Immuno-stimulatory activity of a polysaccharide-enriched fraction of Sutherlandia frutescens occurs by the toll-like receptor-4 signaling pathway

Immunomodulatory mechanisms of an acidic polysaccharide from the fermented burdock residue by Rhizopus nigricans in RAW264.7 cells and cyclophosphamide-induced immunosuppressive mice

RBAPS is an acidic polysaccharide extracted from the burdock residue fermentation by Rhizopus nigricans. In RBAPS-activated RAW264.7 cells, transcriptome analysis identified a total of 1520 differentially expressed genes (DEGs), including 1223 down-regulated genes and 297 up-regulated genes. DEGs were enriched in the immune-related biological processes, involving in Mitogen-activated protein kinase (MAPK) and Toll-like receptor (TLR) signaling pathway, according to Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. The results of the confocal laser scanning microscope (CLSM) observation, antibody neutralization and Western blot verified that RBAPS modulated macrophages activation and cytokines secretion mainly via TLR4/MAPK/NF-κB signaling pathway. The immunomodulatory activity in vivo of RBAPS was investigated in cyclophosphamide (CTX)-induced immunosuppressive mice. RBAPS promoted the counts of white blood cells (WBC), red blood cells (RBC) and platelets (PLT) as well as the levels of immunoglobulins and cytokines (IgG, IgM, TNF-α, and IL-2) in immunosuppressive mice. RBAPS protected the spleen and thymus from CTX-induced injury by increasing the organ indexes, attenuating pathological damage, and promoting splenic lymphocytes proliferation. Importantly, RBAPS ameliorated the intestine integrity and function by promoting the expression of Occuldin, Claudin-5, Atg5, and Atg7, activating TLR4/MAPK signaling pathway in CTX-induced mice. This study suggested that RBAPS was a prime candidate of immunologic adjuvant in chemotherapy for the nutraceutical and pharmaceutical application.

Bioprospecting for Anti-COVID-19 Interventions From African Medicinal Plants: A Review

The emergence of the novel coronavirus (SARS-CoV-2) that emanated from Wuhan in China in 2019 has become a global concern. The current situation warrants ethnomedicinal drug discovery and development for delivery of phytomedicines with potential for the treatment of COVID-19. The aim of this review is to provide a detailed evaluation of available information on plant species used in African traditional medicines with antiviral, anti-inflammatory, immunomodulatory, and COVID-19 symptoms relieving effects. Literature from scientific databases such as Scopus, PubMed, Google scholar, African Journals OnLine (AJOL), Science Direct, and Web of Science were used for this review. A total of 35 of the 38 reviewed plants demonstrated a wide range of antiviral activities. Bryophyllum pinnatum, Aframomum melegueta, Garcinia kola, Sphenocentrum jollyanum, Adansonia digitata, Sutherlandia frutescens, Hibiscus sabdariffa, Moringa oleifera, and Nigella sativa possess a combination of antiviral, immunomodulatory, anti-inflammatory, and COVID-19 symptoms relieving activities. Nine, 13, and 10 of the plants representing 23.7%, 34.2%, and 26.3% of the plants studied had antiviral activity with 3 other activities, antiviral activity with 2 other activities, and antiviral with one pharmacological activity alone, respectively. The plants studied were reported to be relatively safe at the subchronic toxicity level, except for 2. The study provides baseline information on the pharmacological activities, toxicity, and chemical components of 9 African medicinal plants with antiviral, immunomodulatory, anti-inflammatory, and symptoms relieving activities, thereby making the plants candidates for further investigation for effectiveness against COVID-19.

