Abstract

A COMPARATIVE STUDY ON SUNSCREENING AND RADICAL SCAVENGING IN VITRO ACTIVITIES OF SOLVENT EXTRACTS OBTAINED FROM DRIED CANNA (RED) FLOWERS GROWN IN SRI LANKA

Sujeewa Krishanthi Hettihewa* and Shakthi Apsara Thejani Opatha

Abstract

This study was aimed to evaluate total phenolic, flavonoid contents, in vitro sunscreen and radical scavenging activities of four different solvent extracts namely, acidified 70% aqueous acetone (AAD), 70% aqueous acetone (AD), acidified 80% aqueous methanol (AMD) and 80% aqueous methanol (MD) obtained from dried Canna (red) flowers. The crude extracts were subjected to preliminary phytochemical screening tests and quantitative analysis of total phenolic (Folin-Ciocalteu assay), flavonoid contents (aluminiumchloride colorimetric method) and in vitro radical scavenging activity by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay respectively. Sun screening activity was evaluated by spectroscopic measurements followed by Mansur equation for the calculation of sun protective factor (SPF) values. The results of the phytochemical screening exhibited the presence of phenolic compounds, flavonoids, quinones, carbohydrates, reducing sugars and saponins while absence of alkaloids in all four extracts. The significantly high values of total phenolic content (5389.067±681.343 mg Gallic acid equivalent (GAE)/100 g dry weight (DW) of flowers), total flavonoid content (6017.442±158.343mg Catechin equivalents (CAE)/100 g DW of flowers), radical scavenging activity (17.430±2.673 mmol Trolox equivalents/100 g DW of flowers) were exhibited by the acidified 70% aqueous acetone extract. It is also noticed promising sunscreening activity (SPF=32.75) for acidified 70% aqueous acetone extract whereas Dermatone showed SPF=35.48 at the concentration of 1 mg/ml. All extracts revealed to have SPF>40 at the concentration ≥ 1.5 mg/ml. It is concluded that acidified 70% aqueous acetone obtained fromCanna (red) flowers has significantly high amount of total phenolic, flavonoid contents, antioxidant and sunscreening activity which should be further investigated as potential natural sources.

Keywords: Total phenolic content, total flavonoid content, radical scavenging activity and sunscreening activity.