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Free Radicals and Antioxidants
Published in Chuong Pham-Huy, Bruno Pham Huy, Food and Lifestyle in Health and Disease, 2022
Chuong Pham-Huy, Bruno Pham Huy
Pro-oxidant refers to any endobiotic or xenobiotic that induces oxidative stress either by generation of harmful reactive oxygen species (ROS) or by inhibiting helpful antioxidant systems in the body (85–86). Pro-oxidants can damage cells and tissues. In general, the term ‘pro-oxidant’ is reserved for compounds that have antioxidant properties, but in certain conditions such as high dosage or prolonged use, they becomes harmful or toxic to the organism. For example, vitamin C is a strong antioxidant at low doses, and is used to fight or prevent diseases, but it becomes harmful to the body at high doses and can cause diseases. In this case, vitamin C becomes a pro-oxidant compound. Pro-oxidant is different from oxidant although these two compounds can both give oxidative stress and become toxic to the organism. Oxidant denotes a compound that produces an oxidation reaction and does not have antioxidant property in any dose or any physiological situation. For example, ozone O3 and hydrogen peroxide H2O2 are oxidant compounds, and not pro-oxidants because they do not have antioxidant property, in contrast to vitamin C. Therefore, the term ‘pro-oxidant’ is reserved for compounds that have an antioxidant property.
Extraction and Optimization of Saponin and Phenolic Compounds of Fenugreek Seed
Published in Dilip Ghosh, Prasad Thakurdesai, Fenugreek, 2022
Sweeta Akbari, Nour Hamid Abdurahman, Rosli Mohd Yunus
The antioxidant activities of fenugreek seed were evaluated using DPPH and ABTS free radical scavenging assays. The half maximal inhibitory concentration (IC50) of the samples was also determined. Table 6.2 shows the free radical scavenging activities of fenugreek seed against ascorbic acid. It is also seen that, the IC50 values of DPPH in fenugreek seed extract (195.27 ± 0.56) are higher when compared to IC50 values of ABTS assay (157.92 ± 1.11), respectively. The smaller the IC50 value the better the antioxidant activity (Lee et al., 2015). The proton free radicals of ABTS and DPPH compounds can be reduced when exposed to proton radical scavengers (K. J. Lee et al., 2015). Previous findings suggested that the capacity of antioxidant activities in most of the plants was better with ABTS rather than with DPPH, and the reason is the sensitivity of ABTS assay which increases the rate of kinetic reaction. As reported, phenolic and flavonoids also act as antioxidants or hydrogen donors, which is a chemical reaction inside the human body, specifically, phenolic compounds due to the presence of hydroxyl (-OH) group. The free -OH group as an antioxidant is responsible for controlling the oxidative damage by inhibiting the oxidation reaction caused by reactive oxygen species (ROS) in foods (Altemimi et al., 2017; Paj et al., 2019).
The Use of Brain Slices in the Study of Free Radical Actions
Published in Avital Schurr, Benjamin M. Rigor, BRAIN SLICES in BASIC and CLINICAL RESEARCH, 2020
Since lipid peroxidation is unlikely to underlie free radical-induced decreases in synaptic efficacy, a different molecular target must be responsible. Protein oxidation as a possible mechanism was tested by evaluating the actions of the chemical oxidants, N-chlorosuccinimide (NCS) and chloramine-T, on the electrophysiological responses in hippocampal slices. These oxidizing agents are fairly specific for cysteine and methionine residues of proteins.61 Both decrease synaptic efficacy but have no effect on E/S coupling.62 Neither NCS nor chloramine-T produces lipid peroxidation. These data indicate that a protein oxidation reaction is a possible mechanism for the synaptic impairment caused by free radicals.