Ultrasonic-Assisted Extraction of Codonopsis pilosula Glucofructan: Optimization, Structure, and Immunoregulatory Activity

In recent years, multiple edible polysaccharides from Codonopsis pilosula were mainly isolated with high average molecular weights and exhibited various bioactivities, but it was proven that low-molecular-weight polysaccharides could exert stronger activities due to the superior water solubility and permeability. In the present study, the water-soluble polysaccharide C. pilosula with low molecular weight was isolated under ultrasonic assistance at 30 °C, the extraction process was optimized via response surface method (RSM), and the structure and immunoregulatory activity were further investigated. The maximum yield (4.86%) for crude polysaccharides (cCPPs) was obtained under following parameters: ultrasonic power of 370 W, liquid/material ratio of 33 mL/g, ultrasonic time of 81 min. Subsequently, the cCPPs were further purified through dialysis and Sephadex G-25 column to acquire purified polysaccharide (CPPs). Structural analysis indicated that CPPs was a glucofructan (average molecular weight of 4.23 × 10³ Da) with (2→1)-β-D-Fruf and (1→)-α-D-Glcp as the backbone branched by (2→6)-β-D-Fruf. Additionally, CPPs could enhance immunoregulatory function by stimulating NO production and cytokine (IL-6 and TNF-α) secretion of RAW264.7 macrophages dose-dependently, which presented no cytotoxic effects. These data suggest that CPPs have the potential to be used as a nutritional dietary compound and natural immunostimulant supplement in the food industry.

Structure–immunomodulatory activity relationships of dietary polysaccharides

Polysaccharides are usually composed of more than ten monosaccharide units, which are connected by linear or branched glycosidic bonds. The immunomodulatory effect of natural polysaccharides is one of the most important bioactive function. In this review, molecular weight, monosaccharide (including galactose, mannose, rhamnogalacturonan-I arabinogalactan and uronic acid), functional groups (namely sulfate, selenium, and acetyl groups), types of glycoside bond connection (including β-1,3-D-glucosyl, α-1,4-D-glucosyl, β-1,4-D-glucosyl, α-1,6-D-glucosyl, β-1,4-D-mannosyl, and β-1,4-D-Xylopyranosyl), conformation and the branching degrees are systematically identified as their contribution to the immunostimulatory activity of polysaccharides. At present, studies on the structure-activity relationships of polysaccharides are limited due to their low purity and high heterogeneity. However, it is an important step in providing useful guidance for dietary supplements with polysaccharides. The chemical structures and the process of immune responses induced are necessary to be discussed. Polysaccharides may bind with the cell surface receptors to modulate immune responses. This review mainly discusses the structure-activity relationship of dietary polysaccharides.

•

Structure - activity relationships of polysaccharides with immune-enhancing effect are proposed.

•

Polysaccharides with the higher molecular weight are helpful to improve immunity.

•

Higer galactose, mannose, rhamnogalacturonan-I, arabinogalacta,n and uronic acid contents have immunoregulation.

The activation effects of fucoidan from sea cucumber Stichopus chloronotus on RAW264.7 cells via TLR2/4-NF-κB pathway and its structure-activity relationship

Sea cucumber Stichopus chloronotus is a traditional tonic food with high nutritive value in Southern China. Fucoidan from sea cucumber Stichopus chloronotus (Fuc-Sc) is its main bio-active polysaccharide, the immune-activation effects of which have been fully investigated on RAW264.7 cells in the present study. The results indicated that Fuc-Sc could stimulate the RAW264.7 cells by promoting the production of NO, TNF-α, IL-6 and IL-10. Western blot and RT-PCR analysis revealed that TLR4 and TLR2 were involved in the recognition of Fuc-Sc and activation of downstream NF-κB signal pathway. Moreover, the chemical structure parameter molecular weight showed obvious impact on the stimulation effects of Fuc-Sc on NO production. Degraded product of Fuc-Sc with weight average molecular weight of 113.1 × 10⁴ Da exhibited higher activities than that of intact Fuc-Sc, suggesting the existent of optimum chain length to exert its highest activities. Taken together, Fuc-Sc exerted its immunostimulating activity via TLR2/4 activation of NF-κB pathway and showed potentials to be a good immunoadjuvant.

