Bioactive isoflavones from Pueraria lobata root and starch: different extraction techniques and carbonic anhydrase inhibition

Kudzu, the dried root of an important medicinal and edible plant (Pueraria lobata (Willd.) Ohwi), is used in Traditional Chinese Medicine for the important nutritional value strictly related to its isoflavone derivatives. These compounds characterize the quality of kudzu contained in different preparations, as pharmaceutical ingredient as well as dietary/food supplement (e.g. starch) [1]. The optimization of isoflavones recovery, monitored by HPLC-PDA, through different extraction techniques, e.g. microwave-assisted, ultrasound-assisted and conventional extraction represented a suitable challenge for natural derivatives in food compounds. We aimed to optimize the exhaustive recovery of isoflavones from kudzu through innovative and conventional extraction techniques. The impact on the isoflavone content by using ionic liquid-assisted extraction was also evaluated. The inhibitory activity of isoflavones, extracted from kudzu, was further tested in vitro using two tumor-related isoforms (IX and XII) of human carbonic anhydrase (hCA) in addition to their biological activity as estrogenic and anti-oxidant compounds. Results showed that the best extraction conditions for puerarin, daidzin and genistein were achieved by conventional extraction with water as the solvent for 30 minutes, and 1:5 (w:v) as solid:liquid ratio; while for daidzein the best conditions were achieved by MAE with ethanol as the solvent for 30 minutes, and 1:5 (w:v) as solid:liquid ratio. The resulting data demonstrated that the assessed isoflavones may represent new serious carbonic anhydrase inhibitors thus providing a potential therapeutic efficacy versus solid tumors both in vitro and in vivo. Acknowledgements: This paper was supported by FAR-MIUR grant 2016, “G. d’Annunzio” University of Chieti – Pescara, Chieti, Italy. References: [1] Wong, K. H., Li, G. Q., Li, K. M., Razmovski-Naumovski, V., Chan, K., 2011. Kudzu root: traditional uses and potential medicinal benefits in diabetes and cardiovascular diseases. J. Ethnopharmacol. 134, 584–607.