Anti-melanoma Agents Research Articles

Abstract 4893: XIAP downregulation accompanies inhibition of melanoma xenograft growth by mebendazole

Abstract Background: Melanoma's intrinsic resistance to therapy has been attributed to modulation of cellular survival pathways including apoptosis. We originally reported that mebendazole (MBZ), which acts as a microtubule-disrupting agent, is a potent inducer of apoptosis in melanoma cells in vitro via a Bcl-2 dependent mechanism (Molecular Cancer Research, 2008). Here, we show that MBZ is also able to effectively modulate another key anti-apoptotic factor, XIAP, to promote melanoma apoptosis both in vitro and in vivo. Methodology: Safety and efficacy of mebendazole was assessed using a human melanoma xenograft model established from M-14 cells. The effect of MBZ on XIAP expression and induction of apoptotic pathways was evaluated by immunoblotting and co-immunoprecipitation techniques along with densitometric quantification. The growth inhibitory effects of MBZ were determined in a panel of melanoma cell lines with the sulphorhodamine (SRB) assay. siRNA techniques were used to reduce expression of XIAP. Results: Oral MBZ is as effective as the current standard of care temozolomide (TMZ) in reducing melanoma growth in vivo, with no notable toxicities observed. Inhibition of melanoma growth in vivo is accompanied by MBZ specific reduced expression of XIAP and cleavage of caspase 9. In response to MBZ treatment, sensitive cell lines display reduced levels of XIAP expression whereas resistant cell lines do not. Moreover, down-regulation of XIAP expression by siRNA in the MBZ-resistant melanoma cell line UACC1097 was accompanied by a reduction in the IC50 for MBZ from >10 μM to 3.7 μM. Exposure of melanoma cells to MBZ promotes the interaction of SMAC/DIABLO with XIAP, thereby alleviating inhibition of apoptosis by XIAP. Conclusions: In addition to demonstrating efficacy and safety in vivo, our preclinical studies of the promising anti-melanoma agent mebendazole provide insight into characterization of an apoptotic promoting mechanism of action. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4893. doi:1538-7445.AM2012-4893

Synthesis and biological evaluation of novel N, N′-disubstituted urea and thiourea derivatives as potential anti-melanoma agents

Two series of urea and thiourea derivatives (1a–11a, 1b–11b) have been synthesized; all the 22 compounds were reported for the first time. Their anti-proliferative activities against the melanoma cell line B16-F10 were evaluated. Among the compounds tested, compound 6b exhibited the most potent activity in melanoma cells growth inhibition (IC50 = 0.33 μM). The bioassay tests showed that anti-proliferative activities of these novel compounds were possibly caused by inhibition of ERK1/2 phosphorylation level. Therefore, compound 6b can be a potential anti-melanoma agent and an inhibitor of ERK1/2 phosphorylation deserving further research.

1-Phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP) facilitates curcumin-induced melanoma cell apoptosis by enhancing ceramide accumulation, JNK activation, and inhibiting PI3K/AKT activation

The majority of metastatic melanomas are resistant to different chemotherapeutic agents, consequently, the search for novel anti-melanoma agents and adjuvant is urgent. Here, we found that 1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP), an inhibitor of glycosphingolipid biosynthesis, enhanced curcumin-induced cell growth inhibition and apoptosis in two melanoma cell lines (WM-115 and B16). PDMP facilitated curcumin-induced ceramide accumulation; the latter contributed to melanoma cell apoptosis. PDMP also dramatically enhanced curcumin-induced c-Jun N-terminal kinase activation, which was important to melanoma cell apoptosis. Meanwhile, curcumin plus PDMP treatment largely inhibited the activation of pro-survival PI3K/AKT signal pathway. In conclusion, PDMP-sensitized curcumin-induced melanoma cell growth inhibition and apoptosis in vitro due to changes of multiple signal events. Combining PDMP with curcumin may represent a new therapeutic intervention against melanoma.