Point of care blood glucose devices in the hospital setting
Published in Critical Reviews in Clinical Laboratory Sciences, 2023
Nam K. Tran, Clayton LaValley, Berit Bagley, John Rodrigo
Amperometric electrochemical biosensors serve as the mainstay for glucose monitoring technology [23]. Figure 1 illustrates a typical amperometric glucose-oxidase (GO)-based biosensor. In brief, an electrical signal is produced during an enzymatically catalyzed reduction-oxidation reaction. Glucose oxidase is the most common enzyme used in BGMS biosensors. Early GO-amperometric biosensors relied on oxygen as an electron carrier as shown in Figure 1 [24]. Later GO-biosensors utilized artificial electron carriers that had the added benefit of reducing the applied electrical potential on the sensor. Utilizing GO offers the benefit of its high specificity for glucose, but this enzyme can be affected by oxygen tension, as discussed below [9,24]. As such, some manufacturers have developed amperometric sensors that use glucose dehydrogenase (GDH) coupled to electron carriers such as nicotinamide adenine dinucleotide, flavin adenine dinucleotide, or pyrroloquinoline quinone (PQQ). The drawback in using GDH is its reduced specificity for glucose [25]. Glucose sensors using coulometric, colorimetric, or spectrophotometric principles also exist but have become less common.
Strategic developments in the drug delivery of natural product dihydromyricetin: applications, prospects, and challenges
Published in Drug Delivery, 2022
Ruirui Zhang, Hao Zhang, Houyin Shi, Dan Zhang, Zhuo Zhang, Hao Liu
DHM has poor water solubility and only exists stably in low temperatures and weak acidic environments (pH 6.0) (CC Sun et al., 2021). If the temperature exceeds 100 °C, an irreversible oxidation reaction could occur. At 25 °C and 37 °C, the solubility of DHM in water is about 0.2 mg/ml and 0.9 mg/ml, respectively (L Fan et al., 2017). To increase its solubility, permeability, and stability, researchers have developed many new dosage forms for DHM, such as nano-preparations, microemulsions, gels, crystals, phospholipid complexes, and cyclodextrin complexes, etc., thereby improving the medicinal properties of DHM (CC Sun et al., 2020; S Geng, Jiang, et al., 2021; L Liu et al., 2022). It has been reported that DHM can distribute in various tissues and can pass through the blood-brain barrier after oral administration in rats, which provides further conditions for curing various diseases (L Fan et al., 2017). In addition, since the effect of this drug is not ideal when used alone because of its low titer, synergistic application of DHM with other anti-tumor drugs, liver protection drugs, anti-neurodegenerative diseases drugs, etc., should be considered.
Amelioration of hyperglycaemia and modulation of pro-inflammatory cytokines by Tamarix gallica fractions in alloxan induced diabetic rats
Published in Archives of Physiology and Biochemistry, 2022
Maryam Malik, Ali Sharif, Saeed Ul Hassan, Faqir Muhammad, Humaira Majeed Khan, Bushra Akhtar, Myeda Saeed
Diabetes is characterised by incessant hyperglycaemia along with variations in proteins, carbohydrates and lipids breakdown. Prevalence of diabetes mellitus has been increased worldwide due to sedentary life style, dietary changes and obesity (American Diabetes Association 2006, Khan et al.2020). It has been suggested that oxidative cellular damage is responsible for beta cells destruction, leading to chemical induced diabetes (Anwer et al.2019). In laboratory scale, experimental animals with diabetes exhibit suppressed cellular immunity and decreased response to antigens. Similarly, inflammatory response is also impaired in diabetic patients. Alloxan, a diabetogenic agent, is selectively taken up by low affinity glucose transporter type 2 (GLUT2) glucose transporter to beta cells and causes the destruction of transporter protein by generating free radicals. Lymphocytes are also alterations in both type I and type II diabetes. Alloxan induction in rats is associated with abnormalities in leukocytes function followed by decreased production and transcription of pro-inflammatory cytokines (Abel-Salam 2012). Radicals such as hydroxyl, hydrogen peroxide and superoxide anion radicals, known as reactive oxygen species (ROS), are known to be produced as a result of auto-oxidation reaction by glucose. The herbs having potential to control diabetes mellitus are increasingly considered for research as World Health Organisation (WHO) has reported above 150 herbs which could cure diabetes mellitus (Chandran et al.2016).