Microgramma vacciniifolia (Polypodiaceae) fronds contain a multifunctional lectin with immunomodulatory properties on human cells

Microgramma vacciniifolia Frond Lectin: In Vitro Anti-leishmanial Activity and Immunomodulatory Effects Against Internalized Amastigote Forms of Leishmania amazonensis

PURPOSE

The treatment of leishmaniasis, an anthropozoonosis caused by Leishmania protozoa, is limited by factors, such as adverse effects, toxicity, and excessive cost, which has highlighted the importance of novel drugs. In this context, natural products have been considered as sources of antileishmanial agents. This study investigated the leishmanicidal activity of Microgramma vacciniifolia frond lectin (MvFL) on promastigotes and amastigotes of Leishmania amazonensis.

METHODS

The effects of MvFL on promastigote proliferation and macrophage infection by amastigotes were evaluated and mean inhibitory concentrations (IC50) were calculated. As a safety assessment, the hemolytic capacity of MvFL (6.25-200 µg/mL) against mouse and human erythrocytes was determined. Additionally, the ability of MvFL (6.25-100 µg/mL) to modulate lysosomal and phagocytic activities and the nitric oxide (NO) production by murine peritoneal macrophages was also investigated.

RESULTS

After 24 h, MvFL inhibited the proliferation of L. amazonensis promastigotes, with an IC50 of 88 µg/mL; however, hemolytic activity was not observed. MvFL also reduced macrophage infection by amastigotes with an IC50 of 52 µg/mL. Furthermore, treatment with MvFL reduced the number of amastigotes internalized by infected murine peritoneal macrophages by up to 68.9% within 48 h. At a concentration of 25 µg/mL, MvFL stimulated lysosomal activity of macrophages within 72 h, but did not alter phagocytic activity or induce NO production at any of the tested concentrations.

CONCLUSION

MvFL exerts antileishmanial activity and further studies are needed to assess its therapeutic potential in in vivo experimental models of leishmaniasis.

Non-seed plants are emerging gene sources for agriculture and insect control proteins

The non-seed plants (e.g., charophyte algae, bryophytes, and ferns) have multiple human uses, but their contributions to agriculture and research have lagged behind seed plants. While sharing broadly conserved biology with seed plants and the major crops, non-seed plants sometimes possess alternative molecular and physiological adaptations. These adaptations may guide crop improvements. One such area is the presence of multiple classes of insecticidal proteins found in non-seed plant genomes which are either absent or widely diverged in seed plants. There are documented uses of non-seed plants, and ferns for example have been used in human diets. Among the occasional identifiable toxins or antinutritive components present in non-seed plants, none include these insecticidal proteins. Apart from these discrete risk factors which can be addressed in the safety assessment, there should be no general safety concern about sourcing genes from non-seed plant species.

Anti-inflammatory, remorin-like protein from green marine Macroalga Caulerpa sertularioides (S.G.Gmel.) M.Howe

The most prevalent natural source of hydrocolloids, cosmetics, medications, and nutraceuticals is marine seaweed (macroalgae). Numerous bioactivities, including antiviral, anticancer, anti-inflammatory, and immunomodulatory characteristics, have been found in bioactive substances such as polyphenols and sulfated and non-sulfated polysaccharides. As a result, new start-up projects and industries based on seaweed are emerging in all regions of the world with abundant marine biodiversity. In this current investigation, the anti-inflammatory activity of two different marine macroalgae Caulerpa racemosa (CR) and Caulerpa sertularioides (CS) was evaluated. Consequently, CS demonstrated more anti-inflammatory and antioxidant effects at a lower dose than CR. The IC50 value for DPPH inhibition was 456.1 μg/mL, and 180.9 μg/mL for CS and CR respectively. A similar result was obtained in the case of protein denaturation (PD), membrane stabilization (MS), and protease inhibition (PI) anti-inflammatory assays with 127.2 μg/mL, 135.5 μg/mL, and 71.88 μg/mL for CR, and 66.78 μg/mL, 88.96 μg/mL, and 59.54 μg/mL for CS respectively. Based on the SDS-PAGE, the molecular weight of lectin responsible for the anti-inflammatory activity was determined as 17 kDa. Protein mass fingerprinting was performed for the particular lectin by in-gel trypsin digestion, MALDI-MS analysis, and Mascot peptide mass fingerprinting. Because of this, the unidentified lectin protein was discovered to be a remorin-like protein that shared 65% of its sequence with the remorin-like protein of Aegilops tauschii subsp. tauschii. Therefore, it is the hitherto report on the presence of remorin-like protein from the green macroalga Caulerpa sertularioides.

