类固醇Steroid

甾核四个环依次标为 A、B、C、D，共 17 个碳，通常在 C10、C13 上有角甲基，C17 上有侧链。环的稠合方式（如 A/B 反式或顺式）决定分子形状，天然类固醇多为较平坦刚性的骨架。“甾”字形象地表示四个环（田）上带三个支链（巛）。命名中 3β-OH 表示羟基在环平面上方。

The four rings are labelled A to D and contain 17 carbons, usually with angular methyl groups at C10 and C13 and a side chain at C17. The ring fusions, such as A/B trans or cis, set the molecular shape, and natural steroids mostly have a fairly flat, rigid frame. The Chinese character 甾 pictures four rings (田) with three side chains (巛). In names, 3β-OH means the hydroxyl lies above the ring plane.

1928 年维兰德因胆汁酸结构、温道斯因甾醇与维生素 D 的研究分获诺贝尔化学奖。1932 年罗森海姆与金修正了甾核结构。1930 年代布特南特分离出雌酮、雄酮和孕酮，与鲁日奇卡共获 1939 年诺贝尔化学奖。1950 年肯德尔、亨奇和赖希施泰因因肾上腺皮质激素获诺贝尔生理学或医学奖。1951 年伍德沃德完成胆固醇和可的松的全合成。

In 1928 Wieland (for bile acids) and Windaus (for sterols and vitamin D) received Nobel Prizes in Chemistry. Rosenheim and King corrected the steroid nucleus in 1932. In the 1930s Butenandt isolated oestrone, androsterone and progesterone and shared the 1939 Nobel Prize in Chemistry with Ružička. Kendall, Hench and Reichstein received the 1950 Nobel Prize in Physiology or Medicine for adrenal cortical hormones, and Woodward completed total syntheses of cholesterol and cortisone in 1951.

类固醇由乙酰辅酶 A 经甲羟戊酸、异戊二烯单元、角鲨烯环化为羊毛甾醇，再转化为胆固醇；胆固醇是所有类固醇激素的前体。他汀类药物抑制 HMG-CoA 还原酶以降低胆固醇。1951 年马克从墨西哥山药的薯蓣皂苷元半合成孕酮，使口服避孕药成为可能；糖皮质激素（地塞米松）广泛用于抗炎抗过敏。

Steroids are made from acetyl-CoA via mevalonate and isoprene units to squalene, which cyclises to lanosterol and then cholesterol, the precursor of all steroid hormones. Statins lower cholesterol by inhibiting HMG-CoA reductase. Marker's semi-synthesis of progesterone from diosgenin in Mexican yams made oral contraceptives possible, and glucocorticoids such as dexamethasone are widely used against inflammation and allergy.