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Evaluation of skeletal muscle relaxant activity of methanolic extract of Hibiscus rosa sinensis leaves in albino rats.

INTRODUCTION

Skeletal muscle relaxants are drugs that reduce the muscle tone. They act peripherally at the neuromuscular junction (neuromuscular blockers)/muscle fiber itself or centrally in the cerebrospinal axis to reduce muscle tone or cause paralysis. The neuromuscular blocking agents as adjuncts during general anesthesia to provide muscle relaxation for surgery, while centrally acting agents are used for painful muscle spasms and spastic neurological conditions. [1] However, these drugs cause several adverse effects. Thus, looking for an effective alternative has always been a priority in this regard.

Hibiscus rosa sinensis (family - Malvaceae) is a perennial shrub available throughout India. Various parts of this plant such as leaves, flowers, and roots have been known to possess medicinal properties such as aphrodisiac, menorrhagic, and oral contraceptive. [2]

Pharmacological studies have demonstrated that H. rosa sinensis exhibits wide range of properties antinociceptive, anti-inflammatory, [3] antioxidant, wound healing, [4] anticonvulsant, [5] antidiabetic, hypolipidemic, [6-8] anxiolytic, and central nervous system depressant, [9] promotes hair growth, and prevents graying of hair, [10] gastroprotective, [11] and antibacterial. [12] The studies evaluating the skeletal muscle relaxant activity of H. rosa sinensis leaves are limited. The main purpose of the study was to evaluate skeletal muscle relaxant activity of H. rosa sinensis leaves.

MATERIALS AND METHODS

Collection of Plant Material

Leaves of H. rosa sinensis were obtained from local market, and the identification was done.

Preparation of Extract

The leaves were shade dried and pulverized to a fine powder. Methanolic extract of leaves was prepared using Soxhlet apparatus using methanol as solvent. The extract was dried under vacuum. The percentage of yield was 8% w/w stored at room temperature and protected from sunlight.

Animals

Adult albino rats of either sex weighing between 200 and 250 g were used in this study. Animals were obtained from NIN, Hyderabad, India. The animals were stabilized for 1 week at a temperature 25 [+ or -] 1[degrees]C and 60 [+ or -] 5% relative humidity and 12 h dark-light cycles. They have been given a standard pellet diet and water ad libitum. All the experiments were conducted with prior permission taken from the Institutional Animal Ethics Committee.

Drugs and Chemicals

Diazepam (Lupin Laboratories Ltd., India) and other chemicals were analytical grade.

Experimental Models

The rats were randomly allocated into four groups (n = 6) and treated as follows:

* Group I: Control received vehicle only (normal saline 10 ml/kg)

* Group II: Standard received 10 mg/kg diazepam

* Group III: Test rats received methanolic extract of H. rosa sinensis leaves (MEHRL) 200 mg/kg

* Group IV: Test rats received MEHRL 400 mg/kg.

All the drugs were administered orally.

Skeletal Muscle Relaxant Activity (Motor Coordination) [13]

The muscle relaxant activity was assessed with the help of rotarod. Rats were divided in to four groups consisting of six animals each. The animals retained on rotarod (25 rpm) for 5 min were included in the study. Rats were placed on the rotarod; falloff time from rotarod before and 30 min after drug administration was noted.

The difference in the falloff time from rotarod between control and treated rats was taken as index of muscle relaxation.

Locomotor Activity

The spontaneous locomotor activity was assessed with the help of a photoactometer. [14] It consists of six built-in light source, photo sensor, and a digital counter to indicate locomotor activity. The device operates on photoelectric cells which are connected to the circuit with the counter when the beam of light falling on photocells is cut off by the animal, and a count is recorded.

To see the locomotor activity, the photoactometer was turned on and each rat was placed individually in the cage for 5 min. The basal activity score for all the animals was noted. All the drugs were administered orally after 1 h, and the activity score for 5 min was observed. The difference in the activity score before and after drug administration was noted. The percentage decrease in motor activity was calculated.

Statistics

Results were expressed as mean [+ or -] standard deviation. Statistical analysis was performed using one-way analysis of variance followed by Dunnett's test. P < 0.05 was considered statistically significant.

RESULTS

Rotarod (Test for Muscle Relaxation)

The test doses MEHRL 200 mg/kg and 400 mg/kg showed significant dose-dependent reduction in motor coordination, that is, 36% and 48%, respectively. The standard drug showed 68.6% reduction in motor coordination [Table 1].

