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European academic research, vol

EUROPEAN ACADEMIC RESEARCH
Vol. II, Issue 12/ March 2015
Impact Factor: 3.1 (UIF)
ISSN 2286-4822
DRJI Value: 5.9 (B+)
In vitro anti-diabetic activity and phenolic
compound profile of ethanol extracts of
Anisophyllea laurina R. Br. ex Sabine leaves and
stem bark
M'BALU REGINA KARGBO Center of Excellence for Functional Food and Health School of Food Science and Technology Jiangnan University, Wuxi, Jiangsu People's Republic of China
Abstract:

An essential strategy in the control of diabetes mellitus and its consequences, especially in diabetes type 2, is the efficient management of postprandial hyperglycemia. Inhibitors of carbohydrate hydrolyzing enzymes, α-amylase and α-glucosidase are useful in the treatment of diabetes and most medicinal plants also serve as active principal ingredients in averting this menace. Anisophyllea laurinaR.Br.ex Sabine leaves and stem bark are considered useful for the treatment of diabetes mellitus in sub-tropical countries in Africa. In this in vitro enzyme inhibition assays, all tested concentrations of 80 % ethanol (v/v) extracts of the leaves and stem bark showed significant inhibitory activity against α-amylase and α-glucosidase. At a concentration of 4.0 mg/ml, the leaves extract exhibited α-amylase and α- glucosidase inhibitory activity of 78.5 % and 58.2 % respectively, with IC50 values of 2.40 mg/ml and 3.11mg/ml respectively. The stem extracts showed α-amylase and α-glucosidase inhibitory activity of 69.5 % and 63.6 % respectively, with IC50 values of 2.6 mg/ml and 3.5 mg/ml respectively. Acarbose, a drug clinically used for treatment of diabetes had an inhibition of 84 % to both of these enzymes. Digalloyl-HHDP- 1 Corresponding author: [email protected] M'balu Regina Kargbo, Gbago Onivogui, Yuanda Song- In vitro anti-diabetic
activity and phenolic compound profile of ethanol extracts of Anisophyllea
laurina R. Br. ex Sabine leaves and stem bark
glucose isomer, Quercetin 3'- sulfate, Quercetin, Caffeoyl tarrtaric acid hexose, Quercentin 3-O-glucoside, Quercentin 3-rhamnoside, Quercentin Isorhamnetin-O-hexoside isomer and (-)-Epicatechin 3-O-
gallate were the major phenolic compounds identified from leaves and
stem bark extracts. Therefore, Anisophyllea laurinaR.Br.ex Sabine
plant has the potential to be used as a dietary supplement or in the
manufacture of drugs for the control of increased glucose level in the
blood.
Key
Anisophyllea laurinaR.Br.ex Sabine, α-glucosidase inhibitory activity, phenolic
compounds, type 2 diabetes
1. Introduction
Recent years have experienced a sharp increase in the
incidence and prevalence of diabetes mellitus. Diabetes
mellitus, an endocrine disorder characterized by high
concentration of glucose in the blood (hyperglycemia) is
associated with disturbances of carbohydrate, fat and protein
metabolism resulting from defects in insulin secretion, insulin
action, or both [1]. Diabetes mellitus is one of the common
metabolic disorders and 2.8% of the population suffers from this
disease throughout the world and it may reach 5.4% by the year
2025. [2]. Today, numerous therapeutic strategies for the
treatment of diabetes are in use, but one useful therapeutic
approach of treating diabetes is to decrease postprandial
hyperglycemia. This can be achieved by delaying the process of
glucose absorption through the inhibition of carbohydrate
hydrolyzing enzymes α-glucosidase (EC 3.2.1.20) and α-amylase
(EC 3.2.1.1) in the digestive tract. The enzymes involved in the
digestion of carbohydrates, can significantly decrease the
postprandial increase of blood glucose after consumption of a
mixed carbohydrate diet and thereby creating a vital platform
in the management of postprandial blood glucose level in type 2

