Microbial metabolism of pseudoprotodioscin

Area of Science:

• Natural Product Chemistry
• Microbial Transformation
• Steroidal Saponins

Background:

• Furostanol saponins are a class of natural products with diverse biological activities.
• Microbial transformations are employed to generate novel derivatives of natural products.
• Pseudoprotodioscin is a steroidal saponin that can be modified by microorganisms.

Purpose of the Study:

• To investigate the microbial transformation of pseudoprotodioscin using Aspergillus fumigatus.
• To isolate and elucidate the structures of new steroidal metabolites.
• To evaluate the cytotoxic activity of the isolated compounds against cancer cell lines.

Main Methods:

• Microbial transformation of pseudoprotodioscin (1) with Aspergillus fumigatus.
• Isolation and purification of metabolites using chromatographic techniques.
• Structure elucidation of new compounds primarily through 1D and 2D NMR spectroscopy.

Main Results:

• Two new steroidal metabolites, compounds 2 and 3, were isolated and characterized.
• Previously reported steroidal saponins, dioscin (4) and progenin II (5), were also identified.
• Metabolites 2-5 exhibited significant cytotoxicity against A375, L929, and HeLa cancer cell lines, with IC50 values ranging from 1.18 to 17.88 µM.

Conclusions:

• Aspergillus fumigatus effectively transforms pseudoprotodioscin into novel steroidal metabolites.
• The isolated steroidal saponins possess notable cytotoxic properties against tested cancer cell lines.
• These findings highlight the potential of microbial biotransformation in discovering new bioactive steroidal compounds.