Chromatography silica gel is mainly used for column chromatography purification of crude extracts in the production of cyclosporine, especially cyclosporine A, to separate and remove impurities, pigments, and structural analogues, and obtain high-purity target products. ‌‌‌

Mechanism of action: Utilizing the difference in adsorption forces between the silanol groups on the surface of silica gel and cyclosporine A (non-polar cyclic peptide) and impurities, selective elution is achieved in eluents such as petroleum ether/ethyl acetate gradients.

Process stage: Usually after fungal fermentation, ethanol extraction, and preliminary crystallization, as the core purification step (medium pressure or atmospheric pressure column chromatography), the purity of cyclosporine A is increased from about 80-90% of crude product to pharmacopoeial requirements (such as total impurities<1.5%).

Silica gel type: commonly used coarse pore, spherical, 200-300 mesh silica gel to match the molecular weight of cyclosporine A (approximately 1202 Da) and ensure flow rate and loading balance.

Regeneration trend: Traditionally, it is a one-time use material, but in recent years, research has focused on regeneration (such as ethanol/polysorbate backwashing+hydrogen peroxide oxidation), achieving three repeated uses while still meeting standards, reducing environmental and cost pressures. ‌‌

Cyclosporine A is insoluble in water and has strong lipophilicity. Silica gel chromatography is still the mainstream purification method due to its controllable polarity separation and industrial adaptability. Although it has been explored to be replaced by preparative HPLC or simulated moving bed, silica gel column chromatography is still the main method for large-scale production.