EUROPEAN ACADEMIC RESEARCH - Vol. II, Issue 12 / March 2015
M'balu Regina Kargbo, Gbago Onivogui, Yuanda Song- In vitro anti-diabetic
activity and phenolic compound profile of ethanol extracts of Anisophyllea
laurina R. Br. ex Sabine leaves and stem bark
diabetic patients and borderline patients [3, 4]. Recently, there has been keen interest in functional foods and plant based medicines that exert modifying physiological effects in the prevention and cure of diabetes and obesity. Hence the attractive targets like in vitro inhibition of α-glycosidase and α-amylase enzymes are currently in demand. [4] Plant based medicines now serve the new approach of research study used in the fight against diabetes mellitus and other chronic diseases. Plant materials which are being used as traditional medicine for the treatment of diabetes are considered as one of the good sources for new drugs or a lead to make a new chemical entity (NCE). Plant extracts or different folk plant preparations are being prescribed by the traditional practitioners and have also been accepted by the users for the treatment of diabetes and any other diseases in many countries especially in the third world countries. Currently more than 400 plants are being used in different forms for hypoglycemic effects since all the claims of practitioners or users are neither baseless nor absolute. Therefore, a proper scientific evaluation and screening of plants by pharmacological tests followed by chemical investigations is of utmost importance [5]. Anisophyllea laurina R.Br.ex Sabine belongs to the Anisophylleaceae family comprising of 29–34 species of shrubs
and trees occurring in lowland forests and swamps in tropical
Africa, Asia, Malaysia and South America. These species are
placed in four genera with distinct geographical distributions
[6]. Anisophyllea laurina R.Br.ex Sabine commonly called
"monkey apple" is a shrub or tree of 5 to 16m high which grows
widely in West Africa (in Guinea-Bissau to Sierra Leone and
rarely in Ivory Coast) and has been used as a traditional/herbal
medicine among natives of this nations [7]. Its bark is enriched
with astringents like tannin which serves as an important
component in both pharmaceutical and textile industries. A
decoction of the leaves is used as a mouth rinse for toothache
and the leaves are said to have medicinal properties to treat

EUROPEAN ACADEMIC RESEARCH - Vol. II, Issue 12 / March 2015
M'balu Regina Kargbo, Gbago Onivogui, Yuanda Song- In vitro anti-diabetic
activity and phenolic compound profile of ethanol extracts of Anisophyllea
laurina R. Br. ex Sabine leaves and stem bark
diabetes, emetics, oral treatments, pain-killers and the bark is analgesic [8]. However, the wide use of Anisophyllea laurina R.Br.ex Sabine as a medicinal plant has no scientific proof to attest its bioactive components as well as its usage as a medicinal source to treat diabetes. This research delves into the identification and evaluation of its leaves and stem bark extracts for bioactive compounds in relation to their anti-diabetic activity. 2. Methods and materials

All chemicals were purchased from Sigma (St. Louis, MO, USA)
and were of analytical grade unless otherwise stated.
2.1.
Collection of plant materials and preparation of
extracts
Fresh matured whole leaves and stem-bark of Anisophyllea
laurina R. Br. ex Sabine were collected from different farm sites
at Coyah in Kindia region (Guinea, Africa). They were sun-
dried for 3 days. The dried leaves of the plant were pulverized
separately by means of milling. 20 grams for each of the plant
powder from leaves and bark were extracted by maceration in
100mL of 80% ethanol (v/v) for 3 days with frequent agitation
speed of 280 rpm at 28 °C in the dark. The supernatants were
collected, filtered through Whatman No. 1 filter paper and the
filtrate was then concentrated at 60°C using a rotary
evaporator (Buchi Labortechnik, Flawil, Switzerland). Finally
the concentrates were freeze dried (Labconco Corporation,
Kansas City, MO, USA) to yield a dry powder. The yield of the
powder was around 7.3%. 200mg of the powder was dissolved in
10ml 10% dimethylsulfoxide (DMSO) and kept in 4°C fridge for
further use.

