The Chemo-Enzymatic Synthesis of 8,9-Dihydrohydroxysafflor Yellow A and Its Neuroprotective Effects against Cerebral Ischemia-Reperfusion Injury

Hydroxysafflor yellow A (HSYA), the principal bioactive compound of safflower, is clinically used for ischemic cerebrovascular disease. However, the current sources of HSYA are limited and inadequate for clinical applications. In this study, we synthesized 8,9-dihydrohydroxysafflor yellow A (dh-HSYA), an analogue of HSYA, via a chemo-enzymatic approach and investigated its neuroprotective activity. The precursor phloretin-di-<i>C</i>-glucoside (PDG) was biosynthesized de novo in yeast, reaching a titer of 301.15 mg L^-1. Furthermore, efficient production of PDG was achieved by supplementing with phloretin, resulting in a titer of 2.39 g L^-1. Subsequently, dh-HSYA was synthesized from PDG via chemical oxidation, with a yield of 29.02%. The dh-HSYA exerted protective effects on BV2 and HT22 cells under oxygen-glucose deprivation/reoxygenation (OGD/R) conditions and attenuated brain injury in a rat model of middle cerebral artery occlusion/reperfusion (MCAO/R). This study provides a promising strategy for the sustainable production of dh-HSYA, which could potentially serve as a more scalable substitute for HSYA.