Chapter 9 inorganic -sH rea auto-oxidisable redox dyes A list of some examples of these is given in Table 9.2. Are these compounds likely to be toxic to cells? Since they inhibit metabolism, they are likely to be toxic to cells. It is, therefore, usual to add these compounds after the culture has grown and to subsequently add the sterol to be metabolised ring deavage Of the compounds listed in Table 9.2,8-hydroxyquinoline, ax, a -dipyridyl and 1, 10-phenanthroline have found most use. They are usually used in the concentration range 0.1 mmol r. It is, however, essential to use an optimal concentration of these agents in order to get high yields. echanism。 f actlon Chelating agents for Fe Diethyldithiocarbamate a,a'-Dipyrie Dipheny thiocarbazone 8-Hydroxyquinoline Isonicotinic acid hydrazide 5-Nitro-1, 10-phenanthroline 1. 10-Phenanthroline Tetraethylthiuram-disulphide Metal ions replacing iron or blocking N+ Co2+Pb+ SH-functions SeO,AsOh Redox dyes Methylene blue Resazurin Table 9.2 Compounds used to inhibit steroid ring degradation(based on Martin CKA Sterols in Biotechnology Volume 6a Edited by Kieslich K 1984. Verlag Chemie, Weinheim) What will happen if the concentration of the inhibitor is a)too low b)too high? a) If it is too low, complete degradation of the substrate may occur304 Chapter 9 inorganic -SH reagents; 0 auto-oxidisable redox dyes. A list of some examples of these is given in Table 9.2. n Are these compounds likely to be toxic to cells? Since they inhibit metabolism, they are likely tu be tuxic to cells. It is, therefore, usual to add these compounds after the culture has grown and to subsequently add the sterol to be metabolised. Of the compounds listed in Table 9.2, 8-hydroxyquinoline, a,a'-dipyridyl and 1,lO-phenanthroline have found most use. They are usually used in the concentration range 0.1 mm011~~. Itis, however, essential to use an optimal concentration of these agents in order to get high yields. ring cleavage Uechanism of action Compound Zhelating agents for Fe2+ Cupferron Diethyldithiocarbamate a,a' -Dipyridyl Dipheny It hiocarbazone 8-Hydroxyquinoline lsonicotinic acid hydrazide 4-lsopropyltropolone 5-Nitro-l , 1 O-phenanthroline 1,l O-Phenanthroline @Phenylenediamine Tetraeth ytthiuramdisulphide Xanthogenic acid Metal ions replacing iron or blocking Ni2+, Co2+, Pb2' SH-functions w-, Asor 3edox dyes Methylene blue Resazurine Table 9.2 Compounds used to inhibil steroid ring degradation (based on Martin CKA Sterols in Biotechnology Volume 6a Edffed by Kieslich K 1984. Verlag Chemie, Weinheim). n What will happen if the concentration of the inhibitor is a) too low b) too high? a) If it is too low, complete degradation of the substrate may occur