Effect of caffeic acid esters on antioxidant activity and oxidative stability of sunflower oil: Molecular simulation and experiments

Caffeic acid and diabetic neuropathy: Investigating protective effects and insulin-like growth factor 1 (IGF-1)-related antioxidative and anti-inflammatory mechanisms in mice

Diabetic neuropathy (DN) represents a common and debilitating complication of diabetes, affecting a significant proportion of patients. Despite available treatments focusing on symptom management, there remains an unmet need for therapies that address the underlying pathophysiology. In pursuit of novel interventions, this study evaluated the therapeutic effects of caffeic acid-a natural phenolic compound prevalent in various foods-on diabetic neuropathy using a mouse model, particularly examining its interaction with the Insulin-like Growth Factor 1 (IGF-1) signaling pathway. Caffeic acid was administered orally at two dosages (5 mg/kg and 10 mg/kg), and a comprehensive set of outcomes including fasting blood glucose levels, body weight, sensory behavior, spinal cord oxidative stress markers, inflammatory cytokines, and components of the IGF-1 signaling cascade were assessed. Additionally, to determine the specific contribution of IGF-1 signaling to the observed benefits, IGF1R inhibitor Picropodophyllin (PPP) was co-administered with caffeic acid. Our results demonstrated that caffeic acid, at both dosages, effectively reduced hyperglycemia and alleviated sensory behavioral deficits in diabetic mice. This was accompanied by a marked decrease in oxidative stress markers and an increase in antioxidant enzyme activities within the spinal cord. Significantly lowered microglial activation and inflammatory cytokine expression highlighted the potent antioxidative and anti-inflammatory effects of caffeic acid. Moreover, increases in both serum and spinal levels of IGF-1, along with elevated phosphorylated IGF1R, implicated the IGF-1 signaling pathway as a mediator of caffeic acid's neuroprotective actions. The partial reversal of caffeic acid's benefits by PPP substantiated the pivotal engagement of IGF-1 signaling in mediating its effects. Our findings delineate the capability of caffeic acid to mitigate DN symptoms, particularly through reducing spinal oxidative stress and inflammation, and pinpoint the integral role of IGF-1 signaling in these protective mechanisms. The insights gleaned from this study not only position caffeic acid as a promising dietary adjunct for managing diabetic neuropathy but also highlight the therapeutic potential of targeting spinal IGF-1 signaling as part of a strategic treatment approach.

Natural antioxidants enhance the oxidation stability of blended oils enriched in unsaturated fatty acids

BACKGROUND

Rancidity causes unpleasant tastes and smells, and the degradation of fatty acids and natural antioxidants, so that an oil is unfit to be consumed. Natural antioxidants, including tocopherols, polyphenols (sesamol, canolol, ferulic acid, caffeic acid, etc.), β-carotene, squalene and phytosterols, contribute to delay the oxidation of vegetable oils. However, studies on the combination of natural antioxidants to lengthen the shelf life of unsaturated fatty acid-rich blended oil have not been reported.

RESULTS

All of the composite antioxidants had the potential to significantly improve the oxidation stability of blended oil. Blended oil G with 0.05 g kg-1 β-carotene, 0.25 g kg-1 sesamol and 0.25 g kg-1 caffeic acid showed the best anti-autooxidation. It is also effective in improving the oxidative stability of vegetable oils containing various fatty acids. The oxidation stability index of the blended oil containing the optimum composition of natural antioxidants was 2.17-fold longer than that of the control sample. After the end of accelerated oxidation, the oil's peroxide value, p-anisidine value and total oxidation value were 6.59 times, 12.26 times and 6.65 times lower than those of the control sample, respectively.

CONCLUSION

(1) The combination of natural antioxidants β-carotene (0.05 g kg-1 ), sesamol (0.25 g kg-1 ) and caffeic acid (0.25 g kg-1 ) enhances the oxidative stability of unsaturated fatty acid-rich blended oils. (2) β-Carotene is the main antioxidant in the early stages of oxidation. (3) Sesamol and caffeic acid are the main antioxidants in the middle and late stages of oxidation. © 2023 Society of Chemical Industry.

