In vitro shoot cultures of pink rock-rose (Cistus x incanus L.) as a potential source of phenolic compounds

In vitro cultures of Cistus ×incanus (pink rock-rose) were maintained on two variants of Murashige and Skoog (MS) medium differing in terms of composition of plant growth regulators (PGRs): 6-benzyladenine (BA) and 1-naphthaleneacetic acid (NAA) at the following concentrations: 3 mg/L and 0, 3 mg/L and 1 mg/L, respectively, and on a variant without PGRs – a control. Cultures were maintained in a form of agar and agitated shoot cultures. The qualitative and quantitative analyzes of three groups of phenolic compounds (catechins, flavonoids, and free phenolic acids) were performed by using the HPLC-DAD technique in methanolic extracts of in vitro biomasses and of commercial plant raw material. In analyzed extracts from in vitro cultures, the presence of catechin [max. 197.80 mg / 100 g dry weight (DW)], epicatechin gallate (max. 30.74 mg / 100 g DW), gallic acid (max. 83.23 mg / 100 g DW), quercetin (max. 10.15 mg / 100 g DW), and quercitrin (max. 72.89 mg / 100 g DW) was confirmed. The quantities of accumulated compounds varied and depended on the type of in vitro culture and the concentration of PGRs in media. The highest amounts of all estimated compounds were obtained in biomasses from agar cultures cultivated on medium without PGRs in vitro. In extracts obtained from commercial raw material, gallic acid (max. 261.80 mg / 100 g DW) and quercetin (max. 255.96 mg / 100 g DW) were detected as being the dominant compounds.