Phytochemical Profile and Antioxidant and Protective Activities of Various Types of Extracts from Hyssopus officinalis L. and Grindelia robusta Nutt. Herb Grown in Poland

Introduction: The available literature indicates that Hyssopus officinalis and Grindelia robusta are raw materials with great potential for use in prevention and therapy. Therefore, the aims of this study were to assess the phytochemical profile and antioxidant and cytoprotective properties of extracts prepared using various solvents, additionally taking into account different methods of drying the plant material. Methods: Hydrodistilled oil was analysed by GC-MS. The chemical composition of the extracts was estimated by spectrophotometry and the HPLC–DAD method. Antioxidant activity was evaluated using DPPH and FRAP and measuring the intracellular level of ROS. Alamar Blue and Neutral Red tests were used to assess the cytotoxicity of the extracts on skin cells - keratinocytes and fibroblasts. Results: The major components of hyssop essential oil were cis- (44.9%) and trans- (18.2%) pinocamphone, while borneol (16.1%), and α-pinene (12.0%) were predominant in grindelia essential oil. Flavonoids were dominant in the extracts (water:ethanol, water:methanol, and water: glycerol) from hot-air dried hyssop herb, while phenolic acids were the predominant compounds in the grindelia herb extracts. The water:ethanol hyssop extract had the highest total content of flavonoids (42.26 mg CE/mL), among which isoquercitrin and rutin were present in the highest quantities (32.61 mg/mL and 21.47 mg/mL, respectively). In the case of grindelia, the highest total phenolic acid content (26.24 mg CAE/mL) was recorded in the water:ethanol extract, and the dominant compounds among them were 1,5-dicaffeoylquinic and chlorogenic acid (10.85 and 6.39 mg/mL, respectively). The water:ethanol extract from both plants also exhibited the highest antioxidant activity in the DPPH and FRAP tests (79.19% and 1.39 mmol/L, respectively, for grindelia and 67.61% and 1.04 mmol/L for hyssop) and was most effective at reducing the level of ROS in cells. In addition, water:ethanol extracts may have a positive impact on the viability of skin cells in vitro. Conclusion: Water:ethanol extracts from H. officinalis and G. robusta herb are promising sources of active compounds and may find application as natural materials with valuable biological properties, which require further in vitro and in vivo testing.