Holothurin A Inhibits RUNX1-Enhanced EMT in Metastasis Prostate Cancer via the Akt/JNK and P38 MAPK Signaling Pathway.

Due to the challenge of prostate cancer (PCa) management, there has been a surge in efforts to identify more safe and effective compounds that can modulate the epithelial-mesenchymal transition (EMT) for driving metastasis. Holothurin A (HA), a triterpenoid saponin isolated from Holothuria scabra, has now been characterized for its diverse biological activities. However, the mechanisms of HA in EMT-driven metastasis of human PCa cell lines has not yet been investigated. Moreover, runt-related transcription factor 1 (RUNX1) acts as an oncogene in prostate cancer, but little is known about its role in the EMT. Thus, the purpose of this study was to determine how RUNX1 influences EMT-mediated metastasis, as well as the potential effect of HA on EMT-mediated metastasis in endogenous and exogenous RUNX1 expressions of PCa cell lines. The results demonstrated that RUNX1 overexpression could promote the EMT phenotype with increased EMT markers, consequently driving metastatic migration and invasion in PC3 cell line through the activation of Akt/MAPK signaling pathways. Intriguingly, HA treatment could antagonize the EMT program in endogenous and exogenous RUNX1-expressing PCa cell lines. A decreasing metastasis of both HA-treated cell lines was evidenced through a downregulation of MMP2 and MMP9 via the Akt/P38/JNK-MAPK signaling pathway. Overall, our approach first demonstrated that RUNX1 enhanced EMT-driven prostate cancer metastasis and that HA was capable of inhibiting the EMT and metastatic processes and should probably be considered as a candidate for metastasis PCa treatment.

In vitro and in silico studies of holothurin A on androgen receptor in prostate cancer.

The androgen receptor (AR) plays a crucial role in the growth of prostate cancer, and has long been considered the cancer's primary strategic therapeutic target. However, despite the early susceptibility, patients receiving hormonal therapy targeting AR are likely to develops resistance to the treatment and progresses to the castration-resistant stage as a consequence of the mutation at the ligand binding pocket of AR. Interestingly, the surface pocket of the AR called binding function 3 (BF3) has been reported as a great benefit for treating a recurrent tumor. Herein, we investigate the potential of using a marine triterpenoid saponin, holothurin A, on targeting AR expression of prostate cancer using in vitro and in silico studies. Holothurin A reduced the PSA expression, leading to the growth inhibition of androgen sensitive prostate cancer cell line through a downregulation of AR activity. The molecular docking study demonstrated that holothurin A could bind strongly in the BF3 pocket by energetically favorable hydrogen acceptor and hydrophobic with a calculated binding affinity of -13.90 kcal/mol. Molecular dynamics simulations provided the additional evidence that holothurin A can form a stable complex with the BF3 pocket through the hydrophobic interactions with VAL676, ILE680, and ALA721. As a consequence, holothurin A modulates the activation function-2 (AF2) site of the AR through repositioning of the residues in the AF2 pocket. Targeting alternatives sites on the surface of AR via holothurin A will provide a potential candidate for future prostate cancer treatment.Communicated by Ramaswamy H. Sarma.

Natural Merosesquiterpenes Activate the DNA Damage Response via DNA Strand Break Formation and Trigger Apoptotic Cell Death in p53-Wild-type and Mutant Colorectal Cancer.

Colorectal cancer (CRC) is a frequently occurring malignant disease with still low survival rates, highlighting the need for novel therapeutics. Merosesquiterpenes are secondary metabolites from marine sponges, which might be useful as antitumor agents. To address this issue, we made use of a compound library comprising 11 isolated merosesquiterpenes. The most cytotoxic compounds were smenospongine > ilimaquinone ≈ dactylospontriol, as shown in different human CRC cell lines. Alkaline Comet assays and γH2AX immunofluorescence microscopy demonstrated DNA strand break formation in CRC cells. Western blot analysis revealed an activation of the DNA damage response with CHK1 phosphorylation, stabilization of p53 and p21, which occurred both in CRC cells with p53 knockout and in p53-mutated CRC cells. This resulted in cell cycle arrest followed by a strong increase in the subG1 population, indicative of apoptosis, and typical morphological alterations. In consistency, cell death measurements showed apoptosis following exposure to merosesquiterpenes. Gene expression studies and analysis of caspase cleavage revealed mitochondrial apoptosis via BAX, BIM, and caspase-9 as the main cell death pathway. Interestingly, the compounds were equally effective in p53-wild-type and p53-mutant CRC cells. Finally, the cytotoxic activity of the merosesquiterpenes was corroborated in intestinal tumor organoids, emphasizing their potential for CRC chemotherapy.

