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Boron, Manganese, Molybdenum, Nickel, Silicon and Vanadium
Published in Judy A. Driskell, Ira Wolinsky, Sports Nutrition, 2005
Boron is widely distributed in nature and always bound to oxygen. Boron biochemistry is essentially that of boric acid. Dilute aqueous boric acid solutions comprise B(OH)3 and B(OH)4– at the pH of blood (7.4); because the pKa of boric acid is 9.15, the abundance of these two species at pH 7.4 is 98.4% and 1.6%, respectively.1 Boric acid forms ester complexes with hydroxyl groups of organic compounds, preferably when the hydroxyl groups are adjacent and cis.2 Among the many substances of biological interest with which boron forms complexes are diadenosine polyphosphates, S-adenosylmethionine, pyridoxine, riboflavin, dehydroascorbic acid and pyridine nucleotides. Formation of these complexes may be biologically important because some may modulate or regulate some function or reaction. To date, several naturally occurring organoboron compounds have been identified; all of these are boroesters. These compounds include antibiotics produced by microorganisms,3–5 the plant cell wall component, rhamnogalacturonan-II,6,7 and a bacterial extracellular signaling molecule.8
Boron’s neurophysiological effects and tumoricidal activity on glioblastoma cells with implications for clinical treatment
Published in International Journal of Neuroscience, 2019
Meric A. Altinoz, Gulacti Topcu, İlhan Elmaci
In the nature, many boron-containing molecules exist including: fungus-origined antibiotic compounds; bacterial quorum sensing molecules; and vegetal rhamnogalacturonan-II dimers [9]. Boron may involve in cell membrane function, by regulating endocrine responses, signaling through the cell membrane and membrane traversal of cations or anions. This proposal is evidenced by the observations that boron controls the transport of extracellular Ca and the release of intracellular Ca in thrombocytes activated by thrombin [15]. Boron may also act as controlers of metabolism by forming ester compounds or complexes with various substrates including hydroxyl groups in favorable locations. Because these complexes or ester compounds generally lead to a competitive blockage of the activity of several enzymes in vitro, boron action is presumed to be mainly inhibitory [15].
Green synthesis of metallic nanoparticles using pectin as a reducing agent: a systematic review of the biological activities
Published in Pharmaceutical Biology, 2021
Kogilavanee Devasvaran, Vuanghao Lim
The pectin schematic structure (Figure 1) consists of a homogalacturonan (HG) backbone, xylogalacturonan (XGA), rhamnogalacturonan I (RG-I) and rhamnogalacturonan II (RG-II) regions. The pectin foundation comprises of acetylated and methylated α (1–4)-galacturonic acid units. The HG region is the most abundant and stretches up to 100 GalA, comprising approximately 60% of the pectin. The XGA region differs from HG only by substituting O-3 with β-linked xylose (Mohnen 2008).