The effects of selected samples on the bio-stimulatory capacity and anti-aging effects of red light on human skin cells
- Authors: Rudolph, Carlen
- Date: 2024-04
- Subjects: Cell culture -- Technique , Dermatologic agents , Collagen , Biochemistry -- Technique
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64347 , vital:73677
- Description: Photobiomodulation (PBM) has gained a remarkable interest in the cosmeceutical industry, with research demonstrating supporting evidence for its use as anti-aging and skin-rejuvenating strategies. It is defined as photons at a non-thermal irradiance or non-ionizing photonic energy that trigger photochemical changes within the cellular structure to alter certain biological activities. Lasers were the main focus during the developmental years of light-based treatments, but since the introduction of non-ablative, light-emitting diode (LED) devices, the focus has changed because of the reduced concerns associated with lasers, such as costs, ablation cutting, thermally coagulating tissue, no downtime needed after treatment, and no trained staff needed for operation. The precise biochemical mechanism for PBM is still to be elucidated; however, accepted theories suggest that it has an influence on the activity of cytochrome c oxidase, a complex located in the electron transport chain, or on the viscosity of the interfacial water layer (IWL) of the mitochondrial membrane. The interaction of those cellular components with the light then leads to the primary responses of increased ROS, ATP production, and intracellular calcium, which ultimately leads to the stimulation of secondary responses that are desired for skin rejuvenation and anti-aging, such as cell proliferation and collagen production. There is controversy surrounding photobiomodulation (PBM), mostly because of the incomplete understanding behind its biochemical mechanism and the number of parameters that require optimization; however, it still poses as a promising field for research into anti-aging properties, as seen in the literature. Besides the use of devices for skin rejuvenation and anti-aging strategies, it is not uncommon to see plant extracts and other natural products being used in current skin care products for the same reason? This is mostly because of their promising bioactivities, some of which include antioxidant, anti-inflammatory, anti-bacterial, collagen-stimulating, and cell-proliferating activities. The aim of this study was to investigate the bio-stimulatory capacity of red light on skin cells and to evaluate possible effects it could have in combination with samples that already show promising anti-aging properties in research. The samples that were selected for this study are: Aspalathus linearis (rooibos) unfermented extract, L-ascorbic acid 2-phosphate, mangrove bee honey, stingless bee honey, Sargassum oligocystum (brown seaweed) and Ulva fasciata (green seaweed).It was found that red light irradiation did indeed stimulate the primary responses of ROS, ATP production, and intracellular calcium levels in HaCaT keratinocytes, as proposed in the hypothesised theory. However, none of the proposed secondary responses to cell proliferation or collagen production were demonstrated. In fact, the opposite was observed for cell proliferation and collagen production, where red light irradiation seemed to be cytostatic towards Hs27 fibroblast cells and caused significant decreases in collagen production. Red light energy dosages of 10, 20 and 30 J/cm2, yielded different primary responses with 20 and 30 J/cm2 generally causing more significant stimulation than that of 10 J/cm2. It should also be noted that even if the desired secondary responses were not observed in this study, it does not mean that red light does not have the capacity to still stimulate them. It is clear that the responses are energy dosage-dependent, and it is suggested that lower energy dosages could possibly lead to cell proliferation and that longer incubation periods post-irradiation are required before measuring the endpoint of collagen production. For the combination of red light irradiation and selected test samples, it was demonstrated that the order of samples that yielded the best outcomes is: stingless bee honey > mangrove bee honey > U. fasciata > S. oligocystum > 2-PAA > green rooibos. Unexpected results were demonstrated for green rooibos in the presence and absence of red light, which included decreased ATP production and collagen biosynthesis. Further investigation is therefore needed to have a better understanding of these unanticipated results. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
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- Date Issued: 2024-04
The effects of organic perturbants on the structure of soluble collagen
- Authors: Hart, Geoffrey Joseph
- Date: 1971
- Subjects: Chemistry, Organic , Collagen
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3846 , http://hdl.handle.net/10962/d1012157 , Chemistry, Organic , Collagen
- Description: Organic solvents were used in the present study as a means of investigating the non-covalent interactions involved in the maintenance and pertubation of the three-dimensional structure of the collagen macromolecule in solution. The two main types of non-covalent interaction under consideration are hydrogen bond formation and hydrophobic effects. Elucidation of the relative importance of these factors in the maintenance of the solution structure of proteins is an area of intensive investigation and fundamental significance to biochemistry as a whole. During the past decade, considerable progress has been made towards a clearer understanding of the forces involved, and a number of different theoretical and experimental approaches have emerged. Until about 1960, hydrogen bonding was widely believed to be the dominant non-covalent interaction responsible for the maintenance of secondary and tertiary structure in many proteins. Subsequently, an increasingly important role for apolar (hydrophobic) effects was suggested by a number of authors, and at present there is no satisfactorily definitive interpretation of the available experimental evidence. The current work is based on a comparison of the effects of organic solvents on widely different substrates, namely collagen, cellulose, and the chromatographic reference material, catechin. The chromatographic mobility of catechin on cellulose may be regarded as a phenomenon which is mediated entirely by polar interaction mechanisms. The effects of various organic perturbants and of changing solvent/water ratios are readily interpreted on this basis. In the collagenous systems, however, certain results appear to require the introduction of concepts other than those relating exclusively to polar bonding affinities. The experimental evidence shows that there are cases where the enhancement of the polar interaction potential of solvent/water mixtures, in relation to catechin-cellulose systems, is accompanied by an apparent reduction of polar interaction potential of the same solvent/water mixtures with respect to soluble collagen. The anomaly outlined above will be discussed in terms of two fundamentally different theoretical assumptions. In the first of these, the mechanism of perturbant action in collagenous systems is regarded as essentially similar to that governing catechin-cellulose affinity patterns. Thus, interaction processes are all treated as polar phenomena, in which direct hydrophobic destabilization of the collagen triple helix plays no part. In an attempt to explain the effects of perturbants in both collagen and cellulose-containing systems in terms of the above assumption, two hypotheses are examined involving (1) direct polar interaction between perturbant molecules and functional groups of the protein; (2.) the possibility of an enhanced polar interaction potential of water molecules, due to lowering of the environmental dielectric constant when organic solvents are added to the systems. Within the other broad conceptual division, collagen and cellulose substrates are considered to respond in fundamentally different ways to the action of organic perturbants. As before, cellulose-catechin-solvent interactions are treated as entirely polar phenomena, and perturbant effects interpreted in terms of mechanisms such as direct solvation of the substrate, and the enhanced hydrogen bonding activity of water molecules. In contrast, perturbant lyotropic action with respect to soluble collagen i s viewed as the manifestation of a major contribution by hydrophobic interaction processes to macromolecular stability. Thus, solvents that competitively reduce the assumed entropic contribution to the stability of the collagen triple helix, are seen as potential destabilizers of the native state of the protein and inhibitors of the regeneration of co-operative structures during renaturation. Both of the above approaches are critically assessed in the light of the present work and the dominant trends apparent in the recent literature.
