Promotion effect of the propolis from Jeju Island, Korea, on NGF secretion in human glioblastoma cells

Propolis is a resinous mixture of substances collected and processed from various botanical sources by honeybees ( Apis mellifera ). We previously found that propolis collected on Jeju Island, located off the southern coast of Korea, originates from a single plant, Angelica keiskei KOIDZUMI (Ashitaba). A. keiskei has been well-studied as a health food and has been reported to promote nerve growth factor (NGF) production. Propolis formed from the resin of A. keiskei is expected to have a similar promotional effect on NGF production. NGF is a potential pharmacological agent for Alzheimer’s disease. In this study, the effects of an ethanolic extract of propolis from Jeju Island (EEPJ) on NGF secretion and cell viability in T98G human glioblastoma cells were evaluated. Ethanolic extracts of propolis from Brazil ( Baccharis type) and from Uruguay ( Populus type) were also studied for comparison. We found that EEPJ significantly increased NGF secretion in the cells in a concentration-dependent manner. Furthermore, the effects of 27 compounds previously isolated from EEPJ were also evaluated. Several compounds were found to have a promotion effect on NGF secretion, and the structure–activity relationships of the compounds were considered relative to their promotional effect on NGF biosynthesis. The promotional effect of EEPJ is a characteristic biological activity that is not present with other propolis types, so the propolis from Jeju Island may have potential applications as a therapeutic candidate for Alzheimer’s disease. Graphic abstract