Topical Application of Houttuynia Cordata Thunb Ethanol Extracts Increases Tumor Infiltrating CD8+/Treg Cells Ratio and Inhibits Cutaneous Squamous Cell Carcinoma In Vivo

Houttuynia cordata Thunb (HCT) is a medicinal and edible herb which has beneficial effects on various diseases due to its diuretic, anti-inflammatory, anti-oxidative, anti-microbial, anti-viral, anti-cancer and anti-diabetic properties. Most of reports of its anti-cancer activity were conducted in vitro, and its effects on cutaneous squamous cell carcinoma (SCC) has not been investigated yet. Using DMBA/TPA induced SCC mice model, we found that topical treatment by HCT, as well as its bioactive ingredient monomer, efficiently inhibited tumor growth. Mechanistically, we found tumor infiltrating CD4+, Foxp3+ T regulatory cells (Tregs) were significantly reduced and CD8+/Treg cells ratio was largely increased in tumors after HCT treatment. In addition, several chemokines which recruited immune cells were largely reduced when SCC cancer cells were treated by HCT in vitro. Our results demonstrate the therapeutic effects of HCT on cutaneous SCC and indicate it might inhibit cancer through regulating tumor infiltrating lymphocytes and the tumor immune microenvironments.

Photoprotective Effects of a Hyperoside-Enriched Fraction Prepared from Houttuynia cordata Thunb. on Ultraviolet B-Induced Skin Aging in Human Fibroblasts through the MAPK Signaling Pathway

Ultraviolet-B (UVB) irradiation causes skin damage via deleterious effects including oxidative stress, inflammation, and collagen degradation. The photoprotective effects of a hyperoside-enriched fraction obtained from Houttuynia cordata Thunb. (H. cordata) on the attenuation of UVB-induced skin aging in human fibroblasts were investigated. The solvent-partition technique was used to establish the hyperoside-enriched fraction of H. cordata (HcEA). The active compounds identified in the H. cordata extracts were hyperoside, quercitrin, chlorogenic acid, and rutin. With regard to the photoprotective effects of H. cordata on UVB-irradiated dermal fibroblasts, HcEA and hyperoside inhibited intracellular ROS production and inflammatory cytokine secretions (IL-6 and IL-8), while increasing collagen type I synthesis along with downregulating MMP-1 gene and protein expressions. Mechanistically, the hyperoside-enriched fraction obtained from H. cordata inhibited UVB-irradiated skin aging through regulation of the MAPK signaling pathway by attenuating the activation of JNK/ERK/c-Jun in human dermal fibroblasts. The hyperoside-enriched fraction of H. cordata exerted potent anti-skin aging properties against UVB exposure. The findings of this study can be applied in the cosmetics industry, as H. cordata extract can potentially be used in pharmaceutical or cosmetic formulations as a photoprotective or anti-skin aging agent.

Latent Pathogenic Fungi in the Medicinal Plant Houttuynia cordata Thunb. Are Modulated by Secondary Metabolites and Colonizing Microbiota Originating from Soil

Latent pathogenic fungi (LPFs) affect plant growth, but some of them may stably colonize plants. LPFs were isolated from healthy Houttuynia cordata rhizomes to reveal this mechanism and identified as Ilyonectria liriodendri, an unidentified fungal sp., and Penicillium citrinum. Sterile H. cordata seedlings were cultivated in sterile or non-sterile soils and inoculated with the LPFs, followed by the plants’ analysis. The in vitro antifungal activity of H. cordata rhizome crude extracts on LPF were determined. The effect of inoculation of sterile seedlings by LPFs on the concentrations of rhizome phenolics was evaluated. The rates of in vitro growth inhibition amongst LPFs were determined. The LPFs had a strong negative effect on H. cordata in sterile soil; microbiota in non-sterile soil eliminated such influence. There was an interactive inhibition among LPFs; the secondary metabolites also regulated their colonization in H. cordata rhizomes. LPFs changed the accumulation of phenolics in H. cordata. The results provide that colonization of LPFs in rhizomes was regulated by the colonizing microbiota of H. cordata, the secondary metabolites in the H. cordata rhizomes, and the mutual inhibition and competition between the different latent pathogens.