Structural characterization and immunomodulatory mechanisms of two novel glucans from Morchella importuna fruiting bodies

Two novel glucans named MIPB50-W and MIPB50-S-1 were obtained from edible Morchella importuna with molecular weights (M_w) of 939.2 kDa and 444.5 kDa, respectively. MIPB50-W has a backbone of α-(1 → 4)-d-glucan, which was substituted at O-6 position by α-d-Glcp-(1→. Moreover, MIPB50-S-1 has a backbone of α-(1 → 4)-d-glucan, which was substituted at O-6 position by α-d-Glcp-(1 → 6)-α-d-Glcp-(1→. This is the first report about glucan found in Morchella mushrooms. Furthermore, MIPB50-W and MIPB50-S-1 strengthened the phagocytosis function and the promoted secretion of interleukins (IL)-6/tumor necrosis factor-alpha (TNF-α) and nitric oxide (NO), which induced the activation of Toll-like receptor 2 (TLR2), TLR4 as well as mitogen activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) pathways. Interestingly, MIPB50-S-1 performed the better immunomodulatory activity than that of MIPB50-W in almost all tests. Therefore, MIPB50-W and MIPB50-S-1 are potential immune-enhancing components of functional foods.

Activation of RAW264.7 cells by PCp-I, a polysaccharide from Psoralea corylifolia L, through NF-κB/MAPK signalling pathway

PCp-I is a polysaccharide isolated and identified from the Psoralea corylifolia L. by our research group. In this study, the immunomodulatory effects of PCp-I on RAW264.7 cells was evaluated. PCp-I could enhance the level of NO along with up-regulation of iNOS mRNA in RAW264.7 cells. The PCp-I could significantly up-regulate the mRNA expression of TNF-α and IL-6 in RAW264.7 cells, and then the expression of TNF-α, IL-6, ROS and the phagocytic activity were increased. Additionally, PCp-I could significantly up-regulate the phosphorylation level of p65, p38, ERK and JNK proteins, which proved that PCp-I could activate the macrophages by MAPKs and NF-κB signalling pathway and the TLR4 may be one of the receptors of PCp-I regulate the RAW264.7 cells.

Immune-Enhancing Activity of Aqueous Extracts from Artemisia rupestris L. via MAPK and NF-kB Pathways of TLR4/TLR2 Downstream in Dendritic Cells

Artemisia rupestris L. has long been used as a traditional herbal medicine owing to its immunomodulatory activity. Aqueous extracts of Artemisia rupestris L. (AEAR) contain the main functional component and can activate the maturation of dendritic cells (DCs) and enhance the adaptive immunity as the adjuvant against infections. To explore the underlying mechanism of immunomodulatory activities of AEAR, DCs were produced from bone-marrow cells of mice and the effects of AEAR on cell viability were assessed by the Cell Counting Kit 8 (CCK8) method and annexin V/propidium iodide staining assays. Then, the effects of AEAR on the morphology, maturation, and function of DCs were detected using a microscope, flow cytometry-based surface receptor characterization, and endocytosis assays. The secretion levels of cytokines were then analyzed with enzyme-linked immunosorbent assay (ELISA). The activation state of DCs was evaluated by the mixed lymphocyte reaction (MLR). The activity of MAPKs and NF-κB pathways, which were involved in the regulation of AEAR on DCs, was further detected by Western blot. AEAR did not have a cytotoxic effect on DCs or mouse splenocytes. AEAR remarkably enhanced the phenotypic maturation of DCs and promoted the expression of costimulatory molecules and the secretion of cytokines in DCs. AEAR also significantly decreased the phagocytic ability of DCs and augmented the abilities of DCs to present antigens and stimulate allogeneic T-cell proliferation. Simultaneously, AEAR potently activated toll-like receptor (TLR)4-/TLR2-related MAPKs and induced the degradation of IκB and the translocation of NF-κB. In short, AEAR can profoundly enhance the immune-modulating activities of DCs via TLR4-/TLR2-mediated activation of MAPKs and NF-κB signaling pathways and is a promising candidate immunopotentiator for vaccines.

