Protein and Peptide Letters - Online First
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Antimicrobial Activity of a Defensin-Rich Fraction from Capsicum chinense Fruits: Insights for Biotechnological Applications against Fungal Infections
Available online: 16 July 2025More LessBackgroundThe increasing resistance of fungal pathogens to conventional antifungal treatments has led to a global rise in fungal infections, affecting human health (Candida spp.) and agricultural productivity (Colletotrichum and Fusarium spp.). Antimicrobial peptides (AMPs), such as defensins, have gained attention for their potential in controlling these infections due to their broad-spectrum activity.
ObjectivesThe aim of this study was to partially purify and characterize the antifungal activity of a defensin-enriched fraction (F3) from Capsicum chinense fruits. Specifically, we sought to evaluate its efficacy against pathogenic fungi and yeasts, and to assess the relative abundance of defensins in the fraction.
MethodsThe F3 fraction was obtained using ion exchange and molecular exclusion chromatography. Reverse-phase chromatography (HPLC) was then employed for further purification. The antifungal activity of F3 was tested against Colletotrichum, Fusarium, and Candida species. Mass spectrometry was used to identify and characterize the defensin (CcDef3) within the fraction. The presence of the defensin relative to other components was inferred from electrophoretic profiles and peptide analysis.
ResultsThe F3 fraction exhibited significant antifungal activity, with growth inhibition of Colletotrichum lindemuthianum of 51% and 60.9% at concentrations of 100 and 200 μg mL-1, respectively. The fraction also inhibited the growth of several Candida species, notably C. nivariensis (93.8%) and C. bracarensis (79.6%) at 100 μg mL-1. Cell viability analysis indicated a fungistatic effect. Fluorescence microscopy assays showed that F3 induced membrane permeabilization in C. parapsilosis and C. lindemuthianum, and increased ROS production in C. pelliculosa and F. solani. The defensin-rich H8 fraction, containing a 6.5 kDa protein (CcDef3), was identified as a major component via mass spectrometry.
DiscussionThe ongoing development of resistance in fungal strains, particularly Candida species, against traditional antibiotics and antifungals has turned into a significant medical concern and has increased the need for new treatment options.
ConclusionThese results suggest that the F3 fraction, particularly the defensin CcDef3, has potential as an antifungal agent for biotechnological and therapeutic applications. However, further studies are needed to quantify the contribution of CcDef3 relative to other components in the fraction and to fully isolate the defensin for in-depth analysis.
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Use of Plant Peptidases for the Production of Therapeutic Peptides
Available online: 11 April 2025More LessPeptidases play crucial roles in numerous physiological processes within living organisms. Therefore, they have been employed in various pharmaceutical applications. Plant peptidases have attracted considerable attention in various areas due to their specificity, stability across a diverse range of pH and temperatures, and safety profile. Here, we have focused on the use of plant peptidases, mostly papain and bromelain, to produce biologically active peptides, which confer various health advantages, including antioxidant, antimicrobial, antihypertensive, analgesic, antidiabetic, and anti-inflammatory effects. We have also discussed the importance of the action mechanism of peptidases for generating bioactive peptides with specific sequences and functions, the ecological and sustainability benefits of plant-derived peptidases compared to animal alternatives, digestive stability and bioavailability of peptides, as well as some obstacles to the commercialization of bioactive peptides and key challenges in peptidase-based industrial applications. Finally, we have examined enzyme immobilization as a viable method to enhance the production of bioactive peptides, offering numerous advantages in both research and industry contexts.
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Plant-derived Cyclotides in Immunomodulation and their Therapeutic Potential
Authors: Reema Mishra, Preeti Agarwal, Anshita Sharma, Meenal Mittal, Pooja Gulati and Aparajita MohantyAvailable online: 18 March 2025More LessThe incidences of immune-related disorders have drastically increased in recent years across the world population. Treatment and management of these diseases, especially autoimmune disorders, are complex and challenging. Available synthetic drugs are not completely effective and also pose serious side effects for the patients. Cyclotides are a class of plant-derived cyclic peptides (28-37 amino acids) with three conserved disulfide linkages establishing a cyclic cystine knot (CCK) motif that makes them very stable biomolecules. Their inherent stability, bioavailability and membrane-penetrating capabilities render them attractive potential pharmacological agents. Studies have demonstrated that cyclotides can either enhance or suppress immune responses, making them versatile candidates for treating various immune-related disorders. Of more than 1000 cyclotides discovered to date, only up to 15 native cyclotides (e.g. kalata B1, pase and caripe cyclotides) have been screened to demonstrate their immunomodulatory activity. Of special significance is the chemically synthesised lysine mutant of kalata B1 viz. [T20K], where preclinical studies have shown promise in the treatment of the autoimmune disorder, multiple sclerosis. In vivo studies in mice models have demonstrated that daily administration of 1mg/day of [T20K] led to a significant decrease in the level of cytokine secretion, lesser demyelination (<1%) and very low inflammatory index (<0.5), in the immunized mice. Moreover, when compared with other immunosuppressive drugs (azathioprine, prednisolone, and cyclosporine A) there was a notable drop in mortality and morbidity in mice administered with [T20K]. The cyclotides, kalata B1 and MCoTI-I have also been used as scaffolds to graft bioactive peptides with immunomodulatory activity. Subsequent in vitro and in vivo studies of these grafted cyclotides have demonstrated their therapeutic ability. Keeping in view the therapeutic potential of cyclotides as immunomodulatory peptides, the present review discusses its current research scenario and implications for the future in tackling immune-related disorders.
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