Antiobesity and lipid lowering effects of Glycyrrhiza chalcones: Experimental and computational studies

Article abstract of DOI:10.1016/j.phymed.2011.01.002

Twelve flavonoids (1-12), isolated from Glycyrrhiza glabra roots were evaluated for their pancreatic lipase (PL) inhibitory activity in vitro. The structures of the isolated compounds were elucidated by spectroscopic methods. Amongst all the compounds 7, 8, 10 and 11 showed strong inhibition against PL with IC₅₀ values of 7.3 μM, 35.5 μM, 14.9 μM and 37.6 μM, respectively. Molecular docking studies on the most active compound 7 revealed that it binds with the key amino acid residues of the PL active site. In silico absorption, distribution, metabolism and excretion (ADME) parameters were also computed on the active compounds to determine their preliminary pharmacokinetic properties. Further, investigations were carried out to determine the antiobesity and lipid lowering effects of 7 and 10 in high fat diet (HFD) fed male SD rats. In the rats supplemented with compound 7 the body weight increase was only 23.2 ± 3.6 g as compared to 64.2 ± 0.5 g in the HFD control group while in the rats treated with compound 10 showed 23.2 ± 3.6 g weight gain only. Compound 7 decreased the levels of plasma total cholesterol (TC) to 84.6 ± 1.4 mg/dl and plasma total triglycerides (TG) to 128.8 ± 6.0 mg/dl. Compound 10 also lowered the plasma TC and TG levels considerably. The results indicate the potential of the chalcone scaffold as a source of PL inhibitors for preventing obesity.

Full text of DOI:10.1016/j.phymed.2011.01.002

Phytomedicine 18 (2011) 795–801
Contents lists available at ScienceDirect
Phytomedicine
journal homepage: www.elsevier.de/phymed
Antiobesity and lipid lowering effects of Glycyrrhiza chalcones:
Experimental and computational studies
Rahul B. Biraria, Shikhar Guptab, C. Gopi Mohanb, Kamlesh K. Bhutania,∗
a Department of Natural Products, National Institute of Pharmaceutical Education and Research, Sector 67, S.A.S. Nagar, Mohali 160062, Punjab, India
b Centre for Pharmacoinformatics, National Institute of Pharmaceutical Education and Research, Sector 67, S.A.S. Nagar, Mohali 160062, Punjab, India
a r t i c l e i n f o
a b s t r a c t
Keywords:
Obesity
Liquorice
Chalcones
Isoliquiritigenin
Pancreatic lipase
Twelve flavonoids (1–12), isolated from Glycyrrhiza glabra roots were evaluated for their pancreatic lipase
(PL) inhibitory activity in vitro. The structures of the isolated compounds were elucidated by spectro-
scopic methods. Amongst all the compounds 7, 8, 10 and 11 showed strong inhibition against PL with
IC50 values of 7.3 ␮M, 35.5 ␮M, 14.9 ␮M and 37.6 ␮M, respectively. Molecular docking studies on the
most active compound 7 revealed that it binds with the key amino acid residues of the PL active site.
In silico absorption, distribution, metabolism and excretion (ADME) parameters were also computed on
the active compounds to determine their preliminary pharmacokinetic properties. Further, investiga-
tions were carried out to determine the antiobesity and lipid lowering effects of 7 and 10 in high fat diet
(HFD) fed male SD rats. In the rats supplemented with compound 7 the body weight increase was only
23.2 3.6 g as compared to 64.2 0.5 g in the HFD control group while in the rats treated with compound
10 showed 23.2 3.6 g weight gain only. Compound 7 decreased the levels of plasma total cholesterol
(TC) to 84.6 1.4 mg/dl and plasma total triglycerides (TG) to 128.8 6.0 mg/dl. Compound 10 also low-
ered the plasma TC and TG levels considerably. The results indicate the potential of the chalcone scaffold
as a source of PL inhibitors for preventing obesity.
© 2011 Elsevier GmbH. All rights reserved.
Introduction
effects of plant flavonoids might lead to more effective strate-
gies for the treatment of obesity. The health hazards like diabetes,
Physiologically, obesity is a disarray of energy balance and
primarily considered as a disorder of lipid metabolism (Strader
et al., 1998). A growing number of enzymes involved in lipid
metabolic pathways are being identified and characterized. They
represent a rich pool of potential therapeutic targets for obesity
(Shi and Burn, 2004; Melnikova and Wages, 2006). Inhibition of
PL (triacylgycerol acyl hydrolase), the principal lipolytic enzyme,
synthesized and secreted by pancreas (Mukherjee, 2003) is one of
the approaches for the development of newer antiobesity drugs.
