The antioxidant activity of Plectranthus amboinicus and Gynura procumbens / Nurul Nadhirah Rushdinizam

The antioxidant can be clarified as the molecule that is able to slow or prevent the oxidation of other molecules even though biological antioxidant has been described as the substance that is in low concentration compared to the oxidizable substrate, can delay the oxidation of the substrate. In Malaysia, Plectranthus amboinicus known as "Bangun-bangun" and this plant has many pharmacological properties like anti-inflammatory, antimicrobial, wound healing, antioxidant and etc. Gynura procumbens known as "Sambung Nyawa" in Malaysia and this plant are non-toxic and also shows that they are anti-diabetic, anti-inflammatory, anti-hypertensive activities and etc. The present study was conducted to evaluate the antioxidant activity of Plectranthus amboinicus, Gynura procumbens and the combination of Plectranthus amboinicus and Gynura procumbens. The extract was prepared with methanol solvent respectively. 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and Total Phenolic Content (TPC) assay were used to study the antioxidant activity for the three samples. The extracts then were compared to the standard reference which is ascorbic acid and also BHT as the positive control. Plectranthus amboinicus shows the highest antioxidant activity which is 81.26% at 100 mg/ml followed by Gynura procumbens (80.37%) and combination of the two herbs (77.09%) For DPPH assay, ICso was calculated for each sample. Combination of two herbs have the highest value of ICso which is 0.915 mg/ml followed by Gynura procumbens which is -0.020 mg/ml and lastly Plectranthus amboinicus which is -0.337 mg/ml. The lower the value of ICso, the stronger the ability for the extract to act as DPPH scavengers. Total phenolic activity assay were used to measure the amount of phenol compound in plant extracts. The highest extraction has phenol compound is Plectranthus amboinicus (5.572±0.022 mg GAE/g) followed by Gynura procumbens ( 4. 716±0.022 mg GAE/g) and lastly the combination of both of the herbs (4.417±0.022 mg GAE/g). The combination of the herbs does not shows a very high antioxidant activity. In conclusion, the combination of both herbs may not work well if combined together. For the future study, it recommends to use another type of assay and solvent to determine which methods are suitable and have an accurate data. It also recommends to mix with other type of herbs which maybe can have higher antioxidant.