Cytotoxic effect of xanthones from pericarp of the tropical fruit mangosteen (Garcinia mangostana Linn.) on human melanoma cells

Mangosteen (Garcinia mangostana Linn.) is a tropical tree from South East Asia and its fruit pericarp is a well-known traditional medicine. In this study, the cytotoxic effect of three xanthone compounds (α-mangostin, γ-mangostin, and 8-deoxygartanin) from mangosteen pericarp was investigated using the human melanoma SK-MEL-28 cell line. Significant dose-dependent reduction in % cell viability was induced. γ-Mangostin and 8-deoxygartanine at 5μg/ml increased the cell cycle arrest in G1 phase (90% and 92%) compared with untreated cells (78%). All compounds induced apoptosis, of the highest being α-mangostin at 7.5μg/ml that induced 59.6% early apoptosis, compared to 1.7% in untreated cells. The apoptotic effect of α-mangostin was via caspase activation and disruption of mitochondrial membrane pathways as evidenced by 25-fold increased caspase-3 activity and 9-fold decreased mitochondrial membrane potential when compared to untreated cells. In conclusion, these xanthones, especially α-mangostin, are potential candidates as anti-melanoma agents.

Abstract 2645: PEITC induces cell death in melanoma cells through redox mechanisms

Abstract Melanoma is one of the deadliest types of cancers accounting for about 80% of skin cancer deaths. Reactive oxygen species (ROS), produced by the mitochondrial respiratory chain and other biochemical mechanisms, play a critical role in melanoma progression through activation of transcription factors AP-1 and NF- κB and loss of E-cadherin. However, a further elevated level of ROS in cells, beyond a certain cellular threshold, may lead to mitochondrial damage, cytotoxicity and subsequent cell death. Hence, increasing ROS levels by either activating a ROS-generating enzyme or by depletion of antioxidants is a plausible strategy to induce cell killing in melanoma cells. The natural compound β-phenylethyl isothiocyanate (PEITC) found in cruciferous vegetables exhibits significant antitumor activity. Recent studies demonstrated that PEITC selectively induced cancer cell death by disabling the glutathione antioxidant system. Based on these observations, we hypothesize that PEITC may preferentially eliminate melanoma cells through ROS-mediated mechanism due to the increased basal ROS levels in melanoma cells and their high dependence on glutathione. To test this hypothesis, the cytotoxic effect of PEITC was tested in a panel of melanoma cell lines in comparison with normal melanocytes. Our results demonstrated that PEITC had time- and concentration-dependent antiproliferative effect in melanoma cells. The inhibitory effect is melanoma specific, since PEITC had minimum cytotoxic activity in normal melanocytes. Further analysis of ROS by FACS using the fluorescent dye DCFDA revealed that this cell death was primarily due to increased ROS accumulation triggered by PEITC-induced depletion of cellular glutathione. This aberrant increase in ROS caused mitochondrial membrane damage, as determined by biochemical analysis using Rhodamine 123, and subsequent cell death through apoptosis. Importantly, PEITC was very effective in melanoma cells, which exhibited resistance to standard anti-tumor drugs like temozolomide (TMZ) and carmustine (BCNU). Our study suggests that PEITC may be an effective anti-melanoma therapeutic agent that warrants further pre-clinical and clinical investigation. Our work is now directed towards identifying other ROS related cellular mechanisms that can be exploited to increase the therapeutic specificity and sensitivity of PEITC in melanoma cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2645. doi:10.1158/1538-7445.AM2011-2645

4-Methylcatechol-induced oxidative stress induces intrinsic apoptotic pathway in metastatic melanoma cells

There has been a steady rise in fatalities associated with thick melanomas (>4 mm). Although understanding of the biology of the disease has improved, effective treatment strategies for patients with advanced metastatic melanoma remain elusive. Therefore, more intensive testing of agents with therapeutic potential are needed to improve survival of patients with metastatic malignant melanoma. We have tested the ability of 4-methylcatechol, a metabolite of quercetin; a naturally occurring compound that is commonly found in a variety of fruits for its potential as an anti-melanoma agent. Our results show that 4-methylcatechol inhibits proliferation of melanoma cells in culture while not affecting the growth of normal human epidermal melanocytes. Further, the ability of metastatic melanoma cells to form colonies on soft agar was also inhibited. 4-Methylcatechol caused the accumulation of cells in G2/M phase of the cell cycle and induced apoptosis. There was an increase in reactive oxygen species following treatment with 4-methylcatechol that led to apoptosis through the intrinsic mitochondrial pathway. Treatment also inhibited cell survival mediated by Akt, a key player in melanoma cell survival. Taken together our results suggest that 4-methylcatechol exhibits cytotoxicity towards metastatic malignant melanoma cells while sparing normal melanocytes and should be tested further as a potential drug candidate for malignant melanoma.

