Antibacterial and immunological properties of piperine evidenced by preclinical studies: a systematic review.

Aim: To review in vitro, in vivo, and in silico studies examining the antibacterial and immunomodulatory properties of piperine (PPN). Methods: This systematic review followed PRISMA guidelines, and five databases were searched. Results: A total of 40 articles were included in this study. Six aspects of PPN activity were identified, including antibacterial spectrum, association with antibiotics, efflux pump inhibition, biofilm effects, protein target binding, and modulation of immune functions/virulence factors. Most studies focused on Mycobacterium spp. and Staphylococcus aureus. Cell lineages and in vivo models were employed to study PPN antibacterial effects. Conclusion: We highlight PPN as a potential adjuvant in the treatment of bacterial infections. PPN possesses several antibacterial properties that need further exploration to determine the mechanisms behind its pharmacological activity.

In vitro activity of cinnamaldehyde on Leishmania (Leishmania) amazonensis.

Tegumentary leishmaniasis is an endemic disease that urgently needs new and effective treatments. L. amazonensis is one of the main species involved in the transmission of this infectious and non-contagious disease. The currently available treatments for leishmaniasis have high toxicity and vary in efficacy. Natural compounds have been used as alternative therapies for various other diseases, often presenting excellent results with little or no adverse reaction. Cinnamaldehyde is the primary compound of essential oil from cinnamon bark; it is used in the cosmetic, pharmaceutical, and food industries for its antimicrobial and anti-inflammatory effects, as shown in the literature. As far as we know, no studies have evaluated cinnamaldehyde activity against L. amazonensis. In this context, we investigated the anti-Leishmania potential of cinnamaldehyde against promastigote and amastigote forms of L. amazonensis; cytotoxicity in erythrocytes, HaCat cells, and macrophages J774A.1; and its ability to stimulate nitric oxide. Cinnamaldehyde showed anti-Leishmania activity, with an average IC50 of approximately 212 µM against promastigote forms of L. amazonensis (three study periods: 24, 48, and 72 h) and an IC50 of 398.06 ± 42.10 µM against amastigote forms of L. amazonensis. Considerable toxicities to human erythrocytes and HaCat cells were not recorded from treatments with 4000 µM and 1000 µM of cinnamaldehyde, respectively. However, we recorded cytotoxicity with J774A.1 macrophages (0.48-1000 µM), which resulted in a low therapeutic selectivity index. The compound did not alter the production of nitric oxide in the cells evaluated. Overall, we observed that cinnamaldehyde showed anti-Leishmania activity and moderate toxicity. We encourage further research into the use of cinnamaldehyde to treat cutaneous leishmaniasis.

Photodynamic therapy in wound healing in vivo: a systematic review.

Wounds constitute severe problems in public health. Inappropriate manipulation to promote wound healing and indiscriminate use of antibiotics may contribute to failure in wound treatment, leading to bacterial growth and resistance. Appropriate and correct approaches to wound treatment are crucially important. Further, the development of new and effective treatment modalities is important to decrease infection-related mortality and to reduce patient suffering and side effects. Photodynamic therapy (PDT) could be a promising approach to ameliorate this global health problem. We researched articles that used PDT in wound healing in vivo. The systematic review included articles that investigated the effect of PDT on wound healing in animals, published from May 2008 through 2018, in the databases PubMed and Web of Science. The main types of wounds described in the selected articles were burns, abrasions, and excisional wounds. Most of the studies tested PDT in wounds infected by methicillin-resistant Staphylococcus aureus, S. aureus standard strain, or Pseudomonas aeruginosa. The studies demonstrated that PDT contributes in several ways to the wound healing process, such as killing bacterial cells and stimulating the proliferation of fibroblasts and consequently of collagen and elastin. Based on these studies, PDT provided excellent results for the wound healing process, acting in several steps and accelerating tissue repair. PDT has proven to be a promising therapeutic modality, able to inhibit bacterial regrowth or kill bacteria, contributing significantly to accelerate the wound healing process.