Exploring the therapeutic potential of an antinociceptive and anti-inflammatory peptide from wasp venom.

Animal venoms are rich sources of neuroactive compounds, including anti-inflammatory, antiepileptic, and antinociceptive molecules. Our study identified a protonectin peptide from the wasp Parachartergus fraternus' venom using mass spectrometry and cDNA library construction. Using this peptide as a template, we designed a new peptide, protonectin-F, which exhibited higher antinociceptive activity and less motor impairment compared to protonectin. In drug interaction experiments with naloxone and AM251, Protonectin-F's activity was decreased by opioid and cannabinoid antagonism, two critical antinociception pathways. Further experiments revealed that this effect is most likely not induced by direct action on receptors but by activation of the descending pain control pathway. We noted that protonectin-F induced less tolerance in mice after repeated administration than morphine. Protonectin-F was also able to decrease TNF-α production in vitro and modulate the inflammatory response, which can further contribute to its antinociceptive activity. These findings suggest that protonectin-F may be a potential molecule for developing drugs to treat pain disorders with fewer adverse effects. Our results reinforce the biotechnological importance of animal venom for developing new molecules of clinical interest.

Synthesis and Characterization of Peptide-Chitosan Conjugates (PepChis) with Lipid Bilayer Affinity and Antibacterial Activity.

Antimicrobial peptides appear among innovative biopolymers with potential therapeutic interest. Nevertheless, issues concerning efficiency, production costs, and toxicity persist. Herein, we show that conjugation of peptides with chitosans can represent an alternative in the search for these needs. To increase solubility, deacetylated and degraded chitosans were prepared. Then, they were functionalized via N-succinimidyl- S-acetylthiopropionate or via glutathione (GSH), an endogenous peptide linker. To the best of our knowledge, it is the first time that GSH is used as a thiolating agent for the conjugation of peptides. Next, thiolated chitosans were conjugated through a disulfide bond with designed short-chain peptides, one of them derived from the antimicrobial peptide Jelleine-I. Conjugates and respective reaction intermediates were characterized by absorciometry, attenuated total reflectance-Fourier transform infrared, and 1H NMR. Zeta potential measurements showed the cationic nature of these biomacromolecules and their preferential partitioning to Gram-positive bacterial-like model membranes. In vitro investigation using representative Gram-positive and -negative bacteria ( Staphylococcus aureus and Escherichia coli, respectively) showed that the conjugation strategies lead to enhanced activity in relation to the unconjugated peptide and to the unconjugated chitosan. The obtained products showed selectivity toward S. aureus at low cytotoxicity as determined in NIH/3T3 cells. Overall, our study demonstrates that an appropriate choice of antimicrobial peptide and chitosan characteristics leads to increased antimicrobial activity of the conjugated product and represents a strategy to modulate the activity and selectivity of antimicrobials resorting to low-cost chemicals. The present proposal starts from less expensive raw materials (chitosan and short-chain peptide), is based on aqueous solvents, and minimizes the use of reactants with a higher environmental impact. The final biopolymer contains the backbone of chitosan, just 3-6% peptide derived from royal jelly and GSH, all of them considered safe for human use or as a physiological molecule.

Cholesterol modulates curcumin partitioning and membrane effects.

Curcumin, a polyphenol molecule, presents a wide range of biological activities as antioxidant, anticancer, anti-inflammatory, antimicrobial and wound healing. Although some strengths attributed to curcumin derive from promiscuous biological activity, possibly because curcumin can interfere on many membrane located processes, knowledge of underlying interactions are lacking. Mammalian cell membranes characteristically contain 25 to 50% cholesterol/phospholipid ratio; however, most studies involving lipid bilayers and curcumin consider pure phosphatidylcholine and compare effects of curcumin on membranes with those of cholesterol. We investigated the interaction of curcumin with lipid bilayers containing cholesterol mimicking mammalian cells, and used spectroscopy techniques to determine partition coefficients, rigidity parameters and lytic activity. We found that curcumin partitions into different lipid bilayers (104 order coefficients that vary by less than a factor of two), containing cholesterol or not, and in the presence of sphingomyelin or phosphatidylserine. Curcumin decreases rigidity in all tested compositions, except that containing 40% cholesterol in which it increases the lipid packing order. In addition, curcumin induces leakage from giant unilamellar vesicles on a cholesterol concentration dependent way. Our results are compatible with the hypothesis of curcumin interaction with membranes being modulated by the liquid disordered phase and by the coexistence of liquid-ordered/liquid disordered phases. In bilayers containing cholesterol, curcumin assumes a more superficial location, drastically stiffens the 40% cholesterol bilayer and decreases the lytic effect. Our study may help researchers in the analysis of the biological effects of curcumin and curcumin-derived formulations by calling the attention to the discriminating role of the cholesterol content.