2. Materials and Methods
2.1. Collection of Plant Material. The fresh leaves of R. nasutus
were collected from Tirumala Hills, Tirupati, Chittoor
districts of Andhra Pradesh from July to October 2009. The
plant specimen was verified to be the correct species by Dr.
Madhava Setty, a botanist from the Department of Botany, S.
V. University, Tirupati, India.
2.2. Preparation of the Extract. Fresh leaves of R. nasutus
(500 g) were shade-dried and milled into fine powder using
a mechanical grinder (TTK Prestige, Chennai, India). The
powdered plant material was macerated and shaken in
methanol using a bath shaker (Thermo Scientific, Mumbai,
India) for 48 h. The extract was then filtered with filter paper
(Whatman no. 1) and evaporated to dryness under a vacuum
with reduced pressure using a rotary evaporator at 40∘
C. The
concentrate was then placed on aluminum foil before freeze
drying. The residual extract was dissolved in 1 mL of sterile
water before use.
2.3. Chemicals. Streptozotocin (STZ) was purchased from
Sigma (USA). All other chemicals and reagents used in
this study were of analytical grade. Glibenclamide (Sugatrol,
Hyderabad, India) was purchased from a local drug store.
2.4. Experimental Design. Adult male Wistar rats weighing
between 150 and 180 g were obtained from Sri Venkateswara
Enterprises, Bangalore, India. They were individually housed
in clean, sterile polypropylene cages under standard conditions
(12 h light/dark cycles) with free access to standard
chow (Hindustan Lever Ltd., Bangalore, India) and water
ad libitum. Before the commencement of experiments, the
animals were allowed to acclimatize to laboratory conditions
for one week. The animal experiments were designed
and performed in accordance with the ethical standards
approved by the local Ministry of Social Justices and
Empowerment, Government of India, and the Institutional
Animal Ethics Committee Guidelines (Resolution no.
05/(i)/a/CPCSEA/IAEC/SVU/MDN-PVR/dt.13.09.2010).
2.5. Induction of Experimental Diabetes. Diabetes was
induced by a single intraperitoneal injection of a freshly
prepared STZ solution (Sigma, no. 242-646-8) (50 mg/kg
in citrate buffer 0.01 M, pH 4.5) to overnight-fasted rats.
Diabetes was confirmed by the presence of polydipsia and
polyurea as well as by measuring the nonfasting plasma
glucose levels 48 h after STZ injection. Only animals that
were confirmed to have blood glucose levels greater than
250 mg/dL were included in the study. All the animals were
allowed free access to tap water and pellet chow in accordance
with the guidelines of the Institute Animal Ethics committee.
The rats were divided into five groups of six animals each
as follows.
Group I: normal rats (controls—animals receiving
only buffer).
Group II: R. nasutus-treated normal rats (200 mg/
kg/day) [13, 23].
Group III: diabetic rats (untreated).
Group IV: R. nasutus-treated diabetic rats (200 mg/
kg/day).
Evidence-Based Complementary and Alternative Medicine 3
Group V: Glibenclamide-treated diabetic rats (50 mg/
kg/day).
2.6. Acute Toxicity Test. R. nasutus (50–250 mg/kg body
weight) was orally administered to rats for acute toxicity studies.
Each group was observed individually for signs of toxicity
and behavioral changes such as hyperactivity, grooming, convulsions,
sedation, or hypothermia.These observations began
1 h after dosing and were continued at least once daily for 14
days. The mortality rate was also calculated.
2.7. Biochemical Measurements. At the end of the study (30
days), after an overnight fasting, the animals were sacrificed
by cervical dislocation following anesthesia using isoflurane.
The liver tissue was excised and washed with ice-cold saline
and was immediately immersed in liquid nitrogen and stored
at −80∘
C for further biochemical analysis.Then, the measurements
of liver enzyme activity and biochemical assays were
performed.
AST and ALT activities were assayed using the method of
Reitman and Frankel [28].The total carbohydrate content was
estimated based on the method established by Carroll et al.
[29]. Glycogen content was determined as described by
Saifter et al. [30]. The protein content was estimated by the
method of Lowry et al. [31] with slight modifications. All
enzymatic assays in this study were performed using crude
liver homogenate.
2.8. Statistical Analysis. The results were expressed as the
mean ± SD (