Phenolics and Flavonoids Compounds, Phenylanine Ammonia Lyase and Antioxidant Activity Responses to Elevated CO(2) in Labisia pumila (Myrisinaceae)

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