Utilization of a recombinant defensin from Maize (Zea mays L.) as a potential antimicrobial peptide

Application Value of Antimicrobial Peptides in Gastrointestinal Tumors

Gastrointestinal cancer is a common clinical malignant tumor disease that seriously endangers human health and lacks effective treatment methods. As part of the innate immune defense of many organisms, antimicrobial peptides not only have broad-spectrum antibacterial activity but also can specifically kill tumor cells. The positive charge of antimicrobial peptides under neutral conditions determines their high selectivity to tumor cells. In addition, antimicrobial peptides also have unique anticancer mechanisms, such as inducing apoptosis, autophagy, cell cycle arrest, membrane destruction, and inhibition of metastasis, which highlights the low drug resistance and high specificity of antimicrobial peptides. In this review, we summarize the related studies on antimicrobial peptides in the treatment of digestive tract tumors, mainly oral cancer, esophageal cancer, gastric cancer, liver cancer, pancreatic cancer, and colorectal cancer. This paper describes the therapeutic advantages of antimicrobial peptides due to their unique anticancer mechanisms. The length, net charge, and secondary structure of antimicrobial peptides can be modified by design or modification to further enhance their anticancer effects. In summary, as an emerging cancer treatment drug, antimicrobial peptides need to be further studied to realize their application in gastrointestinal cancer diseases.

Advances in Transdermal Delivery of Antimicrobial Peptides for Wound Management: Biomaterial-Based Approaches and Future Perspectives

Antimicrobial peptides (AMPs), distinguished by their cationic and amphiphilic nature, represent a critical frontier in the battle against antimicrobial resistance due to their potent antimicrobial activity and a broad spectrum of action. However, the clinical translation of AMPs faces hurdles, including their susceptibility to degradation, limited bioavailability, and the need for targeted delivery. Transdermal delivery has immense potential for optimizing AMP administration for wound management. Leveraging the skin's accessibility and barrier properties, transdermal delivery offers a noninvasive approach that can circumvent systemic side effects and ensure sustained release. Biomaterial-based delivery systems, encompassing nanofibers, hydrogels, nanoparticles, and liposomes, have emerged as key players in enhancing the efficacy of transdermal AMP delivery. These biomaterial carriers not only shield AMPs from enzymatic degradation but also provide controlled release mechanisms, thereby elevating stability and bioavailability. The synergistic interaction between the transdermal approach and biomaterial-facilitated formulations presents a promising strategy to overcome the multifaceted challenges associated with AMP delivery. Integrating advanced technologies and personalized medicine, this convergence allows the reimagining of wound care. This review amalgamates insights to propose a pathway where AMPs, transdermal delivery, and biomaterial innovation harmonize for effective wound management.

Plants from a semi-arid environment as a source of phytochemicals against Fusarium crown and foot rot in zucchini

Fusarium crown and foot rot, caused by F. solani f. sp. cucurbitae, are major fungal diseases affecting zucchini and other cucurbits. Despite the efficacy of synthetic fungicides, their health and environmental hazards have highlighted the urgent need for safer alternatives, such as phytochemical-based biocides. Owing to the upregulation of the plant secondary metabolism under stressful conditions, bioprospecting in harsh environments could reveal ore plants for bioactive metabolites. In this study, thirteen wild plants were collected from their natural habitat in a semiarid environment (Yanbu, Saudi Arabia) and extracted to obtain phenolics rich extracts. Total polyphenols, flavonoids, antioxidant capacities and the antifungal activities of the extracts against a pathogenic isolate of F. solani were assessed. Fusarium solani was isolated from infected zucchini and characterized by scanning electron microscopy. Hierarchical clustering analysis of the phytochemical screening and in vitro bioactivity revealed that Rosmarinus officinalis, Pulicaria crispa, Achillea falcata and Haloxylon salicornicum were the richest in polyphenols and the most powerful against F. solani. Further, the extracts of these four plants significantly decreased the disease incidence in zucchini, where P. crispa was the premier. Interestingly, results of transmission electron microscopy revealed that extract of P. crispa, as a representative of the powerful group, induced ultrastructural disorders in fungal cells. Therefore, this study suggests the use of R. officinalis, P. crispa, A. falcata and H. salicornicum grown in semi-arid environments as ore plants to develop phytochemical-based biocides against Fusarium crown and foot rot.

Recent advances of bioactive proteins/polypeptides in the treatment of breast cancer

Proteins do not only serve as nutrients to fulfill the demand for food, but also are used as a source of bioactive proteins/polypeptides for regulating physical functions and promoting physical health. Female breast cancer has the highest incidence in the world and is a serious threat to women's health. Bioactive proteins/polypeptides exert strong anti-tumor effects and exhibit inhibition of multiple breast cancer cells. This review discussed the suppressing effects of bioactive proteins/polypeptides on breast cancer in vitro and in vivo, and their mechanisms of migration and invasion inhibition, apoptosis induction, and cell cycle arrest. This may contribute to providing a basis for the development of bioactive proteins/polypeptides for the treatment of breast cancer.

