Phytochemical screening and toxicity assessment of compounds isolated from the leaves of Mangifera indica L. for the control of Spodoptera litura (Lepidoptera; Noctuidae)

Abstract

This study aimed to analyze the phytochemical composition and antioxidative capabilities of mango leaves (Mangifera indica L., Nam Dok Mai), indigenous to Sa Kaeo Province, Thailand. Various solvents with differing polarities, including n-hexane, DCM, ethyl acetate, and MeOH, were utilized for leaf extraction. The findings revealed the existence of eight groups of phytochemical compounds: alkaloids, flavonoids, coumarins, saponins, tannins, terpenoids, steroids, and cardiac glycosides. The MeOH crude extract exhibited the highest concentration of total phenolic compounds at 409.88 ±0.02 mg GAE/g. Furthermore, the MeOH crude extract demonstrated the strongest antioxidant activity, with an IC₅₀ value of 0.52 ±0.02 μg/ml, as determined by the DPPH method. High-performance liquid chromatography (HPLC) was employed to identify gallic acid and mangiferin in the MeOH crude extract. Laboratory tests were conducted using the topical application method to evaluate the toxicity of the M. indica leaf crude extract on 2nd instar Spodoptera litura larvae. The MeOH crude extract exhibited high efficacy, with an LD₅₀ value of 10.58 µg per larvae within 24 hours. Gallic acid and mangiferin were identified as the primary active ingredients, with LCD₅₀ values of 1.19 µg per larvae and 1.90 µg per larvae, respectively, within 24 hours. Additionally, the impact on detoxification enzymes (24 hours post-treatment) was assessed in surviving 2nd instar S. litura larvae using the topical application method. The MeOH extract treatment resulted in 1.31-fold inhibition of carboxylesterase (CE), 1.31-fold inhibition of glutathione-S-transferase (GST), and 1.32-fold inhibition of acetylcholinesterase (AChE).