Gelsedine-type alkaloids: Discovery of natural neurotoxins presented in toxic honey

Abstract

The fascinating collection and evaluation of natural products with enormous structural and chemical diversity can contribute to ensure human health and inspire potential drug discovery. We reported the identification of 14-(R)-hydroxy-gelsenicine (HGE), a new component from poisonous honey, which has recently caused multiple serious intoxications and deaths up on consumption. The prevalence, toxicity, toxicokinetics and metabolic profile of HGE were evaluated through in vitro and in vivo analyses. HGE is a very toxic substance and shows significant gender difference with LD50 of 0.125 mg kg−1 and 0.295 mg kg−1 for the female and male mice, respectively. Toxicokinetics test indicates that HGE has good bioavailability in rats, and is metabolized extensively, in which hydroxylation, reduction, N-demethyl ether and glucuronication are the major metabolic pathways. Additionally, HGE shows specific neurotoxicity by enhancing the binding of γ-aminobutyric acid (GABA) to its receptors. We found that flumazenil, a selective antagonist of GABA receptor, could effectively increase the survival of the tested animals, which provides a potential therapy for future clinical applications.