Evaluation of phytochemical properties and larvicidal activities of Cynodon dactylon, Clerodendrum viscosum, Spilanthes acmella and Terminalia chebula against Aedes aegypti

ABSTRACT

Objective: To investigate the phytochemical, antioxidant and larvicidal property of Cynodon dactylon, Clerodendrum viscosum, Spilanthes acmella and Terminalia chebula against Aedes aegypti. Methods: Antioxidant capacity of methanolic extract of the plants was studied by 2,2- Diphenyl-1-picryl-hydrazyl-hydrate (DPPH) assay, ferric reducing antioxidant power assay, 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate) assay (ABTS), thiobarbituric acid reactive substance (TBARS) assay, superoxide anion scavenging activity and total antioxidant activity assay following standard protocol. Total phenolic content, total flavonoid content, carbohydrate, and plant protein were also estimated following standard protocols. Larvicidal property of plant extracts were determined following World Health Organization standard protocol. Additionally, glutathione-s-transferase (GST) and acetylcholinesterase (AchE) inhibitory property was also tested biochemically. Results: Phytochemically, high protein, carbohydrate and phenolic were found in Terminalia chebula, while Cynodon dactylon showed high flavonoid contents. Similarly, high antioxidant activity was found in Terminalia chebula with IC50 values at 13.7, 2.9, 45.2 and 46.0 μg/mL in DPPH, ABTS, TBARS and superoxide anion scavenging activity, respectively. Larvicidal study showed strongest activity in Spilanthes acmella followed by Cynodon dactylon, and Clerodendrum viscosum and Terminalia chebula. GST and AchE of Aedes aegypti larvae showed reduced enzyme activity when pre-incubated with Cynadon dactylon and Spilanthes acmella. Conclusions: The methanolic crude extracts of Cynodon dactylon, Clerodendrum viscosum, Spilanthes acmella and Terminalia chebula possess strong antioxidant and larvicidal property against Aedes aegypti and therefore, may be further investigated for the molecular mode of action.