Enzymatic reactions can be promoted by disrupting membrane structure using high-hydrostatic-pressure (HHP) treatment to obtain functional substances, because the enzyme protein component is not deactivated under HPP conditions . This makes it possible to control the metabolic response by HHP treatment of medicinal resources during HHP treatment, and thus, allows the examination of the effects of new functional constituents. Using this method, we have previously found that the HHP treatment of Swertia japonica, a traditional Japanese medicine, resulted in increased numbers of new functional constituents. In this study, we investigate the change in the metabolism compounds of the petals of Hypericum patulum upon HHP treatment; these compounds have previously shown anti-allergic and anti-pruritic effects.
Fresh petals of the H. patulum (10 g) which had been stored in vacuum-packed pouches were treated by HHP of 0.1 (control), 200, 400 and 600 MPa for 10 min at 20 °C using an HHP device (KOBELCO). The treated samples were extracted with 50 mL methanol. Subsequent to the in vacuo evaporation of the methanol, the extracts were subjected to TLC and HPLC analyses.
The HHP treatment did not result in any appreciable changes to the outward appearance or the amounts of extracts. However, among the many spots observed in the TLC of the control extract, one major spot was absent following the HHP treatment at > 200 MPa. Upon comparison with spectroscopic methods, it was proposed that the missing structures belonged to a 1:2 mixture of catechin (1) and epicatechin (2). This present study indicates that the enzymatic reaction led to the metabolism of 1 and 2 by HHP treatment. The HPLC analyses and the change in the biological activities of the extracts are currently under investigation. HHP treatment is a promising technique to be applied in the development of new functions for medicinal herbs.