Comparison of conventional and ultrasound-assisted extraction of alkaloids from Lupinus mirabilis leaves

Fabaceae is a plant family broadly distributed worldwide. It has been recognized by its invasive abilities as well as for its high content of products with multi-directional activity. Among the most abundant genera within Fabaceae family it is found Lupinus genus. A chemical feature of several Lupinus species is the production of quinolizidine and bipiperidine alkaloids in large amounts, which are used as defense mechanism against herbivores, microorganisms and competing plants due to their high toxicity/mutagenicity. Lupinus mirabilis is a lupine plant widely distributed in the Bogota-plateau but as far there is no information about its chemical/alkaloidal composition. Thus, as part of our research on Lupine-derived alkaloids, leaves of L. mirabilis was submitted to ultrasound-assisted and conventional protocols for alkaloid extraction in order to explore the effect of ultrasound and time on the composition of the resulting alkaloidal fraction. Comparison of obtained fractions was based on GC-MS analysis. Main identified alkaloids were sparteine, lupanine and 17-oxosparteine which relative abundance was found to be into the 78 – 91% range. Ultrasound-assisted extraction under short periods demonstrated to be comparable with prolonged extraction time in conventional process regarding the relative percentage of quinolizidine alkaloids. Extended use of ultrasound resulted in diminished relative quantities of quinolizidine alkaloids due to extraction of cumulative proportions of other unknown nitrogen-containing compounds. Our results indicated that L. mirabilis is an excellent source of sparteine and ultrasound-assisted protocol might be successfully used for quinolizidine alkaloid extraction at short periods of time. The present work is a product derived by the Project IMP-CIAS-1567 financed by Vicerrectoría de Investigaciones at UMNG – Validity 2014.