Antioxidant hydroxycinnamic acid derivatives isolated from Brazilian bee pollen

Abstract

One novel and three known hydroxycinnamic acid derivatives having antioxidant activities were isolated from a Brazilian bee pollen. They were identified as kaempferol 3-O-[2-O-p-coumaroyl]-α-L-arabinopyranoside, N¹, N⁵, N¹⁰-tri-p-coumaroyl spermidine, N¹, N⁵, N¹⁰, N¹⁴-tetra-p-coumaroyl spermine, and monocaffeoyl-tri-p-coumaroyl spermine, respectively. The structure of the kaempferol glycoside was established on the basis of spectroscopic and chemical investigations. Among the isolated compounds, monocaffeoyl-tri-p-coumaroyl spermine showed the strongest free radical-scavenging activity, which was almost identical to that of α-tocopherol. On the other hand, the antioxidant effect of tri-p-coumaroyl spermidine on autooxidation of linoleic acid was strongest and nearly equal to that of α-tocopherol.

Keywords:

• Bee pollen
• Kaempferol 3-O-(2-O-p-coumaroyl)-α-L-arabinopyranoside
• Spermine
• Spermidine
• Radical scavenging effect
• Antioxidant activity

Acknowledgments

The authors thank Mr Hitoshi Fujitaka, Natural Science Center for Basic Research and Development, Hiroshima University, for the NMR measurements and Professor Hiroki Hamada, Okayama University of Science, for the LC-MS measurement.