Screening of plant extracts for antioxidant activity: a comparative study on three testing methods

Area of Science:

• Analytical Chemistry
• Phytochemistry
• Pharmacognosy

Background:

• Antioxidant activity evaluation is crucial for identifying beneficial plant compounds.
• Standardized methods are needed for reliable screening of plant extracts.
• Different analytical techniques possess unique strengths and limitations.

Purpose of the Study:

• To compare the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method, static headspace gas chromatography (HS-GC), and beta-carotene bleaching test (BCBT) for screening plant extracts.
• To evaluate the influence of sample polarity and extract composition on antioxidant activity assays.
• To determine the most suitable method for rapid and reliable antioxidant screening.

Main Methods:

• Comparative analysis of DPPH, HS-GC, and BCBT assays.
• Testing of plant extracts from the genus Sideritis with varying polarities.
• Inclusion of known antioxidants (butylated hydroxytoluene, rosmarinic acid) as references.

Main Results:

• DPPH method demonstrated independence from sample polarity, making it suitable for diverse extracts.
• BCBT and HS-GC methods showed sensitivity to sample polarity, limiting their application.
• Extract composition and partitioning phenomena influenced antioxidant activity across all tested methods.

Conclusions:

• The DPPH method is highly recommended for rapid, large-scale screening of radical scavenging activity in plant extracts.
• BCBT is best suited for less polar samples, while HS-GC is valuable for assessing inhibition of volatile product formation.
• Method selection should consider sample characteristics and the specific antioxidant properties under investigation.