| dc.description.abstract | Vietnam is a country with high biodiversity, with about 4000 species of plants
used as medicine, in which many medicinal plants are used in folk medicine to treat
diabetes mellitus, including Euphoria hirta Linn. (E. hirta), which belongs to the
family Euphorbiaceae. Previous studies show that E. hirta has potential for the future
production of antidiabetic drugs. The overall objectives of the present study were to
investigate, determine, and quantify the phytochemicals, mainly phenolic
compounds, from E. hirta extracts and to evaluate their antidiabetic activities in in
vitro, in vivo, and in silico approaches.
In in silico study, flavonoids containing in E. hirta gave good interactions with
two enzymes. Due to variations in pharmacophore characteristics, the flavonoid family
has an advantage in binding to these receptors due to relatively strong hydrogen bonds.
Five fractional extracts of E. hirta were obtained after the extraction process,
including EM-1, EP-1, EC-1, EE-1, and EB-1. The value of the phenolic content was
109.86 ± 1.38, 90.89 ± 1.45, 55.86 ± 0.66, 254.96 ± 10.05 and 70.90 ± 0.65 mg of
GAE/g extract for EM-1, EP-1, EC-1, EE-1, and EB-1, respectively. EE-1 had the
highest total phenol content, followed by EM-1, EP-1, EB-1, and EC-1. The values
of the total flavonoid content were 18.92 ± 1.33, 8.48 ± 1.16, 16.41 ± 1.44, 27.66 ±
0.73 and 12.43 ± 1.66 mg of quercetin/g extract for EM-1, EP-1, EC-1, EE-1, and
EB-1, respectively. EE-1 had the highest total flavonoid content.
To investigate the antioxidant activity of E. hirta extracts, a DPPH radical
scavenging assay of E. hirta was carried out. Our results revealed that EM-1 and EE-1
extracts had more potent free radical scavenging activity than other extracts. For lipid
peroxidation inhibitory activity, IC50 values of EM-1, EP-1, EC-1, EE-1, and EB-1 were
also measured. EE-1 extract appeared to be 18.74-fold as potent as Trolox. Anticancerxx
activities of those extracts were examined by sulforhodamine B (SRB) in vitro
cytotoxicity assay on two cancer cell lines, including lung cancer cells NCI-H460 and
liver cancer cells Hep G2. EE-1 at a concentration of 100 μg/mL has significant
inhibitory activity on the growth of lung cancer cells NCI-H460 and liver cancer cells
Hep G2 compared to all other extracts.
To elucidate the antidiabetic activity of those extracts, we investigated the
therapeutic effects of five extracts of E. hirta in AA and AG inhibitory activity (in vitro)
and hypoglycemic activity in normal mice by evaluating the samples on plasma glucose
in oral glucose tolerance test (in vivo). In in vitro study, E. hirta extracts had strong
inhibitory activity against AG and relatively mild AA inhibitory activity. EE-1 had
more potent inhibitory activity of two enzymes than other extracts. Besides, EE-1
expressed higher hypoglycemic effect in the oral glucose tolerance test in normal mice
than the remaining extracts. Our results suggest that EA extract (EE-2) has the most
potent activities, and should be used to determine phytochemicals and mechanisms of
their antidiabetic activity. EA extract was mixed with 20% maltodextrin in a ratio of
1:10 to spray-dry microencapsulation. The spray powder reduced 51% fast blood
glucose (FBG) after 4hrs treatments. Furthermore, administration of spray powder for
15 days significantly lowered fasting blood glucose levels streptozotocin-diabetic mice
by 23.32%, whereas acarbose - a standard antidiabetic drug - and distilled water
reduced fasting blood glucose levels by 30.87% and 16.89%. Our results show that
obtained E. hirta powder has potential antidiabetic activity.
Ten pure compounds were isolated and identified from EE-1, including EA01
(scopoletin), EA02 (methyl gallate), EA03 (gallic acid), EA04 (kaempferol), EA05
(quercetin), EA06 (myricetin), EA07 (afzelin), EA08 (quercitrin), EA09 (myricitrin)
and EA10 (rutin). Among them, five isolated compounds, including EA02 (methyl
gallate), EA03 (gallic acid), EA04 (kaempferol), EA05 (quercetin), and EA08
(quercitrin) were carried out the AA and AG inhibitory activity. Those compounds gave
weaker AA inhibitory activity than acarbose, but it proved phenolic compounds could
inhibit carbohydrate hydrolyzing enzyme and has potential antidiabetic activity. The
AG inhibitory action of all five compounds was stronger than acarbose. Moreover,
EA08 (quercitrin) was subjected to evaluate the effect on fasting plasma glucose level
in normal mice. This study suggests that EA extract might be employed as a functional
food for type 2 DM treatment and by the nutraceutical sector as a source of quercetinxxi
and quercitrin. There are certain similarities in the results of investigating the activities
of the compounds in vitro and in silico. These results give us a theoretical basis for
future research in the development of drugs for type 2 DM | en_US |
