Justicidin A Reduces β-Amyloid via Inhibiting Endocytosis of β-Amyloid Precursor Protein

β-amyloid precursor protein (APP) can be cleaved by α-, and γ-secretase at plasma membrane producing soluble ectodomain fragment (sAPPα). Alternatively, following endocytosis, APP is cleaved by β-, and γ-secretase at early endosomes generating β-amyloid (Aβ), the main culprit in Alzheimer's disease (AD). Thus, APP endocytosis is critical for Aβ production. Recently, we reported that Monsonia angustifolia, the indigenous vegetables consumed in Tanzania, improved cognitive function and decreased Aβ production. In this study, we examined the underlying mechanism of justicidin A, the active compound of M. angustifolia, on Aβ production. We found that justicidin A reduced endocytosis of APP, increasing sAPPα level, while decreasing Aβ level in HeLa cells overexpressing human APP with the Swedish mutation. The effect of justicidin A on Aβ production was blocked by endocytosis inhibitors, indicating that the decreased APP endocytosis by justicidin A is the underlying mechanism. Thus, justicidin A, the active compound of M. angustifolia, may be a novel agent for AD treatment.

The active substance of Rostellularia procunbens and its mechanism in inhibiting nephritis cell proliferation / 中成药

AIM To identify the active anti-chronic nephrotic substance of Rostellularia procunbens (L.) Nees,and to study its mechanism.METHODS Rat glomerular mesangial cells (HBZY-1) were developed into nephrotic cell models by LPS.The activities of extract of petroleum ether,ethyl acetate,n-butanol and water were screened by MTT and ELISA kit,after which isolation and purification of the various compounds were achieved,and their effects on the expression of TLR4/NF-κB pathway were determined by Western blot.RESULTS Both extracts of petroleum ether and ethyl acetate exhibited anti-nephrotic activity,and Justicidin A was determined to be the active compound inhibiting both the proliferation of mesangial cells and the release of cytokines to some extent.CONCLUSION Rostellularia procunbens (L.) Nees may inhibit the expression of inflammatory proteins through TLR4/NF-κB signalling pathway to prevent chronic nephritis.