Immunosuppressive effects of the standardized extract of Phyllanthus amarus on cellular immune responses in Wistar-Kyoto rats

Menaga Ilangkovan, Ibrahim Jantan, Mohamed Ahmed Mesaik, Syed Nasir Abbas BukhariDrug and Herbal Research Center, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Kuala Lumpur, MalaysiaAbstract: Phyllanthus amarus (family: Euphorbiaceae) is of immense interest due to its wide spectrum of biological activities. In the present study, the standardized 80% ethanol extract of P. amarus was investigated for its modulatory activity on various cellular immune parameters, including chemotaxis of neutrophils, engulfment of Escherichia coli by neutrophils, and Mac-1 expression, in leukocytes isolated from treated/nontreated Wistar-Kyoto rats. The detailed cell-mediated activity of P. amarus was also investigated, including analysis of the effects on T- and B-cell proliferation and CD4+ and CD8+ T-cell subsets in splenic mononuclear cells, and estimation of serum cytokine production by activated T-cells. The main components of the extract, phyllanthin, hypophyllanthin, corilagin, geraniin, ellagic acid, and gallic acid were identified and quantitatively analyzed in the extracts, using validated reversed-phase high-performance liquid chromatography (HPLC) methods. N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced neutrophils isolated from rats administered with the extract of P. amarus, at doses ranging from 100 to 400 mg/kg for 14 days, revealed a significant dose-dependent reduction in neutrophil migration (P<0.05). Similar patterns of inhibition were also observed in phagocytic activity and in fMLP-induced changes in expression of β2 integrin polymorphonuclear neutrophils. The results in P. amarus-treated rats also demonstrated a dose-dependent inhibition of both lipopolysaccharide-stimulated B-cell proliferation and concanavalin A–stimulated T-cell proliferation as compared with sensitized control. At a dose of 400 mg/kg (P<0.01), there was a significant decrease in the (%) expression of CD4+ and CD8+ in splenocytes and in serum cytokines of T helper (Th1) (IL-2 and IFN-γ) and Th2 (IL-4). In conclusion, P. amarus showed effective immunosuppressive activities in cellular immune response, by various immune regulatory mechanisms, and may be useful for improvement of immune-related disorders.Keywords: immunosuppression, leukocytes migration, phagocytic activity, splenic mononuclear cells, T- and B-cell proliferatio

Inhibitory effects of compounds from Phyllanthus amarus on nitric oxide production, lymphocyte proliferation, and cytokine release from phagocytes

Yuandani,1,2 Ibrahim Jantan,1 Menaga Ilangkovan,1 Khairana Husain,1 Kok Meng Chan3 1Drug and Herbal Research Center, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur, Malaysia; 2Falkultas Farmasi, Universitas Sumatera Utara, USU-Kampus, Medan, Indonesia; 3Biomedical Science Programme, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur, Malaysia Abstract: Standardized extract of Phyllanthus amarus has previously been shown to have a strong inhibitory effect on phagocytic activity of human neutrophils. The current study was carried out to evaluate the effects of constituents of the extract of P. amarus on nitric oxide (NO) production as well as lymphocyte proliferation and cytokine release from phagocytes. Three compounds, ethyl 8-hydroxy-8-methyl-tridecanoate, 7β,19α dihydroxy-urs-12-ene, and 1,7,8-trihydroxy-2-naphtaldehyde, together with seven known compounds were isolated from the whole plant of P. amarus. The isolated compounds and reference standards, ie, gallic acid, ellagic acid, corilagin, and geraniin, which were quantitatively analyzed in the extracts, were evaluated for their effects on immune cells. Among the compounds tested, the lignans, especially phyltetralin and phyllanthin, showed strong inhibition on lymphocyte proliferation with half maximal inhibitory concentration (IC50) values of 1.07 µM and 1.82 µM, respectively. Ethyl 8-hydroxy-8-methyl-tridecanoate and 1,7,8-trihydroxy-2-naphtaldehyde exhibited strong inhibition on nitric oxide production with IC50 values of 0.91 µM and 1.07 µM, respectively. Of all the compounds, corilagin was the strongest inhibitor of tumor necrosis factor-α release with an IC50 value of 7.39 µM, whereas geraniin depicted the strongest inhibitory activity on interleukin-1β release with an IC50 value of 16.41 µM. The compounds constituting the extract of P. amarus were able to inhibit the innate immune response of phagocytes at different steps. Keywords: Phyllanthus amarus (Euphorbiaceae), immunosuppressive effects, 1,7,8-trihydroxy-2-naphtaldehyde, 7β, 19α-dihydroxy-urs-12-ene, phyllanthin, hypophyllanthi

Inhibitory effects of compounds from Phyllanthus amarus on nitric oxide production, lymphocyte proliferation, and cytokine release from phagocytes

Yuandani,1,2 Ibrahim Jantan,1 Menaga Ilangkovan,1 Khairana Husain,1 Kok Meng Chan3 1Drug and Herbal Research Center, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur, Malaysia; 2Falkultas Farmasi, Universitas Sumatera Utara, USU-Kampus, Medan, Indonesia; 3Biomedical Science Programme, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur, Malaysia Abstract: Standardized extract of Phyllanthus amarus has previously been shown to have a strong inhibitory effect on phagocytic activity of human neutrophils. The current study was carried out to evaluate the effects of constituents of the extract of P. amarus on nitric oxide (NO) production as well as lymphocyte proliferation and cytokine release from phagocytes. Three compounds, ethyl 8-hydroxy-8-methyl-tridecanoate, 7β,19α dihydroxy-urs-12-ene, and 1,7,8-trihydroxy-2-naphtaldehyde, together with seven known compounds were isolated from the whole plant of P. amarus. The isolated compounds and reference standards, ie, gallic acid, ellagic acid, corilagin, and geraniin, which were quantitatively analyzed in the extracts, were evaluated for their effects on immune cells. Among the compounds tested, the lignans, especially phyltetralin and phyllanthin, showed strong inhibition on lymphocyte proliferation with half maximal inhibitory concentration (IC50) values of 1.07 µM and 1.82 µM, respectively. Ethyl 8-hydroxy-8-methyl-tridecanoate and 1,7,8-trihydroxy-2-naphtaldehyde exhibited strong inhibition on nitric oxide production with IC50 values of 0.91 µM and 1.07 µM, respectively. Of all the compounds, corilagin was the strongest inhibitor of tumor necrosis factor-α release with an IC50 value of 7.39 µM, whereas geraniin depicted the strongest inhibitory activity on interleukin-1β release with an IC50 value of 16.41 µM. The compounds constituting the extract of P. amarus were able to inhibit the innate immune response of phagocytes at different steps. Keywords: Phyllanthus amarus (Euphorbiaceae), immunosuppressive effects, 1,7,8-trihydroxy-2-naphtaldehyde, 7β, 19α-dihydroxy-urs-12-ene, phyllanthin, hypophyllanthi