Betulin (betulinol) (lup-20(29)-ene-3β, 28-diol) is an abundant, naturally occurring triterpene. It is commonly isolated from the bark of birch trees where it forms up to 30% of the dry weight of the extractive and is found in birch sap as well.

SREBP:14.5 μM

Betulin（BE）展示了广泛的生物学和药理学特性，其中抗癌和化学预防活性最受关注。研究表明，BE通过抑制癌细胞生长来发挥抗癌特性。BE的抗增殖活性范围较广，根据癌细胞类型的不同，从人类红白血病细胞系（K562）中细胞增殖的弱抑制到人类神经母细胞瘤细胞（SK-N-AS）中的强抑制都有表现，后者效果最为显著。此外，BE还被发现对从卵巢癌、宫颈癌和胶质母细胞瘤患者获得的肿瘤样本中分离出的原发性癌细胞培养表现出显著的细胞毒性，其中IC50值范围从2.8到3.4 μM，与已建立的细胞系相比，这一数值显著较低。粗桦树皮提取物、纯化的betulin和betulinic acid对人类胃癌（EPG85-257）和人类胰腺癌（EPP85-181）药物敏感及抗药性（daunorubicin和mitoxantrone）细胞系的细胞毒活性进行了比较。研究显示，根据所使用的化合物，细胞系之间的敏感性存在显著差异，暗示betulin和betulinic acid可作为治疗癌症的有希望的先导化合物。

Betulin能够改善葡萄糖耐受不良并改变基础学习性能。使用Betulin显著恢复SOD活性并降低海马MDA含量。此外，Betulin显著减少血清和海马中炎症细胞因子的含量。进一步地，BE的管理有效上调了Nrf2、HO-1的表达，并阻断了IκB、NF-κB的磷酸化。总之，通过HO-1/Nrf-2/NF-κB途径，BE可能对STZ诱导的糖尿病大鼠认知下降展现出保护作用[3]。

Chemoresistance is tested using a proliferation assay based on sulphorhodamine B staining. Briefly, 800 cells per well are seeded in triplicate in 96-well plates. After attachment for 24 h, substances are added in dilution series for a 5-day incubation, before SRB staining is performed. Incubation is terminated by replacing the medium with 10% trichloroacetic acid, followed by further incubation at 4°C for 1h. Subsequently, the plates are ished five times with water and stained by adding 100 μL 0.4% SRB in 1% acetic acid for 10 min at room temperature. Ishing the plates five times with 1% acetic acid eliminated unbound dye. After air-drying and re-solubization of the protein bound dye in 10 mM Tris-HCl (pH=8.0), absorbance is read at 562 nm[2].