Alkaloid compounds in Rafflesia cantleyi and host, Tetrastigma tuberculatum were identified using the phytochemical screening method and HPLC technique. The results showed positive test for the host, T. tuberculatum which indicates the presence of alkaloid whereas the screening test for R. cantleyi showed that alkaloid is absenced. Both extract were then subjected to HPLC for alkaloid identification and caffeine was used as standard. The spectroscopic data from HPLC revealed the presence of caffeine in both methanol extracts. The methanol extract of both samples were also tested for antioxidant activity by using DPPH free radical scavenging activity. Result showed that the radical scavenging activity of R. cantleyi and T. tuberculatum are comparable to the standard reference, BHT but higher than the standard alpha tocopherol.