Degradation of phenylethanoid glycosides in Osmanthus fragrans Lour. flowers and its effect on anti-hypoxia activity

Abstract

This study was aimed at investigating the chemical stability (the thermal, light and pH stability) of phenylethanoid glycosides (PhGs) in Osmanthus fragrans Lour. flowers, identifying the degradation products of acteoside and salidroside (major PhGs in O. fragrans flowers) by UPLC–QTOF–MS and studying the anti-hypoxia activity of PhGs after degradation. The degradation of PhGs followed first-order reaction kinetics, and the rate constant of acteoside (4.3 to 203.4 × 10−3 day−1) was higher than that of salidroside (3.9 to 33.3 × 10−3 day−1) in O. fragrans flowers. Salidroside was mainly hydrolyzed to tyrosol during storage, and the degradation products of acteoside were verbasoside, caffeic acid, isoacteoside, etc. In a model of cobalt chloride (CoCl2)-induced hypoxia in PC12 cells, the anti-hypoxia ability of PhGs decreased after degradation, which resulted from the reduction of PhGs contents. Particularly, caffeic acid exhibited stronger anti-hypoxia ability than acteoside and could slightly increase the anti-hypoxia ability of degraded acteoside. The results revealed that high temperature, high pH and light exposure caused PhGs degradation, and thus the anti-hypoxia ability of PhGs reduced.

Relationships Between Chemical Structure and Antioxidant Activity of Isolated Phytocompounds from Lemon Verbena

“…Furthermore, the molecular formula generated for peak 5 ( m/z 299) and the literature allowed for its tentative identification as salidroside for the first time in this specie. Salidroside is a tyrosol (simple phenol) derivative which is present in some lamial species [46,47,48]. Peak 5 presented an absorbance maximum at 280 nm that is the maximum wavelength of absorption observed in tyrosol and its derivatives (Supplementary Figure S1).…”

Rehmannia glutinosa Replant Issues: Root Exudate-Rhizobiome Interactions Clearly Influence Replant Success

“…The core structures of phenylethanoid glycosides are often substituted with such common constituents as caffeic acid, coumaric acid, cinnamic acid, ferulic acid, and isoferulic acid. Importantly, most phenylethanoid glycosides are unstable at alkaline and acidic conditions (Zhou et al, 2017). Thus, we deduced that the phenolic acids previously detected in the R. glutinosa infested soils likely originated from the presence of phenylethanoid glycosides such as those observed in this study.…”

Therapeutic potential of phenylethanoid glycosides: A systematic review

“…At the same temperature (20°C), the degradation rate of TPG in light was significantly higher than dark, indicating PhGs were unstable in light. The degradation patterns of salidroside and verbascoside were the same of TPG 180 . Verbascoside was more stable in a weak acid medium, low temperature, and dark conditions.…”

“…The degradation patterns of salidroside and verbascoside were the same of TPG. 180 Verbascoside was more stable in a weak acid medium, low temperature, and dark conditions. Under the condition of pH 7, verbascoside was completely degraded after 2 weeks (room temperature) and three weeks (40°C).…”

“…PhGs were found to beunstable under light exposure, high temperature, and high pH conditions 180 . The content of total PhGs (TPG) of O. fragrans flowers in water for 90 days was significantly decreased by 87% at 50°C.…”