Catechins and procyanidins of Ginkgo biloba show potent activities towards the inhibition of β-amyloid peptide aggregation and destabilization of preformed fibrils.
Catechins and procyanidins, together with flavonoid glycosides and terpene trilactones, are three important categories of components in the standard extract of Ginkgo biloba leaves (EGb761). In this research, catechins and proanthocyanidins were found to exist in both the extract of Ginkgo leaves and Ginkgo products. By comparing with reference compounds, six of them were identified as (+)-catechin, (-)-epicatechin, (-)-gallocatechin, (-)-epigallocatechin and procyanidins B1 and B3. The activities of these polyphenols in the inhibition of Aβ42 aggregation and the destabilization of preformed fibrils were evaluated using biochemical assays, which showed that all six of the polyphenols, as well as a fraction of the extract of Ginkgo biloba leaves (EGb) containing catechins and procyanidins, exerted potent inhibitory activities towards Aβ42 aggregation and could also destabilize the performed fibrils. Catechins and procyanidins can therefore be regarded as the potent active constituents of EGb761 in terms of their inhibition of Aβ42 aggregation and destabilization of the fibrils. Although quantitative mass spectroscopic analysis revealed that the catechins and procyanidins are only present in low concentrations in EGb761, these components should be studied in greater detail because of their potent inhibitory effects towards Aβ42 aggregation and their ability to destabilize preformed fibrils, especially during the quality control of Ginkgo leaves and the manufacture of Ginkgo products.
School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Kowloon, Hong Kong, China.
Haiyan
H
Xie
School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Kowloon, Hong Kong, China.
Jing-Rong
JR
Wang
School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Kowloon, Hong Kong, China.
Lee-Fong
LF
Yau
School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Kowloon, Hong Kong, China.
Yong
Y
Liu
School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Kowloon, Hong Kong, China.
Liang
L
Liu
School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Kowloon, Hong Kong, China.
Quan-Bin
QB
Han
School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Kowloon, Hong Kong, China. zzzhao@hkbu.edu.hk.
Zhongzhen
Z
Zhao
School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Kowloon, Hong Kong, China. zhjiang@must.edu.mo.
Zhi-Hong
ZH
Jiang
D016229:Amyloid beta-Peptides / Q000037:antagonists & inhibitors* / Q000737:chemistry; D001578:Benzopyrans / Q000737:chemistry* / Q000302:isolation & purification; D044946:Biflavonoids / Q000737:chemistry / Q000302:isolation & purification; D002392:Catechin / Q000031:analogs & derivatives / Q000737:chemistry / Q000302:isolation & purification; D020441:Ginkgo biloba / Q000737:chemistry*; D006801:Humans; D010446:Peptide Fragments / Q000037:antagonists & inhibitors* / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry*; D018515:Plant Leaves / Q000737:chemistry*; D044945:Proanthocyanidins / Q000737:chemistry / Q000302:isolation & purification; D013329:Structure-Activity Relationship; D000096983:Ginkgo Extract
D016229:Amyloid beta-Peptides; D001578:Benzopyrans; D044946:Biflavonoids; D002392:Catechin; D010446:Peptide Fragments; D010936:Plant Extracts; D044945:Proanthocyanidins; C075222:amyloid beta-protein (1-42); C479579:procyanidin B1; C063170:Ginkgo biloba extract; D000096983:Ginkgo Extract; C479581:procyanidin B3; C057580:gallocatechol