BACKGROUND: Globally, pneumonia has been associated as a primary cause of mortality in children aged less than 5 years. Dihydrokaempferol (DHK) has been proposed for being correlated with the process of various diseases. Nevertheless, whether DHK has a role in the progression of infantile pneumonia remains unclear. This study aimed at exploring whether DHK was involved in the progression of infantile pneumonia.
METHODS: Human fibroblast cells WI-38 were treated with lipopolysaccharide (LPS). The viability of WI-38 cells was measured via Cell counting kit-8. Reverse transcription-quantitative polymerase chain reaction was used to evaluate the levels of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α). Western blot analysis revealed the protein levels of IL-1β, IL-6, TNF-α, Bax, and cleaved-caspase 3. Flow cytometry was applied for exploring the apoptosis of WI-38 cells. The concentrations of IL-1β, IL-6, and TNF-α were assessed via enzyme-linked-immunosorbent serologic assay.
RESULTS: DHK modulated the viability of WI-38 cells in infantile pneumonia. Furthermore, we identified that DHK treatment inversely changed LPS induction-mediated elevation on the levels of inflammation biomarkers. Besides, DHK counteracted LPS-induced production of reactive oxygen species (ROS) in WI-38 cells. DHK also decreased LPS-induced elevation of WI-38 cells apoptosis and mediated the levels of apoptosis-associated indexes. Moreover, modulating sirtuin-1 (SIRT1) protein level was lowered by the induction of LPS, and was reversed by DHK treatment. In addition, DHK counteracted LPS induction-mediated elevation of p-p65 and phosphorylated inhibitor of nuclear factor kappa-B kinase subunit alpha (p-IκBα) protein levels.
CONCLUSIONS: DHK alleviated LPS-induced WI-38 cells inflammation injury in infantile pneumonia through SIRT1/NF-κB pathway. The results shed light on the implications of DHK on the prevention and treatment of infantile pneumonia.

Anthocyanins are responsible for the color spectrum of both ornamental and natural flowers. However, not all plant species produce all colors. For example, roses are not blue because they do not naturally possess a hydroxylase that opens the pathway for delphinidin and its derivatives. It is more intriguing why some plants do not carry orange or scarlet red flowers with anthocyanins based on pelargonidin, because the precursor for these anthocyanins should be available if anthocyanins are made at all. The key to this is the substrate specificity of dihydroflavonol 4-reductase (DFR), an enzyme located at the branch point between flavonols and anthocyanins. The most common example is petunia, which does not bear orange flowers unless the enzyme is complemented by biotechnology. We changed a few amino acids in the active site of the enzyme and showed that the mutated petunia DFR started to favor dihydrokaempferol, the precursor to orange pelargonidin, in vitro. When transferred to petunia, it produced an orange hue and dramatically more pelargonidin-based anthocyanins in the flowers.

The Staphylococcus aureus SsbA protein (SaSsbA) is a single-stranded DNA-binding protein (SSB) that is categorically required for DNA replication and cell survival, and it is thus an attractive target for potential antipathogen chemotherapy. In this study, we prepared the stem extract of Sarracenia purpurea obtained from 100% acetone to investigate its inhibitory effect against SaSsbA. In addition, the cytotoxic effects of this extract on the survival, apoptosis, proliferation, and migration of B16F10 melanoma cells were also examined. Initially, myricetin, quercetin, kaempferol, dihydroquercetin, dihydrokaempferol, rutin, catechin, β-amyrin, oridonin, thioflavin T, primuline, and thioflavin S were used as possible inhibitors against SaSsbA. Of these compounds, dihydrokaempferol and oridonin were capable of inhibiting the ssDNA-binding activity of SaSsbA with respective IC50 values of 750 ± 62 and 2607 ± 242 μM. Given the poor inhibition abilities of dihydrokaempferol and oridonin, we screened the extracts of S. purpurea, Nepenthes miranda, and Plinia cauliflora for SaSsbA inhibitors. The stem extract of S. purpurea exhibited high anti-SaSsbA activity, with an IC50 value of 4.0 ± 0.3 μg/mL. The most abundant compounds in the stem extract of S. purpurea were identified using gas chromatography−mass spectrometry. The top five most abundant contents in this extract were driman-8,11-diol, deoxysericealactone, stigmast-5-en-3-ol, apocynin, and α-amyrin. Using the MOE-Dock tool, the binding modes of these compounds, as well as dihydrokaempferol and oridonin, to SaSsbA were elucidated, and their binding energies were also calculated. Based on the S scores, the binding capacity of these compounds was in the following order: deoxysericealactone > dihydrokaempferol > apocynin > driman-8,11-diol > stigmast-5-en-3-ol > oridonin > α-amyrin. Incubation of B16F10 cells with the stem extract of S. purpurea at a concentration of 100 μg/mL caused deaths at the rate of 76%, reduced migration by 95%, suppressed proliferation and colony formation by 99%, and induced apoptosis, which was observed in 96% of the B16F10 cells. Overall, the collective data in this study indicate the pharmacological potential of the stem extract of S. purpurea for further medical applications.

