Ethno botanical surveys have revealed that Brunei Darussalam has a rich source of tropical medicinal plants. As 80% of the country's land is covered by tropical rainforest, Brunei Darussalam may have some medicinal plants with unique characteristics of secondary metabolites. Some plants such as Catharanthus roseus (L.) G. Don and Eurycoma longifolia Jack have long been used by the local communities to treat various disease conditions. However, no research has been done in terms of the constituents or biological activities of the Brunei Darussalam medicinal plants. We have investigated the genetic variability diversity and pharmacological actions of Andrographis paniculata (Burm.f.) Nees [1] also known as Daun Pahit or Chuan Xin Lian or King of Bitters by an interdisciplinary approach, involving DNA-based RAPD and RFLP analyses, HPLC-based chemical analysis as well as cell culture and tissue-based bioassays. We have demonstrated that Andrographis paniculata extr acts exhibited a range of actions including antioxidant, anti-allergies, anti-inflammatory and anti-cancer effects. Some of the pharmacological actions of Andrographis paniculata are co-related with their active constituents Andrographolide (A) and Dehydroandrographolide (D). The study is valued not only in obtaining experimental evidence for supporting traditional use of native medicinal plants but also in establishing a platform for studying other medicinal plants in Brunei Darussalam.