Morinda citrifolia inhibits both cytosolic Ca2+-dependent phospholipase A2 and secretory Ca2+-dependent phospholipase A2

Abstract

This study investigated the effects of the methanol extracts of Morinda citrifolia containing numerous anthraquinone and iridoid on phospholipase A 2 (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 (Ki) of 3.7 μg/ml and 12.6 μg/ml, respectively. These data suggest that methanol extracts of Morinda citrifolia inhibits both Ca2+-dependent PLA 2 such as, cPLA2 and sPLA2. Therefore, Morinda citrifolia may possess anti-inflammatory activity secondary to Ca 2+-dependent PLA2 inhibition.