Flavan-3-ols from the leaves of Malaysian Uncaria longiflora var. pteropoda (Miq.) Ridsd

• Published in: Phytochemistry letters Vol. 6; no. 2; pp. 236 - 240
• Main Authors: Salim, Fatimah, Zain, Mazatulikhma Mat, Ridzuan, Mohd Syafiq Mohammad, Langat, Moses K., Mulholland, Dulcie A., Ahmad, Rohaya
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.05.2013
• Subjects: alkaloids; cell viability; Electronic circular dichroism; Flavan-3-ol; flavanols; Fourier transform infrared spectroscopy; hydrogen peroxide; hydroxybenzaldehyde; leaf extracts; leaves; Neuroprotection; neuroprotective effect; Neurotoxicity; nuclear magnetic resonance spectroscopy; scopoletin; stems; Uncaria; Uncariechin; Neuroprotection; Neurotoxicity; Uncaria; Flavan-3-ol; Electronic circular dichroism; Uncariechin
• ISSN: 1874-3900; 1876-7486
• DOI: 10.1016/j.phytol.2013.02.007

[Display omitted] ► Three flavan-3-ols were isolated from leaves of Uncaria longiflora var. pteropoda. ► Absolute configuration of new uncariechin (1) was confirmed by NMR and ECD data. ► (2) and (3) showed no neurotoxic effects against SH-SY5Y neuroblastoma cell line. ► (2) and (3) showed strong protective potential against H2O2 -induced neurotoxicity. A novel flavonoid, (−)-2R,3R-3,5,4′-trihydoxyflavan-[6,7:5″,6″]-2″-pyranone, named uncariechin (1), was isolated from the methanolic extract of the leaves of Uncaria longiflora var. pteropoda (Miq.) Ridsd. along with the known (−)-epiafzelechin (2) and (−)-epicatechin (3), methyl 4-hydroxybenzoate and 4-hydroxybenzaldehyde, four pentacyclic oxindole alkaloids, isopteropodine, pteropodine, uncarine F and isopteropodic acid, previously found in the stems, and two coumarins, scopoletin and 3,4-dihydroxy-7-methoxycoumarin. Structures of the compounds were elucidated by 1D and 2D NMR, FTIR, UV, MS, and experimental as well as calculated electronic circular dichroism (ECD) data. Compounds 2 and 3 were evaluated for their neurotoxic and neuroprotective properties against differentiated SH-SY5Y neuroblastoma cell lines using the MTS assay. Compounds 2 and 3 did not show any neurotoxic effects but showed strong protective potential against hydrogen peroxide-induced neurotoxicity with maximum cell viability at a concentration of 1μM.