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- Date Issued: 1971
Theoretical aspects of the reaction of zirconium compunds and vegetable tannins with the chromium-collagen complex
- Authors: Williams-Wynn, David Ernest Arthur
- Date: 1969
- Subjects: Zirconium compounds , Collagen , Chromium compounds , Tannins
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4512 , http://hdl.handle.net/10962/d1013455
- Description: Studies have been made of the reactions which take place when zirconium compounds and vegetable tannins react with chromium tanned leather, in order to elucidate the mechanisms of the reactions which occur on retannage. Statistical procedures have been used in all investigations because of the variable nature of the substrate, and computer techniques have been applied to the repetitive statistical computations. Although chromium and vegetable tannages are well understood, further information on the reaction of zirconium with collagen was necessary before attempting to interpret the results of the studies of combination tannages with chromium, and this has been obtained by a comparative study of the reactions of chromium and zirconium with modified collagen. It is concluded that the mechanism of the reaction of basic zirconium sulphate with collagen is multipoint attachment of the tanning material by residual valency forces, although charge effects with basic groups may be supplementary. Zirconyl chloride reacts with carboxyl groups but does not form satisfactory, stable cross-links with collagen. Further evidence for this theory was obtained from the investigation of the reaction of zirconium compounds with chromium tanned collagen. Zirconyl sulphate does not interfere with effective chromium tannage and therefore can have little affinity for the carboxyl groups on the protein, but it displaces chromium complexes loosely held by auxiliary valencies without reducing the shrinkage temperature of the chromium leather Zirconyl chloride, although only fixed to a limited extent, apparently forms co-ordination compounds with the carboxyl groups, disrupting the chromium tannage because there is an over-all loss of hydrothermal stability. There is no evidence that zirconium co-ordinates with, or releases acid from chromium-collagen complexes, since combination chromium/zirconium tanned leathers are stable on storage. Retannage of chromium tanned leather with vegetable tanning materials generally results in loss of strength and a product which tends to deteriorate on ageing. Lower initial strength is probably due to the increased avidity of chromium tanned pelt for vegetable tannins, resulting from the liberation of internally neutralised reactive sites which are not normally available in vegetable tannage, and from the co- ordination of vegetable tannins and non-tannins to the chromium complex with the displacement of sulphate radicals. From a study of the retannage of chromium tanned modified collagen, it appears that basic groups probably play an important part in the rapid absorption of vegetable tannin. These reactions result in overloading of the fibre and an increased number of cross-links, both of which tend to produce weak leather. Deterioration with age is primarily a hydrolytic degradation of the protein which is catalysed by acid liberated from the chromium complexes by the entry of vegetable tannins, those factors which favour the formation of acid causing greater and more rapid deterioration.
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- Date Issued: 1969
Some aspects of the chemistry of zirconium compounds relating to their combination with collagen
- Authors: Williams-Wynn, David Ernest Arthur
- Date: 1960
- Subjects: Zirconium compounds , Collagen
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4513 , http://hdl.handle.net/10962/d1013456
- Description: [Summary] Some properties of zirconium compounds in aqueous solution have been determined using physico-chemical techniques. Zirconium oxychloride was used as the source of zirconium in all detailed investigations; zirconium sulphate was used in a few cases for comparative purposes. The Stokes diaphragm cell method has been used to determine the diffusion coefficient of zirconium in hydrochloric acid solution. It was found that the diffusion coefficient fell progressively with time, a limiting value being reached 4 to 5 weeks after dissolving the salt, and it was demonstrated that particles in the aged solutions were more homogeneous than in freshly prepared solutions. The limiting values were concentration dependent; dilute solutions had a lower diffusion coefficient than the more concentrated solutions when measured at the natural pH. In the presence of added acid the rate of diffusion was increased until a limiting value was reached in 0.5 M acid. The addition of alkali or complexing acids reduced the rate of diffusion.
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- Date Issued: 1960