Immunomodulatory effects of fucosylated chondroitin sulfate from Stichopus chloronotus on RAW 264.7 cells

Sea cucumbers were nutritional food and traditional Chinese medicine. In this study, fucosylated chondroitin sulfate from sea cucumber Stichopus chloronotus (fCS-Sc), a potential anticoagulant agent and immunological adjuvant, was investigated for its immune activation effects on RAW 264.7 macrophage for the first time. The results indicated that fCS-Sc could significantly promote the proliferation, the pinocytic activity of RAW 264.7 cells, and the production of NO, TNF-α, IL-1β, and IL-6. The fluorescence labeling assay indicated that fCS-Sc could bind to the macrophage. Moreover, the specific pattern recognition receptor inhibition assays showed that toll-like receptor 4 (TLR4) and TLR2 were involved in the recognition of fCS-Sc. Western blot assays indicated that fCS-Sc could induce degradation of cytoplasm IκB-α, and promotion of NF-κB p65 subunit translocation to nucleus, leading to a functional improvement of macrophage through NF-κB pathway. The results suggested that fCS-Sc might served as a promising candidate of immunomodulator.

Preparation, structural characterization, and bioactivity of PHPD-IV-4 derived from Porphyra haitanensis

Polysaccharides are a major active component of Porphyra haitanensis, which is an important food source in many countries. Four different molecular-weight fractions, namely PHPD-I (329 kDa), PHPD-II (203 kDa), PHPD-III (128 kDa), and PHPD-IV (10 kDa), were obtained from P. haitanensis polysaccharides by degradation using the H₂O₂/ascorbic acid system. PHPD-IV elicited the highest level of antioxidant and immunostimulatory activity among the four fractions. PHPD-IV was purified by DEAE-cellulose column and five fractions were obtained, designated PHPD-IV-1-PHPD-IV-5. PHPD-IV-4 displayed the greatest biological activity by up-regulating the phosphorylation of MAPK signalling molecules. PHPD-IV-4 was further purified, and its structure was characterized by monosaccharide composition and 1/2D-NMR analysis. The result revealed that PHPD-IV-4 was repeated units of → 3) β-d-galactose (1 → 4) 3, 6-anhydro-α-l-galactose (1→, and → 3) β-d-galactose (1 → 4) α-l-galactose-6-S (1→. This study provides a theoretical basis for the utilisation and structure-activity assessment of P. haitanensis polysaccharides.

Antimicrobial and Immunomodulatory Effect of Gum Arabic on Human and Bovine Granulocytes Against Staphylococcus aureus and Escherichia coli

Gum arabic (GA) is a traditional herbal medicine from Acacia Senegal (L.) Willdenow trees, which consist of a complex mixture of polysaccharides and glycoproteins. It is used in daily applications for several diseases and is considered to protect against bacterial infections. The detailed mechanisms behind these observations are still unclear. In this study, we investigated the direct antibacterial activity of GA water and ethanol extracts against Staphylococcus (S.) aureus or Escherichia (E.) coli and the immunomodulating properties of those extracts on granulocytes as a first line of defense against bacteria. Firstly, the direct antimicrobial effect of GA was tested on three different S. aureus strains and two E. coli strains. The growth of bacteria was analyzed in the presence of different GA concentrations over time. GA water as well as ethanol extracts showed a significant growth inhibition in a concentration-dependent manner in the case of S. aureus Newman, S. aureus Rd5, and E. coli 25922, but not in the case of S. aureus USA300 and E. coli K1. Transmission electron microscopic analysis confirmed an antibacterial effect of GA on the bacteria. Secondly, the immunomodulatory effect of GA on the antimicrobial activity of bovine or human blood-derived granulocytes was evaluated. Interestingly, water and ethanol extracts enhanced antimicrobial activity of granulocytes by the induction of intracellular ROS production. In line with these data, GA increased the phagocytosis rate of E. coli. No effect was seen on neutrophil extracellular trap (NET) formation that mediates killing of extracellular bacteria such as S. aureus. In conclusion, we show that GA exhibits a direct antibacterial effect against some S. aureus and E. coli strains. Furthermore, GA boosts the antimicrobial activities of granulocytes and increases intracellular ROS production, which may lead to more phagocytosis and intracellular killing. These data might explain the described putative antimicrobial activity of GA used in traditional medicine.

