Antibacterial, antifungal and in vivo anticancer activities of chitin-binding lectins from Tomato (Solanum lycopersicum) fruits

Omics-driven bioinformatics for plant lectins discovery and functional annotation - A comprehensive review

Lectins are known for their specific and reversible binding capacity to carbohydrates. These molecules have been particularly explored in plants due to their reported properties, highlighting antimicrobial, antiviral, anticancer, antiparasitic, insecticidal, and immunoregulatory actions. The increasing availability of lectin and lectin-like sequences in omics data banks provides an opportunity to identify important candidates, inferring their roles in essential signaling pathways and processes in plants. Bioinformatics enables a fast and low-cost scenario for elucidating sequences and predicting functions in the lectinology universe. Thus, this review addresses the state of the art of annotation, structural characterization, classification, and predicted applications of plant lectins. Their allergenic and toxic properties are also discussed, as well as tools for predicting such effects from the primary structure. This review uncovers a promising scenario for plant lectins and new study possibilities, particularly for studies in lectinology in the omics era.

Bioactivity of biogenic silver/silver chloride nanoparticles from Maranta arundinacea rhizome extract: Antibacterial and antioxidant properties with anticancer potential against Ehrlich ascites carcinoma and human breast cancer cell lines

Introduction

This study explores the synthesis and characterization of silver/silver chloride nanoparticles (Ag/AgCl-NPs) using Maranta arundinacea rhizome extract and evaluates their bioactivities, including antibacterial, antioxidant, and anticancer potentials.

Methods

The synthesis of Ag/AgCl-NPs was initially confirmed by a color change and a sharp peak at 463 nm in UV-visible spectroscopy. Further characterization was conducted using scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and fourier transform infrared spectroscopy (FTIR). Antibacterial properties were checked against four pathogenic bacteria (Shigella boydii, Escherichia coli, Shigella dysenteriae, and Staphylococcus aureus), and antioxidant activities were assessed using DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid) assay. In addition, the anticancer potential was evaluated in vitro using MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) colorimetric assay and in vivo using the mouse models. Finally, toxicity was determined by employing the brine shrimp nauplii lethality assay.

Results

Ag/AgCl-NPs most effectively inhibited the growth of Staphylococcus aureus, showing maximum zone of inhibition and 7 μg/mL of minimum inhibitory concentration (MIC), and prevented the biofilm formation by Escherichia coli at 40 μg/mL. They displayed antioxidant activities against DPPH and ABTS with IC50 values of 90.65 and 24.34 μg/mL, respectively. In vitro, they inhibited 61.96 % EAC and 49.63 % MCF-7 cells growth at 32 and 128 μg/mL, respectively. Subsequently, inhibition rates of EAC cells growth in mice were measured as 38.30 %, 57.38 %, and 31.81 % after employing 2.5, 5, and 10 mg/kg/day of Ag/AgCl-NPs, respectively. Moreover, Ag/AgCl-NPs treated mice were found to carry more apoptotic EAC cells with distorted morphology. Treated mice showed decreased tumor weight, increased mean survival time, and a lifespan increase of up to 30 %, with improved hematological parameters. Later, Ag/AgCl-NPs exhibited moderate toxicity with an LC50 value of 208.41 μg/mL in brine shrimp nauplii lethality assay.

Conclusion

The promising antibacterial, antioxidant, and anticancer activities along with mild toxicity suggest the potential biomedical uses of Maranta arundinacea rhizome extract-mediated Ag/AgCl-NPs.

Exploring the astonishing beneficial effects of round gourd (Praecitrullus fistulosus) and plant lectins towards cancer: A comprehensive review

Praecitrullus fistulosus, commonly known as round gourd or tinda, is a remarkable source of bioactive substances like polyphenols, antioxidants, carotene, magnesium, and vitamin C. It is considered one of the Cucurbitaceae family due to its medicinal features. Plant lectins are carbohydrate-binding proteins that can bind and identify the carbohydrate moieties upon cancerous cells demonstrated some anticancer potentials. Several plant lectins are helpful as cancer biomarkers because they can find cancer cells and contribute to cell death initiation via apoptosis and autophagy, suggesting the possible role of cancer-inhibiting pathways. Therefore, round gourd and lectins might be useful in the controlling of cancer. This study compiled the most recent scientific literature regarding the round gourd and numerous plant lectins, and the clinical trials of lectins exploring their effects on cancer were examined. Research according to the literature, round gourd, and lectins demonstrated pharmacological alterations not only in cancer but in many other disorders as well. Thus, clinical investigations proved the beneficial impacts of round gourd and lectins on cancer due to their antioxidants, anti-inflammatory, and anticarcinogenic properties. Further studies are required to fully comprehend the potential applications of these plant-derived compounds against cancer, as well as to identify the round gourd components and clarify their mode of action.

