Acid-base extraction is a widely adopted technique for isolating alkaloids from plant materials, offering enhanced selectivity and improved yield and purity compared to conventional methods [37]. However, the use of harsh acidic or basic conditions can sometimes lead to alkaloidal structure modification or degradation and reduced overall yield [38,39].
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Harmalacidine was reported to be isolated in very low yield (15 mg) using the acid-base extraction method by Wang, Zhang, Wang and He [12]. In contrast, Lamchouri, Toufik, Bouzzine, Hamidi and Bouachrine [11] identified it as the dominant alkaloid, accounting for 52 % of the total alkaloid content in P. harmala seeds from Morocco. The substantial variation in reported harmalacidine yields prompted us to investigate the impact of the extraction method on its recovery. Interestingly, the methanolic extraction method produced significantly higher yields of H3 compared to the acid-base extraction methods, as shown in the TLC chromatograms (Fig. 1). The obtained results could explain the reported low yield of harmalacidine obtained by acid-base extraction methods and the limited research attention in several phytochemical studies of P. harmala seeds [40].