Melanogenesis inhibitory pregnane glycosides from Cynanchum atratum.

Bioassay-guided fractionation of the methanolic extract from the roots of Cynanchum atratum has resulted in the isolation of three new pregnane glycosides (1-3) along with four known compounds (4-7). Their structures were identified by analysis of the spectroscopic data including extensive 2D NMR. All of the isolates were evaluated for their potential to inhibit the melanin production in α-melanocyte stimulating hormone (α-MSH)-activated B16 melanoma cells. Of these, compounds 4-7 dose-dependently inhibited the melanin production with the IC50 values ranging from 4 µM to 33 µM.

Piperidylmethyloxychalcone improves immune-mediated acute liver failure via inhibiting TAK1 activity.

Mice deficient in the toll-like receptor (TLR) or the myeloid differentiation factor 88 (MyD88) are resistant to acute liver failure (ALF) with sudden death of hepatocytes. Chalcone derivatives from medicinal plants protect from hepatic damages including ALF, but their mechanisms remain to be clarified. Here, we focused on molecular basis of piperidylmethyloxychalcone (PMOC) in the treatment of TLR/MyD88-associated ALF. C57BL/6J mice were sensitized with D-galactosamine (GalN) and challenged with Escherichia coli lipopolysaccharide (LPS, TLR4 agonist) or oligodeoxynucleotide containing unmethylated CpG motif (CpG ODN, TLR9 agonist) for induction of ALF. Post treatment with PMOC sequentially ameliorated hepatic inflammation, apoptosis of hepatocytes, severe liver injury and shock-mediated death in ALF-induced mice. As a mechanism, PMOC inhibited the catalytic activity of TGF-ß-activated kinase 1 (TAK1) in a competitive manner with respect to ATP, displaced fluorescent ATP probe from the complex with TAK1, and docked at the ATP-binding active site on the crystal structure of TAK1. Moreover, PMOC inhibited TAK1 auto-phosphorylation, which is an axis in the activating pathways of nuclear factor-κB (NF-κB) or activating protein 1 (AP1), in the liver with ALF in vivo or in primary liver cells stimulated with TLR agonists in vitro. PMOC consequently suppressed TAK1-inducible NF-κB or AP1 activity in the inflammatory injury, an early pathogenesis leading to ALF. The results suggested that PMOC could contribute to the treatment of TLR/MyD88-associated ALF with the ATP-binding site of TAK1 as a potential therapeutic target.

Comparison of oncologic outcomes of metastatic rectal cancer patients with or without neoadjuvant chemoradiotherapy.

PURPOSE: The aim of this study is to evaluate the effect of neoadjuvant chemoradiotherapy in stage IV rectal cancer. METHODS: Primary rectal cancer patients with synchronous distant metastases between September 2001 and August 2011 were enrolled. Of 86 patients, 40 patients underwent neoadjuvant chemoradiotherapy (RTX group) and the remaining 46 patients underwent postoperative systemic chemotherapy without radiotherapy (NRTX group). Sharp mesorectal excision according to tumor location was performed. Oncologic outcomes were compared. RESULTS: The lower tumor location was more common in RTX group than NRTX group (60.0 vs. 28.3%, P = 0.003). Clinical T and N status and American Society of Anesthesiologist (ASA) score were similar in both groups. The incidence of pathologic LN metastases in the NRTX group was 93.5% compared with 70.0% in RTX group (P = 0.007). Pattern of distant metastasis was similar between groups. However, metastatectomy was frequently performed in RTX group than NRTX group (57.5 vs. 30.4%, P = 0.020). There was no statistical difference in local recurrence rate between groups (10.0% in RTX vs. 15.2% in NRTX, P = 0.470). The median PFS was similar in both groups (12.00 months in RTX vs. 12.00 months in NRTX, P = 0.768). The median OS between groups was also not different (24.00 months in RTX vs. 27.00 months in NRT, P = 0.510). CONCLUSIONS: Neoadjuvant chemoradiotherapy may not affect local control and overall survival in locally advanced rectal cancer with distant metastasis.

cAMP-binding site of PKA as a molecular target of bisabolangelone against melanocyte-specific hyperpigmented disorder.

Microphthalmia-associated transcription factor (MITF) is inducible in response to cAMP and has a pivotal role in the melanocyte-specific expression of tyrosinase for skin pigmentation. Here we suggest that the cAMP-binding site of protein kinase A (PKA) is a target in the inhibition of the melanogenic process in melanocytes, as evidenced from the molecular mechanism of small molecules such as bisabolangelone (BISA) and Rp-adenosine 3',5'-cyclic monophosphorothioate (Rp-cAMPS). BISA is a sesquiterpene constituent of Angelica koreana, a plant of the Umbelliferae family, whose roots are used as an alternative medicine. BISA competitively inhibited cAMP binding to the regulatory subunit of PKA and fitted into the cAMP-binding site on the crystal structure of PKA under the most energetically favorable simulation. In α-melanocyte-stimulating hormone (α-MSH)-activated melanocytes, BISA and Rp-cAMPS nullified cAMP-dependent PKA activation, dissociating catalytic subunits from an inactive holoenzyme complex. They resultantly inhibited cellular phosphorylation of the cAMP-responsive element-binding protein (CREB) or another transcription factor SOX9, thus downregulating the expression of MITF or the tyrosinase gene with decreased melanin production. Taken together, this study defined the antimelanogenic mechanism of BISA or Rp-cAMPS with a notable implication of the cAMP-binding site of PKA as a putative target ameliorating melanocyte-specific hyperpigmented disorder.

Melanogenesis inhibitory bisabolane-type sesquiterpenoids from the roots of Angelica koreana.

