Baicalein

Baicalein (5,6,7-trihydroxyflavone) is a flavonoid compound with multiple biological activities. It is a xanthine oxidase inhibitor with an IC₅₀ value of 3.12μM^[1]. Baicalein interacts with the benzodiazepine binding site of the GABA_A receptor in mouse cortical membrane preparations with a K_i value of 13.1μM^[2]. Baicalein has anti-tumor and anti-inflammatory activities, and can also play a neuroprotective and mitochondrial protective role^[3].

In vitro, Baicalein (25μM) treatment of mouse spleen lymphocytes for 2h significantly inhibited mitogen-induced T cell proliferation and cytokine secretion, and also inhibited the upregulation of CD69 and CD25 (IL2Rα), but did not inhibit CD54 (ICAM-1) expression^[4]. Baicalein (0-160 μM) was treated for 24 h in two ovarian cancer (OVCAR-3 and CP-70) cell lines and one normal ovarian cell line (IOSE-364), selectively inhibiting cancer cell viability, while the inhibitory effect on normal ovarian cells was significantly less. It also inhibited the expression of oncogenes such as VEGF, HIF-1α, cMyc and NFκB^[5].

In vivo, Baicalein (1, 3 mg/kg) was treated by intratumoral injection in mice inoculated with H-460 tumor cells for 4 weeks, which significantly inhibited tumor growth, reduced the expression of 12-LOX and VEGF in tumor tissue, and reduced the mitotic cell index and microvascular density^[6]. Baicalein (30, 100 mg/kg) was used to treat mice with acidified ethanol-induced acute gastric ulcers, significantly inhibited the formation of acute ulcers, reduced the inflammatory process, stimulated cellular antioxidant mechanisms, and increased gastric mucus secretion^[7].

References:
[1] Shieh D, Liu L T, Lin C C. Antioxidant and free radical scavenging effects of baicalein, baicalin and wogonin[J]. Anticancer research, 2000, 20(5A): 2861-2865.
[2] Liao J F, Hung W Y, Chen C F. Anxiolytic-like effects of baicalein and baicalin in the Vogel conflict test in mice[J]. European journal of pharmacology, 2003, 464(2-3): 141-146.
[3] De Oliveira M R, Nabavi S F, Habtemariam S, et al. The effects of baicalein and baicalin on mitochondrial function and dynamics: A review[J]. Pharmacological Research, 2015, 100: 296-308.
[4] Patwardhan R S, Sharma D, Thoh M, et al. Baicalein exhibits anti-inflammatory effects via inhibition of NF-κB transactivation[J]. Biochemical Pharmacology, 2016, 108: 75-89.
[5] Chen J, Li Z, Chen A Y, et al. Inhibitory effect of baicalin and baicalein on ovarian cancer cells[J]. International journal of molecular sciences, 2013, 14(3): 6012-6025.
[6] Cathcart M C, Useckaite Z, Drakeford C, et al. Anti-cancer effects of baicalein in non-small cell lung cancer in-vitro and in-vivo[J]. BMC cancer, 2016, 16: 1-13.
[7] Ribeiro A R S, do Nascimento Valença J D, da Silva Santos J, et al. The effects of baicalein on gastric mucosal ulcerations in mice: Protective pathways and anti-secretory mechanisms[J]. Chemico-Biological Interactions, 2016, 260: 33-41.

Baicalein（黄芩素；5，6，7-三羟基黄酮）是具有多种生物活性的黄酮类化合物，是黄嘌呤氧化酶抑制剂，IC₅₀值为3.12μM^[1]。Baicalein与小鼠皮质膜制剂中GABA_A受体的苯二氮卓结合位点相互作用， K_i值为13.1μM^[2]。Baicalein具有抗肿瘤、抗炎活性，还可以发挥神经保护、线粒体保护等作用^[3]。

在体外，Baicalein（25μM）处理小鼠脾淋巴细胞2h，可显著抑制丝裂原诱导的T细胞增殖和细胞因子分泌，还抑制了CD69和CD25（IL2Rα）的上调，但没有抑制CD54（ICAM-1）表达^[4]。Baicalein（0-160μM）处理两种卵巢癌（OVCAR-3和CP-70）细胞系和一种正常卵巢细胞系（IOSE-364）24h，选择性地抑制癌细胞活力，而对正常卵巢细胞的抑制作用明显较小，还抑制VEGF、HIF-1α、cMyc和NFκB等促癌基因的表达^[5]。

在体内，Baicalein（1，3mg/kg）通过瘤内注射治疗接种H-460肿瘤细胞的小鼠4周，显著抑制了肿瘤生长，降低了肿瘤组织内12-LOX和VEGF表达，降低了有丝分裂细胞指数和微血管密度^[6]。Baicalein（30，100mg/kg）治疗酸化乙醇诱发的急性胃溃疡小鼠，显著抑制了急性溃疡的形成，减少了炎症过程，刺激了细胞抗氧化机制，增加了胃粘液分泌量^[7]。