In the present study, we used the HHP-EH process, which has several advantages such as higher extraction yield, user friendly, low energy consumption, low temperature,

and no use of chemicals. The results obtained in the present study indicate that the highest extractability selleck of CS in the antler cartilage is related to papain digestion under HHP (100 MPa). The extractability of CS liberated from the antler tissues was estimated from the amount of uronic acid recovered from the papain digest. The estimated extractability under hydrostatic pressure was 6-fold higher at 100 MPa than that obtained at ambient pressure (0.1 MPa) at 50 °C during the 4 h incubation time (Fig. 1). The results show that the catalytic effect of papain is accelerated by

HHP, indicating that the optimal conditions of pressure, incubation time and temperature are obtained at 100 MPa for 4 h at 50 °C, respectively. As a result, the HHP-EH process shows that the extractability of CS is approximately 95% of total uronic acid in antler cartilage tissue as compared to less than 20% extractability from a previous report, STA-9090 research buy which used papain for 24 h at ambient pressure on the 0.5 M sodium acetate soluble fraction from antlers [30]. The low extractability was mainly due to the multiple steps involved in isolating CS from antler cartilage with Dimethyl sulfoxide a high risk of CS loss. In the present study, the high extractability of CS indicates that the mild pressure (100 MPa) is not only directly related to water penetration into the structure of collagen, proteoglycan and other proteins found in extracellular matrix but also, more importantly, to accelerate the present process of papain treatment. Meersman et al. (2006) [18] reported that the high pressure increases the rate of mass transfer, enhances water penetration into the solid material and disrupts cell membranes to release intracellular products.

The rationale behind HHP effects has three main factors: the energy, the densification effect and the chemical reactivity [24]. Due to compressibility, the difference between final and initial volumes under high pressure is always negative (ΔV value <0), leading to low energy and a densification effect. However, this does not give any prediction of the volume changes of chemical reactions in relation to the equilibrium between the states (reaction volume) or the activation volume of the chemical reaction. In addition, the chemical reactivity may be improved by high pressure, inducing an increase in solubility and consequently, the concentration of the solvated species. This phenomenon (electrostriction) leads to the reduction of the average distance between the solvated species, inducing an increase in the kinetic rate of the reaction.