Investigation of a Streptomyces culture known to produce the cyclic adenosine 3', 5'-monophosphate phosphodiesterase inhibitor, griseolic acid, has led to the detection of three griseolic acid analogues. Hplc methodology coupled with photodiode array detection was developed to assist systematically in the search for griseolic acid analogues directly from culture broths. Purification of these components using reversed-phase and ion-exchange chromatographies resulted in the isolation of griseolic acid 111, deoxygriseolic acid [2], dihydrodeoxygriseolic acid 131, and a novel ring-opened griseolic acid analogue 141. Griseolic acid [l], isolated from Streptomyces griseoaurantiacus by Nakagawa et a/. ( 1) is a potent adenosine 3', 5 '-cyclic monophosphate (CAMP) phosphodiesterase (PDE) inhibitor (2). Griseolic acid, which may be considered to be derived from adenosine and tartaric acid, has an adenine base, a bicyclic ring in the sugar moiety, and two carboxylic acid groups. The structure bears resemblance to CAMP. Compounds similar to griseolic acid that can inhibit cAMP PDE will increase the concentration of intracellular CAMP, a fundamental biochemical component widely distributed in mammalian tissues. Because cAMP mediates the effects of a large number of hormones and is involved with many important biochemical functions, chemical factors that inhibit its enzymatic degradation may be of considerable value, particularly as angiocardiokinetic agents (3,4). A study was undertaken to ascertain if novel griseolic acid analogues could be co-produced from S. griseoaurantiacus. An efficient and reproducible hplc method was developed that detected griseolic acid directly from culture filtrates. When S. griseoaurantimus NRRL- 123 14 (obtained from the Agricultural Research Service, Peoria, Illinois) was fermented in its production medium (l), griseolic acid was produced. Results from our laboratory of NRRL-123 14 samples fermented in different media and analyzed by hplc revealed the existence of potential griseolic acid analogues. With the incorporation of photodiode array detector technology (5-7), three structural analogues of griseolic acid co-produced within a given fermentation could be readily detected by comparing online uv spectral scans with the known griseolic acid standard. With the griseolic acid retention time markers in place, the hplc method was utilized to determine the optimum fermentation media conditions that would maximize production of the potential analogues. The information extrapolated from hplc ion-pair reagent studies simplified the isolation of griseolic acid and analogues from culture broth. The scheme, as outlined, is efficient and provides clear advantages over literature techniques (1). Compounds 1, 2, and 3 inhibit phosphodiesterase activity; compound 4 is inactive. Compounds 1 and 3 were isolated previously from culture broth (1,8) and 2 has been synthesized (9); however, this is the first report of detection and subsequent isolation of all four components from culture broth. Spectroscopic details leading to assignment of structure 4 are presented together with nmr data leading to the stereochemical considerations for component 3. These hitherto unreported spectroscopic data support the assignment for the proposed structure 3 (8).