Carabrachiatanins A and B: Two New Phenylpropanoid-Substituted Catechins of Carallia brachiata Merr

Objectives: Carallia brachiata Merr. is a Vietnamese medicinal plant, used to treat mouth ulcers, tongue sores, sore throats, and malaria. This paper focuses on the chemical constituents of C. brachiata and their inhibition of NO production. Methods: The dried and minced sample was extracted with methanol. The crude extract was isolated by various chromatographic methods. The structures of the isolates were determined by HR-ESI-MS, NMR, and CD spectra. The NO inhibition activity was evaluated in LPS-activated RAW264.7 cells. Results: Two new catechin derivatives (carabrachiatanins A (1) and B (2)) and seven known proanthocyanidins (3-9) were isolated from C. brachiata by bioguided fractionation. All isolates significantly showed NO inhibition effects with IC₅₀ values ranging from 13.72 ∼ 34.28 µM. Conclusions: Two new and seven known compounds were isolated from C. brachiata. This is the first report of compounds 3-9 from C. brachiata. Compounds 7 and 8 inhibited NO production with their IC₅₀ values of 16.31 ± 0.61 µM and 16.53 ± 0.83 µM, respectively, compared to that of dexamethasone, which showed IC₅₀ value of 14.94 ± 1.11 µM.