Tetrahydrolipstatin (Orlistat), a commercial anti-obesity drug, is a
known pancreatic lipase inhibitor (Borgstrom, 1988; Hadvary et al.,
1991). Previously, we have given an account of the reported plants
with antiobesity properties (Birari and Bhutani, 2007) and the var-
ious PL inhibitors reported from these natural sources (Bhutani
et al., 2007). Recently, much interest has been shifted on plant
flavonoids that might be beneficial in reducing the risk of obesity
(Peluso, 2006). Dietary catechins and anthocyanins significantly
decrease the weight of abdominal adipose tissues (Murase et al.,
2002; Tsuda, 2008). Accordingly, investigation on the metabolic
obesity and metabolic related disorders are related to the dietary
habits and most of the nutraceutical on the market focuses on these
areas. Anthocyanin-rich berries or derived extracts, procyanidins
rich grape seed, bilberry and cranberry extract are well known for
their antioxidant and lipid lowering ability (Espin et al., 2007).
Roots of Glycyrrhiza glabra (Fabaceae/Papilionaceae), also
known as licorice and sweet root has been used medicinally for
the past 4000 years (Duval et al., 2007; Iritani, 1992). Histori-
cally, the dried rhizome and root of this plant were employed
medicinally by the Egyptian, Chinese, Greek, Indian, and Roman
civilizations as an expectorant and carminative. Several pharmaco-
logical activities, such as antiulcer, antiinflammatory, antidiuretic,
antiepileptic, antiviral, antiallergic and antioxidant properties have
been attributed to the licorice compound glycyrrhizin and gly-
cyrrhizic acid (Visavadiya et al., 2009; Nassiri Asl and Hosseinzadeh,
2008). Licorice flavonoid oil (LFO) suppresses abdominal fat accu-
mulation by regulation of rate-limiting enzyme activities related
to fatty acid synthesis and oxidation in the liver (Nakagawa et al.,
2004).
Licorice extract and its primary constituent glycyrrhizin are
extensively used amongst US population and are considered as
Generally Recognized as Safe (GRAS) for use in foods by the U.S.
FDA (Isbrucker and Burdock, 2006; Nakagawa et al., 2008a,b).
∗
Corresponding author. Tel.: +91 172 2232208; fax: +91 172 2232208.
E-mail address: kkbhutani@niper.ac.in (K.K. Bhutani).
0944-7113/$ – see front matter © 2011 Elsevier GmbH. All rights reserved.
doi:10.1016/j.phymed.2011.01.002

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R.B. Birari et al. / Phytomedicine 18 (2011) 795–801
Scheme 1. Key steps in synthesis of LiOH·H2O. Reaction conditions: (a) dry acetone, K2CO3, MOMCl, reflux 7 h; (b) MeOH, LiOH·H2O, reflux 4 h and (c) 3NHCl, reflux, 30 min.
Various genotoxic studies have indicated that licorice extracts
and glycyrrhizin is neither teratogenic nor mutagenic, and may
even possess anti-genotoxic properties under certain conditions
(Nakagawa et al., 2008a,b; Kaur et al., 2009). Clinical studies have
shown that LFO is safe because no clinically significant adverse
events occurred when it was given daily to healthy or overweight
subjects for up to 12 weeks. These reports suggest the relative safety
of licorice extracts and the chalcone when administered orally in
animals as well as humans (Aoki et al., 2007). Isoliquiritigenin the
major chalcone from G. glabra also has several pharmacological
effects such as antioxidant, anti-inflammatory, anti-tumor, anti-
platelet, and anti-peptic ulcer actions (Haraguchi et al., 1998).
Recently it has shown to have protective effects on mitochondrial
cells against arachidonic acid and iron induced oxidative stress
(Choi et al., 2010). Isoliquiritigenin was reported as quite safe and
well tolerated when given orally (Lee et al., 2008).
