Consecutive Recovery of Bioactive Substances from Desmodium canadense at Different Plant Vegetation Phases by Green Extraction with Supercritical CO2 and Increasing Polarity Pressurized Liquids

What if the same plant could give us two different treasure troves of antioxidants, simply by harvesting it at the right moment? Scientists just found that a humble weed, Desmodium canadense, hides a wealth of bioactive compounds that shift with its life cycle.

Forget one-size-fits-all extraction. Researchers used a green, two-step process to unlock the hidden potential of Desmodium canadense leaves, harvested at five different growth stages—from vigorous growth to the end of blooming. First, supercritical CO2 swept away lipophilic compounds, peaking during massive flowering. Then, the leftover plant material was treated with pressurized liquids of increasing polarity: acetone, ethanol, and water. Water proved the champion extractor, yielding 16.54 g per 100 g of dry weight at the bud formation stage.

But yield isn't everything. The team measured antioxidant power using total phenolic content and three assays (ABTS, CUPRAC, and ORAC). Ethanol extracts stole the spotlight, showing the strongest overall antioxidant activity. At massive flowering, they boasted a maximum phenolic content of 282.1 mg GAE/g extract and an ABTS value of 1010 mg TE/g extract. At bud formation, they hit peak CUPRAC (853.3 mg TE/g) and ORAC (1882 mg TE/g) values.

A deep chemical profiling revealed 37 compounds, mainly C-glycosyl flavones, flavonol O-glycosides, hydroxycinnamic acid derivatives, and low molecular weight organic acids. Water extracts were rich in organic acids, while acetone and ethanol extracts packed the most flavonoids. Citric acid and vitexin were the most abundant compounds.

So, what's the takeaway? Desmodium canadense leaves, especially when harvested from budding to massive flowering, are a promising source of flavonoid-rich antioxidants for nutraceuticals and functional foods. Nature's pharmacy, it seems, is just waiting for the right moment to be tapped.

Key Points

• Two-step green extraction: supercritical CO2 then pressurized liquids.
• Ethanol extracts showed strongest antioxidant activity.
• 37 compounds found; citric acid and vitexin most abundant.