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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An HPLC method for separation and quantitative determination of biflavones in crude leaf extracts from GINKGO BILOBA L. is described. A system using a Lichrosorb(R)-Diol column and the ternary elution system: hexane-chloroform-tetrahydrofuran, was suitable for separation of sciadopitysin, ginkgetin, isoginkgetin and bilobetin. The biflavones were detected at 330 nm; their calibration curves were established and their response factors were calculated using acacetin as internal standard. This method was used for the quantitative determination of the biflavones in crude leaf extracts; the seasonal variations of the biflavone content were studied and showed a higher amount in autumn leaves.

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