In our continuing research on identification of newer antiobe-
sity leads from natural sources, many plant extracts have been
screened for their PL inhibition (Birari et al., 2009). Recently our
group has published the antiobesity and lipid lowering effects of
Murraya koenigii (L.). Spreng leaves extracts and mahanimbine on
high fat diet induced obese rats (Birari et al., 2010). In the present
work, an integrative in vivo-in vitro-in silico approach was followed
to study the antiobesity properties of Glycyrrhiza flavonoids. Twelve
flavonoid aglycones and glycosides isolated from Glycyrrhiza roots
were tested for their PL inhibitory action in vitro. In order to under-
stand the mode of binding of these compounds with the active site
of the PL enzyme, molecular docking approach was employed. In sil-
ico ADME parameters were also computed on the active compounds
to determine their preliminary pharmacokinetic properties. Ani-
mal studies on most active compounds 7 and 10 demonstrated
the potential of these types of compounds in the development of
antiobesity therapeutics.
under standard environmental conditions (temperature 22 2 ◦C;
humidity 55 5%) with a 12 h light/dark cycle at the animal house.
All the animals were housed in polypropylene cages in groups of
3 per cage and had free access to water ad libitum. The protocol of
this experiment was approved by the Institutional Animal Ethics
Committee (IAEC) and the experiments were carried out in accor-
dance with the guidelines of Committee for Control and Supervision
of Experimentation on Animals (CPCSEA, India) given on animal
experimentation.
Extraction and isolation
Dried and powdered roots of G. glabra (1 kg) were subjected to
sequential extraction with hexane, dichloromethane (DCM), ethyl
acetate (EtOAc) and methanol (MeOH) to prepare the respective
extracts. The DCM extract of G. glabra is expected to contain the
prenylated flavonoids and hence, a reported method was followed
(Vaya et al., 1997) to give compound 1–4.
EtOAc extract (GGE; 10 g) was purified on silica gel (#60-120).
Elution was carried out using hexane, CHCl3 and MeOH in increas-
ing order of polarity. Fractions were pooled according to TLC pattern
to give 5 fractions. Non-polar fractions (GGE-1 to GGE-3) were fur-
ther purified on silica gel (#60-120) to give aglycones 5–9. The polar
fractions (GGE-4 and GGE-5) were purified on Sephadex LH-20 to
give the glycosides 10–12.
MeOH extract (45 g) was dissolved in water and partitioned with
butanol (BuOH). BuOH fraction (27 g) was taken for purification. It
was fractionated by vacuum liquid chromatography on silica gel G
(#200-400), using CHCl3/MeOH gradient to yield 5 major fractions.
Purification of Fraction 4 (FrM4) yielded compound 10.
For in vivo studies large quantity of compound
7 was
required hence its synthesis was carried out. mixture of
A
2,4-dihydroxyacetophenone (0.76 g, 5 mmol), anhydrous K2CO3
(2.070 g, 15 mmol), and MOM chloride (0.48 g, 12 mmol) was
refluxed in dry acetone (25 ml) for 7 h. The reaction mixture was
cooled to room temperature and filtered. The filtrate was evap-
orated and the residue subjected to column chromatoghraphy
with pet ether/EtOAc 1:1 as an eluent to yield 7a (68%). Base cat-
alyzed Claisen condensation of 7a with 4-hydroxy benzaldehyde
in presence of LiOH·H2O (Bhagat et al., 2006) gave compound 7b
which upon deprotection (Vogel et al., 2008) yielded compound 7
(Scheme 1).
Materials and methods
Plant material
G. glabra (root) was procured from local market of Chandigarh,
India and identified by qualified botanist and voucher specimen
has been preserved in the herbarium of Department of Natural
Products, NIPER, SAS Nagar, India.
Measurement of PL inhibitory activity
Animals and grouping
PL inhibitory activity was measured using p-nitro phenol palmi-
tate (PNPP) as a substrate. The samples were screened against the
PL using standard protocol previously published from our labora-
Forty-eight male SD rats of weight 175 15 g were procured
from Central Animal Facility, NIPER. The animals were housed

R.B. Birari et al. / Phytomedicine 18 (2011) 795–801
797
Fig. 1. Structures of compounds isolated from G. glabra roots.
tory (Birari et al., 2009). Orlistat was used as a standard in the assay.
