Evaluation Of The Cardiovascular Activity And Toxicity Study Of Alstonia Scholaris Bark Extracts

• Main Author: Bello, Idris
• Format: Thesis
• Language: English
• Published: 2015
• Subjects: RS1-441 Pharmacy and materia medica
• Online Access: http://eprints.usm.my/31680/1/IDRIS_B_ELLO_24.pdf; http://eprints.usm.my/31680/
• Institution: Universiti Sains Malaysia

Tujuan kajian ini adalah untuk memeriksa kesan antihipertensi ekstrak kulit kayu Alstonia scholaris (pulai) dan mekanisme tindakan farmakologinya. Pengekstrakan berturut-turut telah dijalankan untuk mendapatkan ekstrak metanol (ASME) dan air (ASWE) yang diperolehi selepas penyahlemakan dengan eter petroleum. Kesan antihipertensi ekstrak ini telah dinilai pada tikus hipertensi spontan (SHR). Pemberian ASME secara oral setiap hari (1000 mg/kg selama 2 minggu) mempamerkan penurunan ketara tekanan darah (p <0.05) tikus berbanding SHR kawalan. Melalui teknik fraksinasi cecair-cecair, ASME telah difraksikan berturut-turut menggunakan diklorometana, etil asetat dan n-butanol. Semua fraksi (0.125 – 4 mg/mL) menunjukkan vasorelaksi bergantung dos pada sediaan cincin aorta yang telah diprakontraksikan dengan fenileferina (PE; 1 μM) atau kalium klorida (80 mM). Fraksi n-butanol (NBF-ASME) merupakan fraksi yang paling poten (Rmax = 106.4 ± 0.045%). Prainkubasi cincin aorta dengan NBF-ASME (0.5, 1 dan 2 mg/mL) merencat tindak balas kontraksi cincin aorta yang diaruhkan PE dengan ketara (p <0.05-0.001). Pembuangan endotelium dan inkubasi dengan L-NAME, indometasin, atropina dan propranolol tidak menjejaskan dengan ketara relaksi oleh NBF-ASME. The aim of the present study was to investigate the antihypertensive effect of Alstonia scholaris (pulai) bark extracts and its pharmacological mechanism of actions. Successive extraction was carried out to obtain methanol (ASME) and water (ASWE) extract of the bark after defatting with petroleum ether. The antihypertensive effect of these extracts were evaluated on spontaneous hypertensive rats (SHR). Daily oral administration of ASME (1000 mg/kg for 2 weeks) exhibited a significant decrease in the blood pressure (p < 0.05) of the rats compared to control SHR. By means of liquid-liquid fractionation technique, the aqueous ASME solution was successively fractionated using dichloromethane, ethyl acetate and nbutanol. All the fractions (0.125 – 4 mg/mL) gave a dose-dependent vasorelaxation on aortic ring preparations pre-contracted with phenylephrine (PE; 1 μM) or potassium chloride (80 mM). The n-butanol fraction (NBF-ASME) was the most potent fractions (Rmax = 106.4 ± 0.045 %). Pre-incubation of aortic rings with NBF-ASME (0.5, 1 and 2 mg/mL) significantly inhibit the contractile response of the aortic rings to PE-induced contraction (p<0.05-0.001). Removal of endothelium and incubation with L-NAME, indomethacin, atropine, and propranolol did not significantly affect the relaxation effect of NBF-ASME.