C6 ceramide potentiates curcumin-induced cell death and apoptosis in melanoma cell lines in vitro

The majority of metastatic melanomas are resistant to diverse chemotherapeutic agents, and long-term survival for patients with melanoma who have metastatic disease is dismal. Consequently, the search for novel anti-melanoma agents is urgent. Here, we evaluate the potential effects of C6 ceramide to sensitize melanoma cell lines (B16 and WM-115 cells) to curcumin-induced cell death. MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was used to test melanoma cell viability in vitro. Hoechst 33342 fluorescence and Histone DNA ELISA was used to evaluate melanoma cell apoptosis. Apoptosis-associated proteins in melanoma cells after treatments were measured by Western blot. C6 ceramide promotes curcumin-induced cell death and apoptosis in B16 and WM-115 melanoma cell lines. Curcumin itself promotes pro-apoptosis protein Caspase 3 and Caspase 9 cleavage and anti-apoptosis protein Bcl-XL and X-IAP degradation, and combination of C6 ceramide with curcumin dramatically enhances it. Caspase inhibitors largely inhibit C6-ceramide plus curcumin induced cell death and apoptosis. We suggest that C6 ceramide sensitizes melanoma cell to curcumin induced cell death and apoptosis in vitro, which is due to, at least in part, the augment of mitochondria apoptosis pathway. Combining C6 ceramide with traditional chemotherapy drugs such as curcumin may have potential to be used as a new therapeutic intervention against melanoma.

FC15 Combination of Dacarbazine and Dimethylfumarate efficiently reduces melanoma lymph node metastasis

Dimethylfumarate (DMF) has been shown to reduce melanoma growth and metastasis in animal models. We addressed the question of whether DMF is as effective in its antitumor activity as the US Food and Drug Administration-approved alkylating agent dacarbazine (DTIC). We also tested the possibility of an improved antitumoral effect when both therapeutics were used together. Using our severe combined immunodeficiency (SCID) mouse model, in which xenografted human melanoma cells metastasize from primary skin sites to sentinel nodes, we show that these treatments, alone or in combination, reduce tumor growth at primary sites. Our main finding was that metastasis to sentinel nodes is significantly delayed only in mice treated with a combination of DTIC and DMF. Subsequent experiments were able to show that a combination of DTIC/DMF significantly reduced lymph vessel density in primary tumors as examined by real-time PCR and immunohistochemistry. In addition, DTIC/DMF treatment significantly impaired melanoma cell migration in vitro. In vivo, DTIC/DMF therapy significantly reduced mRNA expression and protein concentration of the promigratory chemokines CXCL2 and CXCL11. In addition, our data suggest that this xenotransplantation model is suitable for preclinical testing of various combinations of antimelanoma agents.

Increased Caspase-2 Activity is Associated with Induction of Apoptosis in IFN-β Sensitive Melanoma Cell Lines

Interferon (IFN) is believed to be one of the most effective anti-melanoma agents. Specifically, IFN-beta has the ability to induce apoptosis of melanoma cells. Induction of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has also been suggested to have a critical role in IFN-beta-induced apoptosis. To characterize the signaling pathway involved in IFN-beta-induced apoptosis, we analyzed the biological effects of IFN-beta on the cell death and caspase activation of melanoma cells. IFN-sensitive cell lines, MM418, SK-mel-23, and SK-mel-118, showed increased apoptotic populations correlated with the activation of caspase-2 and caspase-3 by IFN-beta. IFN-beta-induced apoptosis was significantly suppressed by inhibitors for caspase-2 or caspase-3, but not by inhibitors for caspase-8 or caspase-9 in these cell lines. TRAIL expression was observed in IFN-beta-treated cells of SK-mel-23 and SK-mel-118, but not in those cells of MM418, which showed massive IFN-beta-induced apoptosis and resistance to exogenous TRAIL-mediated apoptosis. G361 was resistant to IFN-beta-induced apoptosis but sensitive to exogenous TRAIL-mediated apoptosis. Furthermore, IFN-beta pretreatment significantly increased the sensitivity against exogenous TRAIL-mediated apoptosis and activation of caspase-2 in G361. These results suggested that caspase-2 activation is commonly associated with induction of IFN-beta-induced apoptosis in IFN-beta-sensitive melanoma cells.