Quintaquinone, a Merosesquiterpene from the Yellow Sponge Verongula cf. rigida Esper.

A chemical investigation of the sponge Verongula cf. rigida led to the isolation of 13 merosesquiterpenes, among which quintaquinone (2), 5-epi-nakijiquinone L (3), and 3-farnesyl-2-hydroxy-5-methoxyquinone (4) were isolated and reported here for the first time. Particularly, compound 2 is the first member of merosesquiterpenes with a polyketide side chain substituted on C-19. All of the isolated compounds were examined for steroid 5α-reductase inhibitory activity. Cyclospongiaquinone 1 (5) showed a strong activity in the same range as that of standard finasteride.

Allocation of trisoxazole macrolides in the sponge Penares cf. nux and the impact on epiphytic bacterial cohabitants.

The correlation between the allocation of trisoxazole macrolides in the capitums, appendages, and bases of the sponge Penares cf. nux and the surface-attached bacteria on the corresponding parts was examined. The kabiramide contents were highest in the capitums, followed by the appendages and bases. Conversely, direct counts of cultivable surface-attached bacteria showed that the bacteria aggregate more densely on the surfaces of the bases. This suggested the repelling effects of the kabiramides against the fouling bacteria, particularly on the capitums and appendages. Twenty-two bacterial strains were isolated and identified to 15 species; however, none has shown the potentials as a producer of any secondary metabolites in the sponge P. nux.

A New Sesquiterpenoid Aminoquinone from an Indonesian Marine Sponge.

Sponges are a well-known bioresource for bioactive compounds. In this study, antibacterial activity-guided fractionation of the extract from an Indonesian marine Dactylospongia elegans sponge led to the discovery of four merosesquiterpenoids, namely, a new sesquiterpenoid aminoquinone nakijiquinone V (1), along with illimaquinone (2), smenospongine (3), and dyctioceratine C (4). The structure of compound 1 was elucidated by 1D and 2D NMR as well as by LC-HRESIMS data analysis. Compounds 2⁻4 showed moderate to low antimicrobial activity against Bacillus megaterium DSM32 with a minimum inhibitory concentration (MIC) of 32 µg/mL, 32 µg/mL, and 64 µg/mL, respectively. Furthermore, compounds 2 and 3 both inhibited Micrococcus luteus ATCC 4698 with a MIC of 32 µg/mL. In conclusion, the isolated merosesquiterpenoids, which are known for their cytotoxic effects, showed antibacterial activity and prompt future structure activity relationship (SAR) studies concerning the various bioactivities observed for this group of natural products.

Interruptin B induces brown adipocyte differentiation and glucose consumption in adipose-derived stem cells.

Interruptin B has been isolated from Cyclosorus terminans, however, its pharamcological effect has not been fully identified. In the present study, the effects of interruptin B, from C. terminans, on brown adipocyte differentiation and glucose uptake in adipose­derived stem cells (ASCs) were investigated. The results revealed that interruptin B dose­dependently enhanced the adipogenic differentiation of ASCs, with an induction in the mRNA expression levels of peroxisome proliferator­activated receptor (PPAR)­α and PPAR­Î³. In addition, interruptin B efficiently increased the number and the membrane potential of mitochondria and upregulated the mRNA expression levels of uncoupling protein (UCP)­1 and cyclooxygenase (COX)­2, which are all predominantly expressed in brown adipocytes. Interruptin B increased glucose consumption in differentiated ASCs, accompanied by the upregulation in the mRNA expression levels of glucose transporter (GLUT)­1 and GLUT­4. The computational analysis of molecular docking, a luciferase reporter assay and surface plasmon resonance confirmed the marked binding affinity of interruptin B to PPAR­α and PPAR­Î³ (K(D) values of 5.32 and 0.10 µm, respectively). To the best of our knowledge, the present study is the first report to show the stimulatory effects of interruptin B on brown adipocyte differentiation and glucose uptake in ASCs, through its role as a dual PPAR­α and PPAR­Î³ ligand. Therefore, interruptin B could be further developed as a therapeutic agent for the treatment of diabetes.

