Evaluation of bioactive flavonols and ent-kaurenes in the 2,4-dichlorophenoxyacetic acid-induced calli of Senegalia nigrescens using FTIR and GC–MS

Abstract

The increasing demand for plant-derived pharmacologically active compounds calls for sustainable alternative sources and conservation of medicinal plant species. To this end, the present study investigated the development of a callogenesis protocol for Senegalia nigrescens. The plant growth regulators (PGRs), 2,4-dichlorophenoxyacetic acid (2,4-D) and thidiazuron (TDZ) at concentrations of 0.5 and 1.0 mg L−1 were tested for callus induction in the leaf, stem, cotyledon and root explants of S. nigrescens. 2,4-D was the more effective PGR across the different explant sources with 85 to 100% stem, root and cotyledon explants forming callus (EFC). Hard and compact calli with nodular structures were obtained from the stem explants, the root-derived calli were soft and moist while the cotyledon explants produced glassy and friable calli. Methanol extracts of calli obtained from the stem and root explants were characterised using fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC–MS). The FTIR spectra and GC–MS profiles revealed the presence of the four compounds evaluated, quercetin, quercetin-3-O-methyl ether, ent-kaur-15-en-18-ol and ent-kaur-15-ene-18,20-diol in both 4 and 12-week-old, root-derived calli. This study, therefore, provides preliminary information for the propagation and phytochemical harvesting in S. nigrescens.