For bioactivity assay, all studies were done in triplicate, and mean
values and standard error of mean were calculated.
study, and the active site for docking was defined with the amino
acids Ser152, Asp176 and His263 falling within 9.5 A radius of
the co-crystallized ligand methoxyundecylphosphinic acid (Egloff
et al., 1995). ADME analysis of all the active compounds was per-
formed by the Discovery Studio 2.5 (Accelrys) software and QikProp
module of Schrödinger software.
˚
Computational study
Inordertounderstand thebindingaffinityofthe compound with
the PL enzyme, compounds 3, 4, 7, 8, 10 and 11 were subjected for
docking analysis using FlexX program. These compounds were ini-
tially built on SYBYL7.1 and energy minimized by Powell’s method
using Tripos force field with 0.05 kcal/mol energy gradient conver-
gence criterion. FlexX is a fast, flexible docking method that uses an
incremental construction algorithm to place ligands into the active
site of the protein. The crystal structure of PL-Colipase complex
taken from protein databank (PDB code: 1LPB) was used for docking
Induction of obesity and hyperlipidemia
After 7 days of acclimation, animals were randomly divided
into 8 groups (n = 6): one normal control group, one HFD control
and remaining 3–8 as treatment groups. Animals in normal con-
trol group were fed with normal pellet diet (NPD) while the other
groups were fed with HFD (Srinivasan et al., 2005; Gaikwad et al.,
2007) ad libitum, respectively, throughout the experiment.

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R.B. Birari et al. / Phytomedicine 18 (2011) 795–801
Table 1
PL inhibitory activity and docking analysis of the isolated compounds of G. glabra roots.
Compounds
Percent inhibition at 250 ␮g/ml
IC50 (␮M)
Docking score (kcal/mol)
Residues making hydrogen bonding
1
2
3
4
43.8 2.4
59.3 1.9
61.4 1.8
41.3 2.9
3.3 1.6
ND
ND
404.9
485.6
ND
ND
ND
−10.3
−14.7
ND
ND
ND
Arg256, Trp114
Arg256, Ser152, His263
ND
5
6
2.7 1.1
ND
ND
ND
7
8
9
99.9 1.9
98.8 2.4
2.0 3.1
7.3
35.5
ND
−23.7
−17.1
ND
His263, Phe215, Asp79, Arg256
Asp79, Arg256, Asp257, Phe215
ND
10
11
12
93.3 2.8
98.2 2.1
6.9 3.0
14.9
37.6
ND
−21.9
−17.4
ND
Gly76, Asp79, His263, His151, Ser152, Cys181, Thr115
Asp79, Ser152, His263, His75, Cys181
ND
ND, not determined.
Determination of lipid profile
Blood samples were collected from tail vein of the rats into
micro centrifuge tubes containing heparin (10 ␮l, 1000 IU ml−1).
The plasma was separated by centrifugation (10 min, 10,000 rpm)
and was analyzed for plasma glucose, TG and TC using commercially
available colorimetric diagnostic kits.
Statistical analysis
Statistical analysis was carried out by using commercially avail-
able software sigmastat 3.5. Values are expressed as mean SEM.
For multiple comparisons, one way ANOVA was used followed by
Tuckey and/Dunnet’s test. p value < 0.05 was considered to be sig-
nificant.
Results and discussion
Fig. 2. Molecular docking derived binding pose of the most potent compound 7 in PL
enzyme. The inhibitor is shown as ball and stick model and FlexX software was used
to derive the binding mode. Compound 7 forms one strong hydrogen bond with the
hydrogen atom of the imidazole ring of His263, two strong hydrogen bonds with
the guanidine hydrogen atoms of Arg256, one hydrogen bond with the delta oxygen
atom (O␦) of Asp79 and one hydrogen bond with amide bond carbonyl oxygen (C O)
atom of Phe215.
G. glabra is a rich source of phenolic class of compounds. Four
flavan types of constituents (1–4) were isolated from DCM fraction
of acetone extract. Bioactivity-guided fractionation of the EtOAc
extract of G. glabra, led to the isolation of eight known secondary
metabolites (5–12). The compounds (Fig. 1) were identified by com-
parison of their physicochemical and spectroscopic data (1H, 13C
NMR, 2D NMR and Mass Spectrometry) with those of literature
data as, Hispaglabridin A (1), Glabrol (2), 4ꢀ-O-methoxy glabridin
(3), Glabridin (4) (Vaya et al., 1997), 4ꢀ,7-dihydroxy flavone (5), 7-
hydroxy-4ꢀ-methoxy flavone (6) (Yoo et al., 2004), Isoliquiritigenin
(7) (Ma et al., 2005), 3,3ꢀ,4,4ꢀ-tetrahydroxy-2-methoxychalcone (8)
(Nowakowska, 2007), Liquiritigenin (9), Licuroside (10), Isoliquiri-
toside (11) (Hatano et al., 1998) and Isoononin (12) (Jayaprakasam
et al., 2009) respectively.
