Viola is the largest genus in the Violaceae plant family and is known for its ubiquitous natural production of cyclotides. Many Viola species are used as medicinal herbs across Asia and are often consumed by humans in teas for the treatment of diseases, including ulcers and asthma. Previous studies reported the isolation of cyclotides from Viola species in many countries in the hope of discovering novel compounds with anti-cancer activities; however, Viola species from Vietnam have not been investigated to date. Here, the discovery of cyclotides from three Viola species (V. arcuata, V. tonkinensis, and V. austrosinensis) collected in the northern mountainous region of Vietnam is reported. Ten cyclotides were isolated from these three Viola species: four are novel and six were previously reported to be expressed in other plants. The structures of three of the new bracelet cyclotides are similar to that of cycloviolacin O2. Because cycloviolacin O2 has previously been shown to have potent activity against a wide range of cancer cell lines including HeLa (human cervical cancer cells) and PC-3 (human prostate cancer cells), the cancer cytotoxicity of the cyclotides isolated from V. arcuata was assessed. All tested cyclotides were cytotoxic against cancer cells, albeit to varying degrees. The sequences discovered in this study significantly expand the understanding of cyclotide diversity, especially in comparison with other cyclotides found in plants from the Asian region.

中文翻译：

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探索越南中提琴种环肽的序列多样性。

中提琴是紫罗兰科植物家族中最大的属，以其无处不在的环肽天然产物而闻名。许多中提琴种类在亚洲被用作药材，人们经常将其用于茶中以治疗疾病，包括溃疡和哮喘。以前的研究报道了许多国家从紫堇属植物中分离环肽，希望发现具有抗癌活性的新化合物；然而，迄今为止尚未对来自越南的中提琴物种进行调查。在这里，发现了三种中提琴种（V. arcuata、V. tonkinensis和V. austrosinensis）的环藻类) 采集于越南北部山区。从这三种中提琴物种中分离出 10 种环肽：4 种是新的，而 6 种之前据报道在其他植物中表达过。三种新型手链环肽的结构与环紫素O2相似。由于先前已证明环紫霉素 O2 对包括 HeLa（人宫颈癌细胞）和 PC-3（人前列腺癌细胞）在内的多种癌细胞系具有强效活性，因此从V. arcuata 中分离的环肽的癌症细胞毒性被评估。所有测试的环肽都对癌细胞具有细胞毒性，尽管程度不同。本研究中发现的序列显着扩展了对大环肽多样性的理解，特别是与在亚洲地区植物中发现的其他大环肽相比。