Quantification of phenolic content from stem-bark and root of Hugonia mystax Linn. using RP-HPLC

Hugonia mystax Linn. a woody evergreen plant locally known as Modirakanni has been used in primary health care by tribals from Tiruvannamalai hills, Tamil Nadu, India. Ethnobotanically, the plant parts are used for rheumatism, skin diseases and inflammation. However, there is no data on active phytoconstituents in stem-bark and root mainly contributing to biological activities. In the present study an attempt has been made to quantify plant phenolics from aqueous, ethanolic and methanolic extracts of stem-bark and root of H. mystax. The extracts were also evaluated for their free radical scavenging potential. Quantitative determination of total phenolic content, total flavonoid content and DPPH free radical scavenging activity of plant extracts were carried out using colorimetric methods. Quantitative determination of individual phenolic compounds such as gallic acid, catechol, caffeic acid, vanillin, p-coumaric acid and ferulic acid in stem-bark and roots extracts were analyzed using RP-HPLC. The highest phenolic content was found in ethanol extract of root (262.2 ± 0.96 μg of gallic acid equivalent (GAE)/mg of dry plant material), whereas, the highest amount of flavonoids content was found in aqueous extract of root (18.06 ± 1.25 μg of quercetin equivalent (QE)/mg of dry plant material). Q. The highest amount of phenolic acid present was p-coumaric acid (3.775 mg/g of dry plant material) in methanol extract of stem-bark. All the solvent extracts of stem-bark and root have shown the presence of p-coumaric acid. Methanol extracts of stem-bark and root with IC50 values of 175.48 ± 2.14 μg/ml and 169.15 ± 1.10 μg/ml respectively, show potent free radical scavenging activity. In conclusion it can be said that, the plant is rich in phenolics and the major component p-coumaric acid may probably be responsible for the traditional claims of its biological activities. However, the mechanism of action of the active plant extracts needs to be investigated at the molecular level. Keywords: Hugonia mystax, Reverse phase-high performance liquid chromatography, Total phenolic content, Total flavonoid conten