Constituents of Uncaria lanosa f. philippinensis and their anti-amyloidogenic activity

Abstract

The aggregation of amyloid-β (Aβ) remains the most acceptable pathological hallmark of Alzheimer’s disease (AD). In search for natural products exhibiting anti-amyloidogenic effects, phytochemical analyses were conducted on Uncaria lanosa f. philippinensis leading to the purification of oxindole alkaloid uncarine E (isopteropodine) (1), the phenylethanoid tyrosol (2), the megastigmane vomifoliol (3), and the previously reported alkaloids mitraphylline and isomitraphylline. This is the first report of compounds 1–3 in the title plant, and tyrosol (2) from the genus Uncaria. Assessment of the anti-amyloidogenic potential using Thioflavin T assay showed 91% (at 50 µM) and 70% (at 25 µM) inhibitions for compound 1. Tyrosol (2) gave 76% (at 50 µM) and 63% (at 25 µM) inhibitions. These compounds may be further tested to elucidate their mechanism in the prevention of Aβ aggregation. To the best of our knowledge, this is the first report on the anti-amyloid aggregation activity of compounds 1 and 2.