DIMORPHISM OF THE ALKALOID COLCHICINE HYDRATE. L.Yu.Izotova, K.M.Beketov, B.T.Ibragimov, M.K.Yusupov. Institute of Bioorganic Chemistry, H.Abdullaev str., 83,Tashkent, 700143, Uzbekistan, e-mail root@ibc.tashkent.su

Alkaloid colchicine having different types of the biological activity forms two inclusion compounds with water depending on crystallization conditions.

First of them is dihydrate and it was obtained nearly twenty years ago [1]. X-ray structure analysis of colchicine was carried out namely on this host-guest complex. In the colchicine dihydrate hydrogen bonds of the host-host, host-guest and guest-guest type are existed. Colchicine and water molecules are linked to bilayers by these H-bonds.

We have obtained monohydrate of colchicine and solved its crystal structure. Crystal data are: orthorombic, P212121, a=9.14, b=13.27, c=17.94 A, Z=4 and R=0.06 for 2100 reflections. Theconformation of colchicine molecule is not

distinct from one in dihydrate. Water molecules are connected with three alkaloid molecules by means of H-bonds that gives rise to H-bonded three dimensional network. In the result of this a solubility and melting point of monohydrate is substantially different from ones in other hydrate.

1. Lessinger L., Margulis T.N. Acta Crystallogr.