Background:
Juniperus Phoenicea (JP) and Calicotome Villosa (CV) are used by Jordanian populations as herbal rem‑ edies in traditional medicine. Herein, the phytochemical contents of their methanolic extracts were analyzed and their antioxidant as well as in vitro anti- β-Galactosidase activities were evaluated; their efect on β-Galactosidase enzyme kinetics was evaluated and the thermodynamic of the enzyme was determined. Methods: The antioxidant activity of JP and CV crude methanolic extracts was evaluated using 1,1-diphenyl,2picrylhydrazyl (DPPH) free radical scavenging and ferric reducing antioxidant power (FRAP) assays; however, the efect of the plants’ crude extracts on β-Galactosidase activity and kinetics was evaluated in vitro. Moreover, total phenolic, favonoids, and favonols content in plants’ extracts were determined and expressed in Gallic acid equivalent (mg GAE/g dry extract) or rutin equivalent (mg RE/g dry extract). Results: Phytochemical screening of the crude extracts of JP and CV leaves revealed the presence of phenols, alka‑ loids, favonoids, terpenoids, anthraquinones, and glycosides. Flavonoids and favonols contents were signifcantly higher in JP than in CV (p<0.05). Furthermore, an analogous phenolic content was detected in both JP and CV meth‑ anolic extracts (103.6 vs 99.1 mg GAE/g extract). The ability of JP extract to scavenge DPPH radicals was signifcantly higher than that of CV extract with IC50=11.1 μg/ml and 15.6 μg/ml, respectively. However, their extracts revealed relatively similar antioxidant capacities in FRAP assay; their activity was concentration dependent. The JP extract inhibited β—galactosidase enzyme activity with a signifcant IC50 value compared to CV extract; they exhibited their inhibitory activities at IC50 values 65 µg/ml and 700 µg/ml, respectively. Rutin revealed anti-β-galactosidase activity at IC50=75 µg/ml. The mode of inhibition of β-galactosidase by JP, CV, and rutin was non-competitive, mixed, and com‑ petitive inhibition, respectively. Thermodynamic and enzyme inactivation kinetics revealed that β-galactosidase has a half-life time of 108 min at 55 °C, activation energy of 208.88 kJ mol−1 and the inactivation kinetics follows a frst-order reaction with k-values 0.0023–0.0862 min−1 and positive entropy of inactivation (∆S°) values at various temperatures, indicating non-signifcant processes of aggregation