Bromotyrosine Alkaloids with Acetylcholinesterase Inhibitory Activity from the Thai Sponge Acanthodendrilla sp.

Twenty bromotyrosine alkaloids, including a new compound, 13-oxosubereamolline D (5), were isolated from the Thai sponge Acanthodendrilla sp. Their structures were determined by analyses of 1D- and 2D-NMR, high-resolution mass, and circular dichroism data. The complete 1H and 13C NMR assignments of 5,7ß-dichlorocavernicolin (19) and 5,7α-dichlorocavernicolin (20) are described herein for the first time. The acetylcholinesterase (AChE) inhibitory activity of all isolated compounds was evaluated. Only homoaerothionin (7) and fistularin 1 (10) exhibited inhibitory activity against human recombinant AChE (hrAChE) with IC50s of 4.5 and 47.5 µM, respectively. The hrAChE inhibition kinetics of 7, the most potent alkaloid, showed increased Km and unchanged Vmaxvalues, suggesting its competitive mode of inhibition. The spirocyclohexadienylisoxazole and the length of the alkyl diamine linkage were proposed as the crucial parts for its strong inhibitory activity. This finding indicates a therapeutic potential for 7 in acetylcholine-related diseases, most importantly Alzheimer's disease.

Non-competitive inhibition of acetylcholinesterase by bromotyrosine alkaloids.

Fifteen bromotyrosine-derived alkaloids were isolated from the sponge Pseudoceratina cf. purpurea. The acetylcholinesterase-inhibiting activity of all the isolated compounds were examined; to purealidin Q, isoanomoian A, aplyzanzine A, and aplysamine 2 were active with IC50 values of 1.2, 70, 104, and 1.3 µM, respectively. On the other hand, antiproliferative activity against MCF-7 cells of aerophobin 1 gave an IC50 value of 0.8 µM. The Michaelis-Menten plots of the active alkaloids indicated that all the four compounds inhibited acetylcholinesterase in a non-competitive manner. The structures of the active compounds suggested that the N,N-dimethylaminopropyloxydibromotyramine moiety may play an important role in the enzyme-inhibiting activity, presumably on the anionic and hydrophobic binding sites.

Antiproliferative effects of 12-oxoheteronemin vs heteronemin.

The antiproliferative activities of 12-oxoheteronemin and heteronemin were evaluated in six cancer cell lines and IC50 values ranging from 0.66 to 1.35 microM were obtained. In four of the cell lines, 12-oxoheteronemin and heteronemin were equipotent; however, in two estrogenic receptor-positive cell lines, heteronemin showed a stronger potency. Both compounds had no overt effects on cell cycle distribution in HeLa cells, but did rapidly initiate apoptosis as evidenced by increased sub-G1 populations of cells and caspase-dependent PARP cleavage.

A new antibacterial amino phenyl pyrrolidone derivative from a novel marine gliding bacterium Rapidithrix thailandica.

A recently described marine gliding bacterium Rapidithrix thailandica strain TISTR 1741 was isolated from biofilm specimen collected from the Andaman Sea in Thailand. Four liters fermentation broth of R. thailandica TISTR 1741 cultivated in VY/2 medium were extracted with methanol to yield a novel amino phenyl pyrrolidone derivative compound (1) with antibacterial activities. The chemical structure and physico-chemical properties of 1 were investigated by spectrometry techniques. Compound 1 exhibited selective inhibition against vancomycin-resistant Enterococcus faecalis (VRE) with the MIC of 5.97 mM.