A density functional theory benchmark on antioxidant-related properties of polyphenols

In this work, we present a density functional theory benchmark on antioxidant-related properties for a series of six polyphenols that are well-known antioxidants: caffeic acid, cyanidin, ellagic acid, gallic acid, myricetin, and phloretin. Computations on the 24 O-H bond dissociation enthalpies (BDEs) and 6 ionization potentials (IPs) were performed using twenty-three exchange-correlation functionals combined with four different basis sets in the gas-phase, water, and methanol; calibration against the Domain-based Local Pair Natural Orbital CCSD(T) (DLPNO-CCSD(T)) approach was employed. Mean absolute deviation (MAD) as well as linear fitting results suggested the LC-PBE approach as the most suitable for O-H BDEs in the gas-phase. The LC-PBE, M06-2X, and M05-2X results presented the smallest MADs for O-H BDEs when compared to the reference, in water. The LC-PBE results had the smallest MADs for IPs in the gas-phase while M05-2X, M06-2X, LC-PBE, and LC-ωPBE exhibited the best results for MAD in water. We expect the outcomes from the present work will serve as general guidance for researchers working in the field.

Design and characterization of a multi-epitope vaccine targeting Chlamydia abortus using immunoinformatics approach

Chlamydiosis is a widespread ailment affecting humans, livestock, and wildlife, caused by C. abortus, a member of the Chlamydia genus. This disease leads to reproductive disorders in bovines and poses a zoonotic risk, resulting in adverse outcomes such as abortion, stillbirths, weak offspring, endometritis, repeat breeding, and perinatal mortality. However, current chlamydiosis vaccines have limitations in terms of safety, efficacy, and stability, necessitating the development of effective and safe alternatives. In this study, our objective was to design a multi-epitope vaccine (MEV) targeting all strains of C. abortus using bioinformatics and immunoinformatics approaches. We identified highly antigenic and non-allergic proteins (yidC, yajC, secY, CAB503, and CAB746) using VaxiJen and AlgPred tools. Physicochemical analyses and secondary structure predictions confirmed protein stability through ProtParam and SOPMA methods. Furthermore, we employed IEDB-AR, NETMHCpan, and ToxinPred2 tools to predict cytotoxic T lymphocyte (CTL), helper T lymphocyte (HTL), and B-cell epitopes, resulting in the identification of conserved epitopes for further analysis. The MEV construct, consisting of 545 amino acids, incorporated the adjuvant Beta defensin-3, along with 9 CTL epitopes and 21 HTL epitopes linked by EAAAK, KK, and AAY linkers. We assessed the safety and immunogenicity of the vaccine through comprehensive evaluations of antigenicity, toxicity, allergenicity, and physicochemical properties. Structural stability and quality were examined using 3D modeling via the ab initio approach with the Robetta platform. Molecular docking analysis explored the compatibility of the MEV with Toll-like receptor 9 (TLR9) using ClusPro, while molecular dynamics simulation with the DESMOND Maestro software predicted the stability and flexibility of the docked complex. Despite promising in silico findings, further wet lab investigations are crucial to validate the safety and efficacy of the MEV. Successful development and validation of this MEV hold significant potential in combatting chlamydiosis in both animal and human populations.Communicated by Ramaswamy H. Sarma.

Potential toxicity of bisphenol A to α-chymotrypsin and the corresponding mechanisms of their binding

Bisphenol A (BPA) is an endocrine disruptor widely existing in plastics and resins, which can accumulate in animals and human bodies, posing a potential threat to the physiological and biochemical reactions of human beings or other organisms. α-Chymotrypsin is a kind of proteolytic enzyme existing in humans and animals, which can cause diseases when its activity is excessive. However, there is a lack of research on the mechanism of endocrine disruptors affecting α-chymotrypsin activity. In this study, the interaction between BPA and α-chymotrypsin was proved via multiple spectroscopic approaches, enzyme activity change, isothermal titration calorimetry and molecular docking. Results showed that α-chymotrypsin's polypeptide chains were unfolded, and protein skeletons were loosened with the exposure to BPA. α-Helix content increased and β-sheet content was decreased. The particle size of the BPA-α-chymotrypsin complex became smaller. Fluorescence sensitization may also be explained by a perturbation of the chromophore Trp 141. The thermodynamic parameters of the binding reaction were measured by isothermal titration calorimetry (ITC), which showed that there was hydrophobic interaction between BPA and α-chymotrypsin, which was consistent with the results of molecular docking. Moreover, BPA may stop near the active center of α-chymotrypsin and interact with the key residues His 57 and Ser 195. The above phenomenon explained the result that the activity of α-chymotrypsin increased to 139% when exposed to high dose BPA (40 μM). Taken together, the effects of BPA on the structure and function of α-chymotrypsin were clarified at the molecular level, which made up the gap in the mechanism of BPA on the proteolytic enzyme, and provided a reliable basis for disease avoidance and prevention.