Carbohydrate-Binding Properties and Antimicrobial and Anticancer Potential of a New Lectin from the Phloem Sap of Cucurbita pepo

A Cucurbita phloem exudate lectin (CPL) from summer squash (Cucurbita pepo) fruits was isolated and its sugar-binding properties and biological activities were studied. The lectin was purified by affinity chromatography and the hemagglutination assay method was used to determine its pH, heat stability, metal-dependency and sugar specificity. Antimicrobial and anticancer activities were also studied by disc diffusion assays and in vivo and in vitro methods. The molecular weight of CPL was 30 ± 1 KDa and it was stable at different pH (5.0 to 9.0) and temperatures (30 to 60 °C). CPL recovered its hemagglutination activity in the presence of Ca2+. 4-nitrophenyl-α-D-glucopyranoside, lactose, rhamnose and N-acetyl-D-glucosamine strongly inhibited the activity. With an LC50 value of 265 µg/mL, CPL was moderately toxic and exhibited bacteriostatic, bactericidal and antibiofilm activities against different pathogenic bacteria. It also exhibited marked antifungal activity against Aspergillus niger and agglutinated A. flavus spores. In vivo antiproliferative activity against Ehrlich ascites carcinoma (EAC) cells in Swiss albino mice was observed when CPL exerted 36.44% and 66.66% growth inhibition at doses of 3.0 mg/kg/day and 6.0 mg/kg/day, respectively. A 12-day treatment by CPL could reverse their RBC and WBC counts as well as restore the hemoglobin percentage to normal levels. The MTT assay of CPL performed against human breast (MCF-7) and lung (A-549) cancer cell lines showed 29.53% and 18.30% of inhibitory activity at concentrations of 128 and 256 µg/mL, respectively.

The chitin-binding domain of Bacillus thuringiensis ChiA74 inhibits gram-negative bacterial and fungal pathogens of humans and plants

The chitinase ChiA74 is synthesized by Bacillus thuringiensis and possesses a modular organization composed of four domains. In the C-terminal of the enzyme is located the chitin-binding domain (CBD), which has not been isolated as a single unit or characterized. Here, we aimed to isolate the ChiA74's CBD as a single unit, determine the binding properties, and evaluate its antimicrobial and hemolytic activities. We cloned the ChiA74's CBD and expressed it in Escherichia coli BL21. The single domain was purified, analyzed by SDS-PAGE, and characterized. The recombinant CBD (rCBD) showed a molecular mass of ∼14 kDa and binds strongly to α-chitin, with Kd and Bmax of ∼4.7 ± 0.9 μM and 1.5 ± 0.1 μmoles/g chitin, respectively. Besides, the binding potential (Bmax/Kd) was stronger for α-chitin (∼0.31) than microcrystalline cellulose (∼0.19). It was also shown that the purified rCBD inhibited the growth of the clinically relevant Gram-negative bacteria (GNB) Vibrio cholerae, and V. parahemolyticus CVP2 with minimum inhibitory concentrations (MICs) of 121 ± 9.9 and 138 ± 3.2 μg/mL, respectively, and of one of the most common GNB plant pathogens, Pseudomonas syringae with a MIC of 230 ± 13.8 μg/mL. In addition, the rCBD possessed antifungal activity inhibiting the conidia germination of Fusarium oxysporum (MIC = 192 ± 37.5 μg/mL) and lacked hemolytic and agglutination activities against human erythrocytes. The significance of this work lies in the fact that data provided here show for the first time that ChiA74's CBD from B. thuringiensis has antimicrobial activity, suggesting its potential use against significant pathogenic microorganisms. Future works will be focused on testing the inhibitory effect against other pathogenic microorganisms and elucidating the mechanism of action.

