Production of phenolic compounds, flavonoids, and lupeol by Lycium schweinfurthii suspension cultures in shake flasks and a rocking-motion bioreactor

Abstract

Lycium schweinfurthii, a wild shrub of the Solanaceae family, has received increasing attention in the last decade for its therapeutic potential in traditional medicine due to its diverse array of secondary metabolites, including phenolic substances and terpenoids. The aim of this study was to investigate the accumulation of phenolics, flavonoids, and the terpenoid lupeol in L. schweinfurthii cell suspension cultures cultivated in flasks and in a single-use 2-dimensional rocking motion bioreactor. 3 different media formulations were compared for in vitro cell cultures. Various parameters, such as biomass accumulation, settled cell volume, cell viability (assessed via a 2,3,5-triphenyl tetrazolium chloride assay), and sucrose consumption were recorded as indicators of cell activity and growth. Total phenolic and flavonoid contents were estimated spectrophotometrically and lupeol was quantified via High-Performance Thin Layer Chromatography (HPTLC). Although a higher fresh biomass concentration of 464 g L− 1 was obtained in MS medium supplemented with a combination of each, 1 mg L− 1 of 2,4-Dichlorophenoxyacetic acid (2,4-D) and 1-Naphthaleneacetic acid (NAA), the rocking-motion bioreactor cultivation was performed with 2 mg L− 1 NAA due to its superior reproducibility in viability, productivity, and content of bioactive compounds. A final fresh biomass concentration of 185 g L− 1 was achieved in a 16 L cultivation scale with a notable increase in the concentration of phenolics (1.4-fold) and flavonoids (1.7-fold). Most importantly, the concentration of lupeol, a pentacyclic triterpenoid known for its anti-inflammatory, antibacterial, and anti-atherogenic properties, exhibited a remarkable 5.5-fold increase in the bioreactor cultivation (585 µg g− 1) compared to shake flask cultivations (106 µg g− 1). The current study demonstrated the profound impact of media composition and especially of controlled cultivation conditions in a rocking-motion bioreactor on the accumulation of bioactive compounds. The findings are also relevant for other plant cell cultures.