Niranthin

Antiinflammatory and antiallodynic actions of the lignan niranthin isolated from Phyllanthus amarus. Evidence for interaction with platelet activating factor receptor.[Pubmed:16925995]

Eur J Pharmacol. 2006 Sep 28;546(1-3):182-8.

Previous studies have shown that the extracts obtained from Phyllanthus amarus, and some of the lignans isolated from it, exhibit pronounced antiinflammatory properties. In the present study, we have assessed whether the antiinflammatory actions of these lignans can be mediated by interaction with platelet activating factor (PAF) receptor or interference with the action of this lipid. The local administration of nirtetralin, phyltetralin or Niranthin (30 nmol/paw), similar to WEB2170 (a PAF receptor antagonist, 30 nmol/paw), significantly inhibited PAF-induced paw oedema formation in mice. The extracts of P. amarus (100 microg/ml) and Niranthin (30 microM), but not nirtetralin or phyltetralin (30 microM), decreased the specific binding of [(3)H]-PAF in mouse cerebral cortex membranes. Furthermore, both Niranthin and WEB2170 displaced, in a concentration-dependent manner, the [(3)H]-PAF binding sites. The mean IC(50) values from these effects were 6.5 microM and 0.3 microM, respectively. Additionally, both Niranthin and WEB2170 (30 nmol/paw) inhibited the increase of myeloperoxidase activity induced by PAF injection in the mouse paw. When assessed the mouse model of pleurisy induced by PAF, pretreatment with Niranthin (100 micromol/kg, p.o.) or WEB2170 (1.7 micromol/kg, i.p.) significantly inhibited PAF-induced protein extravasations. Moreover, in the rat model of PAF-induced allodynia, both Niranthin (30 nmol/paw) and WEB2170 (30 nmol/paw) treatment significantly inhibited PAF-induced allodynia. In addition, Niranthin had a rapid onset and long-lasting antiallodynic action when compared with WEB2170. Collectively, the present findings suggest that Niranthin exhibits antiinflammatory and antiallodynic actions which are probably mediated through its direct antagonistic action on the PAF receptor binding sites.

The lignan niranthin poisons Leishmania donovani topoisomerase IB and favours a Th1 immune response in mice.[Pubmed:23027614]

EMBO Mol Med. 2012 Oct;4(10):1126-43.

Niranthin, a lignan isolated from the aerial parts of the plant Phyllanthus amarus, exhibits a wide spectrum of pharmacological activities. In the present study, we have shown for the first time that Niranthin is a potent anti-leishmanial agent. The compound induces topoisomerase I-mediated DNA-protein adduct formation inside Leishmania cells and triggers apoptosis by activation of cellular nucleases. We also show that Niranthin inhibits the relaxation activity of heterodimeric type IB topoisomerase of L. donovani and acts as a non-competitive inhibitor interacting with both subunits of the enzyme. Niranthin interacts with DNA-protein binary complexes and thus stabilizes the 'cleavable complex' formation and subsequently inhibits the religation of cleaved strand. The compound inhibits the proliferation of Leishmania amastigotes in infected cultured murine macrophages with limited cytotoxicity to the host cells and is effective against antimony-resistant Leishmania parasites by modulating upregulated P-glycoprotein on host macrophages. Importantly, besides its in vitro efficacy, Niranthin treatment leads to a switch from a Th2- to a Th1-type immune response in infected BALB/c mice. The immune response causes production of nitric oxide, which results in almost complete clearance of the liver and splenic parasite burden after intraperitoneal or intramuscular administration of the drug. These findings can be exploited to develop Niranthin as a new drug candidate against drug-resistant leishmaniasis.

In vitro and in vivo anti-hepatitis B virus activities of the lignan niranthin isolated from Phyllanthus niruri L.[Pubmed:25009077]

J Ethnopharmacol. 2014 Sep 11;155(2):1061-7.

ETHNOPHARMACOLOGICAL RELEVANCE: Niranthin is a lignan isolated from Phyllanthus niruri L. This plant has long been used in folk medicine for liver protection and antihepatitis B in many Asian countries. This study was designed to evaluate the anti-hepatitis B virus activity of Niranthin using HepG2.2.15 cells and duck hepatitis B virus (DHBV) infected ducks as in vitro and in vivo models. MATERIALS AND METHODS: Niranthin was isolated from Phyllanthus niruri L. (Euphorbiaceae) by extraction and chromatographic procedures and the anti-hepatitis B virus activity was evaluated both in vitro and in vivo. The human HBV-transfected liver cell line HepG2.2.15 was used in vitro assay. And the in vivo anti-hepatitis B virus activity was evaluated on the expression of HBV replication, HBsAg, HBeAg, ALT and AST on day 0, 7, 14, 17 after Niranthin was dosed intragastricly (i.g.) once a day for 14 days at the dosages of 25, 50 and 100 mg/kg/day in the duck hepatitis B virus (DHBV) infected ducks. RESULTS: In the human HBV-transfected liver cell line HepG2.2.15, the secretion of HBsAg and HBeAg were significantly decreased after treatment with Niranthin for 144 h, with IC50 values for HBsAg of 15.6 microM, IC50 values for HBeAg of 25.1 microM. In DHBV-infected ducklings, Niranthin significantly reduced the serum DHBV DNA, HBsAg, HBeAg, ALT and AST. Furthermore, analysis of the liver pathological changes confirmed the hepatoprotective effect of Niranthin. CONCLUSION: The experimental data demonstrated that Niranthin exhibits anti-hepatitis B virus activity both in vitro and in vivo.