Piliostigma thonningii (Schumach.) Milne-Redhead. (Leguminosae) is used for various medicinal purposes in African countries. Phytochemical investigation of P. thonningii yielded two compounds newly isolated from natural sources, 2β-methoxyclovan-9α-ol (1), and methyl-ent-3β-hydroxylabd-8(17)-en-15-oate (2), along with 14 known compounds (3–16). Compounds 1 and 4 (alepterolic acid) showed potential selectivity towards Trypanosoma brucei brucei with IC₅₀ 7.89 and 3.42 μM, respectively. Compound 2 showed activity towards T. brucei and Leishmania donovani Amastigote with IC₅₀ 3.84 and 7.82 μM, respectively. The structure activity relationship (SAR) of the isolated metabolites suggested that hydroxylation at C-2 enhances the antiprotozoal activity towards T. brucei in sesquiterpenes 1 and 3. Similarly hydroxylation at C-3 in labdane diterpenes elevates the antiprotozoal activity towards T. brucei.

中文翻译：

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尼日利亚药用植物 Piliostigma thonningii 的植物化学研究。

Piliostigma thonningii (Schumach.) Milne-Redhead。（豆科）在非洲国家用于各种药用目的。对P. thonningii的植物化学研究产生了两种新从天然来源中分离出来的化合物，2 β -methoxyclovan-9 α -ol ( 1 ) 和methylent -3 β -Hydroxylabd -8(17)-en-15-oate ( 2），以及 14 种已知化合物 ( 3 – 16 )。化合物1和4 （阿普特罗酸）对布氏锥虫具有潜在选择性， IC ₅₀分别为 7.89 和 3.42 μM。化合物2对布氏锥虫和杜氏利什曼原虫无鞭毛体具有活性， IC ₅₀分别为 3.84 和 7.82 μM。分离代谢物的结构活性关系（SAR）表明，C-2 处的羟基化增强了倍半萜1和3中对布氏锥虫的抗原虫活性。类似地，拉丹烷二萜中 C-3 的羟基化提高了对布氏锥虫的抗原虫活性。