New piericidin antibiotics, 7-demethylpiericidin A1 and 7-demethyl-3'-rhamnopiericidin A1.

In the course of our screening program for new antitumor antibiotics, we have reported a new piericidin, 3'-rhamnopiericidin A1 (SN-198-C (4)) isolated from the culture broth of Streptomyces sp. SN-1981>2). Recently, two new piericidin family of antibiotics, SN-198-D (1) and SN-198-B (2), were purified from fermentation broth of the same strain described above. This report is concerned with the isolation, structures and biological properties of these novel antibiotics. The producing microorganism was incubated at 27°C for 96hours in a 30-liter jar fermentor containing 18 liters of mediumcomposed of glucose 2%, soluble starch 1%, meat extract 0.1%, dried yeast 0.4%, soybean flour 2.5%, NaCl 0.2%, and K2HPO4 0.005%, adjusted to pH 6.8. Active principles were extracted with ethyl acetate from the filtered broth and aqueous acetone extract of the mycelium. Activity was traced by cytotoxity against KB cell and growth inhibition against some bacteria. Purification of the active substances was carried out according to the procedure shown in Fig. 1. Finally, SN-198-D (1) (28 mg) was obtained as yellowish oil and SN-198-B (2) (4.2mg) as a white amorphous