Comparative Analysis of Flavonoid Profile, Antioxidant and Antimicrobial Activity of the Berries of Juniperus communis L. var. communis and Juniperus communis L. var. saxatilis Pall. from Turkey

The present study was designed to define and compare the flavonoid composition and the biological potential of berries methanol extracts of Juniperus communis L. var. communis (Jcc) and Juniperus communis L. var. saxatilis Pall. (Jcs) from Turkey. Total polyphenols (Folin-Ciocalteau method) were 3-fold higher in Jcc (59.17 ± 1.65 mg GAE/g extract) than in Jcs (17.64 ±0.09 mg GAE/g extract).
Flavonoid and biflavonoid content, evaluated by HPLC-DAD-ESI-MS analysis, was higher in Jcc (25947 ± 0.86 and 4346 ±3.95 μg/g extract) than in Jcs (5387 ± 34.88 and 1944 ±26.88 μg/g extract). The HPLC analysis of Jcc allowed the separation of 16 flavonoids; hypolaetin-7-pentoside and quercetin-hexoside are the main compounds. Moreover, gossypetin-hexoside-pentoside and gossypetin-hexoside were identified for the first time in Jcc berries. In Jcs eight flavonoids were identified: quercetin-hexoside and isoscutellarein-8-O-hexoside are the most abundant compounds.
The in vitro antioxidant activity was determined using different methods; Jcc was found to be more active than Jcs in the DPPH test (IC50 of 0.63 ±0.09 mg/mL and 1.84 ± 0.10 mg/mL) in reducing power assay (12.82 ±0.10 ASE/mL and 64.14 ±1.20 ASE/mL), and in TBA assay (IC50 of 4.44 ± 0.70 μg/mL and 120.07 ±3.60 μg/mL). By contrast, Jcs exhibited more elevated Fe2+chelating ability than Jcc. The extracts were also studied for their antimicrobial potential, displaying antimicrobial capacity only against Gram-positive bacteria.