Bioreactor culture of Lessertia frutescens adventitious roots and their inhibitory effects on non-enzymatic glycation

Lessertia frutescens, is a perennial shrub of the Fabaceae family that is native to southern Africa and has various pharmacological activities. However, traditional methods of plant material production have proven insufficient to meet the rising demand for its products. This study used an adventitious root (AR) bioreactor culture method to explore the efficient and sustainable production of bioactive compounds of L. frutescens. The bioreactor culture system was established by investigating the effects of sucrose concentration in the medium, inoculation density, aeration rate, and harvest duration on AR biomass and the accumulation of triterpenoids and polysaccharides. The results indicated that a sucrose concentration of 40 g/L, an inoculation density of 5 g/L ARs, an aeration rate of 300 mL/min, and a harvest duration of 50 days significantly (p < 0.05) enhanced AR biomass and bioactive compound content. At these conditions, approximately 50 g/L of AR fresh mass and 4 g of AR dry mass were obtained, and the contents of both triterpenoid saponins and polysaccharides reached approximately 134 mg/g dry mass. Additionally, to evaluate the potential applications of cultured ARs, this study examined their hypoglycemic effects, focusing on the ability of L. frutescens AR extract (LFARE) to inhibit non-enzymatic glycosylation. The result showed that the L. frutescens ARs extract (LFARE) significantly (p < 0.01) inhibited the formation of the fructosamine, an early-stage glycation product, in a bovine serum albumin-glucose system. The inhibition rates at all tested concentrations (0.25, 0.5, and 1 mg/mL) exceeded those of the positive control aminoguanidine (AG). Moreover, LFARE effectively suppressed the formation of intermediate glycation products, glyoxal and 5-hydroxymethylfurfural (5-HMF), with inhibition rates exceeding 48%. Notably, LFARE demonstrated greater efficacy than AG in inhibiting 5-HMF. For advanced glycation end-products (AGEs), LFARE exhibited dose-dependent inhibition, achieving inhibition rates on AGEs above 55% at 1 mg/mL. These results suggest that bioreactor-based AR culture offers a feasible method for producing L. frutescens biomass and demonstrate the potential of LFARE in developing functional foods or therapeutics targeting non-enzymatic glycation. Key message Lessertia frutescens adventitious roots can be successfully cultured in bioreactor systems and produce high yields of triterpenoid saponins and polysaccharides, exhibiting potential inhibitory activity on non-enzymatic glycation at multiple stages.