Recovery and biotransformation of ginger active molecules from industrial waste

The ginger rhizome is a primary ingredient of oriental food, beverage, and herbal medicine catching on Western Countries meals. In 2016 the food sector processed 3.3 million tonnes of ginger generating a pulp waste that was mostly destined to agricultural field, biorefinery, papermaking etc.1 The ginger pulp waste still contains an oleoresin rich in gingerol-like compounds, such as gingerols and shogaols, bioactive components with recognized anti-inflammatory and anticancer properties.2,3 As an alternative valorisation strategy, the recovery of the main ginger waste components and their biotransformation to generate a small library of optically enriched derivatives was herein investigated. The fermented ginger biomass, furnished by a local farm, showed still 30% of unaltered gingerol-like compounds4. For the first time, the enantioselective reduction of prochiral carbonyl moiety of pure isolated 6-gingerol (1), 8-gingerol (2), 6-shogaol (3), 6-paradol (4) and zingerone (5) by different alcohol dehydrogenases (ADHs)4 was investigated. No ketone reduction was observed for 3. As far as the other substrates the ADH from Micrococcus luteus and engineered ADHs from Evoxx led to chiral alcohols with good yield and diastereo- and enantiomeric excess (d.e and e.e) (Figure 1). A preliminary scaling-up to multi-mg of (S)-5 and (R)-5 has proved to be promising strategy to broaden to the other substates for industrial ginger waste valorization.