Phenolic Compounds of Rose Hips of Some Rosa Species and Their Hybrids Native Grown in the South-West of Slovenia during a Two-Year Period (2020–2021)

The genus Rosa is very extensive and variable, so it remains very unpredictable and uninvestigated. This also holds true for values of secondary metabolites in rose hips, which are important for several purposes (human diet, protection of plants against pests, etc.). The aim of our study was to determine the content of phenolic compounds in the hips of R. × R. glauca, R. corymbifera, R. gallica and R. subcanina, which grow wild in nature in southwestern Slovenia. We examined the content of phenolic compounds in different parts of rose hips, in the flesh with skin and in the seeds, depending on the individual species, over a period of two years, 2020 and 2021. We also considered the influence of environmental conditions on the content of the mentioned compounds. In both years, the content of phenolic compounds was higher in the flesh with skin than in the seeds. Considering the total content of phenolic compounds in the flesh with skin, R. gallica stands out (15,767.21 mg/kg FW), but the hips of this species accumulated the lowest number of different phenolic compounds. The lowest content of total phenolic compounds (TPC) was found in R. corymbifera, in the year 2021 (3501.38 mg/kg FW). The content of TPC (in both observed years) in the seeds varied between 1263.08 mg/kg FW (R. subcanina) and 3247.89 mg/kg FW (R. × R. glauca). Among the anthocyanins, cyanidin-3-glucoside was determined, which was predominant in R. gallica (28.78 mg/kg FW), and at least was determined in R. subcanina (1.13 mg/kg FW). When comparing the two years of the period (2020–2021), we found that 2021 was more favorable for the formation of phenolic compounds in the seeds, but 2020 in the flesh with skin.