Graphical abstract

The future of recombinant host defense peptides

The antimicrobial resistance crisis calls for the discovery and production of new antimicrobials. Host defense peptides (HDPs) are small proteins with potent antibacterial and immunomodulatory activities that are attractive for translational applications, with several already under clinical trials. Traditionally, antimicrobial peptides have been produced by chemical synthesis, which is expensive and requires the use of toxic reagents, hindering the large-scale development of HDPs. Alternatively, HDPs can be produced recombinantly to overcome these limitations. Their antimicrobial nature, however, can make them toxic to the hosts of recombinant production. In this review we explore the different strategies that are used to fine-tune their activities, bioengineer them, and optimize the recombinant production of HDPs in various cell factories.

Membrane Permeabilization and Antimicrobial Activity of Recombinant Defensin-d2 and Actifensin against Multidrug-Resistant Pseudomonas aeruginosa and Candida albicans

Antimicrobial resistance requires urgent efforts towards the discovery of active antimicrobials, and the development of strategies to sustainably produce them. Defensin and defensin-like antimicrobial peptides (AMPs) are increasingly gaining pharmacological interest because of their potency against pathogens. In this study, we expressed two AMPs: defensin-d2 derived from spinach, and defensin-like actifensin from Actinomyces ruminicola. Recombinant pTXB1 plasmids carrying the target genes encoding defensin-d2 and actifensin were generated by the MEGAWHOP cloning strategy. Each AMP was first expressed as a fusion protein in Escherichia coli, purified by affinity chromatography, and was thereafter assayed for antimicrobial activity against multidrug-resistant (MDR) pathogens. Approximately 985 µg/mL and 2895 µg/mL of recombinant defensin-d2 and actifensin, respectively, were recovered with high purity. An analysis by MALDI-TOF MS showed distinct peaks corresponding to molecular weights of approximately 4.1 kDa for actifensin and 5.8 kDa for defensin-d2. An in vitro antimicrobial assay showed that MDR Pseudomonas aeruginosa and Candida albicans were inhibited at minimum concentrations of 7.5 µg/mL and 23 µg/mL for recombinant defensin-d2 and actifensin, respectively. The inhibitory kinetics of the peptides revealed cidal activity within 4 h of the contact time. Furthermore, both peptides exhibited an antagonistic interaction, which could be attributed to their affinities for similar ligands, as deduced by peptide–ligand profiling. Moreover, both peptides inhibited biofilm formation, and they exhibited no resistance potential and low hemolytic activity. The peptides also possess the ability to permeate and disrupt the cell membranes of MDR P. aeruginosa and C. albicans. Therefore, recombinant actifensin and defensin-d2 exhibit broad-spectrum antimicrobial activity and have the potential to be used as therapy against MDR pathogens.

Bioactive Potential of Several Actinobacteria Isolated from Microbiologically Barely Explored Desert Habitat, Saudi Arabia

Simple Summary

Bioactive natural products have been regarded as promising tools for treatment of various ailments. Among natural sources, actinomycetes have been widely explored for their potential bioactivity. In this regard, the present study has focused on the phytochemical content and biological activities of several actinobacteria isolates, which were investigated for their phenolic and flavonoid content, as well as their antioxidant, antibacterial and antiprotozoal activities. The most active isolates were further investigated for their antileukemic activity, where such isolates were shown to exert cytotoxic activity against the tested cell lines, following a mechanism that might be due to the ability of the active isolate extracts to reduce cyclooxygenase and lipoxygenase activities. Overall, isolation and characterization of the active molecule from the potential actinomycetes strains will pave the way for the development of drugs against human diseases such as blood cancer.

Abstract

Biomolecules from natural sources, including microbes, have been the basis of treatment of human diseases since the ancient times. Therefore, this study aimed to investigate the potential bioactivity of several actinobacteria isolates form Al-Jouf Desert, Saudi Arabia. Twenty-one actinobacterial isolates were tested for their antioxidant (flavonoids, phenolics, tocopherols and carotenoids) content, and biological activities, namely FRAP, DPPH, ABTS, SOS and XO inhibition, anti-hemolytic and anti-lipid peroxidation as well as their antibacterial and antiprotozoal activities. Accordingly, five isolates (i.e., Act 2, 12, 15, 19 and 21) were selected and their 90% ethanolic extracts were used. The phylogenetic analysis of the 16S rRNA sequences indicated that the most active isolates belong to genus Streptomyces. The genus Streptomyces has been documented as a prolific producer of biologically active secondary metabolites against different cancer types. Thus, the anti-blood cancer activity and the possible molecular mechanisms by which several Streptomyces species extracts inhibited the growth of different leukemia cells, i.e., HL-60, K562 and THP-1, were investigated. In general, the five active isolates showed cytotoxic activity against the tested cell lines in a dose dependent manner. Among the potent isolates, isolate Act 12 significantly decreased the cell viability and showed maximum cytotoxic activities against both HL-60 and K562 cells, while isolate Act 15 exhibited maximum cytotoxic activity against THP-1 cells. Moreover, Act 2 and Act 12 reduced cyclooxygenase (COX-2) and lipoxygenase (LOX) activity, which is involved in the proliferation and differentiation of cancer cells and may represent a possible molecular mechanism underlying leukemia growth inhibition. The bioactive antioxidant extracts of the selected Streptomyces species inhibited leukemia cell growth by reducing the COX-2 and LOX activity. Overall, our study not only introduced a promising natural alternative source for anticancer agents, but it also sheds light on the mechanism underlying the anticancer activity of isolated actinomycetes.