Study on characteristics of biflavanones distribution in Garcinia kola seeds and identification of compounds in gum resin exuded from fresh slices.

Garcinia kola seeds play an important role in African traditional medicine, which are widely used to treat stomachache, gastritis, malaria, venereal diseases and laryngitis. The habitats, specification, different parts of seeds and slicing process are important factors that affect the quality of Garcinia kola seeds. Interestingly, brownish yellow or brownish red spots were derived from gum resin exuded during slicing, whose chemical constituents have not been elucidated. A rapid high performance liquid chromatography method was established for quantitative study of four main biflavanones (GB-2, GB-1, kolaflavanone and GB-1a) in Garcinia kola seeds. We found that the content of the tested biflavanones was slightly different in Garcinia kola seeds from different habitats, while the seeds weight showed no obvious influence on the biflavanones content from the same habitat. With the aid of "spider-web" mode, we unveiled that the accumulation of biflavanones mainly occurred in seed kernels. Furthermore, slices thickness (1-2 mm) was optimized by comprehensive evaluation of biflavanones' content, moisture, cutting-time and drying-time to efficiently dry the slices. By employing of ultra-high performance liquid chromatography coupled with electrospray ionization quadrupole Orbitrap high resolution mass spectrometry (UHPLC/ESI Q-Orbitrap MS), garcinoic acid and its derivatives were successfully identified in gum resin, conducing to the interesting finding about the distribution of biflavanones and derivatives of garcinoic acid in Garcinia kola seeds. Generally, our findings in this research could contribute to standardizing the process of harvesting, processing and quality control for Garcinia kola seeds, and help better development and utilization of this important medicinal plant.