Effects of Fermented Houttuynia cordata Thunb. on Diabetic Rats Induced by a High-Fat Diet with Streptozotocin and on Insulin Resistance in 3T3-L1 Adipocytes

Houttuynia cordata Thunb. (plukaow in Thai language) exhibits several biological properties, and many products of H. cordata are therefore commercially available for human consumption, such as fermented juice or tablets as food supplements. This study aimed to investigate the antidiabetic effects of fermented H. cordata (HC) in high-fat diets and streptozotocin-induced diabetic rats. Oral administration of HC at a dose of 100 mg/kg.bw not only maintained bodyweight, food intake, and water consumption but also reduced blood glucose levels and improved glucose tolerance ability in the diabetic rats. Moreover, HC also decreased oxidative stress markers in serum and inflammatory-related mediators in pancreas tissues, indicating the improvement of pancreatic beta-cell function in the diabetic rats. In order to clarify the mechanism of HC, the effects of ethanolic extract of HC (HCE) on insulin resistance were determined in 3T3-L1 adipocytes. FHE could recover glucose uptake and decrease lipolysis in palmitate-treated 3T3-L1 adipocytes. Taken together, these results demonstrate that HC can improve diabetic symptoms by enhancing insulin sensitivity, reducing oxidative stress, and suppressing inflammation.

Comparison of Essential Oils of Houttuynia cordata Thunb. from Different Processing Methods and Harvest Seasons Based on GC-MS and Chemometric Analysis

Houttuyniae Herba (HH) refers to the dried aerial part of Houttuynia cordata Thunb. (DHC) or the fresh whole grass of Houttuynia cordata Thunb. (FHC), where DHC are harvested in summer and FHC around the year. However, harvest seasons and processing methods (i.e., medicinal parts and drying process) might affect the quality of HH. To compare the essential oils (EOs) of DHC and FHC and their two harvest seasons, GC-MS analysis combined with chemometric analysis was applied. The results showed that the oil yield of FHC (0.076 ± 0.030%) was higher than that of DHC (0.038 ± 0.029%), and oil yield was higher in summer than in autumn (0.044 ± 0.029% for DHC1, 0.036 ± 0.028% for DHC2, 0.084 ± 0.026% for FHC1, and 0.067 ± 0.033% for FHC2, respectively). Moreover, hierarchical cluster analysis (HCA) and principal component analysis (PCA) successfully distinguished the chemical constituents of DHC and FHC oils. Additionally, according to orthogonal partial least squares discriminant analysis (OPLS-DA), eleven components were selected as chemical markers for discriminating DHC and FHC, and two and four chemical markers for discriminating two harvest seasons of DHC and FHC, respectively. Among these markers, the average contents of α-pinene, limonene, β-phellandrene, α-terpineol, 4-tridecanone, and ethyl decanoate were higher in FHC oils. In contrast, the average contents of nonanal, 1-nonanol, β-cyclocitral, n-hexadecanoic acid, and octadecanol were higher in DHC oils. Additionally, the contents of 4-tridecanone and ethyl decanoate were both higher in DHC1 oils than in DHC2 oils. Moreover, the contents of β-myrcene and β-phellandrene were higher in FHC1 oils, while the contents of 2,6-octadien-1-ol, 3,7-dimethyl-, acetate, and (z)-phytol were higher in FHC2 oils. For these reasons, this study provides a scientific basis for quality control and clinical medication.

Suppressive Effect and Molecular Mechanism of Houttuynia cordata Thunb. Extract against Prostate Carcinogenesis and Castration-Resistant Prostate Cancer

Houttuynia cordata Thunb. (HCT) is a well-known Asian medicinal plant with biological activities used in the treatment of many diseases including cancer. This study investigated the effects of HCT extract and its ethyl acetate fraction (EA) on prostate carcinogenesis and castration-resistant prostate cancer (CRPC). HCT and EA induced apoptosis in androgen-sensitive prostate cancer cells (LNCaP) and CRPC cells (PCai1) through activation of caspases, down-regulation of androgen receptor, and inactivation of AKT/ERK/MAPK signaling. Rutin was found to be a major component in HCT (44.00 ± 5.61 mg/g) and EA (81.34 ± 5.21 mg/g) in a previous study. Rutin had similar effects to HCT/EA on LNCaP cells and was considered to be one of the active compounds. Moreover, HCT/EA inhibited cell migration and epithelial-mesenchymal transition phenotypes via STAT3/Snail/Twist pathways in LNCaP cells. The consumption of 1% HCT-mixed diet significantly decreased the incidence of adenocarcinoma in the lateral prostate lobe of the Transgenic rat for adenocarcinoma of prostate model. Similarly, tumor growth of PCai1 xenografts was significantly suppressed by 1% HCT treatment. HCT also induced caspase-dependent apoptosis via AKT inactivation in both in vivo models. Together, the results of in vitro and in vivo studies indicate that HCT has inhibitory effects against prostate carcinogenesis and CRPC. This plant therefore should receive more attention as a source for the future development of non-toxic chemopreventive agents against various cancers.