Bioactivities of naringin and its enzymatic conversion products
The agar disk diffusion procedure was used to assess the antimicrobial activities of naringin and naringenin against three bacterial strains and a fungus, while three complementary in vitro essays: the radical scavenging activities of naringin and naringenin against DPPH radical and hydroxyl radical, and metal chelating ability were used to evaluate the antioxidant activities of naringin and naringenin. The antimicrobial experiments showed that the antimicrobial activities of naringin and naringenin were greatly different at the same concentration, and naringenin showed a relatively better antimicrobial activity than naringin, while naringnin failed to inhibit the growth of all of the tested microorganisms. Moreover, naringenin showed a better antimicrobial activity for Gram-positive bacteria than that for Gram-negative bacteria. The results of in vitro essays against the radical scavenging activities of naringin and naringenin showed that the IC 50 of naringin, naringenin and BHT against DPPH radical was 7.044 mg/mL, 1.277 mg/mL and 0.035 mg/mL, respectively, while the IC 50 of naringin, naringenin and BHT against hydroxyl radical was 1.499 mg/mL, 1.288 mg/mL and 1.081 mg/mL.