Khan Taous, Ali Sayyad, Qayyum Rahila, Hussain Izhar, Wahid Fazli, Shah Abdul Jabbar
Department of Pharmacy, COMSATS Institute of Information Technology, Abbottabad, 22060, Pakistan.
Department of Environmental Sciences, COMSATS Institute of Information Technology, Abbottabad, 22060, Pakistan.
BMC Complement Altern Med. 2016 Jul 27;16:251. doi: 10.1186/s12906-016-1229-3.
Viscum album has shown inhibitory effect on different smooth muscles but underlying mechanisms in gut and vascular smooth muscles are not well defined. Additionally, the plant has also importance in managing hyperactive gut and cardiovascular disorders. The current study was aimed to probe a pharmacological base of the smooth muscle relaxant effect of V. album in gut and vascular preparations.
V. album crude extract (Va. Cr) and its ethyl acetate fraction (Va. EtAc) were studied using in vitro techniques. The antispasmodic activity was performed using isolated rabbit jejunum while the vasorelaxant effects were studied in rabbit aortic rings.
Va. Cr and Va. EtAc inhibited spontaneous and high K(+)-induced contractions with EC50 values of 0.31 mg/mL (0.15-0.57) and 0.62 mg/mL (0.3-0.95), respectively. This advocates an antispasmodic effect probably operated through calcium channels blockade (CBB). The proposed mechanism was confirmed by a pretreatment of the tissue with Va. Cr (0.01-0.3 mg/mL), which shifted the Ca(++) concentration-response curves (CRCs) rightward, similar to verapamil. Moreover, Va. Cr showed a partial relaxation against high K(+) and PE (1 μM) induced contractions in isolated rabbit aorta rings. Va. EtAc caused complete relaxation of high K(+) precontraction and partially relaxed PE (1 μM) induced contractions, suggesting inhibitory effect on Ca(++) entry, in addition to other possible mechanisms. CRCs were shifted to the right correspondingly to verapamil when the aortic rings were pretreated with Va. Cr and Va. EtAc.
These data indicated that Va. Cr possesses smooth muscle relaxant effect mediated through voltage-dependent Ca(++) channel blockade (CCB), which explains its spasmolytic and vasorelaxant activity. The CCB activity is concentrated more in Va. EtAc. This study provides an evidence for the medicinal importance of V. album in gut spasm and possibly hypertension.
槲寄生对不同的平滑肌已显示出抑制作用，但在肠道和血管平滑肌中的潜在机制尚未明确。此外，该植物在治疗肠道功能亢进和心血管疾病方面也具有重要意义。本研究旨在探究槲寄生在肠道和血管制剂中平滑肌松弛作用的药理学基础。
采用体外技术研究槲寄生粗提物（Va.Cr）及其乙酸乙酯馏分（Va.EtAc）。使用离体兔空肠进行抗痉挛活性研究，同时在兔主动脉环中研究血管舒张作用。
Va.Cr和Va.EtAc抑制自发性和高钾诱导的收缩，其半数有效浓度（EC50）值分别为0.31毫克/毫升（0.15 - 0.57）和0.62毫克/毫升（0.3 - 0.95）。这表明其抗痉挛作用可能是通过钙通道阻滞（CBB）实现的。用Va.Cr（0.01 - 0.3毫克/毫升）预处理组织可使钙浓度 - 反应曲线（CRCs）右移，类似于维拉帕米，从而证实了所提出的机制。此外，Va.Cr对离体兔主动脉环中高钾和去甲肾上腺素（1微摩尔）诱导的收缩表现出部分舒张作用。Va.EtAc可使高钾预收缩完全舒张，并使去甲肾上腺素（1微摩尔）诱导的收缩部分舒张，这表明除其他可能机制外，其对钙内流有抑制作用。当主动脉环用Va.Cr和Va.EtAc预处理时，CRCs相应地向维拉帕米方向右移。
这些数据表明，Va.Cr具有通过电压依赖性钙通道阻滞（CCB）介导的平滑肌松弛作用，这解释了其解痉和血管舒张活性。CCB活性在Va.EtAc中更为集中。本研究为槲寄生在肠道痉挛及可能的高血压治疗中的药用重要性提供了证据。