Immunomodulatory effects of an acidic polysaccharide fraction from herbal Gynostemma pentaphyllum tea in RAW264.7 cells

A new acidic polysaccharide (GPTP-3) with a molecular weight of 2.49 × 10⁶ Da was extracted and purified from Gynostemma pentaphyllum tea.

Comparative cardio and developmental toxicity induced by the popular medicinal extract of Sutherlandia frutescens (L.) R.Br. detected using a zebrafish Tuebingen embryo model

Background

Sutherlandia frutescens is one of the most promising commercialized, indigenous and medicinal plants of South Africa that is used as an immune-booster, and a traditional treatment for cancer. However, few studies report on its toxicology and dosage in vivo. There is still room to better understand its cytotoxicity effects in animal systems.

Methods

We prepared two extracts, one with 80% (v/v) ethanol, and the other, with water. Both were studied to determine the maximum tolerable concentration when extracts were applied at 0 to 200 μg/ml to a Tuebingen zebrafish embryo line. The development of zebrafish embryos after 24 h post fertilization (hpf) was studied. A concentration range of 5 μg/ml to 50 μg/ml was then chosen to monitor the ontological development of cultured embryos. A liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) method was used to study the differences of the two experimental extracts. Chemical variation between the extracts was illustrated using chemometrics.

Results

Both extracts led to bleeding and pericardial cyst formation when applied at high concentrations to the zebrafish embryo culture. Chronic teratogenic toxicities, leading to pericardial edema, yolk sac swelling, and other abnormal developmental characteristics, were detected. The aqueous extracts of S. frutescens were less toxic to the larvae than the ethanol extracts, validating preference for aqueous preparations when used in traditional medicine. Chemical differences between the water extracts and alcoholic extracts were analysed using LC-MS/MS. A supervised metabolomics approach, targeting the sutherlandiosides and sutherlandins using orthogonal partial least squares-discriminant analysis (OPLS-DA), illustrated that sutherlandiosides were the main chemical features that can be used to distinguish between the two extracts, despite the extracts being highly similar in their chemical constituents.

Conclusion

The water extract caused less cytotoxic and abnormal developmental effects compared to the ethanolic extract, and, this is likely due to differences in concentrations of extracted chemicals rather than the chemical profile per se. This study provides more evidence of cytotoxicity effects linked to S. frutescens using the zebrafish embryo bioassay as a study tool.

Electronic supplementary material

The online version of this article (10.1186/s12906-018-2303-9) contains supplementary material, which is available to authorized users.

Immunomodulatory effects of a bioactive fraction of Strobilanthes crispus in NMU-induced rat mammary tumor model

ETHNOPHARMACOLOGICAL RELEVANCE

Strobilanthes crispus Blume is traditionally consumed among local Malay and indigenous communities for the treatment of cancer and other ailments such as gastrointestinal disorders, inflammatory wounds of snake bite and immune system activation amongst others. We previously demonstrated that a bioactive fraction of S. crispus leaves (F3) was cytotoxic to breast cancer cells in vitro and inhibited tumor growth in N-methyl-N-nitrosourea (NMU)-induced breast cancer rat model. F3 also normalized the white blood cell count in the tumor-bearing animals, indicating its potential immuno-stimulatory effect.

AIM OF THE STUDY

To evaluate the immune stimulatory effects of F3 from S. crispus in NMU-induced rat mammary tumor model.

