Purine and urate metabolism
Martin Andrew Crook in Clinical Biochemistry & Metabolic Medicine, 2013
Urate is the end product of purine metabolism in humans. In most other mammals, it is further metabolized to the more water-soluble allantoin. Humans lack uricase and thus their uric acid levels are higher. It is because of the poor solubility of urate that humans are prone to the clinical effects of hyperuricaemia, such as gout and renal damage. The purines adenine and guanine are constituents of nucleic acid from deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The purines used by the body for nucleic acid synthesis may be derived from the breakdown of ingested nucleic acid, mostly from cell-rich meat, or they may be synthesized de novo from small molecules. About two-thirds of the body’s urate (3–4 mmol/day) is produced endogenously, with one-third coming from exogenous dietary purines (1–2 mmol/day).
Novel UV Filtering Agents for Next-Generation Cosmetics: From Phytochemicals to Inorganic Nanomaterials
Madhu Gupta, Durgesh Nandini Chauhan, Vikas Sharma, Nagendra Singh Chauhan in Novel Drug Delivery Systems for Phytoconstituents, 2020
It has been studied that the peptide bonds present in various proteins, several lipids (squalene), and nucleotides (allantoin) present in skin are capable of providing natural defense against UV. Phytoextracts augmenting these molecules are therefore prospective prophylactic and therapeutic agents to be used as cosmetic agents. A number of plant peptides, squalene derived from olive oil, and allantoin derived from extracts of comfrey plant have shown extensive UV protection in skin. In fact, some of the ingredients have been tested in clinical trials and approved successfully for their use in cosmetics, in particular, anti-eczema creams, sunscreens, and wound healing creams. A few clinical studies also support the use of allantoin as an enhancer of skin repair (Dinkova-Kostova, 2008). Mishra et al. (2011) have recently reviewed the usage of crude extracts in UV protection in an elaborate review. Besides the use of whole plants and their crude extracts, several purified ingredients have also been studied for their UV-protecting abilities. These naturally occurring classes of UV filters may be primarily divided into two sub-categories: specific purified phytoextracts and whole plants. Some purified phytoextracts studied for UV protective abilities include silymarin, quercetin, carotenoids, and curcumin, whereas compete plants include tea, aloe vera, English walnut, etc. (Korac and Khambholja, 2011). Some of the important UV protectant from plant sources are described in Table 7.1.
Radiotherapy: The Prevention of Secondary Effects, Radiodermatitis, and Long-Term Toxicity
Paloma Tejero, Hernán Pinto in Aesthetic Treatments for the Oncology Patient, 2020
Included in the usual care to prevent radiodermatitis is nonpharmacological care. The guidelines include local hygiene, reduction of exposure and friction of the irradiated area, use of suitable clothing (preferably cotton), and avoidance of contact with extreme temperatures and pruritus in the irradiated area. Direct exposure to the sun should be avoided; use sunscreen with a sun protection factor (SPF) of at least 15. Apply hypoallergenic moisturizing creams without perfumes or preservatives. The natural oil-based emulsion containing allantoin seems to have similar effects for managing skin toxicity compared with aqueous cream up to week 5; however, it becomes significantly less effective at later weeks into the radiation treatment and beyond treatment completion (week 6 and beyond). Avoid the use of acne products that have alcohol or retinoids [14–16].
Development of a combination therapy with silanols complexed with boron citrate and ablative-fractional laser for treatment of wrinkles and stretch marks
Published in Journal of Dermatological Treatment, 2021
Klaudyna Wolak, Roksana Gruszkiewicz-Majczak
Before the treatment with the ‘Pearl Fractional’ fractional ablative laser (Xeo, Cutera, USA) a patient’s phototype was determined based on a phototype classification questionnaire according to Fitzparick attached by the manufacturer of the laser platform. An anesthetic in the form of an ointment (Emla, Aspen Pharma Trading Limited) was applied to the treatment area. After about 40 min before the procedure, the anesthetic was removed from the treatment area. The skin was degreased and disinfected. The treatment parameters and their number were determined individually by the person performing the treatment depending on the phototype and general condition of the skin and the age of the patient. Possible correction of the parameters took place during the procedure depending on the reactivity of the skin undergoing the procedure. After the treatment, the skin was cooled with a gel with methylsilanetriol stabilized with boron citrate from the refrigerator. This remedy was given to the patient for skin care after the treatment for 2–3 days including oiling ointment with allantoin.
Development of quantitative assay for simultaneous measurement of purine metabolites and creatinine in biobanked urine by liquid chromatography-tandem mass spectrometry
Published in Scandinavian Journal of Clinical and Laboratory Investigation, 2022
Dmitri Svistounov, Marit D. Solbu, Trond G. Jenssen, Ulla Dorte Mathisen, Terkel Hansen, Katja Benedikte Prestø Elgstøen, Svetlana N. Zykova
Allantoin and 13C2,15N4-allantoin were dissolved in water to 2561 µM and 121.9 µM, respectively. Xanthine and 13C15N2-xanthine were dissolved in 0.66 mM KOH to 300 µM both. Hypoxanthine and 13C5-hypoxanthine were dissolved in water to 2200 µM and 708.8 µM, respectively. Creatinine and D3-creatinine were dissolved in water to 706,825 µM and 43,040 µM, respectively. UA was dissolved in 14 mM LiOH to 7000 µM and 1,3-15N2-UA was dissolved in 6.2 mM KOH to 3000 µM. All stock solutions were aliquoted and stored at −80 °C.
Pharmacotherapeutic management of gout in patients with cardiac disease
Published in Expert Opinion on Pharmacotherapy, 2018
Chun Wai Chan, Ying Nee Yap
Uricase acts on urate itself, catalyzing oxidization of urate into hydrogen peroxide and 5-hydroxyisourate (5HIU) and subsequently decomposes into allantoin and carbon dioxide. Allantoin is highly soluble in plasma and easily excreted through kidney with very few pathological actions. Uricase is effective in various forms of hyperuricemia including refractory gout by removing urate and pre-existing urate crystals in joints.