ABSTRACT
Objective To obtain antibiotic-resistant mutants producing metabolites with antitumor activity from wild-type actinomycete strains without antitumor activity. Methods An actinomycete strain L35-1 was used as an initial strain for obtaining antibiotic-resistant mutants, which is a marine-derived wild-type strain without antitumor activity with an inhibition rate of 2.8% at the 1000 μg/ml of high sample concentration on K562 cells. The antibiotic-resistant mutants both from auto-mutagenesis and chemical mutagen-induced mutagenesis were selected by single colony isolation on antibiotic-containing plates according to the method for obtaining drug-resistant mutants in ribosome engineering. The antitumor activity was assayed by the MTT method using K562 cells for the mutants with aqueous acetone extracts of the whole broth of their fermentation.Results A total of 114 neomycin-resistant (ner) and 68 streptomycin-resistant (str) mutants, all from auto-mutagenesis, was obtained on drug-containing plates. Among them, the 7 ner and 3 str mutants appeared to be bioactive with an inhibition rate above 20% at the 100 μg/ml sample concentration on K562 cells. On the other hand, 41 str and 32 ner mutants from DES-induced mutagenesis and 46 ner mutants from NTG-induced mutagenesis were obtained by mutagen-induced mutation coupled with the single colony isolation on antibiotic-containing plates, among which, one str mutant from DES-induced mutagenesis and one ner mutant from NTG-induced mutagenesis were bioactive with an inhibition rate over 20% at the 100 μg/ml sample concentration on K562 cells. Conclusions The present result has revealed that the wild-type actinomycete strains without bioactivity might become a great source initial strains to obtain bioactive mutants by drug-resistant mutation technique.
ABSTRACT
The inhibitory and antimutagenic effects of 17 compounds, cysteine (1), cinnamic acid (2), rutin (3), tannic acid (4), germanium dioxide (5), fluro uracil (6), sodium copper chlorophylline (7), B-sitosterol (8), vitamin C (9), coumarin (10), vitamin E (11), L-glutathione (oxidized form) (12), L-glutathione (reduced form) (13), sodium selenile (14), organic germanium (15), L-methioine (16) and proline (17) on the SOS response induced by N-methyl-N'-nitro-N-nitrosoguanidine, niethly muthanesulfonate, benzo (a)pyrine and UV were studied by using SOS chromotest. The results showed that compounds 1~15 revealed inhibitory effects, and compounds 2~8 and 10-11 revealed antimutagenic effects. It was demonstrated that cinnamic acid is the best antimutagen among 17 compounds. Cinnamic acid has not only inhibitory effect but also antimutagenic activity towards a wide variety of mutagens/carcinogens. The modes, specificity and end point of action of antimutagens are discussed.