Schwarzinicines A–D, a series of alkaloids recently discovered from Ficus schwarzii, exhibit pronounced vasorelaxant activity in rat isolated aorta. Building on this finding, a concise synthesis of schwarzinicines A and B has been reported, allowing further investigations into their biological properties. Herein, a preliminary exploration of the chemical space surrounding the structure of schwarzinicine A (1) was carried out aiming to identify structural features that are essential for vasorelaxant activity. A total of 57 analogs were synthesized and tested for vasorelaxant activity in rat isolated aorta. Both efficacy (E_max) and potency (EC₅₀) of these analogs were compared. In addition to identifying structural features that are required for activity or associated with potency enhancement effect, four analogs showed significant potency improvements of up to 40.2-fold when compared to 1. Molecular dynamics simulation of a tetrameric 44-bound transient receptor potential canonical-6 (TRPC6) protein indicated that 44 could potentially form important interactions with the residues Glu509, Asp530, Lys748, Arg758, and Tyr521. These results may serve as a foundation for guiding further structural optimization of the schwarzinicine A scaffold, aiming to discover even more potent analogs.

中文翻译：

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舒瓦津碱A类似物的制备及初步构效关系研究

Schwarzinicines A–D 是最近从Ficus schwarzii中发现的一系列生物碱，在大鼠离体主动脉中表现出明显的血管舒张活性。在此发现的基础上，已报道了黑氨碱 A 和 B 的简明合成，从而可以进一步研究其生物学特性。在此，对黑西尼碱 A ( 1 )结构周围的化学空间进行了初步探索，旨在确定血管舒张活性所必需的结构特征。总共合成了 57 种类似物，并在大鼠离体主动脉中测试了血管舒张活性。比较了这些类似物的功效（E _max）和效力（EC ₅₀ ）。除了确定活性所需的或与效力增强效果相关的结构特征之外，四种类似物显示出与1 种相比高达 40.2 倍的显着效力提高。四聚体44结合的瞬时受体电位规范 6 (TRPC6) 蛋白的分子动力学模拟表明，44可能与残基 Glu509、Asp530、Lys748、Arg758 和 Tyr521 形成重要的相互作用。这些结果可以作为指导进一步优化黑锌碱 A 支架结构的基础，旨在发现更有效的类似物。