Moringin and Its Structural Analogues as Slow H2S Donors: Their Mechanisms and Bioactivity

• Published in: Journal of agricultural and food chemistry 2020-07, Vol.68 (27), p.7235-7245
• Main Authors: Lu, Yuyun, Wang, Xingyi, Pu, Haoliang, Lin, Yi, Li, Dan, Liu, Shao Quan, Huang, Dejian
• Format: Article
• Language: English
• Subjects: Functional Structure/Activity Relationships
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/acs.jafc.0c02358

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.