Cucurbitacin IIa: A review of phytochemistry and pharmacology.

Cucurbitacin IIa was first found in plants and it belongs to tetracyclo triterpenoids. It is one of the most important active components in cucurbitaceae plants. Studies have found that cucurbitacin IIa has a variety of pharmacological effects, such as antitumor, antiinflammatory, antibacterial, antihepatitis B virus, inhibition of human immunodeficiency virus replication, and antidepressant effect. However, the underlying mechanisms, intracellular targets, and structure-activity relationships of cucurbitacin IIa remain to be completely elucidated. This review summarizes the current advances concerning the phytochemistry and pharmacology of cucurbitacin IIa. Electronic databases such as PubMed, Web of Science, Google Scholar, Science Direct, and CNKI were used to find relevant information about cucurbitacin IIa using keywords such as "Cucurbitacin IIa," "Pharmacology," and "Phytochemistry." These pharmacological effects involve the actin cytoskeleton aggregation, the regulation of JAK2/STAT3, ERBB-MAPK, CaMKII α/CREB/BDNF signal pathways, as well as the regulation of survivin, caspases, and other cell cycles, apoptosis, autophagy-related cytokines, and kinases. It has high development and use value.

Biosynthetic pathway of prescription cucurbitacin IIa and high-level production of key triterpenoid intermediates in engineered yeast and tobacco.

Cucurbitacin IIa is a triterpenoid isolated exclusively from Hemsleya plants and a non-steroidal anti-inflammatory drug that functions as the main ingredient of prescription Hemslecin capsules and tablets in China. Synthetic biology provides new strategies for production of such valuable cucurbitacins at a large scale; however, the biosynthetic pathway of cucurbitacin IIa has been unknown, and the heterologous production of cucurbitacins in galactose medium has been expensive and low yielding. In this study, we characterized the functions of genes encoding two squalene epoxidases (HcSE1-2), six oxidosqualene cyclases (HcOSC1-6), two CYP450s (HcCYP87D20 and HcCYP81Q59), and an acyltransferase (HcAT1) in cucurbitacin IIa biosynthesis by heterologous expression in Saccharomyces cerevisiae and Nicotiana benthamiana. We achieved high-level production of the key cucurbitacin precursor 11-carbonyl-20ß-hydroxy-Cuol from glucose in yeast via modular engineering of the mevalonate pathway and optimization of P450 expression levels. The resulting yields of 46.41 mg/l 11-carbonyl-20ß-hydroxy-Cuol and 126.47 mg/l total cucurbitacin triterpenoids in shake flasks are the highest yields yet reported from engineered microbes. Subsequently, production of 11-carbonyl-20ß-hydroxy-Cuol by transient gene expression in tobacco resulted in yields of 1.28 mg/g dry weight in leaves. This work reveals the key genes involved in biosynthesis of prescription cucurbitacin IIa and demonstrates that engineered yeast cultivated with glucose can produce high yields of key triterpenoid intermediates. We describe a low-cost and highly efficient platform for rapid screening of candidate genes and high-yield production of pharmacological triterpenoids.

A key protein from Borrelia burgdorferi could stimulate cytokines in human microglial cells and inhibitory effects of Cucurbitacin IIa.

Lyme neuroborreliosis (LNB) is an infectious disease of the nervous system caused by Borrelia burgdorferi (Bb) infection. However, its pathogenesis is not fully understood. We used recombinant BmpA (rBmpA) to stimulate human microglia cell HMC3, then collected the culture supernatant and extracted total RNA from cells, and used the supernatant for cytokine chip, then ELISA and qPCR technology were used to validate the results from cytokine chip. After rBmpA stimulation of microglia, 24 inflammation-related cytokines showed elevated expression. Among them, six cytokines (IL-6, IL-8, CCL2, CCL5, CXCL1, and CXCL10) increased significantly in mRNA transcription, three cytokines (IL-6, IL-8, and CXCL10) concentrations in the cell supernatant increased significantly after the rBmpA stimulation, and CuIIa could inhibit expression of these cytokines. The BmpA can stimulate human microglia to produce large amounts of cytokines, leading to the occurrence of inflammation, which may be closely related to the development of LNB. CuIIa can inhibit BmpA-induced cytokine production in microglia, which may have potential therapeutic effects on LNB.

Isoforskolin and Cucurbitacin IIa promote the expression of anti-inflammatory regulatory factor SIGIRR in human macrophages stimulated with Borrelia burgdorferi basic membrane protein A.

Certain natural products, derived from medicinal plants, exhibit anti-inflammatory properties, but the mechanism of action of many remains unclear. Borrelia burgdorferi spirochetes are responsible for causing Lyme arthritis through activation of the Toll-like receptor (TLR) signaling pathway. In this study, we investigated the mechanisms by which Isoforskolin (ISOF) and Cucurbitacin IIa (CuIIa), compounds derived from Chinese herbs, can exert anti-inflammatory effects by modulating single immunoglobulin interleukin-1 receptor-related receptor (SIGIRR; also known as Toll/interleukin-1 receptor 8, TIR8) and thereby inhibiting B. burgdorferi basic membrane protein A (BmpA)-induced TLR signaling in human macrophages, specifically the THP-1 human monocytic cell line. After THP-1 cells were exposed in vitro to: i) recombinant (r)BmpA, ii) rBmpA and ISOF or iii) rBmpA and CuIIa, Cytotoxicity assay (Cell Counting Kit-8, CCK-8) are used to measure the effects of ISOF and CuIIa on cell viability. Meanwhile, real-time polymerase chain reaction and Western blotting were used to quantify SIGIRR mRNA and protein levels, respectively, at 6, 12, 24 and 48 h time points post-stimulation. In addition, proinflammatory cytokine tumor necrosis factor-α (TNF-α) was determined by ELISA analysis. Our study showed that rBmpA stimulation of THP-1 cells resulted in a drop in SIGIRR levels in THP-1 cells. More importantly, SIGIRR levels increased significantly in rBmpA-stimulated THP-1 cells following ISOF or CuIIa administration, and the results of ELISA analysis suggested that ISOF or CuIIa reduced the secretion of the proinflammatory cytokine TNF-α. In conclusion, These results reveal new possibilities for the treatment of Lyme arthritis.