Seed extract of Aeginetia indica L induces cytokine production and lymphocyte proliferation in vitro

Optimized Conditions for the Extraction of Phenolic Compounds from Aeginetia indica L. and Its Potential Biological Applications

Aeginetia indica L., a parasitic root in the Orobanchaceae family, is used as a food colorant in traditional Thai desserts. However, scant information is available on its food applications as well as medicinal properties, while overharvesting by the local people has severely depleted wild plant populations. This research, thus, aimed to extract optimized total phenolic content (TPC) in varying extraction conditions using response surface methodology (RSM) and the Box-Behnken design (BBD). Results indicated that an extraction temperature of 90 °C, 80% (v/v) aqueous ethanol, and 0.5% (w/v) solid-to-liquid ratio yielded the highest TPC at 129.39 mg gallic acid equivalent (GAE)/g dry weight (DW). Liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) identified the predominant phenolics as apigenin (109.06 mg/100 g extract) and luteolin (35.32 mg/100 g extract) with trace amounts of naringenin and rutin. Under the optimal extraction condition, the plant extract exhibited antioxidant activities of 5620.58 and 641.52 µmol Trolox equivalent (TE)/g DW determined by oxygen radical absorbance capacity (ORAC) and ferric ion reducing antioxidant power (FRAP) assay, while the scavenging capacity of total radicals at 50% (SC50) was determined to be 135.50 µg/mL using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The plant extract also exhibited inhibitory activities against the key enzymes relevant to type II diabetes, obesity, and Alzheimer's disease, suggesting the potential for medicinal applications.

Pharmacological investigation of analgesic and antipyretic activities of methanol extract of the whole part of Aeginetia indica

ETHNOPHARMACOLOGICAL RELEVANCE

Aeginetia indica (Linn.), commonly known as aankuri bankuri, guan-jen-huang, forest ghost flower, dok din daeng, dapong tubo; is a root parasitic plant of the Orobanchaceae family native to South and South-East Asian region. Different parts of the plant are traditionally used to treat fever, pain, inflammation, arthritis, cough, diabetes, and chronic liver disease. Local practitioners often recommend this plant as a folk remedy for dermal swelling, painful menstrual periods, wounds, and knee pain. However, the antipyretic and analgesic activity of A. indica have never been investigated.

AIM OF THE STUDY

The present study was aimed to evaluate the analgesic and antipyretic potential of Aeginetia indica plant extract to verify its effectiveness as reported in traditional uses.

MATERIALS AND METHODS

Preliminary phytochemical analysis of Aeginetia indica crude extract was performed using previously established methods and antioxidant capacity was determined by phosphomolybdenum assay. In vivo analgesic activity of Aeginetia indica methanol extract (AiME) was evaluated by acetic acid-induced writhing test, formalin-induced paw licking test, and hot plate test model. The antipyretic activity was studied in Baker's yeast induced pyrexia model.

RESULTS

Phytochemicals screening revealed cardiac glycosides, saponins, phenols, tannins, and flavonoids in the crude extract of Aeginetia indica. Total phenolic and flavonoid content were recorded as 101 ± 1.1 mg GAE/g of the extract and 35 ± 0.8 mg QE/g of the extract, respectively. The total antioxidant capacity observed in phosphomolybdenum assay was 68.3 ± 1.3 mg ascorbic acid equivalent per gram of the extract. AiME showed significant dose-dependent analgesic activity against acetic acid-induced writhing, formalin-induced paw licking, and hot plate pain model. A higher dose of A. indica (200 mg/kg) produced significant (P < 0.001) inhibition of writhing by 69% whereas, standard aspirin showed maximum 85.6% inhibition. AiME at all doses showed a significant (P < 0.001) decrease of paw licking time in both early neurogenic and late inflammatory pain phase of formalin-induced licking test. In the hot plate test, AiME at a 200 mg/kg dose produced antinociceptive activity (55.18%) higher than the standard ketorolac (49.88%) at 1 h. However, after 2 h, ketorolac showed a maximum effect of 62.66% and AiME 200 mg/kg showed a 60.24% effect. A significant (P < 0.001) reduction of rectal temperature (4.54 °F↓) was recorded for AiME 200 mg/kg, which was higher than the standard paracetamol (3.86 F°↓) after 24 h of treatment.

CONCLUSION

The in vivo investigational studies' results demonstrated promising analgesic and antipyretic activities of A. indica, which supported the claim of its folk uses.

