Molecules (May 2012)
Phenolics and Flavonoids Compounds, Phenylanine Ammonia Lyase and Antioxidant Activity Responses to Elevated CO<sub>2</sub> in <em>Labisia pumila</em> (Myrisinaceae)
Abstract
A split plot 3 × 3 experiment was designed to examine the impact of three concentrations of CO<sub>2</sub> (400, 800 and 1,200 µmol·mol<sup>−1</sup>) on the phenolic and flavonoid compound profiles, phenylalanine ammonia lyase (PAL) and antioxidant activity in three varieties of <em>Labisia pumila</em> Benth. (var. <em>alata</em>,<em> pumila </em>and<em> lanceolata</em>) after 15 weeks of exposure. HPLC analysis revealed a strong influence of increased CO<sub>2</sub> concentration on the modification of phenolic and flavonoid profiles, whose intensity depended on the interaction between CO<sub>2</sub> levels and <em>L. pumila</em> varieties. Gallic acid and quercetin were the most abundant phenolics and flavonoids commonly present in all the varieties. With elevated CO<sub>2</sub> (1,200 µmol·mol<sup>−1</sup>) exposure, gallic acid increased tremendously, especially in var. <em>alata</em> and <em>pumila </em>(101–111%), whilst a large quercetin increase was noted in var. <em>lanceolata</em> (260%), followed closely by <em>alata</em> (201%). Kaempferol, although detected under ambient CO<sub>2</sub> conditions, was undetected in all varieties after exposure. Instead, caffeic acid was enhanced tremendously in var. <em>alata</em> (338~1,100%) and <em>pumila </em>(298~433%). Meanwhile, pyragallol and rutin were only seen in var. <em>alata</em> (810 µg·g<sup>−1</sup> DW) and <em>pumila</em> (25 µg·g<sup>−1</sup> DW), respectively, under ambient conditions; but the former compound went undetected in all varieties while rutin continued to increase by 262% after CO<sub>2</sub> enrichment. Interestingly, naringenin that was present in all varieties under ambient conditions went undetected under enrichment, except for var. <em>pumila </em>where it was enhanced by 1,100%. PAL activity, DPPH and FRAP also increased with increasing CO<sub>2</sub> levels implying the possible improvement of health-promoting quality of Malaysian <em>L. pumila</em> under high CO<sub>2</sub> enrichment conditions.
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