Background: When conducting plant research, the measurement of photosynthetic pigments can provide basic
information on the physiological status of a plant. High-pressure liquid chromatography (HPLC) is becoming widely
used for this purpose because it provides an accurate determination of a variety of photosynthetic pigments
simultaneously. This technique has a drawback compared with conventional spectroscopic techniques, however, in
that it is more prone to structural modification of pigments during extraction, thus potentially generating erroneous
results. During pigment extraction procedures with acetone or alcohol, the phytol side chain of chlorophyll is
sometimes removed, forming chlorophyllide, which affects chlorophyll measurement using HPLC.
Results: We evaluated the artifactual chlorophyllide production during chlorophyll extraction by comparing
different extraction methods with wild-type and mutant Arabidopsis leaves that lack the major isoform of
chlorophyllase. Several extraction methods were compared to provide alternatives to researchers who utilize HPLC
for the analysis of chlorophyll levels. As a result, the following three methods are recommended. In the first
method, leaves are briefly boiled prior to extraction. In the second method, grinding and homogenate of leaves
are performed at sub-zero temperatures. In the third method, N, N’-dimethylformamide (DMF) is used for the
extraction of pigments. When compared, the first two methods eliminated almost all chlorophyllide-forming activity
in Arabidopsis thaliana, Glebionis coronaria, Pisum sativum L. and Prunus sargentii Rehd. However, DMF effectively
suppressed the activity of chlorophyllase only in Arabidopsis leaves.
Conclusion: Chlorophyllide production in leaf extracts is predominantly an artifact. All three methods evaluated in
this study reduce the artifactual production of chlorophyllide and are thus suitable for pigment extraction for HPLC
analysis. The boiling method would be a practical choice when leaves are not too thick. However, it may convert a
small fraction of chlorophyll a into pheophytin a. Although extraction at sub-zero temperatures is suitable for all
plant species examined in this study, this method might be complicated for a large number of samples and it
requires liquid nitrogen and equipment for leaf grinding. Using DMF as an extractant is simple and suitable with
Arabidopsis samples. However, this solvent cannot completely block the formation of chlorophyllide in thicker
leaves.