Glucosinolate-derived amine formation in Brassica oleracea vegetables

Area of Science:

• Plant biochemistry
• Food science
• Nutritional science

Background:

• Glucosinolates in Brassica vegetables are precursors to health-promoting isothiocyanates (ITCs).
• Enzymatic hydrolysis of glucosinolates typically produces ITCs, nitriles, and epithionitriles.
• The full spectrum of glucosinolate hydrolysis products in Brassica vegetables is not yet fully understood.

Purpose of the Study:

• To investigate the potential formation of amines as enzymatic hydrolysis products of glucosinolates in Brassica vegetables.
• To identify the enzyme responsible for ITC conversion to amines.
• To compare the stability of different amine types under thermal processing.

Main Methods:

• Enzymatic hydrolysis of glucosinolates in cabbage extracts.
• Identification and quantification of hydrolysis products using analytical techniques.
• Enzyme assays to determine substrate specificity of the proposed ITC hydrolase (ITCase).
• Heat treatment experiments on homogenized cabbage material.

Main Results:

• Amines were identified as significant enzymatic hydrolysis products of glucosinolates in Brassica vegetables.
• A plant endogenous ITC hydrolase (ITCase) was proposed to catalyze the conversion of ITCs to amines.
• ITCase showed higher activity towards alkenyl ITCs than methylthioalkyl ITCs and did not convert methylsulfinylalkyl ITCs.
• Heat treatment led to a significant increase in methylsulfinylalkylamine levels, suggesting thermal decomposition of ITCs, while alkenyl amine levels remained stable.

Conclusions:

• Enzymatic hydrolysis of glucosinolates in Brassica vegetables produces amines in addition to ITCs.
• A novel plant enzyme, ITCase, plays a role in converting ITCs to amines.
• Dietary intake of amines derived from glucosinolates in Brassica vegetables is significant.