Antioxidant, antibacterial, total phenolic and flavonoid contents of sungkai leaves (Paronema canescens)

Abstract

The leaves of the sungkai (Paronema canescens) have been used as a traditional medicine to treat various diseases. The present study determined the antioxidant, antibacterial, total phenolic content, and flavonoid content of extracts of P. canescens leaves. Fresh leaves of P. canescens was extracted by maceration using solvents of increasing polarity (n-hexane, ethyl acetate, and methanol). Each extract was tested for antioxidant activity using the DPPH method, antibacterial activity was tested using the disc diffusion method, analysis of the total phenolic content was done using the Folin-Ciocâlteu reagent, and total flavonoid using the aluminium chloride colorimetric method. The study showed that the ethyl acetate extract had higher antioxidant activity than the other extracts with an IC50 of 320 μg/mL. The antibacterial activity test had a minimum inhibitory concentration (MIC) of 62.5 µg/mL against E. coli and S. aureus for all the extracts, but only the n-hexane extract showed MIC of 62.5 µg/mL against S. typhi. Betulinic acid from the n-hexane extract also showed antibacterial activity with MIC of 62.5 µg/mL. In the analysis of total phenolic and flavonoids, the ethyl acetate extract had higher values than the other extracts, with values of 68.71 ± 0.17 mg Gallic Acid Equivalent (GAE)/g and 2.29 ± 0.05 mg Quercetin Equivalent (QE)/g for total phenol and flavonoid content, respectively. It can be concluded that sungkai leaves showed moderate antioxidant activity, moderate antibacterial activity, and much lower flavonoid content than phenolic content.