hydroxyl radicals (羥自由基)

hydroxyl radicals (羥自由基)

hydroxyl radicals (羥基自由基)

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羥自由基 (Hydroxyl Radicals) 被認為是生物系統中化學性質最活潑且最具破壞性的活性氧（ROS）。它們幾乎能與所有類型的生物分子發生反應。

以下是關於羥自由基的逐句對照翻譯與說明：

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• The hydroxyl radical is the most reactive and short-lived species among all reactive oxygen species. (羥自由基 是所有活性氧物種中反應性最強且壽命最短的種類。)

• In biological systems, it is often generated from hydrogen peroxide through the Fenton reaction, involving metal ions like iron or copper. (在生物系統中，它通常經由芬頓反應（Fenton reaction）從過氧化氫產生，此過程涉及鐵或銅等金屬離子。)

• Because of its extreme reactivity, the hydroxyl radical has a very short diffusion distance and reacts immediately with whatever molecule it encounters. (由於其極高的反應活性，羥自由基的擴散距離非常短，會立即與遇到的任何分子發生反應。)

• It can cause irreversible damage to DNA, proteins, and lipids, leading to cell dysfunction or death. (它可以對 DNA、蛋白質和脂質造成不可逆的損傷，進而導致細胞功能障礙或死亡。)

• In the skin, hydroxyl radicals are frequently produced during exposure to ultraviolet radiation or heavy environmental pollution. (在皮膚中，羥自由基經常在暴露於紫外線輻射或嚴重的環境污染時產生。)

• Unlike some other free radicals, there is no specific enzymatic antioxidant that can directly neutralize hydroxyl radicals; defense relies on scavenging molecules like melatonin or glutathione. (與其他某些自由基不同，目前沒有特定的抗氧化酶能直接中和羥自由基；防禦主要依賴褪黑激素或穀胱甘肽等清除分子。)

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羥自由基的破壞機制 (Mechanism of Damage)

• Lipid Peroxidation (脂質過氧化): Hydroxyl Radicals attacks polyunsaturated fatty acids in cell membranes, initiating a chain reaction that destroys membrane integrity. (羥自由基攻擊細胞膜中的多元不飽和脂肪酸，引發破壞膜完整性的連鎖反應。)

• Protein Oxidation (蛋白質氧化): It oxidizes amino acid side chains, leading to protein cross-linking or fragmentation. (它會氧化氨基酸側鏈，導致蛋白質交聯或斷裂。)

• DNA Damage (DNA 損傷): It can cause strand breaks and base modifications, which are critical precursors to skin aging and carcinogenesis. (它會導致鏈斷裂和鹼基修飾，這是皮膚老化和癌症發生的關鍵前兆。)

正如您之前提到的研究，當臭氧（O3）與皮膚脂質反應時，也會間接誘導這些極具攻擊性的羥自由基產生，這也是為什麼補充足夠的親水性（如維生素 C）與親脂性抗氧化劑對皮膚保護至關重要。

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資訊來源：

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Placeholder 湯偉晉編寫的英文字典

Placeholder 湯偉晉編寫的英文字典

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