Gnetol

Biosci Biotechnol Biochem. 2003 Mar;67(3):663-5.

Gnetol as a potent tyrosinase inhibitor from genus Gnetum.[Pubmed: 12723623]

Gnetol (2,3',5',6-tetrahydroxy-trans-stilbene), a naturally occurring compound particularly found in the genus Gnetum, had a strong inhibitory effect on murine tyrosinase activity.
METHODS AND RESULTS:
Gnetol (IC50, 4.5 microM) was stronger than kojic acid (IC50, 139 microM) as a standard inhibitor for murine tyrosinase activity. Moreover, Gnetol significantly suppressed, melanin biosynthesis in murine B16 melanoma cells.

Phytother Res. 2012 Oct;26(10):1564-8.

Stilbenoids from Gnetum macrostachyum attenuate human platelet aggregation and adhesion.[Pubmed: 22511550 ]

Platelets play a critical role in pathogenesis of cardiovascular disorders and strokes. The inhibition of platelet function is beneficial for the treatment and prevention of these diseases. The phytochemical investigation of stilbenoids from Gnetum macrostachyum Hook. f. led to the isolation of trans-resveratrol (1), isorhapotigenin (2), Gnetol (3), bisisorhapontigenin B (4), gnetin C (5), parvifolol A (6), latifolol (7) and gnetuhainin C (8).
METHODS AND RESULTS:
The isolated stilbenoids were evaluated for in vitro antiplatelet activities via agonist-induced platelet aggregation and static platelet-collagen adhesion assays using washed human platelets. Compounds 1, 2 and 3 were active in the inhibition of arachidonic acid (AA)-induced platelet aggregation. Compound 2 and its dimer, compound 4, were the most active stilbenoids in thrombin-induced platelet aggregation. Moreover, compounds 4, 5 and 6, tended to be more potent than monomeric and trimeric stilbenoids in a human platelet-collagen adhesion assay under static conditions.
CONCLUSIONS:
This is the first report of the antiplatelet activity of stilbenoids isolated from G. macrostachyum.

Fitoterapia. 2012 Jun;83(4):780-4.

Potent and selective butyrylcholinesterase inhibitors from Ficus foveolata.[Pubmed: 22450264 ]

METHODS AND RESULTS:
Four stilbenes (1-4), one inseparable mixture of two alkyl diferulates (5a, 5b), one alkyl ferulate (6) and four flavonoids (7-10) were isolated from Ficus foveolata Wall. Except for quercetin (10), the other ten constituents were isolated from F. foveolata for the first time. In addition, one of the two components in mixture 5 is a new compound identified as (1E,22E)-1,22-docosanediol diferulate (5a). All nine isolated compounds, plus the mixture of 5a and 5b known as 5, exhibited a low or no activity against acetylcholinesterase. However, and interestingly, the stilbenes 1-4 showed a high inhibition towards butyrylcholinesterase.
CONCLUSIONS:
Gnetol (4) had the lowest IC(50) value of 1.3μM towards butyrylcholinesterase and showed a reversible and competitive inhibition in the kinetic study.