3-oxoabolene and 1-oxocurcuphenol, aromatic bisabolanes from the sponge Myrmekioderma sp.

Two new aromatic bisabolane sesquiterpenes possessing an oxo functionality on the prenyl chain, (+)-3-oxoabolene (3) and (+)-l-oxocurcuphenol (4), along with two known sesquiterpenes, (+)-curcuphenol (1) and (+)-curcudiol (2), were isolated from the sponge Myrmekioderma sp. The antiproliferative activity of 2-4 was determined and showed an interesting selectivity; i.e., a good activity against HT-29 cells with IC50s in the microM range, but a weak and incalculable toxicity against Hela and normal fibroblast cells.

Bridged tricyclic sesquiterpenes from the tubercle nudibranch Phyllidia coelestis Bergh.

A new sesquiterpene, 1-formamido-10(1→2)-abeopupukeanane (1), was isolated from the tubercle nudibranch Phyllidia coelestis Bergh, along with 2-formamidopupukeanane (2), which is reported here as a natural product for the first time. A rearrangement pathway toward the unprecedented tricyclo[4.4.0.0(2,8)]decane skeleton is proposed. Both compounds showed antiproliferative activity when targeting HeLa, MCF-7, KB, and HT-29 cancer cell lines in the range 0.05-10 µM.

Kabiramide L, a new antiplasmodial trisoxazole macrolide from the sponge Pachastrissa nux.

An extensive search for the trisoxazole macrolides in the Thai specimen of the sponge Pachastrissa nux led to the isolation of a new kabiramide derivative, kabiramide L (1) and the previously reported kabiramide I (2). Both macrolides had a moderate antiplasmodial activity against Plasmodium falciparum K1 with IC50s of 2.6 and 4.5 µM, respectively. To date, P. nux has been the only known source of the trisoxazole macrolides bearing the 30-enone moiety. Both compounds were also added to the list of chemicals postulated to play a defensive role in the P. nux sponge.

Anti-inflammatory activity of diterpenes from Croton stellatopilosus on LPS-induced RAW264.7 cells.

An acyclic diterpene (plaunotol; 1) and two furanoditerpenes (plaunolide, 2 and plaunol E, 3), were isolated from Croton stellatopilosus leaves, and assessed for their inhibitory activity on nitric oxide (NO) production by lipopolysaccharide (LPS)-induced RAW264.7 cells. Plaunotol, plaunolide and plaunol E exhibited inhibitory activity with IC(50) values of 3.41, 17.09 and 2.79 µM, respectively. Cytotoxic effects were observed at concentrations of ≥100 µM for plaunotol and ≥10 µM for plaunol E. In order to understand the mechanism of this anti-inflammatory activity, transcription profiles of the COX-1, COX-2 and iNOS genes were measured using a quantitative RT-PCR technique. The level of gene expression was expressed as a relative quantitation according to the comparative C (T) method. The results indicated that plaunotol stimulated the COX-1 and COX-2 genes, and suppressed expression of the iNOS gene. Treatment of cells with plaunolide caused a downregulation of the expressions of the COX-1, COX-2 and iNOS genes. In contrast, plaunol E inhibited the expression of the COX-2, stimulated COX-1 and iNOS expressions. In summary, the present study shows that different diterpenes from C. stellatopilosus leaves exhibit anti-inflammatory activity towards LPS-activated RAW264.7 cells by different mechanisms. Our results provide data to support further investigations into the possibility that these diterpenes could be alternatives to act as anti-inflammatory agents.

Bifunctionalized amphilectane diterpenes from the sponge Stylissa cf. massa.