MATERIALS AND METHODS

Immunohistochemistry analysis of cellular immune parameters (CD4⁺ or CD8⁺ T cells, CIITA, MHC-II and CD68) was performed on NMU-induced rat mammary tumor nodules, followed by evaluation of the serum level of 34 cytokines using the cytokine antibody array.

RESULTS

Significant increase in MHC-II, CD4⁺ and CD8⁺ T cell and CIITA expression by tumor cells was observed in F3-treated rats compared to the tumor control group. F3-treated rats also displayed a significant decrease in the serum level of CCL2 and CD68⁺ infiltrating macrophages. Serum IFN-γ level in this group was increased by 1.7-fold suggesting enhanced infiltration of T cells, and upregulation of CIITA and MHC-II expression in the tumor cells might be triggered by F3-induced production of IFN-γ.

CONCLUSION

Our findings demonstrated for the first time that a subfraction from S. crispus, F3, is capable of activating the immune system in rats-bearing NMU-induced mammary tumor, which may contribute to the anticancer effects of F3, and additionally support the traditional use of S. crispus leaves to boost the immune system.

Differential Role of B Cells and IL-17 Versus IFN-γ During Early and Late Rejection of Pig Islet Xenografts in Mice

BACKGROUND

Xenogeneic islet transplantation is an emerging therapeutic option for diabetic patients. However, immunological tolerance to xenogeneic islets remains a challenge.

METHODS

The current study used a pig-to-mouse discordant xenogeneic islet transplant model to examine antidonor xenogeneic immune responses during early and late rejection and to determine experimental therapeutic interventions that promote durable pig islet xenograft survival.

RESULTS

We found that during early acute rejection of pig islet xenografts, the rejecting hosts exhibited a heavy graft infiltration with B220 B cells and a robust antipig antibody production. In addition, early donor-stimulated IL-17 production, but not IFN-γ production, dominated during early acute rejection. Recipient treatment with donor apoptotic 1-ethyl-3-(3'-dimethylaminopropyl)-carbodiimide-treated splenocytes significantly inhibited antidonor IL-17 response, and when combined with B cell depletion and a short course of rapamycin led to survival of pig islet xenografts beyond 100 days in approximately 65% recipients. Interestingly, treated recipients in this model experienced late rejection between 100 and 200 days posttransplant, which coincided with B cell reconstitution and an ensuing emergence of a robust antidonor IFN-γ, but not IL-17, response.

CONCLUSIONS

These findings reveal that early and late rejection of pig islet xenografts may be dominated by different immune responses and that maintenance of long-term xenogeneic tolerance will require strategies that target the temporal sequence of antixenogeneic immune responses.

Immunomodulatory Activity of Octenyl Succinic Anhydride Modified Porang (Amorphophallus oncophyllus) Glucomannan on Mouse Macrophage-Like J774.1 Cells and Mouse Primary Peritoneal Macrophages

Porang is a local plant of Indonesia, which has a high content of glucomannan. In this study, porang glucomannan (PG) was esterified with octenyl succinic anhydride (OSA) to enhance emulsion properties to be widely used in food industry. OSA-modified PG (OSA-PG) enhanced the phagocytosis activity of macrophage-like J774.1 cells and mouse peritoneal macrophages. In addition, OSA-PG increased the production of IL-6 and TNF-α by enhancing their gene expression. Immunoblot analysis displayed that OSA-PG tended to activate both nuclear factor-κB and mitogen-activated protein kinase cascades. Treatment of OSA-PG with polymyxin B revealed that cytokine production induced by OSA-PG was not caused by endotoxin contamination. Our findings also indicated that OSA-PG activates macrophages through not only Toll-like receptor (TLR) 4, but another receptor. Overall findings suggested that OSA-PG has a potential as an immunomodulatory food factor by stimulating macrophages.