The PL inhibitory activities of the all the compounds were calcu-
lated as percent inhibition at 250 ␮g/ml (Table 1). Six compounds
inhibited PL activity in a dose-dependent manner. Amongst,
the compounds tested, 7, 8, 10 and 11 exhibited the strong
inhibitory activities, with IC50 values of 7.3 0.7 ␮M, 35.5 0.5 ␮M,
14.9 0.8 ␮M and 37.6 0.7 ␮M, respectively. Interestingly, all
Treatment
Treatments were started from 29th day and continued for two
weeks. The treatment groups 3–5 were given the DCM, EtOAc and
MeOH extracts of G. glabra respectively at 300 mg/kg/day of body
weight by oral root. Treatment groups 6–8 were given compounds
7, 10 and standard drug orlistat respectively at 30 mg/kg/day of
body weight by oral root. During the course of treatment the treat-
ment groups were continued to feed with HFD.
Determination of body weight and food intake
The body weight of each rat was measured once each week and
the total amount of food consumed was recorded 3 times per week.
Table 2
ADME properties of active compounds showing PL inhibition.
Compound no.
ASL
A log P
PSA
41.2
55.6
90.4
116.4
236.7
68.9
log S
%H O Abs
100
100
77
66
0
log D
MWt
HBA
HBD
Rot Bond
3
4
7
8
10
11
2
2
3
3
3
3
4.5
3.7
1.9
−5.3
−4.8
−3.0
−2.7
−3.6
−2.7
4.2
3.7
1.9
338.4
324.4
256.2
302.3
550.5
418.4
3
3
3
6
17
12
1
2
2
4
7
5
2
2
7
9
16
13
1.0
1.9
−1.4
−0.4
−0.1
33
0.6
ASL, ADMET solubility level; PSA, polar surface area; %H O Abs, percent human oral absorption; MWt, molecular weight; HBA, hydrogen bond acceptor; HBD, hydrogen bond
donor; Rot Bond, number of rotatable bonds.

R.B. Birari et al. / Phytomedicine 18 (2011) 795–801
799
Table 3
Effects of HFD on body weight.
Treatment groupsa
Weights (g)
Initial weight
28th Day
43rd Day
Weight gain during treatment
Normal control
HFD control
GG-DCM
GG-EtOAc
GG-MeOH
10
176.0 4.9
163.8 2.6
164.6 2.1
168.2 5.4
172.4 3.0
174.2 9.1
167.8 7.8
168.4 7.4
271.2 2.5
323.4 6.3
306.6 6.3
329.8 10.5
322.6 10.3
322.0 7.0
308.8 2.3
321.4 5.8
307.4 2.2
387.6 6.1
323.8 8.4
343.4 12.8
345.2 11.3
350.2 6.2
332.0 4.7
295.4 11.8
36.2 0.8b
64.2 0.5c
17.2 2.4c
13.6 3.5c
22.6 4.8c
28.2 1.6c
23.2 3.6c
−26.0 10.5c
7
Orlistat
One way ANOVA followed by Tuckey’s multiple comparison test.
a
n = 6 per group; values are expressed in mean SEM.
p < 0.05.
p < 0.001.
b
c
Fig. 3. Effects of treatment groups on the lipid profile of the HFD fed male SD rats. (A) Significant decrease in levels of total TG was observed in post-treatment groups
as compared to normal and HFD control. (B) Significant decrease in levels of TC was observed in post-treatment groups as compared to normal and HFD control. (C) No
significant effects were observed in blood glucose levels of pretreatment and post-treatment groups. n = 6 per group, values are expressed in mean SEM. *p < 0.05 when
compared with the normal control in pretreatment groups, #p < 0.05 when compared with the HFD control in post treatment groups.