Acetaminophen (APAP) overdose is the leading cause of acute liver failure (ALF) in the Western world, with limited treatment opportunities. 3,5,7,4[Formula: see text]-Tetrahydroxyflavanone (Dihydrokaempferol, DHK, Aromadendrin) is a flavonoid isolated from Chinese herbs and displays high anti-oxidant and anti-inflammatory capacities. In this study, we investigated the protective effect by DHK against APAP-induced liver injury in vitro and in vivo and the potential mechanism of action. Cell viability assays were used to determine the effects of DHK against APAP-induced liver injury. The levels of reactive oxygen species (ROS), serum alanine/aspartate aminotransferases (ALT/AST), liver myeloperoxidase (MPO), and malondialdehyde (MDA) were measured and analyzed to evaluate the effects of DHK on APAP-induced liver injury. Western blotting, immunofluorescence staining, RT-PCR, and Transmission Electron Microscope were carried out to detect the signaling pathways affected by DHK. Here, we found that DHK owned a protective effect on APAP-induced liver injury with a dose-dependent manner. Meanwhile, Western blotting showed that DHK promoted SIRT1 expression and autophagy, activated the NRF2 pathway, and inhibited the translocation of nuclear p65 (NF-[Formula: see text]B) in the presence of APAP. Furthermore, SIRT1 inhibitor EX-527 aggravated APAP-induced hepatotoxicity when treating with DHK. Molecular docking results suggested potential interaction between DHK and SIRT1. Taken together, our study demonstrates that DHK protects against APAP-induced liver injury by activating the SIRT1 pathway, thereby promoting autophagy, reducing oxidative stress injury, and inhibiting inflammatory responses.

Severe acute pancreatitis (SAP) is a non-bacterial inflammatory disease that clinically causes a very high rate of mortality. Dihydrokaempferol (DHK) is a natural flavonoid extracted from Bauhinia championii. Our research aimed to establish the treatment function of DHK on SAP-induced pancreas injury and delve into its potential mechanism. In this study, SAP was induced by caerulein (CER) and Lipopolysaccharide (LPS). DHK was administered orally at different doses of 20, 40, or 80 mg/kg. Results from serum amylase/lipase, pancreas hematoxylin-eosin staining technique, pancreas malondialdehyde (MDA), glutathione (GSH), and reactive oxygen species (ROS) showed the therapeutic effect of DHK in a mice SAP model. MTT revealed DHK alleviated CER + LPS induced cytotoxicity in a dose-dependent manner in the pancreatic acinar cells of mice. Next, we verified DHK suppressed the level of Keap1 and promoted transcriptional activation of nuclear Nrf2 in the presence of CER + LPS. The molecular docking study suggested that there is a potential interaction between DHK and Keap1. To further look at the role of Keap1 using in vitro and in vivo models, Keap1 overexpression adenovirus (ad-Keap1) was performed. The results revealed that ad-Keap1suppressed the nuclear translocation of Nrf2 which is enhanced by DHK, and suppressed the antioxidative functionality of DHK both in mice and cell models. Collectively, this research demonstrated that DHK bettered the SAP induced pancreas injury by regulating the Keap1/Nrf2 pathway and regulating oxidative stress injury.

Flavonoids were found to synergize anti-malaria and anti-cancer compounds in Artemisia annua, a very important economic crop in China. In order to discover the regulation mechanism of flavonoids in Artemisia annua, the full length cDNA of flavanone 3-hydroxylase (F3H) were isolated from Artemisia annua for the first time by using RACE (rapid amplification of cDNA ends). The completed open read frame of AaF3H was 1095 bp and it encoded a 364-amino acid protein with a predicted molecular mass of 41.18 kDa and a pI of 5.67. The recombinant protein of AaF3H was expressed in E. coli BL21(DE3) as His-tagged protein, purified by Ni-NTA agrose affinity chromatography, and functionally characterized in vitro. The results showed that the His-tagged protein (AaF3H) catalyzed naringenin to dihydrokaempferol in the present of Fe(2+). The Km for naringenin was 218.03 μM. The optimum pH for AaF3H reaction was determined to be pH 8.5, and the optimum temperature was determined to be 35 °C. The AaF3H transcripts were found to be accumulated in the cultivar with higher level of flavonoids than that with lower level of flavonoids, which implied that AaF3H was a potential target for regulation of flavonoids biosynthesis in Artemisia annua through metabolic engineering.

The first reported investigation into the phytochemical constituents of Commiphora pedunculata led to the isolation of two flavonoids: kaempferol and dihydrokaempferol from the ethyl acetate-soluble fraction of the methanol extract of the stem bark of the plant. The structures of these compounds were characterised by comparing their spectral data including 1D and 2D NMR with those reported in the literature. The two compounds were active against 6 out of 10 tested microorganisms including two resistant strains [methiciline-resistant Staphylococcus aureus and vancomycin-resistant entrococci (VRE)], Candida albicans and Escherichia coli. The zones of inhibition ranged between 24 and 30 mm for both compounds against the microorganisms. The MIC value was as low as 6.25 μg/mL against VRE and Staphylococcus aureus. This is the first report of the isolation of these compounds from the plant.