Biotransformation-guided purification of a novel glycoside derived from the extracts of Chinese herb Baizhi.

Our pursuit of new compounds with enhanced bioavailability and bioactivity prompted us to employ the biotransformation-guided purification (BGP) approach which leverages proficient in vitro biotransformation techniques. Angelica dahurica roots, also called Baizhi in Chinese traditional medicine, are famous for their anti-inflammatory and analgesic properties. Herein, we applied the BGP methodology to Baizhi extracts, employing Deinococcus geothermalis amylosucrase (DgAS), an enzyme demonstrating catalytic competence across diverse substrates, for biotransformation. Initiating with a 70 % methanol extraction, we obtained the crude extract of commercial Baizhi powder, followed by an additional extraction using ethyl acetate. Notably, reactions performed on this extract yielded limited quantities of novel compounds. Subsequently, the extract underwent partitioning into four fractions based on HPLC profiling, leading to the successful isolation of a compound with significant yield from fraction 2 mixtures upon reaction with DgAS. Structural elucidation confirmed the compound as byakangelicin-7″-O-α-glucopyranoside (BG-G), a new alpha glycoside derivative of byakangelicin. Furthermore, validation experiments verified the capacity of DgAS to glycosylate pure byakangelicin, yielding BG-G. Remarkably, the aqueous solubility of BG-G exceeded that of byakangelicin by over 29,000-fold. In conclusion, BGP emerges as a potent strategy combining traditional medicinal insights with robust enzymatic tools for generating new compounds.

A New Stilbene Glucoside from Biotransformation-Guided Purification of Chinese Herb Ha-Soo-Oh.

Ha-Soo-Oh is a traditional Chinese medicine prepared from the roots of Polygonum multiflorum Thunb. The herb extract has been widely used in Asian countries as a tonic agent and nutritional supplement for centuries. To identify new bioactive compounds in Chinese herbs, the biotransformation-guided purification (BGP) process was applied to Ha-Soo-Oh with Bacillus megaterium tyrosinase (BmTYR) as a biocatalyst. The result showed that a major biotransformed compound could be purified using the BGP process with preparative high-performance liquid chromatography (HPLC), and it was confirmed as a new compound, 2,3,5,3',4'-pentahydroxystilbene-2-O-ß-glucoside (PSG) following mass and nucleic magnetic resonance (NMR) spectral analyses. PSG was further confirmed as a biotransformation product from 2,3,5,4'-tetrahydroxystilbene-2-O-ß-glucoside (TSG) by BmTYR. The new PSG exhibited 4.7-fold higher 1,1-diphenyl-2-picrylhydrazine (DPPH) free radical scavenging activity than that of TSG. The present study highlights the potential usage of BGP in herbs to discover new bioactive compounds in the future.

DNMT3b/OCT4 expression confers sorafenib resistance and poor prognosis of hepatocellular carcinoma through IL-6/STAT3 regulation.

BACKGROUND: The inflammatory cytokine interleukin-6 (IL-6) is critical for the expression of octamer-binding transcription factor 4 (OCT4), which is highly associated with early tumor recurrence and poor prognosis of hepatocellular carcinomas (HCC). DNA methyltransferase (DNMT) family is closely linked with OCT4 expression and drug resistance. However, the underlying mechanism regarding the interplay between DNMTs and IL-6-induced OCT4 expression and the sorafenib resistance of HCC remains largely unclear. METHODS: HCC tissue samples were used to examine the association between DNMTs/OCT4 expression levels and clinical prognosis. Serum levels of IL-6 were detected using ELISA assays (n = 144). Gain- and loss-of-function experiments were performed in cell lines and mouse xenograft models to determine the underlying mechanism in vitro and in vivo. RESULTS: We demonstrate that levels of DNA methyltransferase 3 beta (DNMT3b) are significantly correlated with the OCT4 levels in HCC tissues (n = 144), and the OCT4 expression levels are positively associated with the serum IL-6 levels. Higher levels of IL-6, DNMT3b, or OCT4 predicted early HCC recurrence and poor prognosis. We show that IL-6/STAT3 activation increases DNMT3b/1 and OCT4 in HCC. Activated phospho-STAT3 (STAT-Y640F) significantly increased DNMT3b/OCT4, while dominant negative phospho-STAT3 (STAT-Y705F) was suppressive. Inhibiting DNMT3b with RNA interference or nanaomycin A (a selective DNMT3b inhibitor) effectively suppressed the IL-6 or STAT-Y640F-induced increase of DNMT3b-OCT4 and ALDH activity in vitro and in vivo. The fact that OCT4 regulates the DNMT1 expressions were further demonstrated either by OCT4 forced expression or DNMT1 silence. Additionally, the DNMT3b silencing reduced the OCT4 expression in sorafenib-resistant Hep3B cells with or without IL-6 treatment. Notably, targeting DNMT3b with nanaomycin A significantly increased the cell sensitivity to sorafenib, with a synergistic combination index (CI) in sorafenib-resistant Hep3B cells. CONCLUSIONS: The DNMT3b plays a critical role in the IL-6-mediated OCT4 expression and the drug sensitivity of sorafenib-resistant HCC. The p-STAT3 activation increases the DNMT3b/OCT4 which confers the tumor early recurrence and poor prognosis of HCC patients. Findings from this study highlight the significance of IL-6-DNMT3b-mediated OCT4 expressions in future therapeutic target for patients expressing cancer stemness-related properties or sorafenib resistance in HCC.

