Chemiluminescence Detection in the Study of Free-Radical Reactions. Part 1

The present review, consisting of two parts, considers the application of the chemiluminescence detection method in evaluating free radical reactions in biological model systems. The first part presents a classification of experimental biological model systems. Evidence favoring the use of chemiluminescence detection in the study of free radical reactions, along with similar methods of registering electromagnetic radiation as electron paramagnetic resonance, spectrophotometry, detection of infrared radiation (IR spectrometry), and chemical methods for assessing the end products of free radical reactions, is shown. Chemiluminescence accompanying free radical reactions involving lipids has been the extensively studied reaction. These reactions are one of the key causes of cell death by either apoptosis (activation of the cytochrome c complex with cardiolipin) or ferroptosis (induced by free ferrous ions). The concept of chemiluminescence quantum yield is also discussed in this article. The second part, which is to be published in the next issue, analyzes the application of chemiluminescence detection using luminescent additives that are called activators, a.k.a. chemiluminescence enhancers, and enhance the emission through the tripletsinglet transfer of electron excitation energy from radical reaction products, followed by light emission with a high quantum yield.

Multifaceted Clinical Effects of Echinochrome

The marine drug histochrome is a special natural antioxidant. The active substance of the drug is echinochrome A (Ech A, 7-ethyl-2,3,5,6,8-pentahydroxy-1,4-naphthoquinone), the most abundant quinonoid pigment in sea urchins. The medicine is clinically used in cardiology and ophthalmology based on the unique properties of Ech A, which simultaneously block various links of free radical reactions. In the last decade, numerous studies have demonstrated the effectiveness of histochrome in various disease models without adverse effects. Here, we review the data on the various clinical effects and modes of action of Ech A in ophthalmic, cardiovascular, cerebrovascular, inflammatory, metabolic, and malignant diseases.

UJI AKTIVITAS ANTIOKSIDAN EKSTRAK ETANOL AKAR SAMBILOTO (Andrographis paniculata (Burm.F.) Ness.) DENGAN METODE DPPH

Antioxidants are compounds that can inhibit free radical reactions in the body. One of Indonesia's traditional medicinal plants that have antioxidant activity is sambiloto (Andrographis paniculata (Brum) Ness.). This study aimed to examine the antioxidant activity of the extract of bitter root (A. paniculata (Brum) Ness.). The ethanol extract was obtained by extracting the bitter root powder by maceration for 3x24 hours and remaceration for 2x24 hours. The resulting extract is a thick blackish brown extract and has a distinctive odor with a percentage yield of 6.67%. Antioxidant activity was measured by reducing DPPH free radicals with UV-Vis spectrophotometry at a wavelength of 517 nm. The results showed that sambiloto root extract had very strong antioxidant activity with an IC5016,634 g/mL value against DPPH free radicals.Keywords : Bitter root, antioxidant, DPPH AbstrakAntioksidan merupakan senyawa yang dapat menghambat reaksi radikal bebas dalam tubuh. Salah satu tumbuhan obat tradisional Indonesia yang memiliki aktivitas sebagai antioksidan adalah sambiloto (Andrographis paniculata (Brum) Ness.). Penelitian ini bertujuan untuk menguji aktivitas antioksidan ekstrak akar sambiloto (A. paniculata (Brum) Ness.). Ekstrak etanol diperoleh dengan mengektraksi serbuk akar sambiloto dengan cara maserasi selama 3x24 jam dan dilakukan remaserasi kembali selama 2x24 jam. Ekstrak yang dihasilkan merupakan ekstrak kental berwarna coklat kehitaman dan bau khas dengan persen rendamen sebesar 6.67 %. Aktivitas antioksidan diukur melalui peredaman radikal bebas DPPH dengan spektrofotometri UV-Vis pada panjang gelombang 517 nm. Hasil Penelitian menunjukkan ekstrak akar sambiloto yang memiliki aktivitas antioksidan sangat kuat dengan nilai IC5016,634 µg/mL terhadap radikal bebas DPPH.Kata Kunci : Akar sambiloto, antioksidan, DPPH

Preparing Modified Hyaluronic Acid with Tunable Content of Vinyl Groups for Use in Fabrication of Scaffolds by Photoinduced Crosslinking

Materials based on hyaluronic acid (HA) are extensively used in tissue engineering as scaffolds. Photoinduced crosslinking is one way to prepare them, and, for this, HA must be modified with vinyl groups, which are capable of participating in free-radical reactions upon exposure to light. The quantity of grafted vinyl groups, represented as the degree of substitution (DS), is an important parameter of modified HA (mHA) that is related to the mechanical, chemical, and biological properties of scaffolds. Here, we demonstrate the feasibility of tuning DS by varying the reaction parameters (composition and concentration of reaction components and reaction conditions) and investigate the effect of DS on the viscosity of mHA solutions. As example, we consider the photoinduced reaction of mHA in the presence of flavin mononucleotide as the initiator, which can be used in fabrication of noncytotoxic scaffolds by 3D printing. The growth behavior of fibroblasts on the scaffold surface is studied.