Two new amphilectane-type diterpenes, 8-isocyanato-15-formamidoamphilect-11(20)-ene (1) and 8-isothiocyanato-15-formamidoamphilect-11(20)-ene (2), along with two known derivatives, 8-isocyano-15-formamidoamphilect-11(20)-ene (3) and 7-formamidoamphilect-11(20),15-diene (4), were isolated from the sponge Stylissa cf. massa. Diterpenes bearing two different isonitrile-related functionalities, as in 1-3, are rare. The coexistence of these compounds, all of which possess the identical carbon skeleton, in the same sponge specimen suggests interconversion among them. All the isolated compounds were tested for antimalarial activity. Compound 3 proved approximately 10 times more active than 1 and 2, indicating the importance of the isonitrile moiety to antimalarial activity versus the isocyanate and isothiocyanate groups, respectively. Compound 4, which contains only the formamide group, was inactive at the highest concentration tested.

Quantification of 5'-deoxy-5'-methylthioadenosine in heat-treated natural rubber latex serum.

INTRODUCTION: 5'-Deoxy-5'-methylthioadenosine (MTA) is one of the biologically active components found in natural rubber latex (NRL) serum, a common waste product from rubber plantations. In this study the contents of MTA in heat-treated NRL serum were measured in order to assess the potential of the serum as an alternative source of MTA. OBJECTIVE: To devise an HPLC/UV-based quantitative analytical protocol for the determination of MTA, and to determine the effect of heat treatment on the content of MTA in NRL serum from various sources. METHODOLOGY: An HPLC/UV-based determination of MTA using an acidic eluant was devised and validated. In the heat treatment, the effect of refluxing times on MTA liberation was evaluated. RESULTS: The quantification protocol was validated with satisfying linearity, limits of detection and quantitation, precisions for peak areas and recovery percentages from intra- and inter-day operations. The amounts of MTA in the NRL sera from various sources increased with heat treatment to yield 5-12 µg MTA/mL of serum. CONCLUSION: The devised protocol was found to be satisfyingly applicable to the routine determination of MTA in NRL serum. The effect of heat treatment on the content of MTA also indicated another possible use for NRL serum, normally discarded in vast amounts by the rubber industry, as an alternative source of MTA.

Intracolonial allocation of trisoxazole macrolides in the sponge Pachastrissa nux.

Pachastrissa nux has two distinctive growth forms in one colony, i.e., the protruding gorgonian-shaped capitum and the substratum-attached irregular-shaped base. The sponge has the ability to allocate specifically its major secondary metabolites to the two parts in different levels. Using two cytotoxic trisoxazole macrolides, kabiramides C (2) and G (3), as chemical markers, it was found that the capitum accumulated higher contents of either or both compounds than did the base. However, there were neither inductive nor suppressive correlations among the allocation profiles of either compound in either part of the sponge. The allocation of kabiramides was a trade-off with the structural materials involved in reinforcing the strength of the sponge. To date, this is the second report that provides evidence of the specific allocation of bioactive metabolites in two distinctively different organ-like structures in a single sponge colony.

Kabiramides J and K, trisoxazole macrolides from the sponge Pachastrissa nux.

Three trisoxazole macrolides possessing a 30-α,ß-enone moiety, including the known kabiramide G (1) and the new kabiramides J (2) and K (3), were isolated from the sponge Pachastrissa nux, along with the previously reported kabiramides B (4), C (5), and D (6). To date, the enone moiety has been found to associate solely with the trisoxazole macrolides from P. nux. All of the isolated macrolides showed moderate to strong antimalarial and cytotoxic activities, except for 1, which possessed only potent cytotoxicity.

Acetylcholinesterase-inhibiting activity of pyrrole derivatives from a novel marine gliding bacterium, Rapidithrix thailandica.

Acetylcholinesterase-inhibiting activity of marinoquinoline A (1), a new pyrroloquinoline from a novel species of a marine gliding bacterium Rapidithrix thailandica, was assessed (IC(50) 4.9 microM). Two related pyrrole derivatives, 3-(2'-aminophenyl)-pyrrole (3) and 2,2-dimethyl-pyrrolo-1,2-dihydroquinoline (4), were also isolated from two other strains of R. thailandica. The isolation of 3 from a natural source is reported here for the first time. Compound 4 was proposed to be an isolation artifact derived from 3. The two isolated compounds were virtually inactive in the acetylcholinesterase-inhibitory assay (enzyme inhibition < 30% at 0.1 g L(-1)).