Effect of calcium on enzyme activities and phenolic accumulation in Hypericum androsaemum cell cultures

The aerial parts of Hypericum androsaemum L. have been used in folk medicine for its diuretic and hepatoprotective properties [1], which are attributed to the several flavonoids and phenolic acids found in the plant.

Suspension cultures were established from hypocotyl-derived callus using MS medium supplemented with 2,4-D (1mg/L) and BA (0.5mg/L). The total flavonoid and total hydroxycinnamic acid contents of cells were evaluted according to [2] and [3], respectively. Levels of these compounds exhibited a similar pattern of changes over the cell cycle, reaching a minimum on day 7 and a maximum during the stationary phase (day 14).

Culture of cells for 7 and 14 days in nutrient media containing high concentrations of CaCl₂ (15 or 18 mM) induced a substantial increase in the accumulation of flavonoids (up to 2-fold) and a small raise (20–30%) in the levels of hydroxycinnamic acids, with the most pronounced effects being observed at the longer incubation period.

Catalase activity in 7-day treated cultures was 2 to 3-fold higher than in control cultures, while that of superoxide dismutase was 30% lower. By contrast, the levels of both enzyme activities showed no significant alterations in 14-day treated cells possessing the highest amount of phenols.

These results are in agreement with an increased production of H₂O₂ in treated cultures and suggest that phenolic compounds may play a role in protecting cultured cells against oxidative stress.

Acknowledgements: Center of Pharmaceutical Studies

References: 1. Novais, M. et al. (2004), J. Ethnopharmacol. 93: 183–195. 2. Lamaison, J., Carnat, A. (1990), Pharm. Acta Helv. 65: 315–320. 3. Lamaison, J. et al. (1991), Pharm. Acta Helv. 66: 185–188.