Probing binding mode between sodium acid pyrophosphate and albumin: multi-spectroscopic and molecular docking analysis.

Sodium acid pyrophosphate (SAPP) food additive is widely used as a preservative, bulking agent, chelating agent, emulsifier and pH regulator. It is also used as an improver of color and water retention capacity in the processing of various types of seafood, canned food, cooked meat and flour products. For the first time, we evaluated the SAPP interaction with bovine serum albumin (BSA) using spectroscopic methods including UV-Vis absorption, fluorescence spectroscopy, and surface plasmon resonance, and docking analysis to understand the mechanisms of complex formation and binding. The fluorescence intensity of BSA reduces when titrated with various concentrations of SAPP by forming a complex with BSA via a static quenching mechanism. The binding constant between BSA and SAPP decreased from 123,300 to 15,800 (M-1) with rising temperature, which indicates a decrement in complex formation owing to the interaction of SAPP with BSA. A negative ΔG° value means that SAPP binds spontaneously to BSA at all temperatures, and both ΔH° and ΔS° negative values indicate that hydrogen bonds (H-bonding) and van der Waals forces are the primary forces involved in the binding processes. The UV-Vis spectrum of BSA reduced upon increasing SAPP concentrations due to forming a new ground state complex between SAPP and BSA. Molecular docking study shows that residues Arg256, Ser259, Ser286, Ile 289 and Ala 290 play an important role in SAPP binding process to site I (subdomain IIA) of BSA through H-bonding and van der Waals forces, which is supported by the thermodynamic study.Communicated by Ramaswamy H. Sarma.

Spectroscopic aspects on the interaction of nisin with serum albumin: thermodynamic and kinetic studies.

Introduction: Nisin is a bacteriocin produced by Streptococcus and Lactococcus species and has antimicrobial activity against other bacteria. Nisin omits the need to use chemical preservatives in food due to its biological preserving properties. Methods: In the present in vitro study, we investigated nisin interaction with bovine serum albumin (BSA) using fluorescence spectroscopy and surface plasmon resonance (SPR) analysis to obtain information about the mechanisms of BSA complex formation with nisin. Results: The BSA fluorescence intensity values gradually diminished with rising nisin concentration. The BSA fluorescence quenching analysis indicated that a combined quenching mechanism plays the main role. Finally, the Kb values were reduced with increasing temperature, which is demonstrative of nisin-BSA complex stability decrease at high temperatures. The negative values of ΔH° and ΔS° showed that hydrogen bonds and van der Waals forces are the foremost binding force between BSA and nisin. Meanwhile, the negative values of ΔG° demonstrated the exothermic and random nature of the reaction process. The results of the SPR verified the gained results through the fluorescence spectroscopy investigation, which denoted that the BSA affinity to nisin diminished upon increasing temperature. Conclusion: Overall, fluorescence spectroscopy and SPR results showed that the BSA interaction with nisin decreased with rising temperatures.

Pharmacokinetic and toxicological overview of propyl gallate food additive.

The progressive use of food additives in "ultra-processed" food has increased attention to them. Propyl gallate (PG) is an essential synthetic preservative that commonly used in food, cosmetics, and pharmacies as an antioxidant. This study aimed to outline the existing evidence on the toxicological studies of PG including its physicochemical properties, metabolism, and pharmacokinetics effects. The methods include updated searches for the relevant databases. The EFSA has evaluated the use of PG in food industry. It establishes an acceptable daily intake (ADI) of 0.5 mg/kg bw per day. Based on exposure assessment, it can be concluded that at the current level of use, PG is not of safety concern.

In vitro safety assessment of alkyl lactate esters in human umbilical vein endothelial cells (HUVECs).

Safety assessment requires information on both the chronic and acute effects of chemicals. Chemical materials such as food additives have become one of the most critical and compelling issues in the continuing debate on food safety. Calcium lactate (CL) and Sodium lactate (SL) are approved chemicals used in various products. The present study, in vitro study, was designed to evaluate the cyto-genotoxicity effects of CL and SL on human umbilical vein endothelial cells (HUVECs). The cytotoxicity effect of these additives was determined by MTT and Annexin V-FITC apoptosis assays. Besides, genotoxicity parameters such as morphological change of DNA and DNA fragmentation were studied with DAPI staining and DNA ladder assays, respectively. The results showed that the growth of HUVECs decreased upon treatment with CL at higher concentrations, but SL did not significantly alter HUVECs cell number. Annexin V-FITC apoptosis assays revealed that CL could induce cell death based on necrosis rather than apoptosis. In SL, the early and late apoptosis was not considerable in treated cells. Exposure to CL and SL did not lead to morphological change and DNA fragmentation in the HUVECs cell line. Overall, it is concluded from these results that CL and SL have not been cytotoxic and genotoxic effects in low concentrations in human umbilical vein endothelial cells in vitro.