Caesalpinia sappan Linn., belonging to family Caesalpiniaceae, is distributed widely in the tropical and subtropical regions of Southeast Asia. 1 The dried heartwood of the plant, named Sappan Lignum, has been used in folk medicines as a blood tonic, expectorant, and has exhibited a wide range of activities, including anti-malarial, anti-inflammatory and analgesic agent in folk medicine. 2,3 Previous phytochemical investigations on the heartwood of C. sappan, resulted in the isolation and identification of various types of compounds, including homoisoflavonoids, chalcones, dibenzoxocins, and brazilins. 4-8 Many of these components exhibited a variety of biological activities such as anti-inflammatory, 9,10 xanthine oxidase inhibitory, 7,10 antioxidant, 11 antidiabetic, 12 hepatoprotective, 13 and vasorelaxation activities. 14 To search for novel and bioactive compounds from C. sappan, this study focused on phenolics, and led to the isolation and identification of three compounds (1, 2 and 3). MATERIALS AND METHODS General experimental procedure The NMR spectra were measured using a Varian Unity-Inova 400 MHz spectrometer in DMSO-d 6 at 500 MHz for 1 H NMR and 125 MHz for 13 C NMR. Silica gel (63-200 mm; Merck, Darmstadt, Germany) and RP-18 (75 mm; Merck) were used for column chromatography. Thin layer chromatography was carried out on pre-coated silica gel 60 F254 plates and RP-18 F254 plates (both from Merck) and the plates were visualized by spraying with 10% H 2 SO 4 /EtOH solution followed by warming. Sample collection The heartwood of Caesalpinia sappan was collected in Hanoi, Vietnam in 2018. A voucher specimen