Investigation of biological activities of Allamanda blanchetii, the violet Allamanda

Objectives

The objective of the study was to evaluate Allamanda blanchetii extractives for antioxidant, cytotoxic, thrombolytic, membrane stabilizing and antimicrobial activities.

Methods

The plant extractives were evaluated for their phenolic content and their ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals. Brine shrimp lethality bioassay was conducted to identify cytotoxic potential of the extractives. The test samples were also involved in thrombolytic and membrane stabilizing activity assays to evaluate their abilities to promote clot lysis and to stabilize erythrocyte membrane under hypotonic and heat induced conditions. The extractives were involved in disc diffusion assay to measure their ability to give zones of inhibition in cultured bacterial medium.

Results

In DPPH free radical scavenging assay, the carbon tetrachloride soluble fraction demonstrated the highest free radical scavenging activity (IC₅₀ = 40.50 ± 0.32 μg/ml) where as, in brine shrimp lethality bioassay, the hexane soluble fraction revealed the highest cytotoxic activity with LC₅₀ value of 0.78 ± 0.74 μg/ml. While evaluating the thrombolytic activity of the extractives, the chloroform soluble fraction showed 32.50 ± 0.63% of clot lysis. This fraction at 1.0 mg/ml concentration also inhibited 46.74 ± 0.73% and 41.33 ± 0.59% of haemolysis of RBCs induced by hypotonic solution and heat as compared to 71.90% and 42.12% by acetyl salicylic acid (0.10 mg/ml), respectively. In disc diffusion assay, the extractives of A. blanchetii revealed zone of inhibition ranging from 7.0 to 13.0 mm.

Conclusion

Further chemical and bioassay guided investigation on violet Allamanda must be conducted for isolation, identification and characterization of the bioactive constituents.