Effects of a Chinese Herbal Medicine, Guan-Jen-Huang (Aeginetia indica Linn.), on Renal Cancer Cell Growth and Metastasis

Aeginetia indica Linn. (Guan-Jen-Huang, GJH), a traditional Chinese herb, has the potential to be an immunomodulatory agent. The purpose of this study was to explore the effect of GJH in the treatment of renal cancer. Concentration-effect curves for the influence of GJH on cellular proliferation showed a biphasic shape. Besides, GJH had a synergistic effect on cytotoxicity when combined with 5-fluorouracil (5-FU)which may be due to the alternation of the chemotherapeutic agent resistance-related genes and due to the synergistic effects on apoptosis. In addition, treatment with GJH extract markedly reduced 786-O cell adherence to human umbilical vein endothelial cells (HUVECs) and decreased 786-O cell migration and invasion. In a xenograft animal model, GJH extract had an inhibitory effect on tumor cell-induced metastasis. Moreover, western blot analysis showed that the expression of intercellular adhesion molecule-1 (ICAM-1) in 786-O cells was significantly decreased by treatment with GJH extract through inactivation of nuclear factor-κB (NF–κB). These results suggest that GJH extract has a synergistic effect on apoptosis induced by chemotherapeutic agents and an inhibitory effect on cell adhesion, migration, and invasion, providing evidence for the use of water-based extracts of GJH as novel alternative therapeutic agents in the treatment of human renal cancer.

Toll-like receptor 4 mediates the antitumor host response induced by a 55-kilodalton protein isolated from Aeginetia indica L., a parasitic plant

A 55-kDa protein named AILb-A, isolated from the seed extract of Aeginetia indica L., a parasitic plant, induces a Th1-type T-cell response and elicits a marked antitumor effect in tumor-bearing mice. In the present study, we examined the role of Toll-like receptors (TLRs), which have been implicated in pathogen-induced cell signaling, in AILb-A-induced immune responses. In the luciferase assay using a nuclear factor (NF)-kappaB-dependent reporter plasmid, AILb-A induced NF-kappaB activation in the cells transfected with TLR4, but not with those transfected with the TLR2 gene, in a dose-dependent manner. TLR4-mediated NF-kappaB activation induced by AILb-A but not by lipopolysaccharide (LPS) was also observed under serum-free conditions. In in vitro experiments using human peripheral blood mononuclear cells, AILb-A-induced cytokine production was markedly inhibited by anti-TLR4 but not by anti-CD14 antibody, while LPS-induced, TLR4-mediated cytokine production was inhibited by anti-CD14 as well as anti-TLR4 antibodies. Cytokine production, killer cell activities, maturation of dendritic cells, phosphorylation of mitogen-activated protein kinases, and nuclear translocation of interferon-regulatory factor 3 induced by AILb-A were severely impaired in TLR4-deficient but not TLR2-deficient mice. Transfection of TLR4-deficient mouse-derived macrophages with the TLR4 expression plasmid led AILb-A to induce cytokines. Finally, the antitumor effect of AILb-A was also impaired in TLR4-deficient and TLR4-mutated mice. These findings suggest that TLR4 mediates antitumor immunity induced by the plant-derived protein AILb-A.

Immunomodulation by Dok Din Daeng (Aeginetia indica Roxb.) extracts in female B6C3F1 mice

Aeginetia indica Roxbert (Dok Din Daeng, DDD), a parasitic plant that grows on bamboo, is extensively used in Thai traditional medicine to treat various diseases. There have been no published studies on the pharmacological, toxicological or immunological effects of DDD, indigenous to Thailand. The study reported here was focused on the immunological effects (T cells) of the whole plant extract using water (WDDD) or ethanol (EDDD) as a solvent. The extracts were administered to female B6C3F1 mice by gavage for WDDD (10-100%) and intraperitoneally (i.p.) for EDDD (0.25-250 mg/kg) for 28 days. Only mice administrated the highest dose of EDDD exhibited an increase in absolute spleen and liver weights. Three T cell functional assays, including anti-CD3 antibody-mediated T cell proliferation, the mixed leukocyte response (MLR) and the cytotoxic T lymphocyte (CTL) response, were employed to determine the effects of DDD extracts on splenic T cell activities. Exposure to WDDD enhanced the responses in all three assays with significant changes observed in the anti-CD3 and MLR assays. Exposure to EDDD also enhanced the responses in all three assays with significant changes observed in the MLR and CTL assays. Additionally, significant increases in the MLR and anti-CD3 responses were also observed when EDDD was used to treat cells in vitro. Finally, exposure to WDDD decreased both the percentage and absolute number of regulatory CD4(+)CD25(+) T cells in the spleen, which was consistent with a significant increase in interferon-gamma (IFN-gamma) production from Con A-stimulated splenocytes. Overall, this study demonstrated that the extracts from A. indica Roxbert had a T cell stimulatory activity.

