Storage proteins perform essential roles in plant survival, acting as molecular reserves important for plant growth and maintenance, as well as being involved in defense mechanisms by virtue of their properties as insecticidal and antimicrobial proteins. These proteins accumulate in storage vacuoles inside plant cells, and, in response to determined signals, they may be used by the different plant tissues in response to pathogen attack. To shed some light on these remarkable proteins with dual functions, storage proteins found in germinative tissues, such as seeds and kernels, and in vegetative tissues, such as tubercles and leaves, are extensively discussed here, along with the related mechanisms of protein expression. Among these proteins, we focus on 2S albumins, Kunitz proteinase inhibitors, plant lectins, glycine-rich proteins, vicilins, patatins, tarins, and ocatins. Finally, the potential use of these molecules in development of drugs to combat human and plant pathogens, contributing to the development of new biotechnology-based medications and products for agribusiness, is also presented.

Antibiotics are important therapeutic agents commonly used for the control of bacterial infectious diseases; however, resistance to antibiotics has become a global public health problem. Therefore, effective therapy in the treatment of resistant bacteria is necessary and, to achieve this, a detailed understanding of mechanisms that underlie drug resistance must be sought. To fill the multiple gaps that remain in understanding bacterial resistance, proteomic tools have been used to study bacterial physiology in response to antibiotic stress. In general, the global analysis of changes in the protein composition of bacterial cells in response to treatment with antibiotic agents has made it possible to construct a database of proteins involved in the process of resistance to drugs with similar mechanisms of action. In the past few years, progress in using proteomic tools has provided the most realistic picture of the infective process, since these tools detect the end products of gene biosynthetic pathways, which may eventually determine a biological phenotype. In most bacterial species, alterations occur in energy and nitrogen metabolism regulation; glucan biosynthesis is up-regulated; amino acid, protein, and nucleotide synthesis is affected; and various proteins show a stress response after exposing these microorganisms to antibiotics. These issues have been useful in identifying targets for the development of novel antibiotics and also in understanding, at the molecular level, how bacteria resist antibiotics.

Plants have contributed over the years to the discovery of various pharmacological products. Amongst the enormous diversity of herbs with remarkable medicinal use and further pharmacological potential, here in this report we evaluated pulp extracts from Eugenia dysenterica fruits and further identified the active principle involved in such laxative activity in rats. For protein isolation, fruits were macerated with an extraction solution following precipitation with (NH(4))(2)SO(4) (100%). After dialysis, the peptide was applied onto a reversed-phase semi-preparative HPLC column, and the major fraction was eluted with 26% and 66% acetonitrile. The evaluation of molecular masses by MALDI-TOF and Tris/Tricine SDS-PAGE of HPLC fractions showed the presence of a major peptide with approximately 7 kDa. The N-terminal amino acid peptide sequence was determined and showed no similarity to other proteins deposited in the Data Bank. Peptide from E. dysenterica was able to enhance rats' intestinal motility by approximately 20.8%, probably being responsible for laxative activity. Moreover, these proteins were non-toxic to mammals, as observed in histopathology and hemolytic analyses. In conclusion, results here reported indicate that, in the near future, proteins synthesized by E. dysenterica fruits could be utilized in the development of novel biotechnological pharmaceutics with laxative properties for use in chronic constipation and irritable bowel syndrome treatment.

Eugenia dysenterica is a plant typically found in the Cerrado biome and commonly used in popular medicine due to its pharmacological properties, which include antidiarrheal, skin healing, and antimicrobial activities. The effects of ethanolic extract, aqueous extract and infusion of E. dysenterica leaves on intestinal motility and antidiarrheal activity were evaluated using ricin oil-induced diarrhea in rats. At doses of 400 and 800 mg·Kg−1, the ethanolic extract decreased intestinal motility while the other extracts showed no significant effects. Moreover, serum levels of chloride, magnesium, and phosphorus were also measured in rats. Histopathologic and enzymatic analyses were also performed to investigate any toxic effect. Animals treated with infusion, ethanolic extract, ricin oil, and loperamide presented morphological alterations in the small intestine, such as mucosa lesion, epithelial layer damage, and partial loss and/or morphological change of villi. Furthermore, the liver showed congestion and hydropic degeneration. Serum levels of alanine aminotransferase increased significantly in all treatments, but none rose above reference values. In summary, our results suggest that compounds present in leaves of E. dysenterica may have therapeutic benefits on recovery from diarrhea despite their toxic effects.

Bacterial infections directly affect the world's population, and this situation has been aggravated by indiscriminate use of antimicrobial agents, which can generate resistant microorganisms. In this report, an initial screening of proteins with antibacterial activity from corms of 15 species of the Xanthosoma genus was conducted. Since Xanthosoma blandum corms showed enhanced activity toward bacteria, a novel protein with bactericidal activity was isolated from this particular species. Edman degradation was used for protein N-termini determination; the primary structure showed similarities with Kunitz inhibitors, and this protein was named Xb-KTI. This protein was further challenged against serine proteinases from different sources, showing clear inhibitory activities. Otherwise, no hemolytic activity was observed for Xb-KTI. The results demonstrate the biotechnological potential of Xb-KTI, the first proteinase inhibitor with antimicrobial activity described in the Xanthosoma genus.