Loureirin B

Exp Dermatol. 2015 May;24(5):355-60.

Loureirin B inhibits fibroblast proliferation and extracellular matrix deposition in hypertrophic scar via TGF-β/Smad pathway.[Pubmed: 25683490]

The ethanolic extract of Resina Draconis (RDEE) has been reported beneficial to normal wound healing yielding more regularly arranged collagen fibres. Loureirin B, a major component in RDEE, has been supposed to be effective on the prevention and treatment of pathological scars.
METHODS AND RESULTS:
To investigate the therapeutic effects of Loureirin B on hypertrophic scar (HS), fibroblasts from human HS and normal skin (NS) were isolated. Results showed that Loureirin B dose-dependently downregulated both mRNA and protein levels of type I collagen (ColI), type III collagen (ColIII) and α-smooth muscle actin (α-SMA) in HS fibroblasts. Loureirin B also suppressed fibroblast proliferative activity and redistributed cell cycle, but did not affect cell apoptosis. In vivo rabbit ear scar model, Loureirin B significantly improved the arrangement and deposition of collagen fibres, decreased protein levels of ColI, ColIII and α-SMA and suppressed myofibroblast differentiation and scar proliferative activity. In NS fibroblasts, Loureirin B effectively inhibited TGF-β1-induced upregulation of ColI, ColIII and α-SMA levels, myofibroblast differentiation and the activation of Smad2 and Smad3. Loureirin B also affected mRNA levels of major MMPs and TIMPs in TGF-β1-stimulated fibroblasts.
CONCLUSIONS:
Taken together, this study demonstrates that Loureirin B could downregulate the expression of fibrosis-related molecules by regulating MMPs and TIMPs levels, inhibit scar fibroblast proliferation and suppress TGF-β1-induced fibrosis, during which TGF-β1/Smad2/3 pathway is likely involved. These findings suggest that Loureirin B is a potential therapeutic compound for HS treatment.

Sci China C Life Sci. 2004 Aug;47(4):340-8.

Effects of dragon's blood resin and its component loureirin B on tetrodotoxin-sensitive voltage-gated sodium currents in rat dorsal root ganglion neurons.[Pubmed: 15493475]

Using whole-cell patch clamp technique on the membrane of freshly isolated dorsal root ganglion (DRG) neurons, the effects of dragon's blood resin and its important component Loureirin B on tetrodotoxin-sensitive (TTX-S) voltage-gated sodium currents were observed.
METHODS AND RESULTS:
The results show that both blood resin and Loureirin B could suppress TTX-S voltage-gated sodium currents in a dose-dependent way. The peak current amplitudes and the steady-state activation and inactivation curves are also made to shift by 0.05% blood resin and 0.2 mmol/L Loureirin B.
CONCLUSIONS:
These results demonstrate that the effects of blood resin on TTX-S sodium current may contribute to Loureirin B in blood resin. Perhaps the analgesic effect of blood resin is caused partly by Loureirin B directly interfering with the nociceptive transmission of primary sensory neurons.

J Cell Biochem . 2018 Feb;119(2):2012-2021.

Loureirin B promotes insulin secretion through inhibition of K ATP channel and influx of intracellular calcium[Pubmed: 28817206]

Abstract The development of new diabetes drugs continues to be explored. Loureirin B, a flavonoid, extracted from Dracaena cochinchinensis, has been confirmed to increase insulin secretion and decrease blood glucose levels. For searching the promotion of insulin secretion with the treatment of Loureirin B, experiments were employed based on cell experiments and computational methods. First, promotion of insulin secretion was dependent on extracellular glucose concentration. At the genetic level, Loureirin B enhanced the relative mRNA level of Pdx-1 and MafA. Meanwhile the intracellular level of ATP increased due to the continuous absorption of glucose. Further experiments showed that the currents of KATP channel on Ins-1 cells were inhibited and the voltage-dependent calcium channels were subsequently activated. The increase of Cx43 protein expression might mediate the Ca2+ to the intracellular. Through computational simulation, we hypothesized that Loureirin B might interact with KATP channels to promote insulin secretion. In conclusion, it could be concluded that Loureirin B promoted insulin secretion mainly through increasing mRNA level of Pdx-1, MafA, intracellular ATP level, inhibiting the KATP current, influx of Ca2+ to the intracellular. Keywords: KATP channel; influx of Ca; ins-1 cells; insulin secretion; Loureirin B.

