State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, People's Republic of China; University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China.
State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, People's Republic of China; Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education and Yunnan Province, School of Chemical Science and Technology, Yunnan University, Kunming, 650091, People's Republic of China.
J Ethnopharmacol. 2020 Oct 5;260:113103. doi: 10.1016/j.jep.2020.113103. Epub 2020 Jun 20.
Neolamarckia cadamba has been used traditionally to treat inflammation, fever, and pruritus in the Dai ethnopharmacy in Yunnan province, P.R. China. However, according to literature survey, the action basis of anti-inflammatory and analgesic activities of this plant were rarely reported, which accounts for the original intentions of this investigation.
The study aimed to investigate the anti-inflammatory and analgesic action of methanolic extract (ME), ethyl acetate (EA), and aqueous (AQS) fractions of N. cadamba and further explore the accurate compounds responsible for the activities of EA fraction.
The in vivo anti-inflammatory and analgesic activities of ME, EA, and AQS fractions at the doses of 200 and 400 mg/kg and two major constituents (compounds 5 and 7) at 50 and 100 mg/kg via intragastrically administrated, respectively, were evaluated by carrageenan-induced paw edema and acetic acid-stimulated writhing animal models. Aspirin (ASP) was used as the positive control at the dose of 200 mg/kg. The monoterpenoid indole alkaloids (MIAs) in EA fraction were phytochemically studied utilizing chromatographic techniques, and their structures and absolute configurations were established on the basis of multiple spectroscopic analyses and quantum computational chemistry method. Moreover, the in vitro anti-inflammatory activities of all the isolates were assessed by suppressing releases of LPS-activated inflammatory mediators (TNF-α, IL-1β, and COX-2) in RAW 264.7 macrophage cells at a concentration of 10 μg/mL. Dexamethasone (DXM) was used as the positive control.
Three fractions (ME, EA, and AQS) significantly ameliorated the paw edema caused by carrageenan and reduced the number of writhing induced by acetic acid in comparison to the control group at the doses of 200 and/or 400 mg/kg (in vivo). Subsequent phytochemical investigation of EA fraction led to the structural characterization of four new monoterpenoid indole alkaloids, neocadambines A-D (1-4), as well as eight known analogues (5-12). Neocadambine A possesses a novel 14-nor-MIA skeleton that could be derived from the corynantheine-type MIAs via oxidative cleavage of C3-C14 bond and subsequently degradation of C14. Moreover, the structure of a bioactive known MIA, cadambine acid (6), was reassigned by analysis of its NMR spectroscopic data. Further biological assays revealed that the major constituent 3β-dihydrocadambine (7) significantly relieved the paw edema and decreased the number of writhing at 100 mg/kg in vivo. In addition, most of the isolates displayed remarkable in vitro anti-inflammatory effects by inhibiting the secretion of aforementioned inflammatory mediators (COX-2, IL-1β, and TNF-α) at a concentration of 10 μg/mL, and compounds 4, 7, and 9 showed better anti-inflammatory effects than that of positive control, dexamethasone.
This study further validated the anti-inflammatory and analgesic activities of N. cadamba, and revealed that monoterpenoid indole alkaloids could partly contribute to the efficacy of this ethnodrug. The major constituent 3β-dihydrocadambine (7) showed significant anti-inflammatory activities both in vitro and in vivo, which suggested that it could be a promising anti-inflammatory lead compound. Our findings provided scientific justification to support the traditional application of N. cadamba for treating inflammatory and nociceptive disorders.
在中国云南省傣族传统医学中，山香圆被用于治疗炎症、发热和瘙痒。然而，根据文献调查，该植物抗炎和镇痛活性的作用基础很少被报道，这就是本研究的初衷。
本研究旨在研究山香圆的甲醇提取物（ME）、乙酸乙酯（EA）和水（AQS）馏分的抗炎和镇痛作用，并进一步探索负责 EA 馏分活性的准确化合物。
通过角叉菜胶诱导的爪肿胀和醋酸刺激的扭体动物模型，分别以 200 和 400mg/kg 的剂量通过灌胃评估 ME、EA 和 AQS 馏分以及 50 和 100mg/kg 的两种主要成分（化合物 5 和 7）的体内抗炎和镇痛活性。阿司匹林（ASP）以 200mg/kg 的剂量用作阳性对照。利用色谱技术对 EA 馏分中的单萜吲哚生物碱（MIAs）进行了植物化学研究，并根据多种光谱分析和量子计算化学方法确定了它们的结构和绝对构型。此外，所有分离物在浓度为 10μg/mL 时通过抑制 LPS 激活的炎症介质（TNF-α、IL-1β 和 COX-2）的释放，评估了它们在 RAW 264.7 巨噬细胞中的体外抗炎活性。地塞米松（DXM）用作阳性对照。
与对照组相比，三种馏分（ME、EA 和 AQS）在 200 和/或 400mg/kg 剂量下显著改善了角叉菜胶引起的爪肿胀，并减少了醋酸引起的扭体次数（体内）。随后对 EA 馏分进行的植物化学研究导致了四个新的单萜吲哚生物碱，即 neocadambines A-D（1-4）的结构表征，以及八个已知类似物（5-12）。Neocadambine A 具有新颖的 14-去甲-MIA 骨架，可通过 C3-C14 键的氧化断裂和随后的 C14 降解从 Corynantheine 型 MIAs 中衍生而来。此外，通过分析其 NMR 光谱数据，重新分配了生物活性已知 MIA cadambine 酸（6）的结构。进一步的生物学测定表明，主要成分 3β-二氢山香圆碱（7）在体内以 100mg/kg 的剂量显著缓解爪肿胀并减少扭体次数。此外，大多数分离物在浓度为 10μg/mL 时通过抑制上述炎症介质（COX-2、IL-1β 和 TNF-α）的分泌表现出显著的抗炎作用，化合物 4、7 和 9 的抗炎作用优于阳性对照地塞米松。
本研究进一步验证了山香圆的抗炎和镇痛活性，并表明单萜吲哚生物碱可能部分有助于该民族药物的疗效。主要成分 3β-二氢山香圆碱（7）在体内和体外均表现出显著的抗炎活性，这表明它可能是一种有前途的抗炎先导化合物。我们的发现为支持山香圆用于治疗炎症和疼痛障碍的传统应用提供了科学依据。