Bioactivity-guided isolation of the methanolic extract of the roots of Angelica koreana led to the isolation of four new bisabolane-type sesquiterpenoids, osterivolones A-D (1-4) together with four known compounds, bisabolangelone (5), decursinol angelate (6), psoralen (7), and falcarindiol (8). Their structures were elucidated on the basis of spectroscopic data interpretation, especially 2D NMR spectra such as HMQC, HMBC, and NOESY. All compounds were evaluated for their inhibitory effects of the melanogenesis against α-melanocyte stimulating hormone (α-MSH)-activated B16 melanoma cells.

Identification of indoline-2-thione analogs as novel potent inhibitors of α-melanocyte stimulating hormone induced melanogenesis.

Based on the hits, 3,4-dihydroquinazoline-2-thione (1) and benzimidazole-2-thione (2), a series of indole-2-thione (3) and indole-2-thiol inhibitors (4) of melanogenesis were designed, synthesized and evaluated in melanoma B16 cells under the stimulant of α-melanocyte stimulating hormone (α-MSH). The indole-2-thione compounds (3a-g) exhibited an effective inhibitory activity on melanin synthesis. The Structure-Activity Relationship (SAR) studies of 2 have revealed that in potent inhibitor 3a (>100% inhibition at 30 µM, IC50=1.40 µM) the role of nitrogen (3-N) at 3-position is insignificance. In addition, the hydrophobic substituents of 3 were better than the hydrophilic one. However, conversion of thione (-C=S, 3) to thiol (-C-SH, 4) led to decrease in the potency.

Hypopigmenting activity of bisabolangelone isolated from Angelica koreana Maxim. in α-melanocyte stimulating hormone-activated B16 or melan-a cells.

Tyrosinase is a key enzyme in the biosynthetic pathway of melanin pigments. Abnormal accumulation of melanin pigments causes melasma, freckles, and senile lentigo, which can be substantially ameliorated by treatment with arbutin or other tyrosinase inhibitors. In this study, roots of Angelica koreana Maxim. (Umbelliferae) inhibited melanin production in α-melanocyte stimulating hormone ( α-MSH)-activated B16 melanoma cells or melan-a melanocytes. To elucidate the hypopigmenting principle of A. koreana, the plant extracts were subjected to bioassay-guided phytochemical analysis, resulting in the identification of bisabolangelone. Bisabolangelone dose-dependently inhibited α-MSH-induced melanin production in B16 or melan-a cells with IC(15) values of 9-17 µM. The positive control arbutin also inhibited melanin production in B16 cells with an IC(50) value of 317 µM. Bisabolangelone suppressed α-MSH-inducible protein levels of tyrosinase in B16 cells but could not significantly inhibit the catalytic activity of cell-free tyrosinase. Taken together, this study indicates that bisabolangelone is the primary hypopigmenting principle of A. koreana and may have pharmacological potential in the melanin-associated hyperpigmentation disorders.

Evaluation of 3,4-dihydroquinazoline-2(1H)-thiones as inhibitors of alpha-MSH-induced melanin production in melanoma B16 cells.

Novel 3,4-dihydroquinazoline-2(1H)-thiones (QNTs) 1 were found to be potent inhibitors of alpha-MSH-induced melanin production. The effect of QNTs to inhibit melanin formation in B16 melanoma cells was screened in the presence of alpha-MSH. In defining the mechanism of activity, the effects on tyrosinase activity, on tyrosinase synthesis and on the depigmentation of melanin were evaluated. QNTs did not affect the catalytic activity of tyrosinase, but rather acted as an inhibitor of tyrosinase synthesis.

Racemization of 6-methoxydihydrosanguinarine in methanol investigated by enantioselective dynamic HPLC.

A biologically active benzophenanthridine alkaloid, 6-methoxydihydrosanguinarine (MS), was isolated from Hylomecon plants. Although enantiomers of MS can be separated by chiral HPLC, its isomers rapidly form a racemic mixture in methanol. The rate constants for the racemization of MS enantiomers were 9.20x10(-4)s(-1) and 9.95x10(-4)s(-1) for (+)-MS and (-)-MS, respectively, as determined by dynamic HPLC and chiral chromatography. This unusually rapid racemization may originate from the formation of a stable iminium ion intermediate, sanguinarine. Therefore, the variety of biological activities exhibited by MS may be attributable to a combination of (+)-MS, (-)-MS, and sanguinarine.

Structural requirement of chalcones for the inhibitory activity of interleukin-5.

Novel chalcones were found as potent inhibitors of interleukin (IL)-5. 1-(2-Benzyloxy-6-hydroxyphenyl)-3-(4-hydroxyphenyl)-2-propen-1-one (2b, 78.8% inhibition at 50microM, IC(50)=25.3microM) was initially identified as a potent inhibitor of IL-5. This shows the compatible activity with budesonide or sophoricoside. To identify structural requirements, 26 chalcones were prepared and their inhibitory activities were tested against IL-5. Among them, compound 4-[(E)-3-(2-cyclohexylmethoxy-6-hydroxyphenyl)-3-oxoprop-1-enyl]benzenesulfonamide (2w, 99.5% inhibition at 50microM, IC(50)=1.8microM) shows the most potent activity. The important structural requirements of these chalcone analogs exhibiting the inhibitory activity against IL-5 were recognized as the following. (1) The hydrophobic group such as benzyloxy or cyclohexylmethoxy at 6-position of A ring is necessary. (2) The existence of phenolic hydroxyl at 6-position of A ring is critical. (3) Propenone unit as alpha,beta-unsaturated ketone is essential. (4) Electron withdrawing groups with hydrogen acceptor property at 4-position of B ring enhance the activity and quantitative structure-activity relationship of 2 regarding these substituents was determined.