Extraction optimization of neem bioactives from neem seed kernel by ultrasonic assisted extraction and profiling by UPLC-QTOF-ESI-MS

Abstract

BackgroundEfficient utilization of energy is the need of the hour. Being a time saving and energy efficient technique, ultrasonic assisted extraction (UAE) was utilised for optimization of sequential extraction of neem oil and azadirachtinoids from neem seed kernel (NSK) using response surface methodology (RSM). ResultsYield of neem oil from the NSK was 32.5%, whereas 0.19% yield of azadirachtin-A was obtained under optimised conditions. Standardised factors for the oil extraction included solvent:matrix ratio (4.81), time (18.41 min) and amplitude (45.8%), with hexane as solvent, whereas, for the extraction of azadirachtinoids, the corresponding optimised values of process factors were 4.78, 20 min and 50%, using ethanol as extraction solvent. First, azadirachtinoids and neem oil meliacins were characterised by UPLC-QTOF-ESI-MS. Identified neem meliacins were deacetylnimbin, nimbin, deacetylsalanin and salannin with their corresponding m/z value of 499.2333, 541.2438, 555.2955 and 597.3066 for [M+H]+ peak, respectively. Similarly, azadirachtin A, B and H were identified by their sodiated adduct with corresponding value of 743.2520, 685.2466, 685.2468. Aza-A, B and H present in the extract were quantified by UPLC-TQD-MS/MS using MRM technique at transitions 720.20 > 685.25, 662.40 > 645.20 and 663.10 > 57.15, respectively. Optimised method was validated by the real time experimental data and the yield of neem oil and azadirachtin-A was recorded as 31.8 and 0.182%. Greenness of the analytical method for estimation of Aza-A, B and H was calculated by Analytical Eco Scale and Green analytical procedure index metrics and found sufficiently well in terms of its greenness. ConclusionSequential UAE method for extraction of neem oil and azadirachtinoids developed in the present work will prove helpful for neem oil and biopesticide industry in better utilization of NSK as a valuable resource. Analytical method was significantly well in terms of greenness.