Phytochemical profile and antioxidant characteristics of bound and free phenolics from Rosa roxburghii Tratt

Rosa roxburghii Tratt (RRT) is renowned for its abundance of phenolics, various methods have been used to extract free phenolics from RRT, there remains a paucity of research on the comparative distinctions between bound phenolic compounds and their free counterparts in RRT, especially in vitro and in vivo antioxidant potential of RRT-BP necessitates further exploration. This study sought to optimize the process parameters for extracting bound polyphenols through alkaline hydrolysis. Among the bound phenolic compounds, 20 phenolic acids and 34 flavonoids were identified, while the free phenolic compounds comprised 19 phenolic acids and 42 flavonoids. The IC50 values for DPPH and ABTS radical scavenging were 44.92 μg/mL and 60.92 μg/mL for free phenols, 87.02 μg/mL and 95.02 μg/mL for bound phenols, respectively. Compared with the control group, the lifespan of Caenorhabditis elegans fed with 1 mg/mL of free and bound phenol extended from 11.63 d to 16.77 d and 13.88 d, respectively, with no adverse impact on the reproductive capability of the nematodes. The longevity of C. elegans was observed to persist even under thermal and oxidative stress, primarily attributed to elevated superoxide dismutase and catalase activity, coupled with reduced malondialdehyde content in C. elegans. These findings underscore that free polyphenols exhibit superior polyphenolic components and antioxidant properties compared to their bound counterparts. Nevertheless, the potential health effects of bound polyphenols as a supplement to free polyphenols in RRT should not be ignored.