Abstract

Caulerpin, a bis-indole alkaloid is isolated from a new source Sargassum platycarpum, brown alga (family Sargassaceae) for the first time. The structure of caulerpin was characterized by IR, H¹NMR, C¹³ NMR, HSQC, HMBC, EI-MS spectroscopy. Antifungal results suggest that caulerpin has been inhibited Cryptococcus neoformas (12 mm) and Candida albicans (7 mm) than other microbes. In vitro anticancer activity of caulerpin has been explored by cell viability assay against new human cancer cell line (liver-HepG2). The results show that caulerpin has low IC₅₀ value (24.6 ± 2.1 µg/mL) against HepG-2. Based on the least toxic activity of caulerpin, these results encourage for future in vivo anticancer study. The binding of caulerpin molecule with the two nucleobases (T/U) bases has been studied by DFT methods. According to the AIM analysis, there are two types of interactions between caulerpin and T/U bases partially covalent partially electrostatic and electrostatic in gas and water phases. Based on NBO analysis, the charges were transferred from the lone-pair (n) in orbitals of O atoms of caulerpin to the σ* orbitals of T/U bases atoms. ΔE_bin in the state of caulerpin-T bases complexes are lower than those in the caulerpin-U bases complexes in both gas and water phase. MD simulation supported that caulerpin-T/U bases complexes are stable in presence of explicit water phase. Thus, the findings of our study will be useful for giving an insight into the caulerpin/bases complexes that could be helpful in future experimental studies to develop the performance of caulerpin molecules as natural candidate drug.

Communicated by Ramaswamy H. Sarma

摘要

Caulerpin 是一种双吲哚生物碱，首次从新来源的马尾藻属褐藻（马尾藻科）中分离得到。花椰菜的结构通过IR、H ¹ NMR、C ¹³ NMR、HSQC、HMBC、EI-MS光谱表征。抗真菌结果表明，与其他微生物相比，花椰菜对新型隐球菌(12 mm) 和白色念珠菌(7 mm) 的抑制作用。已经通过针对新的人类癌细胞系（肝-HepG2）的细胞活力测定探索了花椰菜素的体外抗癌活性。结果表明，花椰菜具有低 IC ₅₀值 (24.6 ± 2.1 µg/mL) 对 HepG-2。基于花椰菜的毒性最小，这些结果为未来的体内抗癌研究提供了鼓励。已经通过 DFT 方法研究了花椰菜分子与两个核碱基 (T/U) 碱基的结合。根据 AIM 分析，在花椰菜和 T/U 碱基之间存在两种类型的相互作用，部分共价部分静电和气相和水相静电。基于 NBO 分析，电荷从花椰菜 O 原子轨道中的孤对 (n) 转移到 T/U 碱基原子的 σ* 轨道。ΔE _bin在气相和水相中，caulerpin-T 碱基配合物的含量低于 caulerpin-U 碱基配合物。MD 模拟支持 caulerpin-T/U 碱基复合物在显性水相存在下是稳定的。因此，我们的研究结果将有助于深入了解花椰菜/碱基复合物，这可能有助于未来的实验研究，以开发花椰菜分子作为天然候选药物的性能。

由 Ramaswamy H. Sarma 交流