Determination of Azadirachta indica (Neem) Seed Kernel Extract and Its Enzyme Responses in Zonocerus variegatus (Grasshopper): An In vitro Analytical Study

Abstract

This chapter investigated the various chemical compounds of Azadirachta indica seed kernel, and evaluated evaluate the in-vitro effects on selected antioxidant and esterase enzymes of nymph and adult grasshopper, Zonocerus variegatus. The plant product or natural products show an important role in diseases prevention and treatment through the enhancement of antioxidant activity, inhibition of bacterial growth, and modulation of genetic pathways. The therapeutic therapeutics role of a number of plants in diseases management is still being enthusiastically researched due to their less side effect and affordable properties. Azadirachta indica (Neem) has a complex of various constituents including nimbin, nimbidin, nimbolide, and limonoids, and such types of ingredients play role in diseases management through modulation of various genetic pathways and other activities. Azadirachta indica seed kernel extract (AISKE) obtained from the seed kernel, using Soxhlet extraction, was subjected to Fourier-transform (FT-IR) and ultraviolet (UV) spectroscopy as well as High performance liquid chromatography (HPLC) and Gas chromatography- flame ionization detector (GC-FID) for chemical elucidation.  Thirty nymph and adult grasshopper (Zonocerus variegatus) were collected using a sweeping net on a maize farmland in Ogbomoso, Oyo State, Nigeria. Spectrophotometric analysis was used to determine the in-vitro effects of AISKE on the activities of catalase, superoxide dismutase (SOD), carboxylesterase (CE), and acetylcholinesterase (AChE) in nymph and adult grasshoppers, Zonocerus variegatus. The FT-IR data of AISKE reveals seven peaks having wavenumbers 1457.4 cm^-1, 1541.3 cm^-1, 1647.5 cm^-1, 1742.5 cm^-1, 2853.3 cm^-1, 2922.2 cm^-1 and 3285.6 cm^-1, while the UV Spectrum shows maximum absorption between 207nm and 281nm wavelengths. The HPLC analysis of AISKE reveals fourteen peaks, with retention times 0.413, 1.080, 1.226, 1.554, 1.657, 1.834, 2.182, 2.424, 3.838, 4.065, 5.069, 6.261, 6.634, 7.797 minutes. Investigation of the effects of AISKE, CYP and CPF on the in-vitro activity of catalase, the enzyme showed that the three agents significantly reduced the activity in the nymph grasshopper, whereas the activity was increased in adult grasshopper compared with control treatment. The CE activity was significantly reduced by AISKE, CYP and CPF in the nymph, while the activity in adult was increased by AISKE at most concentrations. The AISKE significantly (p < 0.05) reduced the AChE activity in nymph and adult Z. variegatus as against CYP. It is concluded that Azadirachta indica seed kernel extract contains a variety of chemicals that can cause insecticidal effects in Z. variegatus nymphs and adults through oxidative stress, decreased carboxylesterase activity, and cholinergic stress.