Phenolic contents and antioxidant potential of Rhododendron species

In order to assess the antioxidant potential, leaves of 21 species of Rhododendron were studied for their moisture, total phenolic contents (TPC), flavonoids, antioxidant activity (AOA) and free radical scavenging capacity. Out of these, R. baileyii, R. camellieflorum, R. campanulatum, R. cilliatum, R. cinnabarinum, R. griffithianum, R. lepidotum, R. niveum, R. sallignum and R. virgatum were found to have high TPC (91.4-208.9 mg/g GAE), high AOA (73.5-97.2%) and efficient free radical scavengers as evident by their low IC₅₀ (0.07 to 0.19 mg/ml), low EC₅₀ (3.28 to 8.26 mg/mg DPPH), high ARP (antiradical power) (12.10 to 30.48) and high reducing power expressed as ascorbic acid equivalent (ASE/ml) (0.46 to 1.43) as compared to standard quercetin. The promising species were further assayed for their composition of phenolic acids and flavonoids through high performance liquid chromatography. Free radicals can cause damage to cellular bio-molecules leading to several diseases. Rhododendron species with high amounts of phenols, a major group of phytochemicals with antioxidant properties, can help to inactivate them.