Khan Munasib, Shah Abdul Jabbar, Gilani Anwarul Hassan
Natural Product Research Unit, Department of Biological and Biomedical Sciences, Aga Khan University Medical College , Karachi , Pakistan .
Pharm Biol. 2015 Mar;53(3):340-4. doi: 10.3109/13880209.2014.919327.
Vitex negundo Linn. (Verbenaceae) is traditionally used in hyperactive respiratory disorders.
This study explored the mechanisms underlying the effectiveness of Vitex negundo in hyperactive respiratory disorders.
Crude extract of V. negundo leaves was obtained. For in vivo bronchodilatory activity in anesthetized rats, different doses (1, 3, 10, 30, and 50 mg/kg) of the crude extract of V. negundo (Vn.Cr) were tested. The underlying mechanisms were studied in isolated guinea pig tracheal strips, suspended in organ baths at 37 °C.
Intravenous doses of the crude extract of Vn.Cr showed dose-dependent bronchodilatory effect (9-50%) against carbachol (CCh; 100 µg/kg)-induced bronchoconstriction, similar to aminophylline. In isolated guinea-pig tracheal strips, Vn.Crrelaxed CCh (1 µM) and high K(+) pre-contractions with respective EC50 values of 0.72 (0.48-1.10; n = 5) and 3.38 mg/mL (1.84-6.21; n = 4), similar to papaverine. Diltiazem also relaxed both contractions with more potency against high K(+) pre-contraction (p < 0.05). Pre-incubation of the tracheal strips with Vn.Cr potentiated the isoprenaline inhibitory concentration response curves (CRCs), similar to papaverine.
The inhibitory effect against CCh and high K(+) suggests involvement of phosphodiesterase (PDE) inhibitory pathway(s), in addition to an inhibitory effect on Ca(++) entry. This finding was further strengthened when pre-treatment of the tracheal strips potentiated the isoprenaline CRCs.
RESULTS suggest Vn.Cr possesses a combination of papaverine-like PDE inhibitor and diltiazem-like Ca(++) entry blocking constituents, which partly explain its bronchodilatory effect, thus validating its medicinal importance in asthma.
黄荆（马鞭草科）传统上用于治疗呼吸功能亢进症。
本研究探讨黄荆治疗呼吸功能亢进症有效性的潜在机制。
制备黄荆叶粗提取物。在麻醉大鼠体内测试不同剂量（1、3、10、30和50mg/kg）的黄荆粗提取物（Vn.Cr）的支气管舒张活性。在37℃器官浴中对分离的豚鼠气管条进行潜在机制研究。
静脉注射Vn.Cr粗提取物显示出对卡巴胆碱（CCh；100μg/kg）诱导的支气管收缩呈剂量依赖性支气管舒张作用（9 - 50%），与氨茶碱相似。在分离的豚鼠气管条中，Vn.Cr使CCh（1μM）和高钾预收缩松弛，其各自的半数有效浓度（EC50）值分别为0.72（0.48 - 1.10；n = 5）和3.38mg/mL（1.84 - 6.21；n = 4），与罂粟碱相似。地尔硫䓬也使两种收缩松弛，对高钾预收缩的作用更强（p < 0.05）。用Vn.Cr预孵育气管条增强了异丙肾上腺素抑制浓度反应曲线（CRCs），与罂粟碱相似。
对CCh和高钾的抑制作用表明除了对钙离子内流的抑制作用外，还涉及磷酸二酯酶（PDE）抑制途径。当气管条预处理增强异丙肾上腺素CRCs时，这一发现得到进一步加强。
结果表明Vn.Cr具有罂粟碱样PDE抑制剂和地尔硫䓬样钙离子内流阻断成分的组合，这部分解释了其支气管舒张作用，从而证实了其在哮喘治疗中的药用价值。
