Abstract
The objective of our work is to create a practical procedure to produce in vitro cell suspensions of O. basilicum and to ascertain the factors that encourage enhanced secondary metabolite production. We investigated the impact of these metabolites on Rhynchophorus ferrugineus's adult and larval target enzymes. The explants were cultivated on Murashige and Skoog (MS) media with 0.1 to 1 mg/L plant growth regulators (PGRs) to create calluses. 2,4-Dichlorophenoxyacetic acid (2,4-D), kinetin, 1-naphthylacetic acid (NAA), and indole-3-butryic acid (IBA) at 0.5, 0.5, 0.1, and 1 mg/L, respectively, with 3% sucrose led to the highest biomass accumulation. In cell suspensions, the total phenolic content (TPC) and total flavonoid content (TFC) were 39.68 and 5.49 mg/g DW, respectively, with abiotic Verticillium dahliae as an activator. Rosmarinic acid, ursolic acid, nepetoidin A and B, salvigenin, and quercetin-3-O-rutinoside as flavonoids and phenolics were analyzed using UPLC-I TQD MS, with the highest concentrations reached after 40 days. The extract demonstrates insecticidal activity against the fourth-instar larvae of R. ferrugineus, with adults at 1197 µg/mL and 12.5 µg/larvae as LC50 and LD50 values. The extract inhibited acetylcholine esterase (AChE), acid phosphatases (ACPs), alkaline phosphatases (ALPs), and gamma-aminobutyric acid-transaminase (GABA-T) in larval tissue in vitro, with IC50 values of 124.2, 149.3, 157.8, and 204.8 µg/mL, and in vivo, with IC50 values of 157.2, 179.4, 185.3, and 241.6 µg/mL, after 24 h. Pure compounds identified the activity of the extract, showing the inhibition of AChE, ACPs, ALPs, and GABA-T with IC50 values ˂ 200 µg/mL (in vitro). The ABMET examination revealed good oral permeability, and docking tests showed that the compounds bind AChE, ACPs, ALPs, and GABA-T. These findings show that a green bioprocessing method such as an O. basilicum cell suspension is a quick and straightforward technique for producing phenolic compounds, and it may be used to develop sustainable bio-insecticides and new green procedures.