Chemical characterization of a novel polysaccharide ASKP-1 from Artemisia sphaerocephala Krasch seed and its macrophage activation via MAPK, PI3k/Akt and NF-κB signaling pathways in RAW264.7 cells

The aim of this study was to investigate the molecular mechanism underlying the immunomodulatory effect of the purified Artemisia sphaerocephala Krasch seed polysaccharide (ASKP-1) in RAW264.7 macrophages.

Immunomodulatory effect of APS and PSP is mediated by Ca2+-cAMP and TLR4/NF-κB signaling pathway in macrophage

OBJECTIVE

This study is to investigate the role of second messengers and TLR4/NF-κB signaling pathway in the immunomodulatory activities of Astragalus polysaccharide (APS) and Polysaccharopeptide (PSP) in macrophages.

METHODS

RAW 264.7 macrophage cells were treated with APS, PSP, lipopolysaccharide (LPS), or NiCl₂. Power-spectral method was used to detect protein kinase C (PKC) and Griess reaction to detect nitric oxide (NO). ELISA was conducted to detect cyclic adenosine monophosphate (cAMP), diglycerides (DAG), inositol 1, 4, 5-triphosphate (IP3), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). Confocal laser scanning microscopy was performed to detect calcium level. qRT-PCR and Western blot was used to detect mRNA and protein expression of NF-κB.

RESULTS

APS and PSP significantly increased the concentrations of intracellular second messengers (NO, cAMP, DAG, IP3, Ca²⁺) and the activity of PKC in macrophages (p<0.05).The intracellular NF-κB mRNA and protein levels were significantly increased in macrophages treated by APS and PSP (p<0.05), whereas those were significantly decreased after NiCl₂ incubation (p<0.05). Similarly, the secretion of TNF-α and IL-6 were significantly decreased by the treatment of NiCl₂.

CONCLUSION

Our findings strongly suggest that Ca²⁺-cAMP and TLR4/NF-κB signaling pathways are, at least partly, involved in APS and PSP mediated immunomodulatory activities in macrophages.

An Investigation into the Immunomodulatory Activities of Sutherlandia frutescens in Healthy Mice

Sutherlandia frutescens is a medicinal plant that has been traditionally used in southern Africa for cancers, infections, and inflammatory conditions. We recently published experiments demonstrating that an aqueous extract of S. frutescens possessed potent immune-stimulatory activity. This work was carried out with murine macrophages, an immune cell type that plays a pivotal role in host defense from infection and in shaping host inflammatory and immune responses. Here, we conducted a series of follow-up experiments to explore the impact of consuming S. frutescens on host response to bacterial challenge using healthy mice. We found that feeding mice a diet containing S. frutescens failed to significantly alter host response to systemic infection by either a gram-positive or gram-negative bacterium (i.e., L. monocytogenes and E. coli, respectively). In contrast to the in vitro observations, we found no evidence that S. frutescens consumption stimulated in vivo inflammatory responses; instead, consumption of S. frutescens tended to diminish in vivo inflammatory responses. Several possible reasons for this are discussed.

Immunostimulatory effect of spinach aqueous extract on mouse macrophage-like J774.1 cells and mouse primary peritoneal macrophages

We herein report the immunostimulatory effect of spinach aqueous extract (SAE) on mouse macrophage-like J774.1 cells and mouse primary peritoneal macrophages. SAE significantly enhanced the production of interleukin (IL)-6 and tumor necrosis factor-α by both J774.1 cells and peritoneal macrophages by enhancing the expression levels of these cytokine genes. In addition, the phagocytosis activity of J774.1 cells was facilitated by SAE. Immunoblot analysis revealed that SAE activates mitogen-activated protein kinase and nuclear factor-κB cascades. It was found that SAE activates macrophages through not only TLR4, but also other receptors. The production of IL-6 was significantly enhanced by peritoneal macrophages from SAE-administered BALB/c mice, suggesting that SAE has a potential to stimulate macrophage activity in vivo. Taken together, these data indicate that SAE would be a beneficial functional food with immunostimulatory effects on macrophages.

