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

Six new phenylpropanoid glycosides (1–6), two new phenylethanol glycosides (7and 8), one new phenylmethanol glycoside (9), three new phenylpropanoid dimers (10–12), two new phenylpropanoid–flavan-3-ol heterodimers (13and 14), and six known relevant compounds (15–20) were isolated and identified from the well-liked edible and medicinal substance (the bark of Cinnamomum cassia(L.) J.Presl). The structures of these isolates were determined by using spectroscopic analyses, chemical methods, and quantum chemical calculations. Notably, compounds 4–9were rare apiuronyl-containing glycosides, and compounds 13and 14were 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 10and 12exhibited DPPH radical scavenging capacities with IC50values of 20.1 and 13.0 μM, respectively (vitamin C IC50value of 14.3 μM). In the ORAC experiment, all these compounds exhibited different levels of capacity for scavenging free radicals, and compound 10displayed 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 12also showed significant α-glucosidase inhibitory activity with an IC50of 56.3 μM (acarbose IC50of 519.4 μM).