Inhibition of Carrageenan-Induced Acute Inflammation in Mice by the Microgramma vacciniifolia Frond Lectin (MvFL)

Most anti-inflammatory drugs used nowadays have an excessive cost and their prolonged use has been connected with several injurious effects. Thus, the search for new anti-inflammatory agents is increasing. Lectins are carbohydrate-interacting proteins that can modulate immune response and the release of inflammation mediators. The Microgramma vacciniifolia frond lectin (MvFL) was previously reported to be an immunomodulatory agent in vitro. This work aimed to evaluate the effects of MvFL on the in vivo inflammatory status in the carrageenan-induced peritonitis and paw edema, using female Swiss mice. The animals were pretreated intraperitoneally with MvFL (5 and 10 mg/kg). In the peritonitis assay, the total and differential migration of white blood cells was evaluated, as well as the levels of cytokines, nitric oxide (NO), and total proteins in the peritoneal fluid. In the paw edema evaluation, the paw volume was measured in the early (from 30 min–2 h) and late (3–4 h) phases of edema formation. MvFL (5 and 10 mg/kg) was efficient in reducing neutrophil infiltration, pro-inflammatory cytokines (IL-6, IL-17, and TNF-α), NO, and protein content in the peritoneal fluid. It also repressed the edema formation in the late phase of the assay. In conclusion, MvFL showed inhibitory effects in in vivo acute inflammation, which encouraged future studies exploiting its immunomodulatory ability.

Quantum dots conjugated to lectins from Schinus terebinthifolia leaves (SteLL) and Punica granatum sarcotesta (PgTeL) as potential fluorescent nanotools for investigating Cryptococcus neoformans

This study reports the development of conjugates based on quantum dots (QD)s and lectins from Schinus terebinthifolia leaves (SteLL) and Punica granatum sarcotesta (PgTeL). Cryptococcus neoformans cells were chosen to evaluate the efficiency of the conjugates. Lectins were conjugated to QDs via adsorption, and the optical parameters (emission and absorption) were monitored. Lectin stability in the conjugates towards denaturing agents was investigated via fluorometry. The conjugation was evaluated using fluorescence microplate (FMA) and hemagglutination (HA) assays. The labeling of the C. neoformans cell surface was quantified using flow cytometry and observed via fluorescence microscopy. The QDs-SteLL and QDs-PgTeL conjugates, obtained at pH 7.0 and 8.0, respectively, showed the maintenance of colloidal and optical properties. FMA confirmed the conjugation, and the HA assay indicated that the lectin carbohydrate-binding ability was preserved after conjugation. SteLL and PgTeL showed stability towards high urea concentrations and heating. Conjugates labeled over 90% of C. neoformans cells as observed via flow cytometry and confirmed through fluorescence microscopy. C. neoformans labeling by conjugates was inhibited by glycoproteins, suggesting specific interactions through the lectin carbohydrate-binding site. Thus, an effective protocol for the conjugation of SteLL or PgTeL with QDs was proposed, yielding new nanoprobes useful for glycobiological studies.

Evaluation of the In Vivo Acute Toxicity and In Vitro Hemolytic and Immunomodulatory Activities of the Moringa oleifera Flower Trypsin Inhibitor (MoFTI)

BACKGROUND

Protease inhibitors have been isolated from plants and present several biological activities, including immunomodulatory action.

OBJECTIVE

This work aimed to evaluate a Moringa oleifera flower trypsin inhibitor (MoFTI) for acute toxicity in mice, hemolytic activity on mice erythrocytes and immunomodulatory effects on mice splenocytes.

METHODS

The acute toxicity was evaluated using Swiss female mice that received a single dose of the vehicle control or MoFTI (300 mg/kg, i.p.). Behavioral alterations were observed 15-240 min after administration, and survival, weight gain, and water and food consumption were analyzed daily. Organ weights and hematological parameters were analyzed after 14 days. Hemolytic activity of MoFTI was tested using Swiss female mice erythrocytes. Splenocytes obtained from BALB/c mice were cultured in the absence or presence of MoFTI for the evaluation of cell viability and proliferation. Mitochondrial membrane potential (Δψm) and reactive oxygen species (ROS) levels were also determined. Furthermore, the culture supernatants were analyzed for the presence of cytokines and nitric oxide (NO).

RESULTS

MoFTI did not cause death or any adverse effects on the mice except for abdominal contortions at 15-30 min after administration. MoFTI did not exhibit a significant hemolytic effect. In addition, MoFTI did not induce apoptosis or necrosis in splenocytes and had no effect on cell proliferation. Increases in cytosolic and mitochondrial ROS release, as well as Δψm reduction, were observed in MoFTI-treated cells. MoFTI was observed to induce TNF-α, IFN-γ, IL-6, IL-10, and NO release.

CONCLUSION

These results contribute to the ongoing evaluation of the antitumor potential of MoFTI and its effects on other immunological targets.

