X-Message-Number: 8986
Date: Sun, 11 Jan 1998 14:55:40 -0800 (PST)
From: Doug Skrecky <>
Subject: many of ginkgo biloba's effects are mediated by bilobalide

Authors
  Klein J.  Chatterjee SS.  Loffelholz K.
Institution
  Department of Pharmacology, University of Mainz, Germany.
Title
  Phospholipid breakdown and choline release under hypoxic conditions:
  inhibition by bilobalide, a constituent of Ginkgo biloba.
Source
  Brain Research.  755(2):347-50, 1997 May 2.
Abstract
  A marked increase of choline release from rat hippocampal slices was observed
  when the slices were superfused with oxygen-free buffer, indicating
  hypoxia-induced hydrolysis of choline-containing phospholipids. This increase
  of choline release was suppressed by bilobalide, an
  ingredient of Ginkgo biloba, but not by a mixture of ginkgolides. The EC50
  value for bilobalide was 0.38 microM. In ex vivo
  experiments, bilobalide also inhibited hypoxia-induced
  choline release when given p.o. in doses of 2-20 mg/kg 1 h prior to slice
  preparation. The half-maximum effect was observed with 6 mg/kg
  bilobalide. A similar effect was noted after p.o.
  administration of 200 mg/kg EGb 761, a ginkgo extract containing
  approximately 3% of bilobalide. We conclude that ginkgo
  extracts can suppress hypoxia-induced membrane breakdown in the brain, and
  that bilobalide is the active constituent for this effect.

Authors
  Vasseur M.  Jean T.  DeFeudis FV.  Drieu K.
Institution
  Celaster Etudes Recherche et Production, Celle l'Evescault, France.
Title
  Effects of repeated treatments with an extract of Ginkgo biloba (EGb 761),
  bilobalide and ginkgolide B on the electrical activity of
  pancreatic beta cells of normal or alloxan-diabetic mice: an ex vivo study
  with intracellular microelectrodes.
Source
  General Pharmacology.  25(1):31-46, 1994 Jan.
Abstract
  1. The effects of repeated (5-day) treatments with an extract of Ginkgo
  biloba leaves (EGb 761), bilobalide, and ginkgolide B on the
  in vitro electrical activity of insulin-secreting pancreatic beta cells of
  mice have been examined using intracellular microelectrodes. 2. EGb 761 (200
  mg/kg/day, p.o.) protected beta cells against the toxic effects of alloxan
  (50 mg/kg, i.v.), an effect characterized by a restoration of membrane
  potential (Vr) and an increase in spike frequency (Fs/30), an indicator of
  insulin secretion. 3. Treatment of non-diabetic mice with EGb 761 (200
  mg/kg/day, p.o.) increased Fs/30 of their beta cells, as tested by in vitro
  exposure of the cells to 11.1 mM glucose, an effect that also occurred with
  bilobalide (8 mg/kg/day, i.p.) but not with ginkgolide B (4
  mg/kg/day, i.p.). 4. Since bilobalide and ginkgolide B
  caused opposite effects on the sensitivity of beta cells to glucose, the
  stimulatory effect of EGb 761 on Fs/30 may be attributed to its content of
  bilobalide. 5. In contrast to its ex vivo effect, the direct
  in vitro effect of EGb 761 (10 and 25 micrograms/ml) on beta cells favors a
  decrease in electrical activity, indicating that its in vivo action might be
  indirect (e.g. via the formation of an active metabolite).
Authors
  Bruno C.  Cuppini R.  Sartini S.  Cecchini T.  Ambrogini P.  Bombardelli E.
Institution
  Institute of Anatomy and General Physiology, University of Urbino, Italy.
Title
  Regeneration of motor nerves in bilobalide-treated rats.
Source
  Planta Medica.  59(4):302-7, 1993 Aug.
Abstract
  Bilobalide, a terpene extracted from the leaves of the
  Ginkgo biloba tree, has been proposed to exert trophic and protective effects
  on neurons and on Schwann's cells in various neuropathies. The reinnervation
  of the extensor digitorum longus muscle following traumatic nerve damage was
  investigated in rats by using electrophysiological and histological
  techniques. Evaluation parameters included the membrane resting potential of
  muscle cells, the spontaneous quantal release of acetylcholine, and the
  percentage of muscle cells receiving multiple innervation. The percentage of
  muscle cells receiving multiple innervation reached a peak more rapidly in
  treated animals and declined subsequently to values lower than those found in
  controls. These data suggest that the rearrangement of regenerated
  innervation occurs more rapidly in bilobalide-treated
  animals.

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