Chromium exposure disrupts chromatin architecture upsetting the mechanisms that regulate transcription

A Comprehensive Review of the Impact of Chromium Picolinate on Testicular Steroidogenesis and Antioxidant Balance

Low testosterone (T) levels are a major cause of male infertility, as this hormone is crucial for several processes throughout the entire male reproductive tract. Leydig cells (LC) produce T through testicular steroidogenesis. Disrupted LC function can hinder steroid production and fertility. Among the factors that affect steroidogenesis, endocrine-disrupting chemicals (EDCs) raise concerns, as they disturb hormonal signaling. Chromium is classified as an EDC, and its main forms are hexavalent (Cr(VI)) and trivalent chromium (Cr(III)). While Cr(III) is controversially regarded as an essential metal, its compound Cr(III) picolinate (CrPic3) is used as a nutritional supplement due to its antidiabetic and antioxidant properties. This review aims to identify the possible effects of CrPic3 on testicular steroidogenesis and thus, on male fertility. The detriments caused by CrPic3 in LC include the inhibition of enzymes involved in steroidogenesis, and, as in other cells, the induction of mutagenesis and apoptosis. Remarkably, CrPic3 impacts male fertility through the alteration of reactive oxygen species (ROS), T levels, and sperm parameters (sperm motility and abnormal sperm count). However, gaps and inconsistencies exist in the literature concerning its effects on male fertility. Thus, further research is imperative to comprehend the underlying mechanisms of CrPic3 in the physiological processes relevant to male fertility, ensuring the supplement's safety for use by men.

Biosorptive ascendency of plant based biosorbents in removing hexavalent chromium from aqueous solutions - Insights into isotherm and kinetic studies

Chromium is a toxic heavy metal prevalent in higher levels in aqueous matrices owing to industrial applications. Whilst being a key player in industries, the environmental issues caused by Cr(VI) are highly deleterious. Adsorptive remediation is found to be an effective method adopted by researchers in the past decades for Cr(VI) removal from water streams in which variety of naturally available biosorbents have been explored for handling Cr(VI). This review article briefly sketches up the biosorptive potential of plant-based biosorbents used in raw and chemically modified form for the optimum exclusion of Cr(VI) from aqueous sources. Mechanisms and kinetic behavior of the removal process are also discussed. pH of the solution and initial Cr(VI) concentration were found to be the key parameters in Cr removal. The mechanism of Cr removal from aqueous systems was elucidated to be either adsorption or adsorption-coupled-reduction. After precise discussion on various plant-based biosorbents with their maximum adsorption capacities, desorption and regeneration potential, it is perceived that plant-based biosorbents are superior options for Cr(VI) elimination from aqueous streams.

Inhalation cancer risk assessment for environmental exposure to hexavalent chromium: Comparison of margin-of-exposure and linear extrapolation approaches

Hexavalent chromium [Cr(VI)] exists in the ambient air at low concentrations (average upperbound ~0.1 ng/m³) yet airborne concentrations typically exceed EPA's Regional Screening Level for residential exposure (0.012 ng/m³) and other similar benchmarks, which assume a mutagenic mode of action (MOA) and use low-dose linear risk assessment models. We reviewed Cr(VI) inhalation unit risk estimates developed by researchers and regulatory agencies for environmental and occupational exposures and the underlying epidemiologic data, updated a previously published MOA analysis, and conducted dose-response modeling of rodent carcinogenicity data to evaluate the need for alternative exposure-response data and risk assessment approaches. Current research supports the role of non-mutagenic key events in the MOA, with growing evidence for epigenetic modifiers. Animal data show a weak carcinogenic response, even at cytotoxic exposures, and highlight the uncertainties associated with the current epidemiological data used in risk assessment. Points of departure from occupational and animal studies were used to determine margins of exposure (MOEs). MOEs range from 1.5 E+3 to 3.3 E+6 with a median of 5 E+5, indicating that current environmental exposures to Cr(VI) in ambient air should be considered of low concern. In this comprehensive review, the divergent results from default linear and MOE assessments support the need for more relevant and robust epidemiologic data, additional mechanistic studies, and refined risk assessment strategies.

Aegle marmelos extract rich in marmelosin exacted ameliorative effect against chromium-induced oxidative stress and apoptosis through regulation of Gadd45 in HepG2 cell line

Hexavalent chromium [Cr (VI)] is highly toxic compared to other valence states of chromium. In the process of metabolic reduction, Cr (VI) converts to trivalent chromium. Aegle marmelos (Bael), a sacred plant of India and its fruits are being consumed as traditional formulations against various diseases such as ulcer, gastric mucosal damage, inflammations, febrile delirium, acute bronchitis, anxiety, etc. The present study assessed the protective effects of marmelosin (MAR) from Aegle marmelos against K₂ Cr₂ O₇ -induced toxic effects in HepG2 cell line through its antiapoptotic mechanism. Results of the study revealed that pretreatment of MAR ameliorated cell viability, mitochondrial damage, and DNA damage induced by K₂ Cr₂ O₇ in HepG2 cell line as evidenced by cell morphology, MTT, LDH, and MMP assays. Pretreatment of MAR attenuated K₂ Cr₂ O₇ -induced oxidative stress by downregulating intracellular ROS and RNS. Further, pretreatment of MAR significantly downregulated K₂ Cr₂ O₇ -induced apoptotic markers, such as Bax, Caspase 3, and Gadd45. Our results suggested that application of marmelosin could be beneficial in ameliorating chromium-induced apoptotic cell death by suppressing oxidative stress and regulating excessive DNA damage. PRACTICAL APPLICATIONS: The study focused on protective mechanism of marmelosin from Aegle marmelos against chromium-induced oxidative stress for the first time. In this research, we reported that marmelosin effectively ameliorated K₂ Cr₂ O₇ -induced morphological changes such as oxidative stress and apoptotic cell death by regulating Gadd45, Bcl-2, Bax, and Caspase 3 gene expressions, and inhibition of intracellular ROS and RNS. The study provides a better understanding of the pharmacological mechanisms of Aegle marmelos and its bioactive compound, that is, marmelosin in the management of intoxication of heavy metals associated with excessive DNA damage.