Adiponectin-synthesis-promoting compounds possess therapeutic potential to treat diverse metabolic diseases, including obesity and diabetes. Phenotypic screening to find adiponectin-synthesis-promoting compounds was performed using the adipogenesis model of human bone marrow mesenchymal stem cells. The extract of the endolichenic fungus <i>Daldinia childiae</i> 047215 significantly promoted adiponectin production. Bioactivity-guided isolation led to 13 active polyketides (<b>1</b>-<b>13</b>), which include naphthol monomers, dimers, and trimers. To the best of our knowledge, trimers of naphthol (<b>1</b>-<b>4</b>) have not been previously isolated as either natural or synthetic products. The novel naphthol trimer 3,1',3',3″-ternaphthalene-5,5',5″-trimethoxy-4,4',4″-triol (<b>2</b>) and a dimer, nodulisporin A (<b>12</b>), exhibited concentration-dependent adiponectin-synthesis-promoting activity (EC<sub>50</sub> 30.8 and 15.2 μM, respectively). Compounds <b>2</b> and <b>12</b> bound to all three peroxisome proliferator-activated receptor (PPAR) subtypes, PPARα, PPARγ, and PPARδ. In addition, compound <b>2</b> transactivated retinoid X receptor α, whereas <b>12</b> did not. Naphthol oligomers <b>2</b> and <b>12</b> represent novel pan-PPAR modulators and are potential pharmacophores for designing new therapeutic agents against hypoadiponectinemia-associated metabolic diseases.