Antimicrobial, anti-inflammatory and anti-arthritic activity of hemolymph lectin (NagLec) isolated from the freshwater crab, Oziotelphusanaga

Lectins are non-immune glycoproteins or proteins having a unique capacity to interact with carbohydrate ligands found on the surface of their host cells. In the present investigation, the lectin was purified from the hemolymph of freshwater crab, Oziotelphusa naga and its antimicrobial, anti-inflammatory and anti-arthritic activity was analysed. The preliminary characterization of the hemagglutinin was carried out to identify the erythrocyte and sugar specificity, optimum pH and temperature and cation dependency. The agglutinin was found to be highly specific to rabbit erythrocyte and inhibited by fetuin and α-lactose. Maximum hemagglutination activity was noted at pH 7.5-8 and temperature 20-40 °C. An O-acetyl sialic acid specific 75 kDa hemolymph lectin, designated as NagLec was isolated from the freshwater crab, Oziotelphusa naga by affinity chromatography on fetuin coupled Sepharose 4 B, with a purification fold of 185. The bacteria Staphylococcus aureus, Proteus mirabilis and fungus Candida albicans had the greatest zone of inhibition when treated with NagLec. The results of the Minimum inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) assays showed that the purified lectin inhibited the growth of Staphylococcus aureus at 0.031 and 0.065 μg/ml, which proved the bactericidal property of NagLec. NagLec generated alterations on the bacterial cells and led to protein leakage, which was dosage (24 and 48 μg/ml) and time dependent (10-40 min). COX and LOX enzyme was inhibited to 49.43% and 61.81% with 100 μg/ml concentration of NagLec respectively, demonstrating NagLec's ability to reduce inflammation. Furthermore, NagLec (500 μg) suppressed protein denaturation up to 77.12% whereas diclofenac sodium (a standard drug) was inhibited by 89.36%. The results indicate that NagLec, a sialic acid specific lectin isolated from the freshwater crab O. naga could be formulated as a nano drug in future owing to its antimicrobial, anti-inflammatory and anti-arthritic potential that could be targeted to specific pathogenic microbes and treat arthritis.

Proteins and their functionalization for finding therapeutic avenues in cancer: Current status and future prospective

Despite the remarkable advancement in the health care sector, cancer remains the second most fatal disease globally. The existing conventional cancer treatments primarily include chemotherapy, which has been associated with little to severe side effects, and radiotherapy, which is usually expensive. To overcome these problems, target-specific nanocarriers have been explored for delivering chemo drugs. However, recent reports on using a few proteins having anticancer activity and further use of them as drug carriers have generated tremendous attention for furthering the research towards cancer therapy. Biomolecules, especially proteins, have emerged as suitable alternatives in cancer treatment due to multiple favourable properties including biocompatibility, biodegradability, and structural flexibility for easy surface functionalization. Several in vitro and in vivo studies have reported that various proteins derived from animal, plant, and bacterial species, demonstrated strong cytotoxic and antiproliferative properties against malignant cells in native and their different structural conformations. Moreover, surface tunable properties of these proteins help to bind a range of anticancer drugs and target ligands, thus making them efficient delivery agents in cancer therapy. Here, we discuss various proteins obtained from common exogenous sources and how they transform into effective anticancer agents. We also comprehensively discuss the tumor-killing mechanisms of different dietary proteins such as bovine α-lactalbumin, hen egg-white lysozyme, and their conjugates. We also articulate how protein nanostructures can be used as carriers for delivering cancer drugs and theranostics, and strategies to be adopted for improving their in vivo delivery and targeting. We further discuss the FDA-approved protein-based anticancer formulations along with those in different phases of clinical trials.

Plant lectins: A new antimicrobial frontier

Pathogenic bacteria, viruses, fungi, parasites, and other microbes constantly change to ensure survival. Several pathogens have adopted strict and intricate strategies to fight medical treatments. Many drugs, frequently prescribed to treat these pathogens, are becoming obsolete and ineffective. Because pathogens have gained the capacity to tolerate or resist medications targeted at them, hence the term antimicrobial resistance (AMR), in that regard, many natural compounds have been routinely used as new antimicrobial agents to treat infections. Thus, plant lectins, the carbohydrate-binding proteins, have been targeted as promising drug candidates. This article reviewed more than 150 published papers on plant lectins with promising antibacterial and antifungal properties. We have also demonstrated how some plant lectins could express a synergistic action as adjuvants to boost the efficacy of obsolete or abandoned antimicrobial drugs. Emphasis has also been given to their plausible mechanism of action. The study further reports on the immunomodulatory effect of plant lectins and how they boost the immune system to curb or prevent infection.