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ASSESSMENT OF
THE ANTIOXIDANT AND CYTOPROTECTIVE ABILITIES OF GINKGO BILOBA
Balasubramanian, D.1
L. V. Prasad Eye Institute, Hyderabad 500034, India1
Abstract-
The main bioactive components of the leaf extract of the Chinese plant
Ginkgo Biloba are biflavonoids, flavonoids and their glycosides, and
terpenoids. Together, these seem to account for the pharmacological
and therapeutic properties, and hence for the popularity of ginkgo biloba
extract (GBE), which is readily available in drugstores and natural
food shops. Of late, GBE has also been tried in human volunteers for
some ophthalmic conditions such as glaucoma, with encouraging results.
In light of the interesting possibilities and applications of GBE, we
have monitored its potential antioxidant and cytoprotective abilities.
We find that it is an excellent antioxidant (using ESR spin trapping
and ABTS assays); the 50% ethanolic extracts (and the Ginkgoba capsules)
are better than the aqueous extract, which is better than the "standard"
preparation called Egb 761, made by Ipsen-Beaufour. GBE effectively
inhibits oxidative crosslinking of proteins (monitored by SDS PAGE),
prevents single strand breakage of DNA in intact cells (using the comet
assay), protects cell populations from (photodynamic, and alloxan induced)
stress- mediated killing, and also apoptotic death (monitored by the
MTT assay). In animal experiments where oxidative cataract was induced
in rat pups by subcutaneous selenite injection, GBE proved to be an
effective cataracto-static agent. Thus, GBE appears to be an effective
antioxidant and cytoprotective agent in vitro and in vivo. On the other
hand, however, overdosage- dependent side effects are reported for GBE.
Some of these are gastrointestinal disorders, dizziness, allergic skin
reactions and occasional renal difficulty. The use of appropriate dose
is thus important.
Keywords: ginkgo
biloba, antioxidant, cytoprotective agent, cataract of the eye lens
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