EUROPEAN ACADEMIC RESEARCH - Vol. II, Issue 12 / March 2015
M'balu Regina Kargbo, Gbago Onivogui, Yuanda Song- In vitro anti-diabetic
activity and phenolic compound profile of ethanol extracts of Anisophyllea
laurina R. Br. ex Sabine leaves and stem bark
2.2 Alpha-glycosidase inhibition assay
The alpha-glycosidase was assayed using a method modified by
Apostolidis et al [9]. Aliquot 0 - 4 mg/ml in DMSO (v/v 1:1) of
80% ethanol extract of leaves and stem bark was prepared. 50
μl of each concentration extract was mixed well with100 μl of
0.1 M phosphate buffer (pH 6.9) containing α-glucosidase
solution (1.0 U/ml) and the mixtures were then incubated in 96-
well plates at 25°C for 10 min. After pre-incubation, 50 μl of 5
mM p-nitrophenyl-α-D-glucopyranoside solution in 0.1 M
phosphate buffer (pH 6.9) was added to each well at timed
intervals. The reaction mixtures were incubated at 25°C for 5
min. Before and after incubation absorbance readings were
recorded at 405 nm using a micro-plate reader (Thermomax,
Molecular device Co., Virginia, USA) and compared to a control
which contained 50 μl of the buffer solution instead of the
extracts. The experiments were performed in triplicate and the
α-glucosidase inhibitory activity was expressed as percentage
inhibition. Acarbose was prepared in distilled water and used
as positive controls. The percentage inhibition was calculated
using the formula;
% Inhibition = {(Ac – Ae)/Ac} 100 Where Ac and Ae are the absorbance of the control and extract,
respectively.
IC50 values (inhibitor concentration at which 50% inhibition of
the enzyme activity occurs) of the plant extracts were
determined by plotting graph with varying concentrations of
the plant extracts against the percent inhibition.
2.3 Alpha-amylase inhibition assay
The inhibition of alpha-amylase was determined using an assay
modified from the Worthington Enzyme Manual [10]. Aliquot 0
- 4 mg/ml in DMSO (v/v 1:1) of 80% ethanol extract of leaves

EUROPEAN ACADEMIC RESEARCH - Vol. II, Issue 12 / March 2015
M'balu Regina Kargbo, Gbago Onivogui, Yuanda Song- In vitro anti-diabetic
activity and phenolic compound profile of ethanol extracts of Anisophyllea
laurina R. Br. ex Sabine leaves and stem bark
and stem bark was prepared and 500 μl of each concentration extract was mixed with 500 μl of 0.02 M sodium phosphate buffer (pH 6.9) containing α-amylase solution (0.5 mg/ml) and incubated at 25°C for 10min. After pre-incubation, 500 μl of a 1% starch solution in 0.02 M sodium phosphate buffer (pH 6.9) was added to each tube at timed intervals. The reaction mixtures were then incubated at 25°C for 10 min. The reaction was stopped with 1.0 ml of dinitrosalicylic acid colour reagent. The test tubes were then incubated in a boiling water bath for 5 min and cooled to room temperature. The reaction mixture was then diluted by adding 15 ml of distilled water, and the absorbance was measured at 540 nm using a micro-plate reader (Thermomax, Molecular device Co., Virginia, USA). The experiments were performed in duplicate and the absorbance of sample blanks (buffer instead of enzyme solution) and a control (buffer in place of sample extract) were also recorded. The absorbance of the final extract was obtained by subtracting its corresponding sample blank reading. Acarbose was prepared in distilled water and used as positive controls The percentage inhibition was calculated using the % Inhibition = {(Ac – Ae)/Ac} 100 Where Ac and Ae are the absorbance of the control and extract,
respectively
IC50 values (inhibitor concentration at which 50% inhibition of
the enzyme activity occurs) of the plant extracts were
determined by plotting graph with varying concentrations of
the plant extracts against the percent inhibition.
2.4 Isolation and Identification of Ethanol Extracts of
Leaves and Stem Bark
The ethanol extracts of Anisophyllea laurina R. Br. ex Sabine
leaves and stem bark showed very good in vitro α-amylase

