Ginkgo biloba extract is known to be efficient in diseases associated with free radical generation. The purpose of this work was to study, under in vitro conditions, the action of Ginkgo biloba extract (Gbe) against superoxide anion (O2-.), which is directly or indirectly implicated in cell damage. Gbe appears to have both an O2-. scavenging effect and also a superoxide dismutase activity. Its antiradical effect was demonstrated by low temperature electron spin resonance and in a non-enzymatic system (phenazine methosulfate-NADH), and its enzymatic activity was shown by polarographic determination.
The following valepotriates: valtrate and didrovaltrate, isolated from the roots of Valeriana wallichii D. C., as well as baldrinal, a degradation product of the valtrate, were tested for their cytotoxic and antitumor activities, respectively in vitro on cultured rat hepatoma cells (HTC line), and in vivo, on female mice KREBS II ascitic tumors. It appears that the three valepotriates are very potent cytotoxic agents for the HTC hepatoma cells, and that the didrovaltrate induces a perceptible high per cent definitive remissions of the KREBS II ascitic tumors.
Materials and MethodsAir-dried and powdered aerial parts (2.3 kg) of C. indicum var. tuneful (collected during the flowering stage from gardens in the environs of Plovdiv, Herb. No 146969 SOM in the Botanical Institute of the Bulgarian Academy of Sciences) were extracted with hexane and then with CHCI3. The CHCI3 extract (21.2 g) was treated with 60 % aqueous EtOH at 50°C; the solution was precipitated with Pb(OAc)2 and worked up as described in Ref.(4) to give a gummy residue (4.45 g). This was chromatographed over an Si02 column using CHCI3 and mixtures of CHCI3 with increasing amounts of MeOH as eluents. The early fractions eluted with CHCI3-MeOH (25: 1.5) after PTLC separation (Si02, hexane-Et20-MeOH, 1: 5 :0.3) and purification (Si02-AgNO3) afforded 19 mg 1 (R:0.48), 8 mg 3 (R,:0.43), and 15mg 2 (Rf:0.34). Chrysetunone (1) Colourless oily liquid, [a]°: +31° (c 0.2, CHCI3); IR v CflCl: 3605, 3422, 1663 cm1; UV ?'': 236 nm; MS(EI) m/z (%): 252
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