Kaempferol 3-sophoroside-7-rhamnoside

Enzymatic Synthesis of a Novel Kaempferol-3-O-beta-d-glucopyranosyl-(1-->4)-O-alpha-d-glucopyranoside Using Cyclodextrin Glucanotransferase and Its Inhibitory Effects on Aldose Reductase, Inflammation, and Oxidative Stress.[Pubmed:28300406]

J Agric Food Chem. 2017 Apr 5;65(13):2760-2767.

Kaempferol-3-O-beta-d-glucopyranoside (astragalin, AS), a major flavonoid that exists in various plants, exerts antioxidant, antitumor, anti-human immunodeficiency virus (HIV), and anti-inflammatory effects. However, the low water solubility of AS limits its use. In this study, we used cyclodextrin glucanotransferase (CGTase) with maltose (G2) as a donor molecule to enzymatically modify AS to improve its water solubility and physiochemical properties. We isolated the glycosylated astragalin (G1-AS) and identified the structure of G1-AS as kaempferol-3-O-beta-d-glucopyranosyl-(1-->4)-O-alpha-d-glucopyranoside, where one glucose residue was transferred to AS. G1-AS retained the antioxidative activity of the original AS compound; however, the solubility of G1-AS was 65-fold higher than that of AS. In addition, G1-AS showed enhanced anti-inflammatory effects and aldose reductase inhibitory activity compared to AS when applied to rat lenses.

Kaempferol inhibited VEGF and PGF expression and in vitro angiogenesis of HRECs under diabetic-like environment.[Pubmed:28273207]

Braz J Med Biol Res. 2017 Mar 2;50(3):e5396.

Diabetic retinopathy (DR) is one of the common and specific microvascular complications of diabetes. This study aimed to investigate the anti-angiogenic effect of kaempferol and explore its underlying molecular mechanisms. The mRNA expression level of vascular endothelial growth factor (VEGF) and placenta growth factor (PGF) and the concentrations of secreted VEGF and PGF were measured by qTR-PCR and ELISA assay, respectively. Human retinal endothelial cells (HRECs) proliferation, migration, and sprouting were measured by CCK-8 and transwell, scratching wound, and tube formation assays, respectively. Protein levels were determined by western blot. High glucose (25 mM) increased the mRNA expression levels of VEGF and PGF as well as the concentrations of secreted VEGF and PGF in HRECs, which can be antagonized by kaempferol (25 microM). Kaempferol (5-25 microM) significantly suppressed cell proliferation, migration, migration distance and sprouting of HRECs under high glucose condition. The anti-angiogenic effect of kaempferol was mediated via downregulating the expression of PI3K and inhibiting the activation of Erk1/2, Src, and Akt1. This study indicates that kaempferol suppressed angiogenesis of HRECs via targeting VEGF and PGF to inhibit the activation of Src-Akt1-Erk1/2 signaling pathway. The results suggest that kaempferol may be a potential drug for better management of DR.

Kaempferol Modulates DNA Methylation and Downregulates DNMT3B in Bladder Cancer.[Pubmed:28278502]

Cell Physiol Biochem. 2017;41(4):1325-1335.

BACKGROUND: Genomic DNA methylation plays an important role in both the occurrence and development of bladder cancer. Kaempferol (Kae), a natural flavonoid that is present in many fruits and vegetables, exhibits potent anti-cancer effects in bladder cancer. Similar to other flavonoids, Kae possesses a flavan nucleus in its structure. This structure was reported to inhibit DNA methylation by suppressing DNA methyltransferases (DNMTs). However, whether Kae can inhibit DNA methylation remains unclear. METHODS: Nude mice bearing bladder cancer were treated with Kae for 31 days. The genomic DNA was extracted from xenografts and the methylation changes was determined using an Illumina Infinium HumanMethylation 450 BeadChip Array. The ubiquitination was detected using immuno-precipitation assay. RESULTS: Our data indicated that Kae modulated DNA methylation in bladder cancer, inducing 103 differential DNA methylation positions (dDMPs) associated with genes (50 hyper-methylated and 53 hypo-methylated). DNA methylation is mostly relied on the levels of DNMTs. We observed that Kae specifically inhibited the protein levels of DNMT3B without altering the expression of DNMT1 or DNMT3A. However, Kae did not downregulate the transcription of DNMT3B. Interestingly, we observed that Kae induced a premature degradation of DNMT3B by inhibiting protein synthesis with cycloheximide (CHX). By blocking proteasome with MG132, we observed that Kae induced an increased ubiquitination of DNMT3B. These results suggested that Kae could induce the degradation of DNMT3B through ubiquitin-proteasome pathway. CONCLUSION: Our data indicated that Kae is a novel DNMT3B inhibitor, which may promote the degradation of DNMT3B in bladder cancer.

Development and Validation of a Rapid LC-MS/MS Method for Simultaneous Determination of Kaempferol and Quercetin in Thespesia populnea Extract.[Pubmed:28300024]

J AOAC Int. 2017 Jul 1;100(4):971-975.

In this study, a simple and rapid LC with tandem MS method was developed and validated for the simultaneous determination of kaempferol and quercetin in Thespesia populnea extract. The compounds were eluted using a Gemini C18 column (50 x 2.0 mm, 3 mum), with the mobile phase consisting of acetonitrile-0.3% formic acid in water at the flow rate of 0.400 mL/min. The assay exhibited a linear dynamic range of 25-2500 ng/mL for both kaempferol and quercetin. The values for intra- and interday precision and accuracy were well within the generally accepted criteria for analytical methods (<15%). Selectivity, linearity, LOD, LOQ, accuracy, and precision were evaluated for both analytes. The proposed method is accurate and sensitive and can be used for the routine quantification of kaempferol and quercetin in the herbal extract and in polyherbal formulations.