LC-DAD-ESI-MS and HPLC-DAD phytochemical investigation and in vitro antioxidant assessment of Rosa sp. stem pruning products from different northern areas in Tunisia

Introduction: Rosa species are known by their richness in bioactive compounds useful in cosmetic, perfumery, food and phytotherapy. These metabolites are influenced by several factors accordingly affecting the plant properties in different environments. Objective: Exploration of polyphenolic composition and antioxidant activity of stem extracts from Rosa moschata Herrm., R. canina L. and R. sempervirens L. growing in different northern areas in Tunisia. Methods: Phytochemical composition was carried out by means of high-performance liquid chromatography diode-array detector (HPLC-DAD) and HPLC-DAD-ESI-MS (electrospray ionisation mass spectrometry). Antioxidant activity was measured using the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging assay, the FRAP (ferric reducing antioxidant power) test, the TEAC (Trolox equivalent antioxidant capacity) and the ORAC (oxygen radical absorbance capacity) assays. Results: Rosa stem profiles were dominated by flavonols but qualitative variation was recorded between sections (Caninae and Synstylae). Aromadendrin-O-hexoside-deoxyhexoside, quercitrin and quercetin 3-O-glucoside were identified as the major compounds of R. sempervirens, R. moschata and R. canina, respectively. Quantitative differences were found between species, provenances and extracts either for the individual compounds or for the total phenolic contents. This variability was also highlighted in Rosa scavenger ability results. The highest mean values were recorded by methanolic extracts of R. moschata from Bizerte (TEAC and FRAP) and R. canina for DPPH. However, for ORAC assay, the most active extract was obtained by ethyl acetate from stems of R. canina. Conclusion: Results allow concluding that stems of R. sempervirens, R. moschata and R. canina could present a new natural residual source of bioactive phytochemicals, to be employed as additives in pharmaceutical products or in cosmetic and food preparations.