We report on a facile method to detect the aggregation and co-aggregation of peptides by tryptophan fluorescence spectroscopy. Peptide aggregates (PAs) play a pivotal role in neurodegenerative diseases, such as Alzheimer’s and Parkinson’s. The detection of the formation of aggregates, especially in the early stage, will facilitate the diagnosis and treatment of the associated disease. In this study, by choosing a tryptophan-containing peptide of EP2, we investigated its fluorescence spectroscopic characteristics in the process of PAs. The results showed that the intensity of emission spectra was significantly enhanced with the formation of PAs within 48 h. In addition, by employing EP2 as a fluorescence probe, we found that EP2 was able to effectively monitor the aggregation of other peptides/proteins that are otherwise difficult to detect with conventional approach. Thus, these preliminary data provide a promising diagnostic tool to detect the formation of PAs.

•A series of short arginine, lysine and tryptophan containing lipopeptides have been designed and synthesized.•Their antimicrobial activities were evaluated against Staphylococcus aureus, Escherichia coli, and Candida albicans.•The hemolytic effects of these peptides were tested.•The structure and activity relationships of these peptides were discussed.•Peptides C10-RKWWK showed a good antimicrobial activity, moderate cytotoxicity and multiple modes of action.Tryptophan and arginine rich antimicrobial peptides (AMPs) possess high potencies against both gram positive and gram negative bacteria, while lipopeptides represent another family of promising antimicrobial agents to combat invading pathogens. In the present study, we have synthesized a series of very short arginine, lysine and tryptophan containing lipopeptides and evaluated their antimicrobial activities against a panel of pathogenic microorganisms including Staphylococcus aureus, Escherichia coli, and Candida albicans. The results showed that most of these peptides were effective against tested strains with MIC values ranging from 3.9 to 62.5 μg/mL. In addition to the small size, potent bactericidal activity, low to moderate hemolytic toxicity and membrane disruption ability, several peptides such as C10-RIKWWK and C10-RKWWK apparently retarded the migration of DNA on agarose gel in the DNA-binding assay, which implied the multiple modes of action in their bacteria-killing mechanism. These peptides revealed a promising therapeutic potential to develop as new antimicrobial agents.A series of short lipopeptides have been synthesized and evaluated for their antimicrobial activity. C10-RKWWK and C10-RIKWWK showed the DNA-binding potential and membrane disruption ability in addition to the potent antimicrobial activities.

A new hydroanthraquinone derivative, 6-O-demethyl-4-dehydroxyaltersolanol A (1), and two new azaphilones, 8,11-didehydrochermesinone B (6) and (7S)-7-hydroxy-3,7-dimethyl-isochromene-6,8-dione (8), along with five known analogues (2–5 and 7), were isolated from the culture broth of Nigrospora sp. YE3033, an endophytic fungus obtained from Aconitum carmichaeli. Their structures were elucidated on the basis of spectroscopic analyses. Biological activity test indicated that compounds 1–3, and 7 exhibited the inhibitory effects on influenza viral strain of A/Puerto Rico/8/34 (H1N1) with the IC50 values of 2.59, 8.35, 7.82, and 0.80 μg/mL, respectively, while the low cytotoxicity of 7 with the CC50 value of 184.75 μg/mL, displaying a promising potential of 7 in the development of anti-influenza A virus drugs.Download high-res image (225KB)Download full-size image