GB785191A - Hydrogenated spiramycins - Google Patents

Abstract

<PICT:0785191/IV (a)/1> A new antibiotic is an hydrogenated spiramycin containing at most 4 hydrogen atoms, additional to those present in the spiramycin, or a salt of such hydrogenated product. The spiramycin is the mixture of the spiramycins I, II and III which is obtained by the fermentation of S. ambofaciens, according to Specification 758,726, the individual spiramycins I, II and III or any admixture thereof. The spiramycin or a salt thereof, is subjected to catalytic hydrogenation preferably in solution and under normal pressures and room temperature. The catalyst may be Raney nickel, but a noble metal, e.g. palladium or platinum is preferred, particularly palladium which may be supported on alumina, carbon or barium sulphate. Using a palladium catalyst absorption stops automatically after four hydrogen atoms have been absorbed and is particularly suitable for the preparation of dihydrospiramycin I. Specified solvents are alcohols such as methanol, ethanol and isopropanol, ethers such as diethyl ether and dioxane and esters such as ethyl acetate. Examples relate to the preparation of (a) tetrahydrospiramycin, (b) tetrahydrospiramycin sulphate, (c) dihydrospiramycin I, (d) tetrahydrospiramycin I, (e) tetrahydrospiramycin II, (f) tetrahydrospiramycin III, (g) mixture of tetrahydrospiramycins II and III. Tetrahydrospiramycin has a melting point of 120-125 DEG C., optical rotation of [d]17D = - 71.5 DEG (C=1 per cent methanol), ultraviolet absorption maximum 820 mm , E1cm.1%=14 (ethanol) and infrared absorption spectrum at the following frequencies expressed in reciprocal centimetres 3470, 2930, 2800, 1730, 1620, 1462, 1453, 1410, 1372, 1318, 1289, 1270, 1232, 1182, 1160, 1120, 1075, 1050, 1015, 991, 971, 956, 903, 841, 808 and 783. The properties of the other hydrogenated spiramycins of the examples are given. The antibacterial properties of the hydrogenated spiramycin are superior to those of the spiramycins from which they are obtained.