The root extract of Scutellaria baicalensis Georgi promotes β cell function and protects from apoptosis by inducing autophagy

Jiali Zhou; Yushuang Luo; Xincong Kang; Fangzhou Bian; Dongbo Liu

doi:10.1016/j.jep.2021.114790

The root extract of Scutellaria baicalensis Georgi promotes β cell function and protects from apoptosis by inducing autophagy

J Ethnopharmacol. 2022 Feb 10:284:114790. doi: 10.1016/j.jep.2021.114790. Epub 2021 Nov 1.

Authors

Jiali Zhou¹, Yushuang Luo¹, Xincong Kang², Fangzhou Bian³, Dongbo Liu⁴

Affiliations

¹ Horticulture and Landscape College, Hunan Agricultural University, Changsha, 410128, China; State Key Laboratory of Subhealth Intervention Technology, Changsha, 410128, China.
² Horticulture and Landscape College, Hunan Agricultural University, Changsha, 410128, China; Hunan Key Laboratory of Crop Germplasm Innovation and Utilization, Hunan Agricultural University, Changsha, 410128, China.
³ University of California Irvine, Irvine, CA, 92697, United States.
⁴ Horticulture and Landscape College, Hunan Agricultural University, Changsha, 410128, China; State Key Laboratory of Subhealth Intervention Technology, Changsha, 410128, China; Hunan Key Laboratory of Crop Germplasm Innovation and Utilization, Hunan Agricultural University, Changsha, 410128, China; Hunan Co-Innovation Center for Utilization of Botanical Functional Ingredients, Changsha, 410128, China. Electronic address: liudongbo@hunau.net.

PMID: 34737007
DOI: 10.1016/j.jep.2021.114790

Abstract

Ethnopharmacological relevance: Scutellaria baicalensis Georgi (SBG) is a traditional Chinese medicine with a remarkable remedial effect on diabetes mellitus. However, the precise mechanism involved has not been fully elucidated yet. Here, we aimed to explore the anti-diabetes effects of its traditional decoction in vitro and elucidate the autophagy-related mechanism.

Aim of the study: This study was designed to investigate the effects of the water extract of SBG (WSB) on the β cell viability, insulin secretion and the mechanism related to autophagy.

Materials and methods: Detection of insulin secretion using an enzyme immunoassay method, and analysis of apoptosis rate in MIN-6 cells by the flow cytometry with PI and Annexin V-FITC staining. In addition, the autophagy levels and pathways were evaluated from the number of autophagosomes and the expression of autophagy-related proteins. 3-Methyladenine (3-MA) was used as the autophagy inhibitor. Autophagosomes were observed using a confocal microscopy, and autophagy-related proteins (LC3-II/I, p62, S6k, p-AMPK/AMPK, p-mTOR/mTOR) were measured by Western blot.

Results: Here we detected a significant increase in insulin release from MIN-6 cells after treated with WSB. It is about 1.6 times as much as that of the control group with 2.8 mM glucose and 2.2 times more than the 16.8 mM glucose group. At the same time, WSB increased the number of autophagosomes and the ratio of LC3 Ⅱ/LC3 Ⅰ, indicating that autophagy were activated in MIN-6 cells. When inhibiting autophagy, there was no significant difference in insulin release between the two groups. The apoptotic rate of the high glucose group was as high as 33.23%. After pretreatment with WSB, the apoptotic rate decreased to 14.95%, and increased to 22.57% when treated with 3-MA and WSB. At the same time, WSB treatment enhanced the phosphorylation of AMPK, but had no significant effect on the expression of mTOR and S6K.

Conclusion: Our data suggested that WSB increased insulin secretion and reduced apoptosis under high glucose by inducing autophagy through the AMPK pathway, which elucidated the mechanism of WSB in the treatment of diabetes.

Keywords: Apoptosis; Autophagy; Insulin secretion; Scutellaria baicalensis Georgi; β cells.

MeSH terms

Apoptosis / drug effects*
Autophagy / drug effects*
Insulin-Secreting Cells / drug effects*
Plant Extracts / chemistry
Plant Extracts / pharmacology*
Plant Roots / chemistry*
Scutellaria baicalensis / chemistry*

Substances

Plant Extracts