Morinda citrifolia Inhibits Both Cytosolic Ca2+-dependent Phospholipase A2 and Secretory Ca2+-dependent Phospholipase A2

摘要

This study investigated the effects of the methanol extracts of Morinda citrifolia containing numerous anthraquinone and iridoid on phospholipase A₂ (PLA₂) isozyme. PLA₂ activity was measured using various PLA₂ substrates, including 10-pyrene phosphatidylcholine, 1-palmitoyl-2-[14C]arachidonyl phosphatidylcholine ([14C]AA-PC), and [3H]arachidonic acid (AA). The methanol extracts suppressed melittin-induced [₃H]AA release in a concentration-dependent manner in RAW 264.7 cells, and inhibited cPLA₂/sPLA₂-induced hydrolysis of [14C]AA-PC in a concentration- and time-dependent manner. A Dixon plot showed that the inhibition by methanol extracts on cPLA₂ and sPLA₂ appeared to be competitive with inhibition constants ( K_i ) of 3.7μg/ml and 12.6μg/ml, respectively. These data suggest that methanol extracts of Morinda citrifolia inhibits both Ca2+-dependent PLA₂ such as, cPLA₂ and sPLA₂. Therefore, Morinda citrifolia may possess anti-inflammatory activity secondary to Ca2+-dependent PLA₂ inhibition.