Deoxylapachol is isolated and purified from the leaves of Catalpa ovata G. Don. Deoxylapachol has anti-wood rot activity, it can inhibit the brown rot fungi Gloeophyllum sepiarium CBS 353.74 and Gloeophyllum trabeum CBS 318.50 and the white rot fungi Merulius tremellosus CBS 280.73 and Phlebia brevispora CBS 509.92.