Antinociceptive and Anti-Inflammatory Effects of Saline Extract and Lectin-Rich Fraction from Microgramma vacciniifolia Rhizome in Mice

Previous studies have characterized a saline extract from Microgramma vacciniifolia rhizome and its lectin (MvRL)-rich fraction with low acute toxicity. In the present study, we evaluated these preparations for acute toxicity (1,000 mg/kg) and antinociceptive and anti-inflammatory activities (100-400 mg/kg for the extract and 25-50 mg/kg for the fraction). No signs of toxicity were observed. Both the extract and fraction increased the latency period for nociception in the hot plate assay, decreased writhing induced by acetic acid, and promoted analgesic effects in phases 1 and 2 of the formalin test. The antinociceptive mechanism was attributed to interactions with opioid receptors and K⁺ ATPase channels. The extract and fraction decreased carrageenan-induced paw edema in 46.15 % and 77.22 %, respectively, at the highest doses evaluated. Furthermore, the fraction was shown to act on the bradykinin pathway. The ability to decrease leukocyte migration after treatment was also verified in the peritonitis and air pouch models. In exudates collected from air pouches, decreased tumor necrosis factor (TNF)-α and increased interleukin (IL)-10 levels were noted. Both the extract and fraction also effectively inhibited the development of granulomatous tissue. In conclusion, the substances investigated in this study can be used for the development of novel therapeutic options for pain and inflammatory processes.

Schinus terebinthifolia leaf lectin (SteLL) is an immunomodulatory agent by altering cytokine release by mice splenocytes

Schinus terebinthifolia leaf lectin (SteLL) was reported to be an antimicrobial and antitumor agent. In this work, we evaluated the immunomodulatory activity of SteLL on mice splenocytes and also determined its native molecular mass and putative sequence similarities with plant proteins. The effects of SteLL (12.5 μg/mL) on viability, cytosolic Ca²⁺ concentration ([Ca²⁺]_cyt), cytosolic and mitochondrial levels of reactive oxygen species (ROS), and mitochondrial transmembrane potential (ΔΨm) of mice splenocytes were determined. In addition, the culture supernatants were collected for quantification of interleukins (IL), tumor necrosis factor (TNF), interferon-gamma (IFN-γ) and nitric oxide (NO). SteLL showed a native molecular mass of 12.4 kDa and tandem mass spectrometry (MS/MS) ions search revealed similarities with adenosine triphosphate (ATP) synthase and F1-ATPase from plants (4% and 6% coverage, respectively). SteLL was not toxic to splenocytes, did not alter the [Ca²⁺]_cyt and ROS levels, and slightly reduced ΔΨm. The presence of SteLL stimulated the cells to release pro-inflammatory cytokines (IL-17A, TNF-α, IFN-γ and IL-2) and also of IL-4, an anti-inflammatory cytokine that can prevent exacerbated inflammation. SteLL induced decrease in the secretion of NO. In conclusion, SteLL has biotechnological potential as an immunomodulator agent for use in studies employing cultures of immune cells. In addition, the anti-infectious and antitumor properties of the leaves may involve the immunomodulation property of SteLL.

Evaluation of antitumor activity and toxicity of Schinus terebinthifolia leaf extract and lectin (SteLL) in sarcoma 180-bearing mice

ETHNOPHARMACOLOGICAL RELEVANCE

Schinus terebinthifolia Raddi is a plant broadly used in folk medicine and the use of its leaf extract as an antitumor agent has been reported.

AIM OF THE STUDY

To evaluate the antitumor potential and the toxicity of saline extract (SE) and lectin (SteLL) from S. terebinthifolia leaves in sarcoma 180-bearing mice.

MATERIALS AND METHODS

Cytotoxicity to sarcoma 180 cells was tested in vitro, and antitumor assay was performed using Swiss female mice. The treatments (0.15 M NaCl, negative control; methotrexate 1.5 mg/kg, positive control; SE 100 mg/kg; SteLL 1 and 5 mg/kg) by intraperitoneal injections started on the 8th day after tumor inoculation and lasted 7 days. It was analyzed: tumor weight; number and gauge of tumor vessels; hematological and biochemical parameters; histopathological changes; and occurrence of micronuclei in bone marrow cells.

RESULTS

SE and SteLL showed IC₅₀ values (concentrations that reduced cell viability to 50%) of 301.65 and 8.30 μg/mL, respectively. The lectin was able to induce apoptosis. Treatments with the extract and lectin caused a 57.6-73.6% reduction in tumor weight, which was not significantly different from the reduction in the methotrexate group. Tumors of animals treated with SteLL at 5 mg/kg showed reduced number of secondary vessels while the gauge was lower in all treated groups. In the groups treated with SteLL, tumors showed reduced and slightly vascularized parenchyma, with necrosis in the center and at the periphery. No alterations in the blood levels of urea, creatine, and glucose were detected while serum AST level was moderately increased in the SE group. Histopathological analysis revealed vacuolization and steatosis in the liver of animals treated with the extract and lectin. In addition, the treatments with SE and SteLL resulted in the reduction of filtration space and alterations in tubular architecture in kidneys. In respect to hematological parameters, it was only detected increase in the number of monocytes in SE group. The extract and lectin did not induce the formation of micronuclei in the bone marrow cells.

CONCLUSIONS

SE and SteLL had antitumor effect against sarcoma 180 without inducing hematological changes and genotoxic effects in mice; however, some degree of hepatic and renal toxicity was observed, suggesting the evaluation of drug delivery strategies in the future.