Antioxidant Activity, Total Phenolics and Fatty Acid Profile of Delonix regia, Cassia fistula, Spathodea campanulata, Senna siamea and Tibouchina granulosa

Tropical plants are utilized in traditional medicine and are a storehouse of secondary metabolites, some of which display medicinal properties. Five plants were selected for investigation, namely Cassia fistula, Delonix regia, Senna siamea, Spathodea campanulata and Tibouchina granulosa. Extracts of the inflorescence of these plants were prepared and their antioxidant, total phenolics and fatty acid profile were evaluated. Antioxidant and free radical scavenging activities were determined by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay and total phenolics by the Folin-Ciocalteu assay. Lipids were Soxhlet extracted, methylated and analyzed by gas chromatography mass spectrometry. C. fistula and S. siamea exhibited the highest antioxidant and free radical scavenging activities. T. granulosa however contained the highest total phenolic content. Linoleic acid was identified as the predominant unsaturated fatty acid in C. fistula and D. regia, whereas oleic acid, was the predominant unsaturated fatty acid found in S. campanulata, T. granulosa and S. siamea. Palmitic acid was the major saturated fatty acid in all the lipid extracts with highest percentages being observed in S. siamea. Tropical flowers are an untapped source of natural antioxidants with potential health benefits.