Preliminary In-vitro Assessment of Some Phytochemical Constituents and Radical Scavenging Activity of Methanol Extracts of Five Flowers Varieties

This work evaluated some phytochemical constituents and radical scavenging activity of the flower samples of Allamanda carthica, Delonix regia, Hibiscus rosasinensis, Plumeria rubra and Tercoma stans. Methanol extracts of different flower samples were used for the phytochemical analysis. The result obtained showed that Tercoma stans has the highest yield (14.45%) followed by Hibiscus rosasinensis (12.36%), Delonix regia(11.36%), Allamanda Cathartica (10.11%) and Plumeria rubra (8.99%) while the preliminary qualitative phytochemical screening showed that alkaloid was absent in all the extracts. The methanol extracts of the five flower samples indicated the presence of flavonoids and saponins in significant quantities. With the exception of Allamanda Cathartica and Delonix regia all other extracts dictates the presence of protein. Glycosides were not detected in Allamanda carthica and Tercoma stans, but were found in other samples. Tannins were detected in small quantities in the five flower samples. Methanol extract of Allamanda Cathartica, Delonix regia, Hibiscus rosasinensis, Plumeria rubra and Tercoma stans were prepared for the assessment of the antioxidant scavenging properties using the DPPH model and ascorbic acid as standard. The result obtained from the antioxidant activity was used to plot a graph of absorbance against time. The ascorbic acid standard showed the highest activity at 0.8 mg/dl. The methanol extracts of the flower samples showed varying degree of antioxidant activity in the decreasing order, as follows: Plumeria rubra>Tercoma stans>Allamanda Cathartica>Hibiscus rosasinensis>Delonix regia. The result suggests that the phytochemical and antioxidant properties of the flowers could be used for medicinal purposes since some insects and birds depend on the nectar produced from these flowers for survival.