Bioactive Phenylpropanoid Glycosides, Dimers, and Heterodimers from the Bark of (L.) J.Presl.

Six new phenylpropanoid glycosides (-), two new phenylethanol glycosides ( and ), one new phenylmethanol glycoside (), three new phenylpropanoid dimers (-), two new phenylpropanoid-flavan-3-ol heterodimers ( and ), and six known relevant compounds (-) were isolated and identified from the well-liked edible and medicinal substance (the bark of (L.) J.Presl). The structures of these isolates were determined by using spectroscopic analyses, chemical methods, and quantum chemical calculations. Notably, compounds - were rare apiuronyl-containing glycosides, and compounds and were heterodimers of phenylpropanoids and flavan-3-ols linked through C-9″-C-8 bonds. The antioxidant and α-glucosidase inhibitory activities of all isolates were evaluated. Compounds and exhibited DPPH radical scavenging capacities with IC values of 20.1 and 13.0 μM, respectively (vitamin C IC value of 14.3 μM). In the ORAC experiment, all these compounds exhibited different levels of capacity for scavenging free radicals, and compound displayed extraordinary free radical scavenging capacity with the ORAC value of 6.42 ± 0.01 μM TE/μM (EGCG ORAC value of 1.54 ± 0.02 μM TE/μM). Compound also showed significant α-glucosidase inhibitory activity with an IC of 56.3 μM (acarbose IC of 519.4 μM).