Highly isoxanthohumol enriched hop extract obtained by pressurized hot water extraction (PHWE). Chemical and functional characterization

Abstract

Hop (Humulus lupulus) is one of the richest natural sources of a prenylfalvonoids such as xanthohumol (XN), desmetylxanthohumol (DMX), isoxanthohumol (IX) or 8-prenylnaringenin (8-PN), being XN the most abundant of them in the raw material. So far, obtention of prenylflavonoids has been done by chemical synthesis or extraction with organic solvents, with no described methods for the isolation of IX, which has been reported to have anti-inflammatory properties. In this study, pressurized hot water extraction (PHWE) is shown not only as an effective method to extract some prenylflavonoids but also to selectively change the relative amount of them, favoring the extraction of IX against XN. Thus, pressurized water extraction at 150 °C showed a high selectivity towards IX, being proposed as a method to enrich natural hop's extracts in IX. On the other hand, the extracts thus obtained were chemically characterized and evaluated for their anti-inflammatory activity, which was higher than the expected by its content in IX. One of the few commercial segments of the food industry with growing potential is functional foods. In this paper we present an environmentally friendly method to obtain hop extracts with anti-inflammatory properties. We are applied for a national (Spanish) patent (application number: P-201131014) to protect a method to produce an anti-inflammatory beverage. Inflammation underlies a bunch of pathologies and altered physiological status such as obesity, atherosclerosis, etc. Other potential use of the process, and the product, is to be the first step in the production of pernylnaringenin, which is the strongest phytoestrogen ever known, over 1000 times more potent than soy isoflavones, and with a putative medical use. Notwithstanding, further steps such as anaerobic fermentation to selectively methylate the isoxanthohumol are needed.