Abstract 1375: Amlexanox inhibits FGF-mediated paracrine and autocrine activity of tumor-derived melanoma cell lines and cell strains

Abstract Melanoma is a highly invasive disease characterized by widespread lymphatic and systemic metastases. Although angiogenesis is critical for this to occur, the responsible mechanisms within melanoma cells remain unclear. The purpose of this study is to identify factors secreted by tumor-derived melanoma cells which can mediate these processes. Serum-free conditioned medium (CM) isolated from two melanoma cell lines and four newly derived melanoma cell strains promote both the growth in culture and angiogenic outgrowth activity of HUVEC and HMEC1 in 3-dimensional (3-D) collagen gel culture. Substantial amounts of both FGF1 (acidic) and FGF2 (basic) are found in the conditioned medium (CM). The addition of neutralizing antibodies to FGF1 (5 μg/ml) and FGF2 (3 μg/ml) to the melanoma CM significantly decreased the proliferation of HUVEC and HMEC1 by (20%) and (40%), respectively, and the angiogenic activity of HMEC1 by (20%). Amlexanox (AMX) is an anti-inflammatory agent that binds intracellular S100A13, one component of the putative FGF1-secretion complexes. AMX suppresses constitutive release of FGF1, but not FGF2, from these melanoma cells. AMX-treated melanoma-CM results in significant reduction of: HUVEC mitogenic activity, endothelial migration into 3-D collagen gel as well as melanoma cell proliferation. These AMX-mediated effects correlate with a concomitant decrease of FGFR1 phosphorylation in melanoma cells. The sum of these results point to the importance of the FGF-1 pathway and nominate AMX as a significant anti-melanoma agent by virtue of its impact on both paracrine and autocrine activity. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1375.

Combination of Dacarbazine and Dimethylfumarate Efficiently Reduces Melanoma Lymph Node Metastasis

Dimethylfumarate (DMF) has been shown to reduce melanoma growth and metastasis in animal models. We addressed the question of whether DMF is as effective in its antitumor activity as the US Food and Drug Administration-approved alkylating agent dacarbazine (DTIC). We also tested the possibility of an improved antitumoral effect when both therapeutics were used together. Using our severe combined immunodeficiency (SCID) mouse model, in which xenografted human melanoma cells metastasize from primary skin sites to sentinel nodes, we show that these treatments, alone or in combination, reduce tumor growth at primary sites. Our main finding was that metastasis to sentinel nodes is significantly delayed only in mice treated with a combination of DTIC and DMF. Subsequent experiments were able to show that a combination of DTIC/DMF significantly reduced lymph vessel density in primary tumors as examined by real-time PCR and immunohistochemistry. In addition, DTIC/DMF treatment significantly impaired melanoma cell migration in vitro. In vivo, DTIC/DMF therapy significantly reduced mRNA expression and protein concentration of the promigratory chemokines CXCL2 and CXCL11. In addition, our data suggest that this xenotransplantation model is suitable for preclinical testing of various combinations of antimelanoma agents.

Abstract A93: Topical ISC-4 for the prevention of melanoma

Abstract New strategies are urgently needed to prevent development of melanoma. Currently, surgical excision is the mainstay for eliminating early melanocytic lesions or preventing development of more aggressive cancer. However, use of sunscreen or body lotions containing topical agents with chemopreventive efficacy could be potentially useful for preventing cancer development. Therefore, novel topical chemopreventive agents with negligible systemic toxicity to prevent melanocytic lesion development would be a highly significant. In order to meet this unmet medical need, potent anti-melanoma agents called isoselenocyanates (ISC) have been developed from naturally occurring isothiocyanates (ITC), which are derived from plants. In these agents, sulfur has been replaced with selenium and the alkyl side chain has been lengthened from 1 or 2 to 4 or 6. The chemopreventive efficacy of ISC-4 for preventing melanoma development was evaluated in a human skin melanoma model containing early or advanced stage melanocytic lesion cell lines. Cumulative topical application of ISC-4 resulted in a >75% reduction in melanoma nodule developed in 3-D human skin reconstructs. Histological examination of drug treated skin reconstructs confirmed the chemopreventive efficacy without any obvious damage to skin cells. Furthermore, topical application of ISC-4 also effectively prevented melanoma tumor development in animals by ∼70% at 3. 83 mM with negligible toxicity compared to vehicle control. Mechanistically, ISC-4 decreased melanoma tumorigenesis causing an 3-fold increase in apoptosis by reducing pAkt3 and pPRAS40 levels and triggered caspase-3/7 activity. Furthermore, ISC-4 treatment reduced G0–G1 phase cells (30–40% decrease), and increased G2-M population by 50–60%. A 15-fold increase in the sub-G0–G1 cell population was also observed upon ISC-4 treatment compared to vehicle control treated cells. Thus, ISC-4 is a potent selenium-containing topical chemopreventive agent with significant potential to prevent melanocytic lesion development. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A93.

