We set out to identify new bioactive compounds from Streptomyces sp. isolated from soil collected in Bangkok, Thailand. A new strain Streptomyces sp. DC3 was isolated, and a novel butanoate derivative compound designated as streptanoate (1-amino-3-methyl-1-oxobutan-2-yl-2-hydroxy-3-methylbutanoate) was obtained from it. The strain was identified by morphological characteristics and 16S rRNA gene sequence analysis, and the compound structure was elucidated using NMR, APCI-TOF-MS, IR, and UV techniques. Antimicrobial activity assays showed that streptanoate inhibited microorganisms such as Bacillus subtilis, Bacillus thuringiensis, Saccharomyces cerevisiae, and Candida albicans. Anticancer activity assays revealed that streptanoate had notable cytotoxicity against cancer cell lines including HuCCA-1 (human cholangiocarcinoma), A549 (human non-small cell lung cancer), and HL-60 (acute promyelotic leukemia) with IC50 values of 2.2, 1.4, and 3.8 μg/ml respectively, while it was relatively nontoxic to the normal embryonic lung cell line MRC-5, exhibiting a similar degree of cytotoxicity as the positive control drug doxorubicin (18.1% vs 18.3%). These results indicate that streptanoate, which possesses both antimicrobial and anticancer activities, low toxicity to normal cells, a small molecular size, and functional groups suitable for side chain modification to enhance water solubility and cellular uptake, is a promising candidate for further development as an anticancer agent.