Bioactive compounds from Quercus Infectoria (manjakani) were extracted with six different types of solvents: 100% methanol, ethanol, acetone, aqueous and 70% methanol and ethanol. High Performance liquid chromatography (HPLC) was used to identify and quantify the active compounds, namely gallic acid and tannic acid. Total phenolics content were determined by Folin-Ciocalteu while antioxidant and antibacterial activity were tested using DPPH free radicals scavenging and disc diffusion assay. The result revealed that aqueous extract contained the highest concentration of bioactive compounds compared to other types of solvents which are 51.14 mg/g sample and 1332.88 mg/g sample of gallic acid and tannic acid respectively.. The highest level of phenolic compound was found in 100% acetone extract (121 mg GAE/g). The results demonstrated that aqueous extract gives the highest antioxidant activity approximately 94.55% while acetone extract gives the largest inhibition zone for disc diffusion assay which is 19.00 mm respectively. The results revealed rich sources of gallic acid and tannic acid in Q. infectoria which might provide a novel source of these natural antioxidant and antibacterial activity.
In this work, the bioactive compounds which was obtained by extracting Quercus infectoria via two extraction methods; Soxhlet and supercritical carbon dioxide (SC-CO2) extraction, were analyzed using total phenolic content and DPPH (2,2-diphenyl-1-picryl hydrazyl) free radical scavenging activity analysis. The aim of this study is to compare the total phenolic content and antioxidant activity of Quercus infectoria extract acquired from SC-CO2 extraction with those from Soxhlet extraction method. The results showed the used of SC-CO2 extraction give the lowest extraction yield as compared to Soxhlet extraction. The selectivity of Q. infectoria extracts using SC-CO2 extraction was better which in contrast with Soxhlet extraction method since it shows higher total phenolic content (143.75 ± 1.06 mg GAE/g sample). This study also revealed that the extracts from both extraction methods can posses’ antioxidant activity and comparable to those obtained from commercial antioxidant.
Quercus infectoria gall, which is known as manjakani in Malaysia, was traditionally used in treating diseases. The bioactive compounds from the galls can be extracted using various extraction methods. In this study, supercritical carbon dioxide (SC-CO2) extraction was used to study the effects of CO2 flow rate on the yield, total phenolic content and antioxidant activity of Q. infectoria extract by fixing the pressure and temperature at the highest density (P: 30 MPa, T: 40°C). The results were compared with those acquired from the Soxhlet extraction method. The results showed that the Soxhlet extraction had a higher percentage of extraction yield than SC-CO2 extraction. The selectivity of Q. infectoria extracts using SC-CO2 extraction was better than the Soxhlet extraction method. Meanwhile, the extraction efficiency using the SC-CO2 extraction ranged from 46% to 53%. The SC-CO2 extraction also yielded higher total phenolic content than using the Soxhlet extraction method when 2 mL/min of CO2 flow rate was applied (203.53 mg GA/g sample). This study also revealed that the extracts from the SC-CO2 extraction showed a better radical scavenging activity compared to the Soxhlet extraction when analysed using DPPH (2,2-diphenyl-1-picryl hydrazyl) radical scavenging activity assays.radical scavenging activity compared to the Soxhlet extraction when analysed using DPPH (2,2-diphenyl-1-picryl hydrazyl) radical scavenging activity assays.