The protective effect of α-lipoic acid against bisphenol A-induced neurobehavioral toxicity

Bisphenol A (BPA), a well-known xenoestrogen, is ubiquitously utilized in manufacturing of polycarbonated plastics. Convincing evidence suggests that BPA induces neurotoxicity and certain behavioral deficits. α-Lipoic acid (ALA) supplementation has shown protective effect against heart and liver diseases, diabetes, and neurological debility associated with aging. We studied the neuromodulatory effect of ALA against neurotoxicity of BPA in vitro in C8-D1A mouse astrocyte cell line and in vivo in C57BL/6J male mice. In vitro ALA (100 μM) protected cells from BPA (30 μM)-induced reactive oxygen species generation and increased activity of glial fibrillary acidic protein. ALA showed reduction in cell death in astrocytes treated with BPA. In vivo ALA (50 mg/kg) increased the neurospecific acetylcholinesterase activity and decreased the monoamine oxidase activity altered by BPA exposure (10 mg/kg, per os x 30 days). In addition to neuroprotective effects, ALA also showed protective effects against BPA-induced oxidative stress. We observed that ALA significantly replenished the declined neurobehavioral and cognitive performances, decreased muscle coordination and alerted short-term recognition memory in mice exposed to BPA. Our results suggest that ALA has a promising role in modulating BPA-induced neurotoxicity in C8-D1A mouse astrocyte cells as well as neurochemical and neurobehavioral deficits in C57BL/6J male mice and its antioxidant and free radical scavenging activities may in part be responsible for such an effect.

Significantly enhanced heme retention ability of myoglobin engineered to mimic the third covalent linkage by nonaxial histidine to heme (vinyl) in synechocystis hemoglobin

Heme proteins, which reversibly bind oxygen and display a particular fold originally identified in myoglobin (Mb), characterize the "hemoglobin (Hb) superfamily." The long known and widely investigated Hb superfamily, however, has been enriched by the discovery and investigation of new classes and members. Truncated Hbs typify such novel classes and exhibit a distinct two-on-two α-helical fold. The truncated Hb from the freshwater cyanobacterium Synechocystis exhibits hexacoordinate heme chemistry and bears an unusual covalent bond between the nonaxial His(117) and a heme porphyrin 2-vinyl atom, which remains tightly associated with the globin unlike any other. It seems to be the most stable Hb known to date, and His(117) is the dominant force holding the heme. Mutations of amino acid residues in the vicinity did not influence this covalent linkage. Introduction of a nonaxial His into sperm whale Mb at the topologically equivalent position and in close proximity to vinyl group significantly increased the heme stability of this prototype globin. Reversed phase chromatography, electrospray ionization-MS, and MALDI-TOF analyses confirmed the presence of covalent linkage in Mb I107H. The Mb mutant with the engineered covalent linkage was stable to denaturants and exhibited ligand binding and auto-oxidation rates similar to the wild type protein. This indeed is a novel finding and provides a new perspective to the evolution of Hbs. The successful attempt at engineering heme stability holds promise for the production of stable Hb-based blood substitute.