Melanogenesis inhibition by homoisoflavavone sappanone A from Caesalpinia sappan.

Homoisoflavanone, sappanone A, was isolated from Caesalpinia sappan and proven to dose-dependently inhibit both melanogenesis and cellular tyrosinase activity via repressing tyrosinase gene expression in mouse B16 melanoma cells. To our knowledge, sappanone A is the first homoisoflavanone to be discovered with melanogenesis inhibitory activity. Our results give a new impetus to the future search for other homoisoflavanone melanogenesis inhibitors.

Murine tyrosinase inhibitors from Cynanchum bungei and evaluation of in vitro and in vivo depigmenting activity.

Two natural acetophenone derivatives, 2,5-dihydroxyacetophenone (2,5-DHAP) and 2,6-DHAP, were purified from Cynanchum bungei and identified as murine tyrosinase inhibitors. Investigation into 2,5-DHAP showed it to be an uncompetitive inhibitor of murine tyrosinase (K(I) 0.28 mm). 2,5-DHAP strongly inhibited both melanogenesis and cellular tyrosinase activity in vitro in 3-isobutyl-1-methylxanthin-stimulated B16 mouse melanoma cells or in vivo in zebrafish and mouse models, but showed no cytotoxicity at the concentrations used. In B16 cells, 2,5-DHAP inhibition was dose-dependent and was fourfold greater than that of arbutin. 2,5-DHAP had no effect on the expression of tyrosinase protein or mRNA, as confirmed by Western blotting and quantitative real-time reverse transcription polymerase chain reaction, respectively. A 2% gel preparation of 2,5-DHAP applied to the skin of mice significantly increased the average skin-whitening index (L value), indicating its potential use as a treatment for skin hyperpigmentation in humans.

Inhibitory effect of a water extract from Pemphis acidula on melanogenesis in mouse B16 melanoma cells.

The inhibitory effect of a water extract from Pemphis acidula on melanogenesis in mouse B16 melanoma cells was investigated. The results showed that the P. acidula extract (PAE) inhibited melanogenesis in 3-isobutyl-1-methylxanthin (IBMX)-stimulated B16 cells in a dose-dependent manner, with an IC50 value of 33.5 µg/ml. In addition, PAE also inhibited cellular tyrosinase activity. Moreover, western blot and real-time reverse transcriptase polymerase chain reaction (qRT-PCR) analyses respectively confirmed that PAE down-regulated levels of tyrosinase protein and its mRNA in IBMX-stimulated B16 cells. These results demonstrated that PAE inhibits melanogenesis of B16 cells by reducing tyrosinase gene expression. From the present study, PAE is proven to be a good candidate as a skin-whitening agent for treatment of skin hyperpigmentation.

Inhibitory effect of danazol on melanogenesis in mouse B16 melanoma cells.

In the present study, more than 200 generic drugs were screened to verify their applicability as a skin-lightening agent using mouse B16 melanoma cells. Of the numerous agents, danazol was found to inhibit melanogenesis in B16 cells in a dose-dependent manner with an IC(50) value of 9.3 µM. In addition, danazol reduced cellular tyrosinase activity in B16 cells but did not directly inhibit the murine tyrosinase activity in the cell-free system. Western blotting analysis confirmed that danazol downregulated the levels of tyrosinase protein in B16 cells, and reverse-transcription polymerase chain reaction (RT-PCR) analysis revealed that danazol did not downregulate the levels of tyrosinase mRNA in the cells. These results indicate that danazol inhibits melanogenesis in B16 cells via reducing the tyrosinase activity by post-transcriptional regulation.