Phytochemicals and botanical extracts regulate NF-κB and Nrf2/ARE reporter activities in DI TNC1 astrocytes

The increase in oxidative stress and inflammatory responses associated with neurodegenerative diseases has drawn considerable attention towards understanding the transcriptional signaling pathways involving NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) and Nrf2 (Nuclear Factor Erythroid 2-like 2). Our recent studies with immortalized murine microglial cells (BV-2) demonstrated effects of botanical polyphenols to inhibit lipopolysaccharide (LPS)-induced nitric oxide (NO) and enhance Nrf2-mediated antioxidant responses (Sun et al., 2015). In this study, an immortalized rat astrocyte (DI TNC1) cell line expressing a luciferase reporter driven by the NF-κB or the Nrf2/Antioxidant Response Element (ARE) promoter was used to assess regulation of these two pathways by phytochemicals such as quercetin, rutin, cyanidin, cyanidin-3-O-glucoside, as well as botanical extracts from Withania somnifera (Ashwagandha), Sutherlandia frutescens (Sutherlandia) and Euterpe oleracea (Açaí). Quercetin effectively inhibited LPS-induced NF-κB reporter activity and stimulated Nrf2/ARE reporter activity in DI TNC1 astrocytes. Cyanidin and the glycosides showed similar effects but only at much higher concentrations. All three botanical extracts effectively inhibited LPS-induced NF-κB reporter activity. These extracts were capable of enhancing ARE activity by themselves and further enhanced ARE activity in the presence of LPS. Quercetin and botanical extracts induced Nrf2 and HO-1 protein expression. Interestingly, Ashwagandha extract was more active in inducing Nrf2 and HO-1 expression in DI TNC1 astrocytes as compared to Sutherlandia and Açaí extracts. In summary, this study demonstrated NF-kB and Nrf2/ARE promoter activities in DI TNC1 astrocytes, and further showed differences in ability for specific botanical polyphenols and extracts to down-regulate LPS-induced NF-kB and up-regulate the NRF2/ARE activities in these cells.

Inhibition of Hedgehog-Signaling Driven Genes in Prostate Cancer Cells by Sutherlandia frutescens Extract

Sutherlandia frutescens (L) R. Br. (Sutherlandia) is a South African botanical that is traditionally used to treat a variety of health conditions, infections and diseases, including cancer. We hypothesized Sutherlandia might act through Gli/ Hedgehog (Hh)-signaling in prostate cancer cells and used RNA-Seq transcription profiling to profile gene expression in TRAMPC2 murine prostate cancer cells with or without Sutherlandia extracts. We found 50% of Hh-responsive genes can be repressed by Sutherlandia ethanol extract, including the canonical Hh-responsive genes Gli1 and Ptch1 as well as newly distinguished Hh-responsive genes Hsd11b1 and Penk.

Unveiling the anti-inflammatory activity of Sutherlandia frutescens using murine macrophages

Sutherlandia frutescens is a botanical widely used in southern Africa for treatment of inflammatory and other conditions. Previously, an ethanolic extract of S. frutescens (SFE) has been shown to inhibit the production of reactive oxygen species (ROS) and nitric oxide (NO) by murine neurons and a microglia cell line (BV-2 cells). In this study we sought to confirm the anti-inflammatory activities of SFE on a widely used murine macrophage cell line (i.e., RAW 264.7 cells) and primary mouse macrophages. Furthermore, experiments were conducted to investigate the anti-inflammatory activity of the flavonol and cycloartanol glycosides found in high quantities in S. frutescens. While the SFE exhibited anti-inflammatory activities upon murine macrophages similar to that reported with the microglia cell line, this effect does not appear to be mediated by sutherlandiosides or sutherlandins. In contrast, chlorophyll in our extracts appeared to be partly responsible for some of the activity observed in our macrophage-dependent screening assay.