MEHRL (200 mg/kg and 400 mg/kg) showed significant (P < 0.001) skeletal muscle relaxant activity.

Actophotometer: (Test for Locomotor Activity)

The percentage of reduction in the locomotor activity after 1 h was 62% and 69% at the doses of 200 mg/kg and 400 mg/kg MEHRL, respectively, and the standard drug showed 84.5% reduction when compared to control.

MEHRL (200 mg/kg and 400 mg/kg) showed statistically significant (P < 0.001) reduction in locomotor activity [Table 2].

DISCUSSION

In recent years, the herbal medicines have been extensively used in various diseases due to their safety profile. The objective of the present study was to evaluate the effect of MEHRL on muscle relaxant activity in experimental animals. Actophotometer is used for evaluating the locomotor activity and antianxiety activity in rodents and rotarod for muscle relaxant activity. MEHRL significantly reduced motor coordination and locomotor activity in experimental animals. A decrease in locomotor activity indicates sedative action. Diazepam used as standard here at 10 mg/kg orally showed significant muscle relaxant activity in comparison with control as well as extract. Diazepam has low muscle relaxant sedation ratio, and sedation limits the dose used for muscle relaxation. [15]

Previous neuropharmacological studies on H. rosa sinensis roots showed significant skeletal muscle relaxant and sedative effect. [16] Our study also collaborates to these findings.

The MEHRL containing flavonoids (hibiscitin) phenolic content as well as terpenoid compounds such as betasitosterol and campesterol [17] is probably responsible for the actions.

The major limitation of the study is that phytochemical analysis was not done to identify the exact constituents. Further, extensive phytochemical analysis and research are necessary to identify the exact constituents and elucidation of its possible mechanism of action underlying the muscle relaxant activity of MEHRL.

CONCLUSION

MEHRL showed significant muscle relaxant activity in a dose-dependent manner.

REFERENCES

[1.] Tripati KD. Essentials of Medical Pharmacology. 8th ed. New Delhi: JayPee Brother Medical Publishers; 2018. p. 373-85.

[2.] Nadkarni AK. Indian Materia Medica. 3rd ed. Bombay: Popular Prakashan Pvt. Ltd.; 2005. p. 634-51.

[3.] Tomar V, Kannojia P, Jain KN, Dubey KS. Anti-noceceptive and antinflammatory activity of leaves of Hibiscus rosa sinensis. Int J Res Ayurveda Pharm 2010;1:201-5.

[4.] Mondal S, Ghosh D, Sagar N, Ganapaty S. Evaluation of antioxidant toxicological and wound healing properties of Hibiscus rosa sinensis L. (Malvaceae) ethonolic leaves extract on different experimental animal models. Indian J Pharm Educ Res 2016;50:620-36.

[5.] Kasture VS, Chopde CT, Deshmukh VK. Anticonvulsive activity of Albizzia lebbeck Hibiscus rosa sinensis and Butea Monospera in experimental animals. J Ethnopharmacol 2000;71:65-75.

[6.] Sachdewa A, Khemani LD. Effect of Hibiscus rosa sinensis Linn. Ethanol flower extract on blood glucose and lipid profile in streptozotocin induced diabetes in rats. J Ethnopharmacol 2003;89:61-6.

[7.] Pethe M, Yelwatkar S, Gujar V, Varma S, Manchalwar S. Anti diabetic, hypolipidemic and antioxidant activities of Hibiscus rosa Sinensis flower extract in alloxan induced diabetes in rabbits. Int J Biomed Adv Res 2017;8:138-43.

[8.] Kumar V, Singh P, Chander R, Mahdi F, Singh S, Singh R, et al. Hypolipidemic activity of Hibiscus rosa sinensis root in rats. Indian J Biochem Biophys 2009;46:507-10.

[9.] Ganatra TH, Joshi UH, Patel MN, Desai TR, Tirgar RR. Study of sedative, anxiolytic, CNS-depressant and skeletal muscle relaxant effect of methanolic extract of Hibiscus rosa sinensis on laboratory animals. J Pharm Sci Res 2011;3:1146-55.

