Synthesis of a biologically active fluorescent derivative of GM1, a main Ginseng saponin metabolite formed by intestinal bacteria

Synthesis and antitumor activity of three novel ginsenoside M1 derivatives with 3'-ester modifications

Ginsenoside M1 (M1) was considered to be the main antitumor component of ginsenoside metabolites in the body. In order to enhance its potency on antitumor effect, three novel M1 3'-ester derivatives (1c, 2c, 3c) were synthesized and evaluated. The yield of these derivatives was between 41% and 69%. Compared with M1, 2c and 3c can improve the efficacy of the inhibition on breast cancer MCF-7 and MDA-MB-231 cells, especially for MCF-7 (fold: 0.7-4.2, p < 0.0001). Further study suggested that 2c and 3c may cause cell autophagy and promote apoptosis in MCF-7 cells. The results indicated the 3'-ester modified M1 derivatives 2c and 3c possess higher abilities of inhibition growth towards triple-positive breast cancer and provided a new source for synthesis of potential anti-breast cancer drugs.

Synthesis of esters of ginsenoside metabolite M1 and their cytotoxicity on MGC80-3 cells

Monoesters of ginsenoside metabolite M1 at the 3-OH, 4-OH and 6-OH positions of the glucose moiety at M1 were synthesized via the reaction of M1 with acyl chloride, or acid-N,N'-diisopropylcarbodiimide in the presence of DMAP. Their structures were fully characterized by spectral methods. The cytotoxicity of these compounds against then MGC80-3 human gastric cancer cell line was also assessed. High inhibitory effects were found at a concentration of 100 μg/mL.

Synthesis and preclinical evaluation of QS-21 variants leading to simplified vaccine adjuvants and mechanistic probes

QS-21 is a potent immunostimulatory saponin that is currently under clinical investigation as an adjuvant in various vaccines to treat infectious diseases, cancers, and cognitive disorders. Herein, we report the design, synthesis, and preclinical evaluation of simplified QS-21 congeners to define key structural features that are critical for adjuvant activity. Truncation of the linear tetrasaccharide domain revealed that a trisaccharide variant is equipotent to QS-21, while the corresponding disaccharide and monosaccharide congeners are more toxic and less potent, respectively. Modification of the acyl chain domain in the trisaccharide series revealed that a terminal carboxylic acid is well-tolerated while a terminal amine results in reduced adjuvant activity. Acylation of the terminal amine can, in some cases, restore adjuvant activity and enables the synthesis of fluorescently labeled QS-21 variants. Cellular studies with these probes revealed that, contrary to conventional wisdom, the most highly adjuvant active of these fluorescently labeled saponins does not simply associate with the plasma membrane, but rather is internalized by dendritic cells.