Synthesis of 4′-ester analogs of resveratrol and their evaluation in malignant melanoma and pancreatic cell lines

4′-Ester analogs of the disease preventative agent resveratrol were synthesized and evaluated for their potential as anti-melanoma and pancreatic cancer agents. A decarbonylative Heck coupling was used to assemble the protected stilbene core structure. The 4′-acetate and the palmitoate analogs demonstrated selective activity with DM443 and DM738 cells over normal NHDF cells.

Structure–toxicity relationship of phenolic analogs as anti-melanoma agents: An enzyme directed prodrug approach

The aim of this study was to identify a phenolic prodrug compound that is minimally metabolized by rat liver microsomes, but yet could form quinone reactive intermediates in melanoma cells as a result of its bioactivation by tyrosinase. In current work, we investigated 24 phenolic compounds for their metabolism by tyrosinase, rat liver microsomes and their toxicity towards murine B16-F0 and human SK-MEL-28 melanoma cells. A linear correlation was found between toxicities of phenolic analogs towards SK-MEL-28 and B16-F0 melanoma cells, suggesting similar mechanisms of toxicity in both cell lines. 4-HEB was identified as the lead compound. 4-HEB (IC 50 48 h, 75 μM) showed selective toxicity towards five melanocytic melanoma cell lines SK-MEL-28, SK-MEL-5, MeWo, B16-F0 and B16-F10, which express functional tyrosinase, compared to four non-melanoma cells lines SW-620, Saos-2, PC3 and BJ cells and two amelanotic SK-MEL-24, C32 cells, which do not express functional tyrosinase. 4-HEB caused significant intracellular GSH depletion, ROS formation, and showed significantly less toxicity to tyrosinase specific shRNA transfected SK-MEL-28 cells. Our findings suggest that presence of a phenolic group in 4-HEB is critical for its selective toxicity towards melanoma cells.

Efficacy of Caffeic Acid Phenethyl Ester (CAPE) in skin B16-F0 melanoma tumor bearing C57BL/6 mice

In current work, we investigated the in-vitro efficacy of Caffeic acid Phenethyl Ester (CAPE) as an anti-melanoma agent in five melanoma cell lines B16-F0, B16F10, SK-MEL-28, SK-MEL-5, and MeWo and in-vivo efficacy study in skin B16-F0 melanoma tumor model in C57BL/6 mice. The IC(50) (48 h) of CAPE in above five melanoma cell lines was 15 µM. CAPE (20-200 µM) led to intracellular GSH depletion of 16-54%, and 10-25 fold increase in Reactive Oxygen Species (ROS) formation in B16-F0 cells. CAPE (15-30 µM) caused 5-7 fold increase in apoptosis in B16-F0 cells. CAPE (10, 20 and 30 mg/Kg/day) led to tumor size growth inhibition by 39 ± 33%, 54 ± 36%, and 57 ± 18%, respectively. The respective therapies led to plasma Alanine Amino Transferase (ALT) levels corresponding to 85 ± 18, 107 ± 26, 154 ± 35 IU/L in comparison to controls 66 ± 14 IU/L. At corresponding doses, the lipid peroxidation levels as measured by malondialdehyde (MDA) formation in liver homogenates were 255 ± 8 μM, 304 ± 21 μM, and 342 ± 14 μM in comparison to 208 ± 6 μM in controls. The level of MDA in kidney homogenates was 263 ± 21 μM, 282 ± 18 μM, and 350 ± 28 μM, respectively, in comparison to 212 ± 8 μM in controls. Administration of CAPE (10, 20, 30 mg/Kg/day) diminished free thiol contents in liver for 21 ± 15%, 40 ± 17%, and 44 ± 19% and in kidney homogenates for 25 ± 15%, 37 ± 18%, and 40 ± 22%, respectively, as compared to controls. Our study suggests that CAPE at 10 mg/Kg/day has significant anti-melanoma efficacy with minimal toxicity.

