Determination of the volatile and polyphenol constituents and the antimicrobial, antioxidant, and tyrosinase inhibitory activities of the bioactive compounds from the by-product of Rosa rugosa Thunb. var. plena Regal tea.

BACKGROUND: The phytochemical constituents and biological activities of Rosa rugosa Thunb. var. plena Regal flower cell sap (RFCS) were investigated.

METHODS: Volatile constituent, such as linalool, phenylethyl alcohol, citronellol, α-bisabolol, were identified by GC-MS. The contents of hyperoside, kaempferol-3-O-rutinosid, rutin, and luteolin as well as the total flavonoid content in RFCS were determined by HPLC and HPLC-MS. The total polyphenol content was evaluated by the Folin-Ciocalteu colorimetric method. The antioxidant activities of RFCS and the standards were evaluated by DPPH and ABTS radical scavenging assays. The tyrosinase inhibitory activities of the rose samples and standard substance were determined by a spectrophotometric method. The antimicrobial effects of RFCS were evaluated in terms of minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) or minimum Fungicidal concentrations (MFCs).

RESULTS: The rose fraction exhibited a high content of biologically active ingredients. The total content of volatile compounds in RFCS was approximately 48.21 ± 2.76 ng/mL. The total phenolic acid content and total flavonoid content were 0.31 ± 0.01 mg/mL and 0.43 ± 0.01 mg/mL, respectively. Its IC50 value in the DPPH assay was 1120 ± 42 μg/mL, and its IC50 value for ABTS radical scavenging activity was 1430 ± 42 μg/mL.RFCS strongly inhibited L-tyrosine oxidation with an IC50 value of 570 ± 21 μg/mL. Every compound identified in RFCS exhibited broad-spectrum antimicrobial activity. F. nucleatum was most susceptible to RFCS with an MIC of 64 μg/mL and MBC of 250 μg/mL.

CONCLUSIONS: Due to its rose-like aroma, phenylethyl alcohol may be combined with linalool for use as a natural skin-whitening agent and skin care additive in the and pharmaceutical industries.