[10.] Kumar S, Kumar VS, Sharma A, Shuklay N, Singh AK. Traditional Medicinal Plants in Skin Care. Lucknow: Central Institute of Medicinal and Aromatic Plants; 1994. p. 103.

[11.] Phanikumar K, Annapurna A, Ramya G, Shebe D, Krishna CH, Sudeepthi NL. Gastroprotective effect of flower extract of Hibiscus rosa sinensis against acute gastric lesion models in rodents. J Pharmacogn Phytochem 2014;3:137-45.

[12.] Agarwal S, Prakash R. Evaluation of antibacterial activity of Hibiscus rosa sinensis flower extract against E.coli and B. Subililis. Biol Int J 2014;6:194-6.

[13.] Ghosh MN. Fundamentals of Experimental Pharmacology. 2nd ed. Kolkata: Scientific Book Agency; 1984. p. 156.

[14.] Vogel HG. Drug Discovery and Evaluation Pharmacological Assay. 3rd ed. New York, Berlin Heidel: Springer Verlag; 2008. p. 1103.

[15.] Nair PV, Nair B. Muscle relaxant activity of hydroalcholic extract of Mimosa pudica whole plant in mice. Natl J Physiol Pharm Pharmacol 2017;7:432-7.

[16.] Nade VS, Kawale LA, Dwivedi S, Yadav AV. Neuropharmacological evaluation of Hibiscus rosa sinensis roots in experimental animals. J Natl Remedies 2009;9: 142-51.

[17.] Bajracharya MB. Ayurvedic Medicinal Plants and General Treatment. Kathmandu: Jore Ganesh Press; 1979.

Sudha Madhuri A, Roopa C R

Department of Pharmacology, Navodaya Medical College, Raichur, Karnataka, India

Correspondence to: Sudha Madhuri A, E-mail: allellisudhamadhuri@gmail.com

Received: December 12, 2018; Accepted: January 02, 2019

Source of Support: Nil, Conflict of Interest: None declared.

DOI: 10.5455/njppp.2019.9.1237703012019
Table 1: Effect of MEHRL on muscle coordination on the rotarod apparatus

Groups                         Fall of time (s)
                          Before              After

Group I - control NS  311.66[+ or -]2.18  313.5[+ or -]3.06
(10 mg/kg)
Group II - standard   328.5[+ or -]2.84   103.16[+ or -]2.38 (*)
(10 mg/kg) diazepam
Group III - MEHRL     318.33[+ or -]1.86  203.5[+ or -]2.26 (*)
(200 mg/kg)
Group IV - MEHRL      335.66[+ or -]2.32  174.66[+ or -]1.84 (*)
(400 mg/kg)

Groups                % reduction

Group I - control NS   -
(10 mg/kg)
Group II - standard   68.596
(10 mg/kg) diazepam
Group III - MEHRL     36.072
(200 mg/kg)
Group IV - MEHRL      47.965
(400 mg/kg)

Results expressed as mean[+ or -]SD. P<0.001 (*) compared to control.
SD: Standard deviation, MEHRL: Methanolic extract of Hibiscus rosa
sinensis leaves

Table 2: Effect of MEHRL on the locomotor activity in the actophotometer

Groups               Actophotometer score % reduction
                     5 min before        60 min after
                     administration      administration

Group I - control    177.6[+ or -]2.96   173.16[+ or -]1.08
NS (10 mg/kg)
Group II - standard  185.33[+ or -]2.06   30.66[+ or -]2.26 (*)
(10 mg/kg) diazepam
Group III - MEHRL    198.5[+ or -]1.02    75.33[+ or -]2.84 (*)
(200 mg/kg)
Group IV - MEHRL     173.66[+ or -]2.18   53.55[+ or -]1.92 (*)
(400 mg/kg)

Groups               % reduction

Group I - control     -
NS (10 mg/kg)
Group II - standard  84.45
(10 mg/kg) diazepam
Group III - MEHRL    62
(200 mg/kg)
Group IV - MEHRL     69.16
(400 mg/kg)

Results expressed as mean[+ or -]SD. P<0.001 *compared to control. SD:
Standard deviation, MEHRL: Methanolic extract of Hibiscus rosa sinensis
leaves
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Title Annotation:RESEARCH ARTICLE
Author:Sudha Madhuri, A; Roopa, C R
Publication:National Journal of Physiology, Pharmacy and Pharmacology
Date:Mar 1, 2019
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