EUROPEAN ACADEMIC RESEARCH - Vol. II, Issue 12 / March 2015
M'balu Regina Kargbo, Gbago Onivogui, Yuanda Song- In vitro anti-diabetic
activity and phenolic compound profile of ethanol extracts of Anisophyllea
laurina R. Br. ex Sabine leaves and stem bark
and alpha glucosidase inhibition activities. Therefore it was
necessary to isolate and identify the bioactive compounds
involved from the ethanol extracts. The extracts were subjected
to column chromatography for separation. About 200mg of
dried extracts was chromatographed over silica gel which was
packed into a glass column (700 mm x100 mm) and elution was
carried out from non-polar to polar solvents by gradient elution
method. The column was eluted with a solvent gradient of
hexane: ethyl acetate (100:0 to 0:100 v/v) at a flow rate of
1mL/min, and then eluted with 100% ethyl acetate, ethanol:
ethyl acetate (1:4) and 100% ethanol. The fractions were
collected and concentrated using rotary evaporator. Each
fraction was freeze dried and as a result of their inhibition,
ethyl acetate showed a higher inhibition percentage, hence was
subjected to LC-ESI-MS mass spectra for phenolic profile.
2.5. Phenolic profile analysis by UPLC LC-ESI-MS
The LC-ESI-MS mass spectra were recorded using the Waters
ACQUITY UPLC® SYNAPTTM High Definition Mass
Spectrometer systems (Waters, Milford, USA) equipped with an
electrospray ion source and hybrid quadrupole-time-of-flight (Q-
TOF) mass spectrometer with the MSE model. The Q-TOF
instrument was operated in V mode for MS experiments with
the TOF data been collected between m/z 100 and 1500. The
optimized condition was desolvation gas at 500 L/h at a
temperature of 400◦C, cone gas at 50 L/h and source
temperature at 100◦C, capillary and cone voltages at 3kv and
30v, respectively.
UPLC data were produced using the Waters ACQUITY UPLC systems (WATERS MALDI SYNAPT Q-TOF MS,
Milford, USA) equipped with a binary pump, an auto sampler, a
degasser, and a diode-array detector (DAD). The system was
controlled with Mass Lynx V4.1 software. The DAD was
monitored in the range 200–600 nm. The chromatographic
column UPLCTM BEH AMIDE C18 (2.1 mm x 100 mm, 1.7μm)

EUROPEAN ACADEMIC RESEARCH - Vol. II, Issue 12 / March 2015
M'balu Regina Kargbo, Gbago Onivogui, Yuanda Song- In vitro anti-diabetic
activity and phenolic compound profile of ethanol extracts of Anisophyllea
laurina R. Br. ex Sabine leaves and stem bark
was used and eluted with a linear gradient of A:100% Acetonitrile and B: 0.1 % Formic acid A+B=100% at a flow rate of 0.3 ml/min and at a temperature of 45◦C: 0-5% A, 0-17min; 5-60%A, 17-20 min; 60-100%A, 20-22min; 100-5% A 22-22.1min; 22.1-25min, 5%A. The injection volume was 0.5μL. The accurate mass and composition for the precursor and fragment ions were calculated using the Mass Lynx 4.1 software. 2.6 Statistical Result
The result of three replicate experiments were pooled and
expressed as mean ± standard deviation. A one-way analysis of
variance (ANOVA) and positive analysis was done using
Duncan multiple test. Significance was accepted at P ≤ 0.05.
3. Results and discussion
3.1.
In vitro α-glucosidase and α –amylase inhibitory
Management of the blood glucose level is a critical strategy in
the control of diabetes complications. Inhibitors of saccharide
hydrolyzing enzymes (α-amylase and α-glucosidase) have been
useful as oral hypoglycemic drugs for the control of
hyperglycemia especially in patients with type-2 diabetes
mellitus [11 12]. Medicinal plants or natural products involve
retarding the absorption of glucose by inhibiting the
carbohydrate hydrolyzing enzymes. Several α- amylase
inhibitors including acarbose, voglibose and miglitol are
clinically used for treatment but their prices are high and have
clinical side effects [13 14]. Hence, screening of these enzymes
inhibitors from plants and synthetic sources are increasing. In
this study, anti-diabetic activity of the ethanol extracts from
leaves and stem bark were investigated with reference to α-
glucosidase and α-amylase inhibition. It was found that the
plant used in this study, Anisophyllea laurina R. Br. ex Sabine
leaves and stem bark ethanol extracts showed potential

