor is also given.
Crude fenugreek gum (3.74% protein) was purified by dissolving in aqueous solvent and centrifugation to remove impurities which yielded a purified gum fraction containing 1.10% protein residue. Further purification of the gum was achieved by treating the gum solution with phenol to obtain protein free fenugreek gum (0.16% protein residue). The three types of fenugreek gums were evaluated for: molecular weight, surface activity and rheological performance. Surface and interfacial tension, measured by a Du Nouy ring, indicated that the removal of protein in the gum significantly reduced its surface activity. However, the crude fenugreek gum exhibited lower intrinsic viscosity and radius of gyration compared to the purified and protein free fenugreek gums. It was found that both protein residue and gum concentration affected the elastic modulus (G′), viscous modulus (G″), and complex viscosity (η∗).
Fenugreek gum was extracted from defatted, deactivated fenugreek seeds (produced in Canada) at 10°C for 2h to give a yield of 22% with only 2.36% protein contaminates. Further purification of fenugreek gum was achieved by treating the gum solution with pronase to reduce the protein contaminates to 0.57%. High performance size exclusion chromatography showed that the enzyme treatment did not affect the molecular weight of the galactomannans. Monosaccharide and methylation analysis suggested that the extracted fenugreek galactomannans were highly substituted and the ratios of galactose to mannose were from 1.00:1.02 to 1.00:1.14. Although fenugreek gum exhibited higher molecular weight compared to locust bean gum and guar gum, the intrinsic viscosity and rheological behavior of fenugreek gum were reduced. This was attributed to the influence of the substitution patterns of the galactose on the mannosyl backbone chain. The purified fenugreek gum demonstrated less surface activity compared to the unpurified gum, which is in contradiction with the results reported in the literature. Detailed structural characterization of fenugreek gum has been done in order to elucidate the structure–functionality relationship of this gum and it will be reported in a subsequent paper.
In addition to being consumed as food, starch is considered for replacement of petroleum-based plastics, but imparts negative effect like water absorption and solubilization in water. In this study, the effects of sodium hydroxide and sodium trimetaphosphate concentrations on the water absorption and solubility indices of starch cross-linked by sodium hydroxide and sodium were evaluated. Starch was granulated, and 0.3 kg granulated starch was mixed with 65 ml sodium hydroxide at three concentrations (0.2, 0.6, and 1.0 M), sodium trimetaphosphate at two levels (0.015 and 0.045 kg sodium trimetaphosphate corresponding to 5 and 15% of starch), and water to adjust moisture content to 40% (dry basis). The samples were extruded in a single-screw extruder at a barrel temperature of 130 °C and screw speed of 140 rpm. Phosphorus content and pasting viscosity of starch extrudates showed that starch was cross-linked with phosphorus that was incorporated into starch during extrusion. The extrusion and cross-linking of starch with 5% sodium trimetaphosphate reduced water absorption index, and increasing sodium trimetaphosphate percentage reduced water absorption index further at high levels of sodium hydroxide. On the other hand, the reduction in water solubility of starch extrudates required the extrusion of starch with more than 5% sodium trimetaphosphate, but increasing the sodium hydroxide level increased the water solubility index of extrudates.
The 2,2-diphenyl-1-picrylhydrazyl (DPPH) test is largely used in plant or food biochemistry to evaluate the free radical scavenging effect of specific compounds or extracts. In its radical form, DPPH has a broad absorption band in the visible region at 517 nm, while if it is protonated by an antiradical compound, it loses this property.This study regarded the effect on DPPH reduction by ascorbic acid in function of its dissolution in water or ethanol and in addition of acetic, malic and citric acid, which are widely diffused organic acids in the plant kingdom.The tested acids gave no scavenging activity in the absence of ascorbic acid, while their action was significant when used in the presence of ascorbic acid. They generally enhanced the scavenging activity of ascorbic acid on DPPH at a steady rate, while malic and citric acid slowed the reaction during the first minute.
Hypoglycemic effect of Fenugreek seed powder (Trigonella foenum graecum) was studied in 60 non-insulin dependent diabetic patients. A prescribed diet with and without Fenugreek seed powder was given to patients for 7 days of a control period and for 24 weeks of the experimental period. During the experimental period twenty five grams of Fenugreek seed powder divided into two equal doses was added to the diet and served during lunch and dinner. Diet containing Fenugreek seed powder lowered fasting blood glucose levels and improved glucose tolerance. Insulin levels were also diminished. Twenty four hour urinary sugar excretion was reduced significantly (p < 0.001). Glycosylated hemoglobin measured at the end of the 8th week of Fenugreek seed powder administration was reduced significantly (p < 0.001). This shows that feeding Fenugreek seed powder is beneficial to diabetic subjects.
To assess the potential of arabinoxylan (AX)-rich psyllium (Plantago ovata Forsk) seed husk (PSH) as a source for production of arabinoxylo-oligosaccharides (AXOS), the parameters determining PSH AX extraction yield and the chemical and enzymic hydrolysis of PSH AX were investigated. The seed husk material had a high content of AX (62.5%) with an arabinose to xylose ratio of 0.41. The water extractability of PSH AX was affected by suspension concentration rather than by temperature. Maximally, 27% of all AX could be extracted, even when using very dilute suspensions (0.1% w/v). When subjected to alkaline conditions, a pH of at least 12 was needed to significantly increase extractability (up to 77% of all AX). The extractability-increasing effect of alkali was, however, reversible, as extractability decreased again when lowering the pH. Acid hydrolysis at high temperature drastically increased AX extraction yields (up to 97% of all AX), released monomeric arabinose (up to 38%), and lowered the average degree of polymerisation (DPavg) of the AX (down to 31). The presence of substituents (arabinose, xylose, rhamnose and galacturonic acid) on the xylan backbone was an important factor limiting degradation by xylanases. Enzyme preparations containing substituent-removing enzymes were far better for enhancing the extractability of a large portion of the AX population (up to 82%) and for degrading the extracted fragments (down to DPavg 14) than preparations lacking such activities. The above results show that PSH is a good source for the production of AXOS, since both chemical and enzymic treatments significantly increase the extractability of PSH AX and convert PSH AX molecules into small fragments.