Qualitative and Quantitative Analysis of Antioxidants and Antimicrobial Activity of Strobilanthes Crispus Using Ethanol Extract

Koh, Thiam Young (2022) Qualitative and Quantitative Analysis of Antioxidants and Antimicrobial Activity of Strobilanthes Crispus Using Ethanol Extract. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Strobilanthes crispus which is one of the most well-known medicinal plants in Indonesia and South East Asia countries, which also often referred as “jin batu” and “black face general” by the locals. Despite the popularity of Strobilanthes crispus leaves, information regards to antioxidant and antimicrobial activities of other parts of the plant such as stem and root were very limited. Thus, this project aims to study and compare the antioxidant and antimicrobial activities of the 80% ethanol extract of stem and root of Strobilanthes crispus via Folin-Ciocalteu method to assess its total phenolic content(TPC), Aluminium Chloride method to assess total flavonoid content(TFC), DPPH assay to determine radical scavenging properties, and lastly minimum inhibitory concentration (MIC) and Disc Diffusion Test (DDT) to calibrate the antimicrobial activity of the extracts. The 80% ethanol stem and root extract was prepared via ultrasonic bathe extraction(UAE) method, at 35°C, 60minutes, power of 9 and frequency of 40kHz. Small portion of the extracted 80% ethanol stem and root extract was then used directly for antioxidant test, while the rest of the extracts were concentrated with the help off rotary evaporator at 40°C at 115mbar until the volume of crude extract had been reduced by 80% to ensure all ethanol was removed and will not interfere the antimicrobial tests. The concentrated stem and root extract were then diluted using either 5% DMSO or autoclaved distilled water to different concentrations to assess its antimicrobial activity. It was recorded that the TPC, TFC and % DPPH scavenging activity of the stem extract at 5000ppm is 1.772 ± 0.015mg GAE/g plant powder, 10.38 ± 0.233 mg of QE/g plant powder and 84.76 ± 0.83 % while root extract at 50000ppm was recorded at 0.159 ± 0.001mg GAE/g plant powder, 1.000 ±0.004mg quercetin/g plant powder and 83.49% ± 1.46% respectively. On the other hand, the concentrated root and stem ethanol extract dissolved in both DMSO and MilliQ water shows no form of any conspicuous zone of inhibition across all concentrations from 1.96ppm up to the most concentrated 33333ppm(1g sample:30mL 5%DMSO). Despite no comparison can be made in terms of antimicrobial activity due to no inhibition was observed, but it is expected that the leaf extract has much better antimicrobial activity than stem and root extract, due to the fact that few antimicrobial compounds were detected in leaf but not in stem and root based on GC-MS analysis. In conclusion, it seems that the stem and root have the potential to be used as a natural antioxidants but not effective in acting as a natural antimicrobial agent in replacement of the artificial ones