EUROPEAN ACADEMIC RESEARCH - Vol. II, Issue 12 / March 2015
M'balu Regina Kargbo, Gbago Onivogui, Yuanda Song- In vitro anti-diabetic
activity and phenolic compound profile of ethanol extracts of Anisophyllea
laurina R. Br. ex Sabine leaves and stem bark
antidiabetic activities. From the α-glucosidase and α–amylase inhibitory assays, the plant extracts showed significant antidiabetic activity. The in vitro α-glucosidase inhibition study showed that the ethanol extract of both leaves and stem bark at concentrations of 4.0, 3.2, 2.4, 1.6 and 0.8 mg/ml inhibited α-glucosidase in a dose dependent manner. The highest concentration of 4.0 mg/ml showed a maximum inhibition of 78.53% and 69.5% for the leaves and stem bark respectively, while the lowest concentration of 0.8 mg/ml showed a minimum inhibition of 12.2% and 24.1% as well respectively (Figure 1). The IC50 values of the 80% ethanol extracts of leaves and stem bark were 2.41 and 3.1 mg/ml, respectively. Our results suggested that the leaves extract of the plant were more active than the stem back, and is comparable to acarbose activity. The standard acarbose showed a higher inhibition activity of 84.01% with IC50 1.90mg/ml value. The ethanol extract of both leaves and stem bark showed a weaker inhibition of the α-amylase enzyme. Figure 2 shows
the percentage inhibition values of the ethanol extract of the
leaves, stem bark and acarbose against α-amylase. The
maximum inhibition of the stem bark extract was 63.6 % at a
concentration of 4.0 mg/ml whereas the leaves were 58.2%. At
the lower concentrations, the stem bark extract did not have
significant inhibition difference when compared to that of the
leaves extracts Figure 2(b)). Acarbose showed a maximum
percentage inhibition of 74.0% at 4.0 mg/ml with an IC50 of 2.2
mg/ml. The IC50 values for the 80% ethanol extract of leaves
and stem bark were 3.1 mg/ml and 3.5 mg/ml, respectively.
For α-amylase inhibition, both the leaves and stem extracts gave good results of around 60% inhibition
respectively. The results for both enzymes (α-amylase and α-
glucosidase) inhibitory assays showed that ethanol extracts of
the Anisophyllea laurina R. Br. ex Sabine plant were strong
inhibitors of α-glucosidase but mild inhibitors of α-amylase

EUROPEAN ACADEMIC RESEARCH - Vol. II, Issue 12 / March 2015
M'balu Regina Kargbo, Gbago Onivogui, Yuanda Song- In vitro anti-diabetic
activity and phenolic compound profile of ethanol extracts of Anisophyllea
laurina R. Br. ex Sabine leaves and stem bark
especially the leaves as shown in figure 1 and 2. It is known that dietary management of hyperglycemia linked to type 2 diabetes can be targeted through foods or botanical supplements that have high α-glucosidase and a moderate α-amylase inhibition (15). Concentration of extract(mg/ml) Concentration of extracts(mg/ml) Figure 1: α -glucosidase inhibitory activities (a), and α -amylase
inhibitory activities of leaves extracts of Anisophyllea laurina R. Br.
ex Sabine (b).

concentration of extract(mg/ml) Concentration of extract(mg/ml) Figure 2: α-glucosidase inhibitory activities (a), and α -amylase
inhibitory activities (b) of stem bark extracts of Anisophyllea laurina
R. Br. ex Sabine.

