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Chemical fungicides have been instrumental in protecting crops from fungal diseases. However, increasing fungal resistance to many of the single‐site chemical fungicides calls for the development of new antifungal agents with novel modes of action (MoA). The sequence‐divergent cysteine‐rich antifungal defensins with multisite MoA are promising starting templates for design of novel peptide‐based fungicides. Here, we experimentally tested such a set of 17‐amino‐acid peptides containing the γ‐core motif of the antifungal plant defensin MtDef4. These designed peptides exhibited antifungal properties different from those of MtDef4. Focused analysis of a lead peptide, GMA4CG_V6, showed that it was a random coil in solution with little or no secondary structure elements. Additionally, it exhibited potent cation‐tolerant antifungal activity against the plant fungal pathogen Botrytis cinerea, the causal agent of grey mould disease in fruits and vegetables. Its multisite MoA involved localization predominantly to the plasma membrane, permeabilization of the plasma membrane, rapid internalization into the vacuole and cytoplasm, and affinity for the bioactive phosphoinositides phosphatidylinositol 3‐phosphate (PI3P), PI4P, and PI5P. The sequence motif RRRW was identified as a major determinant of the antifungal activity of this peptide. While topical spray application of GMA4CG_V6 on Nicotiana benthamiana and tomato plants provided preventive and curative suppression of grey mould disease symptoms, the peptide was not internalized into plant cells. Our findings open the possibility that truncated and modified defensin‐derived peptides containing the γ‐core sequence could serve as promising candidates for further development of bio‐inspired fungicides. A short variant of a plant defensin‐derived peptide containing the γ‐core motif exhibits potent antifungal activity, multifaceted modes of action, and potential for development into a bio‐inspired fungicide.

Herein, ruthenium nanoparticles (RuNPs) were synthesized using Tridax procumbens leaf extract as a reducing and stabilizing agent. The synthesis was optimized by adjusting temperature, leaf extract concentration, and reaction time. The synthesized RuNPs were characterized using UV-visible, XRD, EDAX, FTIR spectroscopy, SEM, and TEM, revealing uniform size and morphology. UV-visible spectroscopy confirmed RuNP formation with an absorption peak at 288 nm. FTIR analysis identified functional groups, with a peak at 600–800 cm-1 indicating metallic Ru. XRD patterns showed peaks corresponding to RuNPs, with an average crystal size of 12.9 nm. SEM and TEM images revealed spherical RuNPs with an average diameter of 11.30 nm. The biological properties of the RuNPs were evaluated, demonstrating significant antibacterial and antifungal properties, and notable antioxidant activity. Antimicrobial activity was observed against Gram-positive bacteria (B. cereus, S. aureus) and Gram-negative bacteria (P. aeruginosa, E. coli) at concentrations of 50 µg/mL and above. The RuNPs showed antifungal activity against Candida albicans at 75 µg/ml and 100 µg/ml, but no activity against Aspergillus niger. The highest antioxidant activity was 77.13 ± 0.64% at a concentration of 100 µl. This study highlights the feasibility of utilizing Tridax procumbens leaf extract for the environmentally friendly synthesis of ruthenium nanoparticles, demonstrating their potential in biomedical applications and green chemistry.