Enzyme-assisted extraction of naphthodianthrones from Hypericum perforatum L. by 12C6+-ion beam-improved cellulases

The production of cellulase by Aspergillus niger and Trichoderma viride strains was significantly enhanced via irradiation with a 12C6+-ion beam. Successive mutants showed a clearance zone on cellulose Congo red medium and increased cellulase activities. By using these cellulases, enzyme-assisted extractions of the naphthodianthrones hypericin and pseudohypericin from Hypericum perforatum L. were examined for the first time. The strong disruption of plant tissue structure through cellulase maceration was observed with scanning electron microscopy. Optimum conditions for improving the extraction yield of naphthodianthrones with the purified cellulases were as follows: the dried plant powder was treated with a cellulase solution of 150 U/g substrate and incubated at pH 5 for 6 h at 40 °C. The extraction yields of purified hypericin and pseudohypericin were up to 166.5 μg/g and 260.6 μg/g, respectively, in the cellulase-treated sample, representing higher yields than sonication and Soxhlet extractions. Cellulase-assisted extraction was proven to be highly efficient in the degradation of plant cell-wall polysaccharides and could be used in natural product extraction on a large scale.