3.2. Identification of phenolic compound
A total of twenty six peaks of phenolic compounds were
obtained from both leaves and stem bark samples, with fifteen
of them present in the leaves and eleven in the stem bark which
contributed to the α-glucosidase and α-amylase inhibitory
activities. The LC-ESI-MS chromatograms of the plant ethanol
extracts are shown in Fig. 3 (a) and (b). Identification of the MS
chromatogram peaks of phenolic compounds by detached
molecular weight was done based on the search for [M-H]- ions,

EUROPEAN ACADEMIC RESEARCH - Vol. II, Issue 12 / March 2015
M'balu Regina Kargbo, Gbago Onivogui, Yuanda Song- In vitro anti-diabetic
activity and phenolic compound profile of ethanol extracts of Anisophyllea
laurina R. Br. ex Sabine leaves and stem bark
using extracted ion mass chromatograms together with the interpretation of their ESI/IT/MS fragments in comparison with those found in reported literature. Characterised compounds in leaves and stem bark are summarised in Table 1. Our extracts from both leaves and stem bark showed the presence of compounds such as, catechin, flavonoids and
phenolic acids as well as others. The phenolic compounds
identified from leaves extracts were: Peak 2 at RT 0.907 min
revealed an ion at m/z 575 which was identified as
proacnthocynaidins A type isomer with fragments m/z 418, 341
and 304 [16, 17]. At RT 1.23 mins, peak 3 at a protonated
molecule of 401 m/z showed Benzyl alcohol hexose pentose as
the base peak [18]. Peak 4 at RT 1.90 mins was identified as
malvidin 3-0-galactoside [M-H]- at m/z 493 and fragments m/z
331, 271 and 198 are in conformity to [19 20]. Base peaks 5 and
6 at different RT 2.29 and 2.532 mins with protonated molecule
ion of 783 m/z and their fragmentation pattern involved the loss
of galloyl and hexahydroxydiphenoyl moieties m/z 633 and 481
respectively were detected as diagalloyl-HHDP-glucose isomer
[21] However, peak 8 and 10 were characterised based on their
molecular ions at m/z 463 and 431 and the presence of an
intense product ion at m/z 301 was identified as quercetin 3-0-
glucoside and quercetin-rhamnoside respectively [22]. The base
peak 9 showed [M-H]- at m/z 447.06 with the fragment at m/z
301 ([M-H-146]-, the loss of coumaroyl) was assigned as
Quercetin-3-rhamnoside and has been previously reported in
olives [23]. Peak 11 which eluted at RT 4.36 mins was detected
at m/z 439 with its fragments at m/z 417 and 409. Thus, this
compound was identified as (-)-Epicatechin 3-O-vanillate [20]. A
base peak 12 identified as Quercetin [M–H]- ion at 301 m/z with
fragmented ions m/z 289, 179 and 151. Syringic acid derivative
of base peak 13 was detected at m/z 401 RT 5.607 mins and a
base peak 14 at m/z 499 was tentatively identified as Quercetin
Caffeoyl-coumaroyl hexoside [24]. At RT 5.94 peak 15 was
identified as (–)-epicatechin 3-O-gallate [M-H]-, at m/z 442 with

EUROPEAN ACADEMIC RESEARCH - Vol. II, Issue 12 / March 2015
M'balu Regina Kargbo, Gbago Onivogui, Yuanda Song- In vitro anti-diabetic
activity and phenolic compound profile of ethanol extracts of Anisophyllea
laurina R. Br. ex Sabine leaves and stem bark
fragment ions m/z 438, 290 and 249. In leaves extracts protonated molecules at m/z 725 with base peaks 1 was identified as unknown compound. For stem bark, the base peak 1 was identified as epigallocatechin at m/z 305 with RT 0.61mins. Syringic acid (peak 3,198 m/z) was detected at RT 1.191 mins. Base peak 4 revealed a protonated ion at 723 m/z with fragment ion at 587 m/z indicating the loss of hexose. The parent compound was identified as (Epi)afzelchine(epi)Catechin isomer. Peak 5 was identified as Procyanidin dimer B isomer [M-H]- at m/z 647, whereas peak 6 was tentatively identified as Quercetin 3'-O-sulfate [M-H]- at m/z 381. The fragmentation pattern shown by these compounds was in agreement with that reported by [25, 26]. Caffeoyl tartaric acid hexose at m/z 327 with MS2 fragments at m/z 311, 248 and 154. Peak 9 with ion m/z 439 corresponded with the compound (-)-Epicatechin 3-O-gallate [27]. Peak 10 was tentatively identified as isorhamnetin-O-hexoside isomer ion at m/z 557 and MS2 fragmentation on negative mode was detected at m/z 477 and base peak 11 at m/z 254 was identified as chrysin [28]. From the chromatogram results, peaks 4, 8, 9 and 12 showed a high peak area in leaves while peaks 2, 6, 7, 8, 9 and 10 in stem bark also showed the similar trend and are therefore considered to be in abundance. Phenolic compounds are naturally occurring compounds that possess rich sources of antioxidant and free radical scavenging properties as well as medicinal properties. They have been reported to be good inhibitors of α-glucosidase and α- amylase. Additionally they are also regulators of hyperglycemia and other diabetic complications [29].
EUROPEAN ACADEMIC RESEARCH - Vol. II, Issue 12 / March 2015

