Seven new diterpenoids (1–7) and five known analogs (8–12) were isolated from the tuber of Icacina oliviformis. Their chemical structures were elucidated by spectroscopic analyses, with the spatial configurations defined based on calculated ¹³C NMR-DP4 analysis and electronic circular dichroism methods. Oliviformislactones A (1) and B (2) are the first examples of rearranged 3,4-seco-pimarane possessing a 6/6/5/5 tetracyclic ring system featuring an unprecedented 4,12-dioxatetracyclo[8.6.0.0^2,7.0^10,14]hexadecane core; secopimaranlactone A (3) and secocleistanthone A (4) are the first examples of 3,4-seco-pimarane and 3,4-seco-cleistanthane type diterpenoids, respectively, obtained from the Icacinaceae family. The plausible biosynthetic routes for 1–3 are proposed. Compounds 1–4 and 12 exhibited PTP1B inhibitory activity with IC₅₀ values ranging from 3.24 to 58.05 μM. Among them, 1 (IC₅₀ = 6.78 μM, K_i = 1.51 μM) and 3 (IC₅₀ = 3.24 μM, K_i = 1.25 μM) displayed uncompetitive inhibition responses. In addition, the 16-p-bromobenzoyl derivative of oliviformislactone A (1a) displayed higher potency (IC₅₀ = 87.51 nM, K_i = 0.44 μM) than its natural precursor.

中文翻译：

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改良的伊卡西纳氏菌块茎中的二萜类化合物，作为蛋白质酪氨酸磷酸酶1B抑制剂

从臭豆的块茎中分离出了七个新的二萜（1-7）和五个已知的类似物（8-12）。通过光谱分析阐明了它们的化学结构，并基于计算的¹³ C NMR-DP4分析和电子圆二色性方法定义了空间构型。Oliviformislactones A（1）和B（2）被重新排列3,4-的第一实施例开环-pimarane具有一个6/6/5/5四环系统设有一个前所未有4,12- dioxatetracyclo [8.6.0.0 ^2,7 .0 ^10,14 ]十六烷核；secopimaranlactone A（3）和secocleistanthone A（4）是3,4-的第一实施例开环-pimarane和3,4-开环分别-cleistanthane型二萜类化合物，从茶茱萸科家族获得。提出了合理的1-3种生物合成途径。化合物1-4和12表现出PTP1B抑制活性，IC ₅₀值为3.24至58.05μM。其中，1（IC ₅₀ = 6.78μM，K _i = 1.51μM）和3（IC ₅₀ = 3.24μM，K _i = 1.25μM）显示出非竞争性抑制反应。此外，16- poliviformislactone A（1a）的-溴苯甲酰基衍生物显示出比其天然前体更高的效价（IC ₅₀ = 87.51 nM，K _i = 0.44μM）。