Loureirin A

Eur J Pharmacol. 2015 Jan 5;746:63-9.

Antiplatelet activity of loureirin A by attenuating Akt phosphorylation: In vitro studies.[Pubmed: 25445049]

Loureirin A is a flavonoid extracted from Dragon׳s Blood that has been used to promote blood circulation and remove stasis in Chinese traditional medicine. However, the mechanisms of these effects are not fully understood.
METHODS AND RESULTS:
We explored the anti-platelet activity and underlying mechanism of Loureirin A in vitro. Our results indicated that Loureirin A negatively affected agonist-induced platelet aggregation such as collagen, collagen-related peptide (CRP), ADP and thrombin. Loureirin A inhibited collagen-induced platelet ATP secretion and thrombin-stimulated P-selectin expression in a dose-dependent manner. Platelet spreading on immobilized fibrinogen was significantly impaired in the presence of Loureirin A. Immunoblotting analysis indicated that 100μM of Loureirin A almost completely eliminated collagen-induced Akt phosphorylation at Ser473. Interestingly, a submaximal dose (50μM) of Loureirin A had an additive inhibitory effect with the phosphoinositide 3-kinase (PI3K) inhibitor Ly294002 on collage-induced Akt phosphorylation in platelets.
CONCLUSIONS:
Taken together, Loureirin A had an inhibitory effect on platelet activation, perhaps through an impairment of PI3K/Akt signaling.

Journal of Kunming Medical University, 2016 , 37 (6) :13-17.

Effect of Loureirin A on Proliferation and Frizzled-4Expression of Rat Hepatic Stellate Cells in vitro[Reference: WebLink]

To investigate the molecular mechanism of Loureirin A mediated anti- hepatic fibrosis by evaluting its effects on proliferation,secretion of α- smooth muscle actin(α- SMA) and transforming growth factor- beta1(TGF- β1), and expression of rat hepatic stellate cells in vitro.
METHODS AND RESULTS:
Primary hepatic stellate cells were isolated and cultured from Sprague- Dawley rats. After activating and inducing primary hepatic stellate cells from q HSC to a HSC, the activated hepatic stellate cells model in vitro was established. Then we observed the morphological changes of static hepatic stellate cells and activated hepatic stellate cells with inverted phase contrast microscope. Cultured hepatic stellate cells were treated with different concentrations of Loureirin A and the inhibitory rate of HSCs proliferation was measured by MTT assay. The expression of Frizzled- 4 was measured by western blot analysis. The content of α- SMA and TGF- β1 in the cultured HSCs' supernatant were measured by enzyme- linked immunosorbent assay(ELISA). Loureirin A the proliferation of inhibited activated hepatic stellate cells in a time- dose- dependent manner compared with the control group,IC50=0.30 μg/μL. After Loureirin A treatment of the HSCs, western blot analysis showed that Frizzled- 4 expression level was obviously lower than control group.Loureirin A also inhibited α- SMA and TGFβ1(P0.05) secretion in the cultured HSCs' supernatant in different degree by the assay of ELISA.
CONCLUSIONS:
The molecular mechanism of Loureirin A and Wnt signaling pathway mediated anti- hepatic fibrosis and anti- angiogenesis may involve down- regulation the expression of Frizzled- 4,inhibiting the synthesis and secretion of α- SMA,TGF- β1and the proliferation of HSCs.

Journal of Biomaterials & Tissue Engineering, 2016 , 6 (6) :427-432.

Loureirin A Activates Wnt/β-Catenin Pathway to Promote Wound with Follicle Stem Cell-Seeded Tissue-Engineered Skin Healing[Reference: WebLink]

Hair follicle stem cells (FSCs) can participate in the formation of hair follicles and epidermis. FSCs are well known as the ideal seed cells for tissue-engineered skin. Loureirin A, the major constituent of resina draconis, can promote skin wound healing.
METHODS AND RESULTS:
In this study, FSCs and hair follicle fibroblasts were combined with Pelnac® scaffold to construct tissue-engineered skin. The tissue-engineered skin was grafted into full-thickness skin defects of BALB/c-nu mice. Loureirin A was incorporated into the transplanted tissue-engineered skin. On day 3 of post-transplantation, Loureirin A could inhibit inflammatory reaction. On day 7 of post-transplantation, Loureirin A promoted the fibroblasts proliferation to repair dermis, and the newly formed epidermis was thicker than normal epidermis. On day 14 of post-transplantation, Loureirin A promoted the newly formed skin tending to the normal skin. All of these results showed that Loureirin A could promote skin wound repair. Wnt/β-catenin pathway controls natural hair follicle regeneration and epidermis' repairing on skin injuries. In order to validate whether Wnt/β-catenin pathway can be activated by Loureirin A, it was used to stimulate FSCs in vitro. The results displayed that Loureirin A could promote FSCs proliferation and change the cell cycle. Western blot showed that GSK-3β was down-regulated and β-catenin was up-regulated in FSCs by Loureirin A. Simultaneously, downstream genes of Wnt/β-catenin pathway, c-Myc, cyclin D1, Tcf3 and Lef1, also increased.
CONCLUSIONS:
Overall, these results demonstrate that Loureirin A activates Wnt/β-catenin pathway and promotes FSC-seeded tissue-engineered skin to repair skin wound.

Eur J Med Chem. 2015 Mar 26;93:492-500.

Comparison between loureirin A and cochinchinenin C on the interaction with human serum albumin.[Pubmed: 25734332]

METHODS AND RESULTS:
The interactions of Loureirin A (LA) and cochinchinenin C (CC) with human serum albumin (HSA) under simulated physiological conditions (pH = 7.4) have been studied with fluorescence, UV-vis absorption spectroscopic method and molecular docking technique. The results indicated that there was a synergistic interaction between LA and CC, and the fluorescence quenching of HSA by LA (or CC) was a combined quenching procedure (dynamic and static quenching). At low compound concentrations, the quenching constants KSV of CC was larger than that of LA, which meant the CC efficacy may be better than that of LA. The negative △H and △S values suggested hydrogen bonds and van der Waals forces played the major role in the binding of LA (or CC) to HSA. The efficiency of energy transfer and distance between the compounds and HSA was calculated.
CONCLUSIONS:
Moreover, the results of synchronous and three-dimensional fluorescence demonstrated that the HSA microenvironment was changed in the presence of LA (or CC). Finally, the binding of LA (or CC) to HSA was modeled by molecular docking, which is in good accordance with the experimental studies.