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R.B. Birari et al. / Phytomedicine 18 (2011) 795–801
these compounds are chalcone class of compounds, which shows
the potential of this type of naturally occurring scaffold for the PL
inhibition. Orlistat was found to be a potent inhibitor of PL with
calculated IC50 value of 0.015 0.1 ␮M. The flavan class of com-
pounds (1–4) moderately inhibited the PL, while the flavone and
dihydroflavone aglycones (5, 6 and 9) and flavone glycoside (12)
showed a weak PL inhibition.
23.2 3.6 g as compared to 64.2 0.5 g in the HFD control group
while in the rats treated with compound 10 showed 23.2 3.6 g
weight gain only. Fig. 3 shows the plasma TG, TC and glucose lev-
els of the experimental animals. Significant increase in the levels of
plasma TG and TC levels were observed in the HFD fed groups for
the initial 28 days while no significant effects on plasma glucose
levels were observed. After the treatment, however, the plasma TG
and TC levels were considerably decreased in the treatment groups
while glucose levels did not changed significantly. Compound 7
decreased the levels of plasma TC to 84.6 1.4 mg/dl and plasma
TG to 128.8 6.0 mg/dl. Compound 10 also lowered the plasma TC
and TG levels considerably. Neither of these compounds altered
the plasma glucose levels significantly suggesting that they may
not have any effect on glucose metabolism. This indicates that the
extracts as well as the compounds do not have hypoglycemic or
hyperglycemic effects in the treated animals. These results clearly
suggest that these extracts/compounds have definite effect on lipid
metabolism and their effects may be due to inhibition of PL reducing
the intestinal absorption of dietary fats.
Molecular docking was performed on compounds 3, 4, 7, 8,
10 and 11 to understand the affinity and mode of binding with
the PL enzyme active site residues. Docking analysis showed a
high binding potential of compound 7 towards the active site of
PL with total docking score of −23.7 kcal/mol. The docking score
of other compounds 3, 4, 8, 10 and 11 along with the hydrogen
bonding interaction residues are illustrated in Table 1. In human
PL, N-terminal domain residues Ser152, Asp176, and His263 form
the catalytic triad while C-terminal domain binds to co-lipase,
the cofactor required for the activity (Luthi-Peng et al., 1992). To
achieve an active conformation, the open lid structure of the PL
requires the interactions of Arg257 (Arg256 in PDB: 1LPB) and
Asp258 (Asp257 in PDB: 1LPB) with the core residues (Lowe, 2002).
Any disruption of the interactions with these residues prevents
the lid from attaining an optimal conformation. From the dock-
ing pose of ligand as shown in Fig. 2 within the PL enzyme active
site, it is clearly observed that compound 7 formed strong hydro-
gen bonding interactions with the active site amino acid residues
of the enzyme (Table 1). The compounds binding to these catalytic
and other nearby residues are expected to play an important role
in PL inhibition (Luthi-Peng et al., 1992; Lowe, 2002), support-
ing the stronger PL inhibitory activity of the compound 7 in our
in vitro assay (Table 1). Interestingly, the trend of variation of the
PL inhibitory activity (IC50) and docking score of these compounds
was excellent, and highly significant correlation coefficient of 0.85
was obtained.
It is well known that the poor pharmacokinetic properties are
one of the main reasons for terminating the development of drug
candidates in advance stages. Hence, all the active compounds
were subjected for in silico ADME evaluation. Specifically, some
key parameters along with the Lipinski’s rule of five (Lipinski et al.,
2001) that are examined as part of multiple property optimizations
are molecular weight (MW), octanol/water partition coefficient
(log p), computed aqueous solubility (log S) and polar surface area
(PSA). All the active compounds (except compounds 10 and 11, due
to sugar moieties) followed the entire Lipinski parameters (Table 2).
In the particular case of the PL inhibitors like Orlistat, the site of
action is in the lumen and thus systemic absorption is not needed
for activity. Orlistat has minimal systemic absorption (Zhi et al.,
1996). Interestingly, in silico analysis of the most active compound
7 showed good oral bioavailability. Though there is no advantage
of good oral bioavailability of compound 7 inhibiting the PL, it
may result in lesser activity in vivo as it will get absorbed in the
body and will not be fully available for the action on PL. Its di-
glycoside, licuroside (compound 10), which also strongly inhibited
PL in vitro, showed minimal or no absorption in the in silico analysis
(Table 2). This indicates that chemical modifications of compound 7
may provide stronger PL inhibitor with necessary pharmacokinetic
properties.
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