Atomistic mechanism of leptin and leptin-receptor association.

The leptin-leptin receptor complex is at the very core of energy homeostasis and immune system regulation, among many other functions. In this work, we built homology models of leptin and the leptin binding domain (LBD) of the receptor from humans and mice. Docking analyses were used to obtain the coordinates of the native leptin-LBD complexes and a mixed heterodimer formed by human leptin and mouse LBD. Molecular dynamics (MD) simulations were performed using all models (monomers and heterodimers) as initial coordinates and the GROMACS program. The overall structural and dynamical behaviors are similar for the three complexes. Upon MD simulations, several new interactions appear. In particular, hydrophobic interactions, with more than 90% persistence, seem to be the most relevant for the stability of the dimers, as well as the pair formed by Asp85Lep and Arg468LBD. This in silico analysis provides structural and dynamical information, at the atomistic level, about the mechanism of leptin-LBD complex formation and leptin receptor activation. This knowledge might be used in the rational drug design of therapeutics to modulate leptin signaling.Communicated by Ramaswamy H. Sarma.

The Resilience of Pseudomonas aeruginosa to Antibiotics and the Designing of Antimicrobial Peptides to Overcome Microbial Resistance.

Pseudomonas aeruginosa (P. aeruginosa) is a bacterium of medical concern known for its potential to persist in diverse environments due to its metabolic capacity. Its survival ability is linked to its relatively large genome of 5.5-7 Mbp, from which several genes are employed in overcoming conventional antibiotic treatments and promoting resistance. The worldwide prevalence of antibiotic-resistant clones of P. aeruginosa necessitates novel approaches to researching their multiple resistance mechanisms, such as the use of antimicrobial peptides (AMPs). In this review, we briefly discuss the epidemiology of the resistant strains of P. aeruginosa and then describe their resistance mechanisms. Next, we explain the biology of AMPs, enlist the present database platforms that describe AMPs, and discuss their usefulness and limitations in treating P. aeruginosa strains. Finally, we present 13 AMPs with theoretical action against P. aeruginosa, all of which we evaluated in silico in this work. Our results suggest that the AMPs we evaluated have a carpet-like mode of action with a membranolytic function in Gram-positive and Gramnegative bacteria, with a clear potential of synthesis for in vitro evaluation.

Brazilin: Biological activities and therapeutic potential in chronic degenerative diseases and cancer.

Caesalpinia sappan and Haematoxylum brasiletto belong to the Fabaceae family, predominantly distributed in Southeast Asia and America. The isoflavonoid brazilin has been identified from the bark and heartwood of these plants. This review summarizes the studies describing the biological activities of these plants and brazilin. Mainly, brazilin protects cells from oxidative stress, shows anti-inflammatory and antibacterial properties, and hypoglycemic effect. In addition, it has a biological impact on various pathologies such as Alzheimer's disease, Parkinson's disease, fibrillogenesis, and osteoarthritis. Interestingly, most of the antecedents are related to the anticancer effect of brazilin. In several cancers such as osteosarcoma, neuroblastoma, multiple myeloma, glioblastoma, bladder, melanoma, breast, tongue, colon, cervical, head, and neck squamous cell carcinoma, brazilin induces autophagy by increasing the levels of the LC3-II protein. Furthermore, it inhibits cell proliferation and induces apoptosis through increased expression of Bcl-2, Bcl-XL, p21, p27, activation of caspase-3 and -7, and the cleavage of PARP and inhibiting the expression of Bax. In addition, it blocks the expression of JNK and regulates the nuclear translocation of Nrf2. Together, these data positions brazilin as a compound of natural origin with multiple bioactivities and therapeutic potential in various chronic degenerative diseases and cancer.