Biochemically active sesquiterpene lactones from Ratibida mexicana

Area of Science:

• Natural Product Chemistry
• Phytochemistry
• Plant Biochemistry

Background:

• Ratibida mexicana is a plant species with potential medicinal properties.
• Sesquiterpene lactones are a class of natural compounds known for diverse biological activities.

Purpose of the Study:

• To isolate and characterize bioactive compounds from Ratibida mexicana roots.
• To evaluate the herbicidal, cytotoxic, and antifungal activities of isolated compounds.
• To investigate the mechanism of action of isoalloalantolactone on photosynthesis.

Main Methods:

• Bioactivity-directed fractionation of methanol extract.
• Isolation and structural elucidation of sesquiterpene lactones.
• Bioassays for radicle growth inhibition, cytotoxicity, and antifungal activity.
• Photosynthetic electron transport studies.

Main Results:

• Two sesquiterpene lactones, isoalloalantolactone and elema-1,3,11-trien-8,12-olide, were isolated.
• Both compounds inhibited radicle growth of Amaranthus hypochondriacus and Echinochloa crus-galli.
• Moderate cytotoxic activity against solid tumor cell lines and significant inhibition of phytopathogenic fungi were observed.
• Isoalloalantolactone inhibited ATP synthesis and electron transport, specifically Photosystem II, acting as a Hill's reaction inhibitor.

Conclusions:

• Sesquiterpene lactones from Ratibida mexicana exhibit significant herbicidal, cytotoxic, and antifungal properties.
• Isoalloalantolactone's inhibition of Photosystem II offers insights into its mode of action.
• These findings highlight the potential of Ratibida mexicana as a source of novel bioactive compounds.