Mustard derived compounds as insecticides and modulators of human metabolism

The current investigation aims to decipher the comparative anti-feeding and insecticidal potential of the purified form of Allyl isothiocyanate (AITC), a byproduct of glucosinolate hydrolysis, and three different mustard oils (black, brown and white) against Aulacophora foveicollis (red pumpkin beetle) adults and Spodoptera litura (tobacco cutworm) larvae. The in silico investigation undertakes the interaction of AITC with two anti-oxidant enzymes found in vertebrates, as AITC is also known to be an anti-oxidant and anti-cancerous compound for humans. The study also explores the AITC and protein-protein interaction among pepsin and mustard seed proteins, cruciferin and napin, as mustard contains abundant protein content but remains bio-unavailable due to presence of similar anti-nutritional factors like glucosinolates potentially having insect deterring potential. Through in vitro bioassays, it was found that the AITC was having higher insect anti-feeding potential (ranging from 74.63 to 88.22%) than the three mustard oils (ranging from 40.18 to 78.92%) against two insect pests studied in present investigation. The brown mustard oil showed LC₅₀ as 602.23 mg/mL and 251.99 mg/mL, black mustard showed LC₅₀ as 677.18 and 429.82 mg/mL while, white mustard oil showed LC₅₀ as 835.21 mg/mL and 620.31 mg/mL against A. foveicollis and S. litura, respectively. The LC₅₀ of AITC was observed to be higher, 3990 mg/mL (A. foveicollis) and 3690 mg/mL (S. litura). The in silico analysis revealed that leucine and aspartic acid are key mediators of Glutathione-S-transferase (GST)-AITC and Sulfonyl transferase (SULT)-AITC interactions in humans, respectively. The study also showed a stronger binding between human digestive enzyme (pepsin) and seed storage proteins of mustard (napin and cruciferin). In terms of insect deterrence, brown mustard oil outperformed both black and white mustard oils due to its higher glucosinolate concentration. It also showed greater efficacy than AITC at lower doses, likely because of the presence of various fatty acids in the oil that are known to deter insect pests. In the near future, the metabolites of mustard may be explored as an economical bio-control agent thus elaborating their role in replacing harmful synthetic insecticides that are a hurdle in attaining the goal of sustainable agriculture.