Tsumura Research Laboratories, Tsumura & Co., Ibaraki 300-1192, Japan.
Department of Dermatology, Tohoku University Graduate School of Medicine, Miyagi 980-8574, Japan.
Molecules. 2017 Oct 27;22(11):1829. doi: 10.3390/molecules22111829.
Stratum corneum tryptic enzyme kallikrein 5 (KLK5) is a serine protease that is involved in the cell renewal and maintenance of the skin barrier function. The excessive activation of KLK5 causes an exacerbation of dermatoses, such as rosacea and atopic dermatitis. Some triterpenoids are reported to suppress the serine proteases. We aimed to investigate whether bioactive triterpenoids modulate the KLK5 protease. Nineteen triterpenoids occurring in medicinal crude drugs were evaluated using an enzymatic assay to measure the anti-KLK5 activity. The KLK5-dependent cathelicidin peptide LL-37 production in human keratinocytes was examined using immunoprecipitation and Western blotting. Screening assays for evaluating the anti-KLK5 activity revealed that ursolic acid, oleanolic acid, saikosaponin b₁, tumulosic acid and pachymic acid suppressed the KLK5 protease activity, although critical molecular moieties contributing to anti-KLK5 activity were unclarified. Ursolic acid and tumulosic acid suppressed the proteolytic processing of LL-37 in keratinocytes at ≤10 μM; no cytotoxicity was observed. Both triterpenoids were detected in the plasma of rats administered orally with triterpenoid-rich crude drug Jumihaidokuto. Our study reveals that triterpenoids, such as ursolic acid and tumulosic acid, modulate the KLK5 protease activity and cathelicidin peptide production. Triterpenoids may affect the skin barrier function via the regulation of proteases.
角质层丝氨酸蛋白酶 5（KLK5）是一种丝氨酸蛋白酶，参与皮肤屏障功能的细胞更新和维持。KLK5 的过度激活会导致皮肤病恶化，如酒渣鼻和特应性皮炎。一些三萜类化合物被报道能抑制丝氨酸蛋白酶。我们旨在研究生物活性三萜类化合物是否能调节 KLK5 蛋白酶。使用酶促测定法评估了 19 种存在于药用粗提物中的三萜类化合物，以测量其抗 KLK5 活性。用人角质形成细胞的免疫沉淀和 Western blot 检测 KLK5 依赖性抗菌肽 LL-37 的产生。用于评估抗 KLK5 活性的筛选测定表明，熊果酸、齐墩果酸、柴胡皂苷 b₁、土莫酸和巴库酸抑制 KLK5 蛋白酶活性，尽管未阐明对抗 KLK5 活性有贡献的关键分子部分。熊果酸和土莫酸在≤10 μM 时抑制角质形成细胞中 LL-37 的蛋白水解加工；未观察到细胞毒性。这两种三萜类化合物均在口服给予富含三萜类化合物的粗提取物 Jumihaidokuto 的大鼠血浆中被检测到。我们的研究表明，三萜类化合物如熊果酸和土莫酸，可调节 KLK5 蛋白酶活性和抗菌肽的产生。三萜类化合物可能通过调节蛋白酶来影响皮肤屏障功能。
