Comparison of bee products based on assays of antioxidant capacities

Abstract

Background: Bee products (including propolis, royal jelly, and bee pollen) are popular, traditional health foods. We compared antioxidant effects among water and ethanol extracts of Brazilian green propolis (WEP or EEP), its main constituents, water-soluble royal jelly (RJ), and an ethanol extract of bee pollen.

Methods: The hydrogen peroxide (H2O2)-, superoxide anion (O2.-)-, and hydroxyl radical (HO.)- scavenging capacities of bee products were measured using antioxidant capacity assays that employed the reactive oxygen species (ROS)-sensitive probe 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate, acetyl ester (CM-H2DCFDA) or aminophenyl fluorescein (APF).

Results: The rank order of antioxidant potencies was as follows: WEP > EEP > pollen, but neither RJ nor 10-hydroxy-2-decenoic acid (10-HDA) had any effects. Concerning the main constituents of WEP, the rank order of antioxidant effects was: caffeic acid > artepillin C > drupanin, but neither baccharin nor coumaric acid had any effects. The scavenging effects of caffeic acid were as powerful as those of trolox, but stronger than those of N-acetyl cysteine (NAC) or vitamin C.

Conclusion: On the basis of the present assays, propolis is the most powerful antioxidant of all the bee product examined, and its effect may be partly due to the various caffeic acids it contains. Pollen, too, exhibited strong antioxidant effects.

Figure 1

Time-kinetic and concentration-response data for antioxidant activities of Brazilian green propolis towards production of various ROS (H₂O₂, O₂^·-, HO^·) in term of fluorescence intensity. (A-C) Water extract of propolis (WEP) was added to RGC-5 cultures for 1 h, followed by addition of CM-H₂DCFDA (10 μM) or APF (10 μM) for 20 min. "Control" exhibited no ROS stimulation, while vehicle plus ROS induced ROS stimulation that was concentration-dependently reduced by WEP treatment. Kinetics of the DCFH oxidation induced by (A) H₂O₂, (B) O₂^·-, and (C) kinetics of the APF oxidation induced by HO^· in RGC-5. (D-F) Integrals of ROS production were calculated from the time-kinetics curves (see A-C), as described in "Methods". ROS were (D) H₂O₂, (E) O₂^·-, (F) HO^·. (D-F) WEP. (G-I) EEP. Data are shown as mean ± S.E.M., n = 6. *P < 0.05, **P < 0.01 vs. vehicle plus ROS. V: vehicle, W: WEP, E: EEP.

Figure 2

Antioxidant activities of bee products and trolox towards production of various ROS (H₂O₂, O₂^·-, HO^·) in term of fluorescence intensity. (A-C) Bee pollen. (D-F) Royal jelly (RJ). (G-I) Trolox (a derivative of α-tocopherol). Integrals of ROS production were calculated from time-kinetics curves. ROS were (A, D, G) H₂O₂, (B, E, H) O₂^·-, (C, F, I) HO^·. Data are shown as mean ± S.E.M., n = 6. **P < 0.01 vs. vehicle plus ROS. V: vehicle.

Figure 3

Antioxidant activities of main constituents of WEP (caffeoylquinic acid derivatives) towards production of various ROS (H₂O₂, O₂^·-, HO^·) in term of fluorescence intensity. (A-C) 3,4-di-O-caffeoylquinic acid. (D-F) 3,5-di-O-caffeoylquinic acid. (G-I) 3-caffeoylqic acid (Chlorogenic acid). Integrals of ROS production were calculated from time-kinetics curves. ROS were (A, D, G) H₂O₂, (B, E, H) O₂^·-, (C, F, I) HO^·. Data are shown as mean ± S.E.M., n = 6. *P < 0.05, **P < 0.01 vs. vehicle plus ROS. V: vehicle.