Catechin degradation with concurrent formation of homo- and heterocatechin dimers during in Vitro digestion

Catechins were subjected to in vitro gastric and small intestinal digestion. EGCG, EGC, and ECG were significantly degraded at all concentrations tested, with losses of 71-91, 72-100, and 60-61 %, respectively. EC and C were comparatively stable, with losses of 8-11 and;7-8%, respectively. HLPC-ESI-MS/MS indicated that EGCG degradation under simulated digestion resulted in production of theasinensins (THSNs) A and D (m/z 913) and P-2 (m/z 883), its autoxidation homodimers. EGC dimerization produced the homodimers THSN C and E (mlz 609) and homodimers analogous to P-2 (mlz 579). ECG homodimers were not observed. EGCG and EGC formed heterodimers analogous to the THSNs (mlz 761) and P-2 (mlz 731). EGCG and ECG formed homodimers analogous to the THSNs (m/z 897). This study provides an expanded profile of catechin dimers of digestive origin that may potentially form following consumption of catechins. These data provide a logical basis for initial screening to detect catechin digestive products in vivo.