Intensity of free-radical reactions in metastasizing cervical cancer.

e17508 Background: Cervical cancer (CC) is one of the main causes of death among patients with gynecological tumors. As a rule, patients die from relapses and metastases which rates reach 30-45%. According to research data, treatment of patients with distant metastases is ineffective, and half of them die within 9.7 months, while the average survival is 15.9±0.26 months. The development of many pathological processes is considered to be associated with an increase in free-radical reactions leading to oxidative damage to various biomolecules. The purpose of the study was to analyze some characteristics of the free-radical oxidation and antioxidant defence in metastasizing CC. Methods: The study included 56 patients aged 29-73 years with stage IIB-IV CC after antitumor treatment. The main group – 27 patients who developed metastases within 4 months to 8 years after the CC diagnosis; controls – 29 patients with non-metastatic CC; donors – 19 healthy women aged 27-61 years. The accumulation of carbonyl derivatives in blood plasma proteins was detected in the reaction with 2, 4-dinitrophenylhydrazine. The induced oxidative modification of proteins was stimulated with Fenton's reagent. Free-radical processes was evaluated by the intensity of peroxide-induced luminol-dependent plasma chemiluminescence and the content of nitric oxide metabolites; the intensity of lipid peroxidation - by the content of malondialdehyde (MDA); the activity of catalase and ceruloplasmin was also studied. Results: CC progression was accompanied by increasing lipid peroxidation and spontaneous oxidation of blood plasma proteins. MDA levels in patients with metastases increased by 57.8% compared to donors and by 34.3% compared to patients without metastases (p < 0.05). The concentration of 2, 4-dinitrophenylhydrozones increased on average by 4 times compared to donors and by almost 2 times compared to patients without metastases. Patients with metastasizing CC demonstrated elevated levels of products of the interaction of nitric oxide and its derivatives with proteins and peptides - 3-nitrotyrosine and nitrosoglutathione, compared to both donors (by 31.4% and 55.3%) and patients in remission (by 38.1% and 34.5%). Chemiluminescence activity increased by 54.5% compared to donors (p < 0.05) and by 93% (p < 0.01) compared to controls. Catalase activity in the blood plasma of patients with metastases increased by 54.1% compared to donors, but was lower than the values in the control group (by 22.1%). Ceruloplasmin activity was increased only in patients without metastases (by 33%). Conclusions: The process of CC metastasis is accompanied by a greater intensity of oxidative processes of both proteins and lipids, as well as depletion of the adaptive capabilities of the body's antioxidant system.

The activity of the enzyme link of the antioxidant defense system of cows organism in experimental fasciolosis

The antioxidant defense system of the organism controls and inhibits all stages of free radical reactions, starting from their initiation and ending to the formation of hydroperoxides and TBA-active products. The main mechanism of control of these reactions is associated with the chain of reversible redox reactions of metal ions, glutathione, ascorbate, tocopherol and other substances, the value of which is especially important for the preservation of long-standing macromolecules of nucleic acids and proteins, some components of membranes. The purpose of the research was to investigate the activity of the enzyme link of the antioxidant defense system of cows organism in experimental fasciolosis. Twelve cows of 4–5 years of age, Black-Spotted breed, were selected for the experiments, from which 2 groups were formed, six animals in each. Animals in control group (C) were clinically healthy. Animals of experimental group (E) were experimentally infected with adolescents. During the research, the rules of compulsory experiments were followed – selection and keeping of analogue animals in groups. The cows' ration was balanced in terms of nutrients and minerals. All animal manipulations were carried out in accordance with the European Convention for the Protection of Vertebrate Animals, which are used for experimental and scientific purposes. According to the results of our research, in cows affected by fasciolosis invasion, catalase activity in their blood decreased by 21.5 %, and superoxide dismutase activity by 30 %. In the research of the glutathione link of the antioxidant defense system, it was found that the activity of both glutathione peroxidase and glutathione reductase is also reduced in experimental fasciolosis. Thus, on the 25th day of the experiment, a decrease in these enzymes by 26.6 and 20.5 % is set. Thus, with the development of fasciolosis in ruminants, the balance in the complex “Antioxidant system – Lipid peroxidation” is disturbed, which in turn leads to complications of the disease. In the future it is planned to investigate the state of the non-enzymatic part of the antioxidant defense system of cows organism with experimental fasciolosis.

ANTIOXIDANT ACTIVITY OF RED ROSE LEAVES (Rosa chinensis Jacq.) EXTRACT

Background: Background: Antioxidants are compounds that can neutralize free radical reactions. The red rose leaves (Rosa chinensis Jacq.), usually disposed of as waste, have been shown to have antioxidant activity. Objective: This study aims to determine the antioxidant activity of red rose leaves extracts. Methods: The red rose leaves were extracted by the maceration method in ethanol, methanol, ethyl acetate, and n-hexane. The antioxidant activity was measured by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and was expressed as IC50 and an antioxidant activity index (AAI).Results: The results showed that the red rose leaves ethanol, methanol, ethyl acetate, and n-hexane extracts had an antioxidant activity with an IC50 value of 1.8, 8.7, 210.3, 48.7 µg/mL, respectively, and an AAI value of 17.3, 3.5, 0.1, 0.6, respectively. The main content of ethanol and methanol extracts are flavonoid, saponin, and tannin.Conclusion: The ethanol and methanol extract showed the most potent antioxidant activity.

Cecil Edwin Henry Bawn. 6 November 1908 — 19 September 2003

Cecil Bawn was a physical chemist with particular expertise in chemical kinetics. Early in his career he made pioneering studies of free radical reactions in the gas phase and, during the war years, on the chemistry of high explosives. From mid career, he was one of the pioneers of polymer chemistry and established and led a strong and diverse group of polymer scientists at the University of Liverpool. He was a private and enigmatic person, with a strong sense of duty. His caring and helpful attitude was greatly appreciated locally by his students and younger faculty members. Nationally, he made outstanding service contributions to physical chemistry and polymer chemistry.

The initial reaction mechanism and thermal sensitivity of a fluoropolymer-containing energetic molecular system: the coupling effect of interfacial interactions and free radical reactions

A strategy combining classic and reactive molecular dynamics is applied to find the coupling effect of interfacial interactions and free radical reactions during the initial thermal decomposition of fluoropolymer-containing molecular systems.