Secang woods (Caesalpinia sappan L.) is well known as ingredients for a variety of Indonesian traditional beverages. Generally served with spices in warm conditions, this can change the properties of the natural ingredient of secang woods and their activity as medicinal potential. The efficacy of concoction drinks has been influenced by changes in pH and temperature during the serving process, so it is necessary to study these effects. Barks of Caesalpinia sappan L was extracted with ethanol 70% by maceration. Next, vacuum liquid chromatography (VLC) was used for the fractionation of extracts. The extracts have met the requirements of the Indonesian Herbal Pharmacopoeia 1st edition. The resulting fraction with the best potential from thin layer chromatography (TLC) was treated in various pH ranges from 4-10 and warm temperatures (600 and 800C) to observe changes in antioxidant potential. The antioxidant potential was investigated via DPPH (2,2-diphenyl-1-picrylhydrazyl) methods. The best potential fraction which has to inhibit the free radical scavenging was fraction VLC–C with an IC50 value of 4.993. Antioxidant activity tends to decrease by the effect of alkaline solution and temperature given. Antioxidant activity has shown to be influenced by alkaline solutions and warm temperatures. So, when serving a wood concoction drink, it is necessary to control it so that it does not reach above pH 8 and a temperature of 800C.

Keywords: Secang wood, pH, heat, antioxidant activity