Cell Biosci. 2014 Dec 12;4:78.

Loureirin B, an essential component of Sanguis Draxonis, inhibits Kv1.3 channel and suppresses cytokine release from Jurkat T cells.[Pubmed: 25937895]

Sanguis draxonis (SD), also known as "Dragon's Blood", is a traditional herb medicine that has been used to treat a variety of complications with unknown mechanisms. Recent studies show that SD displays immunosuppressive activities and improves symptoms of type I diabetes in animal models. However, the mechanisms underlying SD's immunosuppressive actions are not completely understood. The voltage-gated Kv1.3 channel plays a critical role in the pathogenesis of autoimmune diseases by regulating the functions of both T cells and B cells.
METHODS AND RESULTS:
Here we investigated the effect of SD and one of its active components Loureirin B (LrB) on Kv1.3. Both SD and LrB inhibited Kv1.3-mediated currents, produced a membrane depolarization, and reduced Ca(2+) influx in Jurkat T cells. In addition, application of LrB inhibited phytohemagglutinin (PHA)-induced IL-2 release from activated Jurkat T cells. Furthermore, point mutations in the selective filter region significantly reduced the inhibitory effect of LrB on Kv1.3.
CONCLUSIONS:
The results of these experiments provide evidence that LrB is a channel blocker of Kv1.3 by interacting with amino acid residues in its selective filter region. Direct inhibition of Kv1.3 in T cells by SD and LrB might be the cellular and molecular basis of SD-mediated immunosuppression.

Shandong Medical Journal, 2012, 52(13):7-9.

Effect of loureirin B on proliferation and extracellular matrix secretion of rat hepatic stellate cells in vitro.[Reference: WebLink]

To investigate the effects of Loureirin B on proliferation and extracellular matrix secretion of rat hepatic stellate cells in vitro.
METHODS AND RESULTS:
HSC-T6 was cultured in 96-well plates for 24 hours.Then they were incubated with different concentration of Loureirin B for 48 hours.MTT was used for assaying proliferation of HSC.Inhibition rate was calculated.Hyaluronic acid,laminin and collagen type Ⅳ were measured by radioimmunoassay. Addition of Loureirin B into culture medium significantly inhibited HSC proliferation,and the higher concentration of the Loureirin B were,the stronger inhibition rate of the HSC had.It also inhibited hyaluronic acid,laminin and collagen type Ⅳ secretion in different degree.
CONCLUSIONS:
Loureirin B significantly inhibits HSC proliferation and extracellular matrix secretion.

Chinese Journal of Experimental Traditional Medical, 2013, 19(23):254-7.

Protective Effects of Loureirin B on Dysfunction of Pacreatic Islet β Cell Induced by Palmitate.[Reference: WebLink]

To study the protective effects and mechanism of Loureirin B on the dysfunctiion of pancreatic islet β cell induced by palmitic acid.
METHODS AND RESULTS:
NIT-1 cells were cultured in medium added palmitic acid,and treated with Loureirin B.Cell apoptosis ratio and content of reactive oxygen species(ROS) were detected by flow cytometry,the expressions of glucose tnansport receptor-2(GLUT2) was examined by semiquantitate reverse transcript PCR.Compared with palmitic acid treated group,survival rate of NIT-1 with Loureirin B(20,10 μmol·L- 1) was increased significantly(P0.05).Loureirin B(20,10,5 μmol·L- 1)scavenged excessive ROS and lowered its concentration significantly(P0.05).Loureirin B(20 μmol·L- 1) was increased the expressions of GLUT2(P0.05),and Loureirin B(20,10,5 μmol·L- 1) was effective on reducing apoptosis ratio induced by palmitic acid(P0.05).
CONCLUSIONS:
Loureirin B can increase the survival rate of NIT-1 cultured in the medium added palmitic acid,scavenge excessive ROS induced by palmitic acid,decrease the cell apoptosis ratio and elevate the expressions of GLUT2.This indicates Loureirin B may accomplish its islet cell protection effects by reducing ROS within cell and reversing glucose metabolism disorder rand other effects induced by forkhead box protein-1(FOXO1) activated by oxidative stress.