In the course of screening for new alkaloids from microorganisms, we found 1,3-diphenethylurea as a metabolite in the culture broth of the soil isolate Streptomyces sp. strain No. AM-2498. The sporophore of strain No. AM-2498 was spiral, representative of the section Spirales of PRIDHAM et al. and the spore was oval with a spiny surface. The aerial mass color was white and melanoid pigment was not produced. The cell wall preparation from strain No. AM-2498 contained LL-diaminopimelic acid. Strain No. AM-2498 was inoculated into 100 ml of medium in a 500-ml SAKAGUCHI flask and incubated at 27°C. A 48-hour culture was transferred into 20 liters of medium in a 30-liter jar fermentor and the fermentation carried out at 27°C for 30 hours. The composition of the seed medium was 2% glucose, 0.5% peptone, 0.5% meat extract, 0.3% dried yeast, 0.5% NaCl and 0.3% CaCO3 (pH 7 before sterilization) and the production medium was 1% glucose, 2% starch, 0.5% yeast extract, 0.5% peptone and 0.4% CaCO3 (pH 7 before sterilization). Adekanol LG-109 was used as antifoam agent. Metabolite AM-2498 was detected by DRAGENDORFF reaction on silica gel TLC, CHCl3 - CH3OH (10:1, v/v) (Rf=0.68). The culture broth was extracted with 4 liters benzene and the solvent layer was dried over anhydrous sodium sulfate and concentrated in vacuo to dryness to yield 1.84 g of a brown paste. The paste was treated twice with 100 ml of benzene to give 420 mg of a pale green powder. The powder was recrystallized from methylalcohol to afford colorless needles (250 mg) of metabolite AM-2498. Metabolite AM-2498 showed the following physicochemical properties: Melting point 138-141°C, UV MeOH max nm (ε) 248 (308), 251 (411), 253 (446), 256 (535), 259 (549), 262 (543), 265 (419), 269 (351). IR νKBr max cm⁻¹ 3320, 1950, 1875, 1810, 1740, 1610, 1570, 745, 695. PMR (100 MHz, CDCl3) δ 2.70 (4H, sharp triplet, -CH2- × 2), 3.28 (4H, sharp quartet, -CH2-NH × 2), 4.45 (2H, broad ringlet, -NH- × 2), 7.12 (10H, sharp doublet, aromatic ring × 2). The molecular formula C17H20N2O was determined on the basis of elemental analysis (C 76.06, H 7.51, N 10.33%) and its mass spectrum (M⁺, m/e 268). These spectroscopic properties and proton noise-decoupled 13C-NMR spectrum are consistent with 1,3-diphenethylurea as the structure of metabolite AM-2498. In a preliminary test the metabolite was found to possess weak antidepressant activity. No acute toxicity of the metabolite was observed in mice after 100 mg/kg intraperitoneal injection.