A new steroidal saponin from Dioscorea cayenensis

Area of Science:

• Phytochemistry
• Natural Products Chemistry
• Mycology

Background:

• Dioscorea species are a rich source of bioactive saponins.
• Saponins possess diverse pharmacological properties, including antifungal activity.
• Investigating the chemical constituents of Dioscorea cayenensis is crucial for discovering new therapeutic agents.

Purpose of the Study:

• To isolate and characterize chemical constituents from the rhizomes of Dioscorea cayenensis.
• To evaluate the antifungal activity of the isolated compounds against human pathogenic yeasts.

Main Methods:

• Extraction and isolation of compounds from Dioscorea cayenensis rhizomes.
• Structure elucidation using advanced spectroscopic techniques, primarily 600 MHz 2D-NMR.
• Antifungal activity testing using broth microdilution assays to determine Minimum Inhibitory Concentrations (MICs).

Main Results:

• A new furostanol saponin (1) was isolated and characterized.
• Three known compounds, methyl protodioscin (2), asperoside (3), and prosapogenin A of dioscin (4), were also identified.
• Prosapogenin A of dioscin (4) demonstrated significant antifungal activity against Candida albicans, Candida glabrata, and Candida tropicalis, with MICs of 20.8, 6.25, and 25 µg/mL, respectively.
• Saponins 1, 2, and 3 were found to be inactive against the tested Candida species.

Conclusions:

• Dioscorea cayenensis rhizomes contain a complex mixture of saponins.
• Prosapogenin A of dioscin (4) is a promising candidate for further investigation as an antifungal agent against Candida infections.
• The study highlights the potential of natural products from Dioscorea species in combating fungal pathogens.