Moringin (rhamnobenzyl isothiocyanate) is a major bioactive compound in moringa seeds, which have been used as a healthy food. However, its bioactivity mechanisms are not well understood. We investigated moringin and its structurally similar analogues, including benzyl isothiocyanate and 4-hydroxylbenzyl isothiocyanate, for their hydrogen sulfide (H₂S)-releasing activity triggered by cysteine. These isothiocyanates rapidly formed cysteine adducts, which underwent intramolecular cyclization followed by slowly releasing (a) organic amine and raphanusamic acid and (b) H₂S and 2-carbylamino-4,5-dihydrothiazole-4-carboxylic acids. The product distributions are highly dependent on para-substituents on the phenyl group. Moringin has higher cytotoxicity to cancer cells and is a more potent anti-inflammatory agent than benzyl and hydroxybenzyl analogues, while benzyl isothiocyanate is a better antibacterial agent. Taken together, their bioactivity may not be directly related to their H₂S donation activity. However, other metabolites alone do not have cytotoxicity and anti-inflammatory activity. These findings indicated that their activity may be the combination effects of different metabolites via competitive pathways as well the para-substituent groups of benzyl ITCs.

中文翻译：

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辣木素及其作为慢H2S供体的结构类似物：其机理和生物活性。

辣木（辣木苄基异硫氰酸酯）是辣木种子中的主要生物活性化合物，已被用作健康食品。但是，其生物活性机制尚不十分清楚。我们研究了moringin及其结构相似的类似物，包括异硫氰酸苄酯和4-羟基异硫氰酸苄酯，其半胱氨酸引发的硫化氢（H ₂ S）释放活性。这些异硫氰酸酯迅速形成半胱氨酸加合物，将其进行分子内环化，然后缓慢释放（a）有机胺和萝卜酸和（b）H ₂S和2-羰基氨基-4,5-二氢噻唑-4-羧酸。产物分布高度依赖于苯基上的对位取代基。辣木素对癌细胞具有更高的细胞毒性，并且是比苄基和羟基苄基类似物更有效的抗炎剂，而异硫氰酸苄酯是一种更好的抗菌剂。两者合计，它们的生物活性可能与它们的H ₂ S供体活性没有直接关系。但是，仅其他代谢物不具有细胞毒性和抗炎活性。这些发现表明，它们的活性可能是不同代谢物通过竞争途径以及苄基ITC的对位取代基的组合效应。