Ellagic acid derivatives and a ferulic acid ester derivative from the leaves and twigs of Pachycentria formosana

Pachycentria formosana Hayata (Melastomataceae) is an endemic creeping shrub distributed in forests at altitude 300–2100m throughout Taiwan. The plants of the family Melastomataceae are rich in tannins, flavonoids, and triterpenoids as the major constituents, some of which have demonstrated cytotoxic and anti-oxidant activities. Investigation on CH₂Cl₂- soluble fraction of the leaves and twigs of P. formosana has led to the isolation of two new ellagic acid derivatives, 5-hydroxy-5′-methoxy-3,4,3′,4′-tetra-O-methylellagic acid (1), 3,4,3′,4′-di-O-methyleneellagic acid (2) and a ferulic acid ester derivative, (2Z,2′Z)-tetracosane-1,24-diyl bis(3-phenylacrylate) (3) together with thirteen known compounds. The structure of new compounds were determined through spectral analyses including extensive 2D nuclear magnetic resonance data. Among the isolates, oleanolic acid and octacosanoyl ferulate exhibited inhibition (IC₅₀ values=3.12 and 6.30µg/mL, respectively) of superoxide anion generation by human neutrophils in response to formyl-L-methionyl-L-leucyl-L-phenylalanine/cytochalasin B (fMLP/CB).

Acknowledgements: This work was supported by grant from the National Science Council of the Republic of China.

References: 1. Chang CE, Hartley TG. Rutaceae in Flora of Taiwan. 2nd edition. Editorial Committee of the Flora of Taiwan, Taipei, Taiwan: 1993; Vol. 3: 905–28.