Immunomodulation by Dok Din Daeng (Aeginetia indica Roxb.) extracts in female B6C3F1 mice

In the previous report, we have provided evidence that Aeginetia indica Roxbert (DDD) extracts enhance T cell-mediated immune responses. The study reported here was focused on the hematological and immunological effects, including B cells, natural killer (NK) cells, macrophages and neutrophils, of the whole plant extract using water (WDDD) or ethanol (EDDD) as the solvent. The extracts were administered to female B6C3F1 mice by gavage for WDDD (10-100%) and intraperitoneally for EDDD (0.25-250 mg/kg) for 28 days. In addition to hematological evaluation, several quantitative measures and functional assays (e.g., the splenic phenotypic analysis, IgM antibody-forming cell responses, natural killer cell activity, mononuclear phagocyte system [MPS] and neutrophil activity) were employed to examine the effects of DDD extracts on the innate and humoral immunities. The results from this study demonstrated that exposure to WDDD and EDDD produced minimal changes in the activities of B cells and natural killer cells, macrophages and neutrophils. Overall, hematological parameters were not affected by exposure to WDDD or EDDD. Taken together, the enhancing effect of DDD extracts on T cells may be primarily responsible for the successful and long-time use of this traditional herbal medicine in Thailand.

Purification and characterization of cytokine-inducing protein of seed extract from Aeginetia indica L., a parasitic plant

We have isolated 55 kDa protein from the seed extract of Aeginetia indica L. (AIL), a parasitic plant, by an affinity chromatography on N-hydroxysuccinimide (NHS)-activated Sepharose High Performance column bound F3 monoclonal antibody which neutralizes cytokine-inducing and antitumor effect of AIL. In in vitro model using human peripheral blood mononuclear cells (PBMC), the 55 kDa protein (AILb-A) induced multiple cytokines, such as IFN-gamma, tumor necrosis factor (TNF)-alpha, granulocyte macrophage-colony stimulating factor (GM-CSF), IL-2, IL-6, IL-10, IL-12 and IL-18, and also accelerated killer cell activities of PBMC. When compared with a commonly used immunotherapeutic agent OK-432, AILb-A induced Th1 cytokines are greater than OK-432. Of the Th2 cytokines, the amounts of IL-6 and IL-10 induced by AILb-A were lower than those by OK-432. No significant induction of IL-4 and IL-13 was observed in AILb-A-stimulated PBMC. TNF family including TNF-alpha, TNF-beta, Fas ligand (FasL) and TNF-related apoptosis-inducing ligand (TRAIL) were suggested to be important for AILb-A-induced killing activity of PBMC by reverse transcription-polymerase chain reaction (RT-PCR) analysis. Furthermore, the neutralizing test using cytokine-specific antibodies demonstrated that IL-18 plays a most significant role for IFN-gamma- and killer cell-inducing ability of AILb-A among the cytokines tested. These findings clearly indicated that AILb-A, a 55 kDa protein of AIL, is a potent Th1 cytokine inducer and may be a useful immunotherapeutic agent for the patients with malignancies.

Antimitogenic effect of Larrea divaricata Cav.: participation in arachidonate metabolism

Aqueous extracts of the leaves of Larrea divaricata Cav. exert antimitogenic effects on tumor cells (BW 5147 murine immature T-lymphoma) and normal, stimulated lymphocytes. The effective concentration was four times smaller in the case of tumor cells than in the case of normal, stimulated lymphocytes. Inhibitor studies of arachidonate pathway suggest that the proliferative effect of the extract is due to the activation of lipoxygenase metabolism, while the inhibitory action could be a direct effect.

Dissociation between the mitogenic effect and antitumor activity of seed extract from Aeginetia indica L

The extract from seeds of Aeginetia indica L. (AIL), a parasitic plant, induces potent antitumor immunity against Meth A fibrosarcomas in BALB/c mice. AIL also possesses a thymocyte co-stimulatory effect in vitro with suboptimal dose of Con A, a B cell mitogenic effect, and stimulates AIL-primed CD4+ T cells to produce Th1-type cytokines. In this study, we investigated the relationship between mitogenicity and antitumor activity with AIL. When AIL was analyzed by SDS-PAGE, there was strong and diffuse staining in the region between 14 kDa and the bottom of polyacrylamide gel and it was unaffected when AIL was digested with proteinase K (PK) before SDS-PAGE. Some bands with different molecular mass were also found in silver-stained gel and they disappeared completely by incubating AIL with PK before SDS-PAGE. The in vitro thymocyte co-stimulatory and B cell mitogenic effects were not influenced by digesting AIL with PK but were completely suppressed by the oxidation of AIL with sodium periodate before culture. In contrast, the in vivo antitumor activity was completely abolished by PK, but it was not affected by periodate oxidation. We generated mAbs specific for AIL and investigated the influence on the antitumor activity of AIL in vivo. Around 60-80% of tumor-bearing mice failed to recover from a challenge tumor when they were treated with supernatants isolated from mAb-induced precipitation reactions. Immunoblotting (Western blotting) revealed that all the mAbs reacted exclusively with a 50-60 kDa protein and that this reactivity was not influenced after oxidizing the blots with sodium periodate. We demonstrated that AIL contains polysaccharides and proteins. The polysaccharides induced B cell mitogenic and thymocyte co-stimulatory effects in vitro, while the proteins, especially a 50-60 kDa protein containing non-carbohydrate epitopes recognized by the mAbs, mediated antitumor activity in vivo.