An Insight Into the Modulatory Effects and Mechanisms of Action of Phyllanthus Species and Their Bioactive Metabolites on the Immune System.

Phyllanthus species (family; Euphorbiaceae) have been intensively studied for their immunomodulating effects due to their wide-ranging uses to treat immune-related diseases in indigenous medicine, which are primarily lack of scientific basis. The focuses of this review are on the significance of Phyllanthus species and their bioactive metabolites particularly corilagin (1), geraniin (2), gallic acid (3), phyllanthin (4), hypophyllanthin (5), ellagic acid (6), phyltetralin (7), niranthin (8), catechin (9), quercetin (10), astragalin (11), and chebulagic acid (12) in the modulation of both innate and adaptive immune systems through various mechanisms and their possible therapeutic benefits for treatment of immune-related diseases. We have compiled all significant findings published in the literature, and the data were analyzed critically to provide perspectives and directions for future research for the plants as a prospective source of novel immunomodulating agents. Various Phyllanthus species particularly Phyllanthus amarus, Phyllanthus emblica, Phyllanthus niruri, and Phyllanthus urinaria have been documented to possess significant immunomodulatory effects. However, the possible challenges encountered by the application of extracts of various Phyllanthus species and their bioactive constituents as immunomodulators need to be addressed. Most reports on the biological and pharmacological studies of the plants were based on crude extracts. The extracts were not chemically characterized, and the contributions of their chemical constituents to the bioactivities were not identified. The underlying mechanisms involved in the immunomodulatory effects of the Phyllanthus species were not indepthly studied due to limitations in terms of design, conduct, and interpretation. Extensive experimental and preclinical studies on the immunomodulating potential of Phyllanthus species should be carried out to provide sufficient data to prove that their traditional uses are inherently effective and safe and will allow clinical trials to be pursued for their further development as therapeutic agents to treat immune-related disorders.

Phyllanthin from Phyllanthus amarus inhibits cellular and humoral immune responses in Balb/C mice.

BACKGROUND: Phyllanthin found in many Phyllanthus species has various biochemical and pharmacological properties especially on its hepatoprotective effects. However, its effect on the immune system has not been well documented. PURPOSE: In the present study, phyllanthin isolated from Phyllanthus amarus was investigated for its immunosuppressive effects on various cellular and humoral immune responses in Balb/C mice. METHODS: Male mice were treated daily at 20, 40 and 100mg/kg of phyllanthin for 14 days by oral gavage. The effects of phyllanthin on cellular immune responses in treated /non treated mice were determined by measuring CD 11b/CD 18 integrin expression, phagocytosis, nitric oxide (NO) production, myeloperoxidase activity (MPO), T and B cells proliferation, lymphocyte phenotyping, serum cytokines production by activated T-cells and delayed type hypersensitivity (DTH). Its effects on humoral immune responses were evaluated by determining the serum levels of lysozyme and ceruloplasmin, and immunoglobulins (IgG and IgM). RESULTS: Phyllanthin dose-dependently inhibited CD11b/CD18 adhesion, the engulfment of E. coli by peritoneal macrophages molecules, NO and MPO release in treated mice. Phyllanthin caused significant and dose-dependent inhibition of T and B lymphocytes proliferation and down-regulation of the Th1 (IL-2 and IFN-γ) and Th2 (IL-4) cytokines. Phyllanthin at 100mg/kg caused a significant reduction in the percentage expression of CD4+ and CD8+ in splenocytes and the inhibition was comparable to that of cyclosporin A at 50mg/kg. At 100mg/kg, phyllanthin also dose-dependently exhibited strong inhibition on the sheep red blood cell (sRBC)-induced swelling rate of mice paw in DTH. Significant inhibition of serum levels of ceruloplasmin and lysozyme were observed in mice fed with higher doses (40 and 100mg/kg) of phyllanthin. Anti-sRBC immunoglobulins (IgM and IgG) antibody titer was down-regulated in immunized and phyllanthin-treated mice in a dose-dependent manner with maximum inhibition being observed at 100mg/kg. CONCLUSION: The strong inhibitory effects of phyllanthin on the cellular and humoral immune responses suggest that phyllanthin may be a good candidate for development into an effective immunosuppressive agent.

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

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, 7ß,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-1ß 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.

Inhibitory Effects of the Standardized Extract of Phyllanthus amarus on Cellular and Humoral Immune Responses in Balb/C Mice.

Phyllanthus amarus has been shown to have strong inhibitory effects on phagocytic activity of human neutrophils and on cellular immune responses in Wistar-Kyoto rats. In this study, we investigated the effects of daily treatment of standardized extract of P. amarus at 50, 100 and 200 mg/kg for 14 days in Balb/C mice by measuring the myeloperoxidase activity (MPO), nitric oxide (NO) release, macrophage phagocytosis, swelling of footpad in delayed type hypersensitivity (DTH), and serum immunoglobulins, ceruloplasmin and lysozyme levels. Qualitative and quantitative analyses of the extract using validated reversed-phase HPLC methods identified phyllanthin, hypophyllanthin, corilagin and geraniin as the biomarkers. Significant dose-dependent inhibitions of MPO activity and NO release were observed in treated mice. The extract also inhibited E. coli phagocytic capacity of peritoneal macrophages of treated mice and inhibited the sheep red blood cells (sRBC)-induced swelling rate of mice paw in the DTH. There was also a significant decrease in non-specific humoral immunity including ceruloplasmin and lysozyme levels in the extract-fed groups as well as the release of serum level immunoglobulins. The strong inhibitory effects of the extract on the cellular and humoral immune responses suggest the potential of the plant to be developed as an effective immunosuppressive agent. Copyright © 2016 John Wiley & Sons, Ltd.

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

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 ß2 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.

Inhibitory Effects of Standardized Extracts of Phyllanthus amarus and Phyllanthus urinaria and Their Marker Compounds on Phagocytic Activity of Human Neutrophils.

The standardized methanol extracts of Phyllanthus amarus and P. urinaria, collected from Malaysia and Indonesia, and their isolated chemical markers, phyllanthin and hypophyllanthin, were evaluated for their effects on the chemotaxis, phagocytosis and chemiluminescence of human phagocytes. All the plant extracts strongly inhibited the migration of polymorphonuclear leukocytes (PMNs) with the Malaysian P. amarus showing the strongest inhibitory activity (IC50 value, 1.1 µ g/mL). There was moderate inhibition by the extracts of the bacteria engulfment by the phagocytes with the Malaysian P. amarus exhibiting the highest inhibition (50.8% of phagocytizing cells). The Malaysian P. amarus and P. urinaria showed strong reactive oxygen species (ROS) inhibitory activity, with both extracts exhibiting IC50 value of 0.7 µ g/mL. Phyllanthin and hypophyllanthin exhibited relatively strong activity against PMNs chemotaxis, with IC50 values slightly lower than that of ibuprofen (1.4 µ g/mL). Phyllanthin exhibited strong inhibitory activity on the oxidative burst with an IC50 value comparable to that of aspirin (1.9 µ g/mL). Phyllanthin exhibited strong engulfment inhibitory activity with percentage of phagocytizing cells of 14.2 and 27.1% for neutrophils and monocytes, respectively. The strong inhibitory activity of the extracts was due to the presence of high amounts of phyllanthin and hypophyllanthin although other constituents may also contribute.