M'balu Regina Kargbo, Gbago Onivogui, Yuanda Song- In vitro anti-diabetic
activity and phenolic compound profile of ethanol extracts of Anisophyllea
laurina R. Br. ex Sabine leaves and stem bark
Figure 3. Phenolic profile of ethanol extracts of leaves (A) and stem
bark (B) of Anisophyllea laurina R. Br. ex Sabine.

Table 1: Identification of phenolic compounds of leaves and stem
bark extracts of Anisophyllea laurina R. Br. ex Sabine.
Leaves extract 1 657, 453,385, 317, 249 Proanthocyanidins A type Isomer 481, 341, 304, 268, 161 Benzyl alcohol hexose pentose 389, 344, 318, 296, 173 Malvidin 3-galactoside 331, 271, 198, 161 Digalloyl-HHDP-glucose isomer 633, 301, 289, 169 Digalloyl-HHDP-glucose isomer 633, 301, 289, 169 577,301, 289,169 Quercentin 3-O-glucoside Quercentin 3-rhamnoside Kaempferol- 3-orhamnoside 286, 243, 198, 125 (-)-Epicatechin 3-O-vanillate Syringic acid derivates 255, 198, 178, 161 Quercetin caffeoyl-coumaroyl hexoside 463, 301, 289, 125 (-) -Epicatechin 3-O-gallate 438, 291, 249, 165,139 Stem bark extract 1 (-)-egallocatechin 289, 207, 175, 139 Cafferic acid hexoside dimer 377, 341, 304, 268 (Epi) afzelchine (epi) catechin isomer 647, 463, 417, 289, 196 Procyanidin dimer B1 isomer 577, 467, 289, 163 Quercetin 3'- sulfate 351, 241, 197, 162 Caffeoyl tarrtaric acid hexose 661, 425, 287, 198, 161 (-) Epicatechin 3- O- vanillate Isorhamnetin-O-hexoside isomer 477, 315, 301, 169 221, 198, 179, 161

EUROPEAN ACADEMIC RESEARCH - Vol. II, Issue 12 / March 2015
M'balu Regina Kargbo, Gbago Onivogui, Yuanda Song- In vitro anti-diabetic
activity and phenolic compound profile of ethanol extracts of Anisophyllea
laurina R. Br. ex Sabine leaves and stem bark
4. Conclusion

Based on the results presented in this study, it can be
concluded that ethanol extracts of Anisophyllea laurina R. Br.
ex Sabine leaves and stem bark exerts an inhibitory effect on α-
glycosidase and α-amylase. These could be from the phenolic
compounds identified in the plant. Therefore these results
suggested the potential use of this plant as a dietary
supplement or in the manufacture of drugs for the control of
increased blood glucose level in the body.

ACKNOWLEDGEMENTS
The authors gratefully acknowledge the National Natural
Science Foundation of China (31271812, 81071685), the
National High Technology Research and Development Program
of China (863 Program 2012AA022105C for providing financial
support for the study and Jeannine Sogony Koivogui from
Guinea for facilitating transportation of raw materials to
China.
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