Antinociceptive activities of Artocarpus lacucha Buch-ham (Moraceae) and its isolated phenolic compound, catechin, in mice.

The present study evaluated the antinociceptive effect of the bark of Artocarpus lacucha, which is used for the treatment of stomachache, headache and boils in the traditional system of medicine.

The antinociceptive activity was investigated by the tail immersion, hot plate, acetic acid- & formalin-induced nociception and carrageenan-induced paw edema tests using a hydro-methanolic extract of A. lacucha bark. The plant extract was found to contain a substantial amount of phenolic compounds according to the total phenolic and flavonoid content assay. A phenolic metabolite, (+)-catechin, has been isolated using different chromatographic techniques. The compound was characterized with 1D and 2D NMR spectroscopic data. (+)-catechin, isolated from A. lacucha was assessed for antinociceptive effects swiss albino mice. Furthermore, the possible involvement of opioid receptors and ATP-sensitive K⁺ channel for the effect of the plant extract and (+)-catechin has been justified using naloxone and glibenclamide, respectively.

Oral administration (p.o) of the plant extract (50-200 mg/Kg b.w.) resulted in significant thermal pain protection in the hot plate and tail immersion tests. The action of the plant extract was significantly antagonized by naloxone, a non-selective opioid antagonist, in the hot plate and tail immersion tests, which supports the involvement of opioid receptors. Both the plant extract and (+)-catechin, (50-200 mg/Kg b.w., p.o.) significantly diminished the acetic acid- & formalin-induced nociception, and carrageenan-induced paw edema. Glibenclamide, an ATP-sensitive K⁺ channel blocker, significantly reversed their effect in the acetic acid-induced writhing test which indicates the participation of ATP-sensitive K⁺ channel system.

The investigation revealed potential central and peripheral antinociceptive effects of A. lacucha bark supports its applications in the traditional system of medicine.