Evaluation of the phenolic content and antioxidant potential ofAlthaea roseacultivated in Egypt

Abstract

Objective The aim of this study was to evaluate the total phenolic content (TPC) and antioxidant potential of Althaea rosea Cav., family Malvaceae, as well as to isolate and identify the flavonoid content of the methanolic extract of the aerial parts. In addition, a comparison between the TPC and antioxidant capacity of the methanolic extract of both aerial parts and flowers was carried out to discover new active constituents that can be utilized in drug industry. Materials and methods The extraction of the flavonoid compounds was carried out by percolation of the dried aerial parts of the plant under investigation with 70% methanol until exhaustion. The combined extract was then concentrated and defatted with petroleum ether (60-80°C). After separation of the lipoidal matter, the remaining extract was purified from mucilage and subjected to several column chromatographic techniques for isolation of the flavonoids. The identification of flavonoid compounds was carried out using physical, chemical, and spectral methods such as ultraviolet, 1 H NMR, and 13 C NMR. The antioxidant potential of the methanolic extracts of both aerial parts and flowers was determined using the s[table 2], 2-diphenyl-1-picrylhydrazyl free radical scavenging activity method. Furthermore, their TPC was also determined using the Folin-Ciocalteu method. Results Five flavonoid compounds were isolated from the aerial parts of A. rosea Cav., which were identified as quercetin 3-O-β-d-glucuronopyranoside-8-C-β-d-glucopyranoside, kaempherol-3-O-β-d-rutinoside, kaempherol-4΄-O-β-d-glucoside, kaempherol-3-O-β-d-glucoside, and kaempherol. The antioxidant activity was measured in terms of their IC 50 . The IC 50 values of the methanolic extracts of the aerial parts and flowers were 11 and 1 mg/ml, respectively, whereas the TPCs were 48 and 73 μg/ml, respectively. Conclusion The methanolic extracts of both aerial parts and flowers of A. rosea Cav. are rich in phenolic compounds and have a prominent antioxidant activity. The antioxidant activity of both extracts may be attributed to their phenolic content.