Synthesis and Preliminary in Vitro Biological Evaluation of 4-[(4-Hydroxyphenyl)sulfanyl]but-3-en-2-one, a 4-Mercaptophenol Derivative Designed As a Novel Bifunctional Antimelanoma Agent

We report the synthesis and preliminary in vitro biological evaluations of 4-[(4-hydroxyphenyl)sulfanyl]but-3-en-2-one, a compound designed as a potential bifunctional antimelanoma agent, bearing both a tyrosinase-activatable phenolic moiety and a GSH-reactive alpha,beta-unsaturated carbonyl group. Both the E (1) and Z (2) isomers of the synthesized compound proved to be very good substrates of mushroom tyrosinase, reacted quickly with GSH at physiological pH, and showed a significant cytotoxic activity against B16F1 murine melanoma cells.

Genetically engineered Newcastle disease virus for malignant melanoma therapy

Despite the advances in cancer therapies in the past century, malignant melanoma continues to present a significant clinical challenge due to lack of chemotherapeutic response. Systemic therapy with immunostimulatory agents such as interferon and interleukin-2 (IL-2) has shown some promise, though each is associated with significant side effects. Over the past 50 years, oncolytic Newcastle disease virus (NDV) has emerged as an alternative candidate for cancer therapy. The establishment of reverse-genetics systems for the virus has allowed us to further manipulate the virus to enhance its oncolytic activity. Introduction of immunomodulatory molecules, especially IL-2, into the NDV genome was shown to enhance the oncolytic potential of the virus in a murine syngeneic colon carcinoma model. We hypothesize that a recombinant NDV expressing IL-2 would be an effective agent for therapy of malignant melanoma. We show that recombinant NDV possesses a strong cytolytic activity against multiple melanoma cell lines, and is effective in clearing established syngeneic melanoma tumors in mice. Moreover, introduction of murine IL-2 into NDV significantly enhanced its activity against syngeneic melanomas, resulting in increased overall animal survival and generation of antitumor immunity. These findings warrant further investigations of IL-2-expressing NDV as an antimelanoma agent in humans.

The Triterpene Constituents of the Root Bark of a Hybrid between Morus alba L. and M. rotundiloba Koidz. and its Antityrosinase Activities

Mulberry plants have various traditional uses in Thailand, China, Korea and Vietnam. Recently, the root bark of Morus alba L. is used as whitening ingredient in various skin preparations. This paper describes the isolation of two triterpenes from the root bark of a 5 years old hybrid between M. alba L. and M. rotundiloba Koidz., a mulberry sericulture NM60 which is widely grown in Thailand for tea and silk industries. Pentacyclic triterpenes, α-amyrin acetate and betulinic acid, were isolated and identified, their structures were elucidated on the basis of spectroscopic analyses. The antityrosinase activities were tested having the IC50 values of 1.57 mM and 0.50 mM respectively. A validated HPLC technique for betulinic acid was also reported. Linear regression analysis of betulinic acid fell within the range of 61.25-409.15 μg/mL with a linear coefficient of 0.9992. The percentage of recovery is in accordance with that specified by the USP. The limit of detection and limit of quantification were 14.7 and 61.25 μg/mL, respectively. The analysis of the crude methanolic extract revealed 0.14% w/w betulinic acid in the root bark. These findings promote the use of the root bark extract of Thai mulberry hybrid in whitening cosmetics using betulinic acid as a marker and promote further study for the development of antimelanoma agent.

Identification of anti-melanoma agents by survival-based screening of small-molecule chemical library

Kichina, J.; Prokvolit, A.; Leonova, Y.; Zhang, J.; Kandel, E.; Gudkov, A. Author Information

Synthesis of Carbon-11 Labeled Triphenylacetamides as Novel Potential PET Melanoma Cancer Imaging Agents

New carbon-11 labeled triphenylacetamides (TPAs), N-(4-[ 11 C]methoxyphenyl)-2,2,2-triphenyl-acetamide ([ 11 C]MTA) and 3-phenyl-(R)-2-(2,2,2-triphenylacetylamino)propionic acid [ 11 C]methyl ester ([C]PAME), were designed and synthesized as potential positron emission tomography (PET) melanoma cancer imaging agents. The single crystal structure of the potent anti-melanoma agent, N-(4-methoxyphenyl)-2,2,2-triphenylacetamide (MTA) is reported.