Concise synthesis and PTP1B inhibitory activity of (R)- and (S)-dihydroresorcylide.

The present study was designed to develop a concise synthetic route for macrolide, with the purpose of confirming the absolute configuration of natural dihydroresorcylide (1) and making it more easily accessible for biological evaluation. The absolute configuration of C-3 in natural 1 was revised to be R by comparison of the rotation sign of synthetic (R)- and (S)-1. The synthetic (R)-1 was found to be a novel highly specific PTP1B inhibitor with an IC50 value of 17.06 µM.

Asymmetric Total Synthesis of Distaminolyne A and Revision of Its Absolute Configuration.

The first total synthesis of a marine derived polyacetylene, distaminolyne A, and its enantiomer were achieved from the commercially available undec-10-en-1-ol. A key proline-catalyzed asymmetric α-aminooxylation of an aldehyde intermediate was used to introduce the chiral center en route to the enantiomerically pure 1,2-amino alcohols. The absolute configuration of both synthesized enantiomers of distaminolyne A was confirmed by using chiral derivatizing agents, leading to revision of the natural product absolute configuration from 2S to 2R. Antibacterial, pancreatic lipase (PL) inhibitory, and protein-tyrosine phosphatase 1B (PTP1B) inhibitory activities were evaluated.

Design, synthesis and in vitro activity of phidianidine B derivatives as novel PTP1B inhibitors with specific selectivity.

A series of phidianidine B derivatives were synthesized by introducing various heterocyclic rings. Their inhibitory effects on PTP1B and other PTPs (TCPTP, SHP1, SHP2 and LAR) were evaluated. A majority of them displayed significant inhibitory potency and specific selectivity over PTP1B. The SAR and molecular docking analysis were also described.

Design and synthesis of novel 1,2-dithiolan-4-yl benzoate derivatives as PTP1B inhibitors.

A series of novel 1,2-dithiolan-4-yl benzoate compounds were synthesized and evaluated for in vitro PTP1B inhibitory activity. Some derivatives exhibited improved PTP1B inhibitory activity and selectivity compared to hit 6a, a compound from in-house library screening inspired by marine cyclic disulfide. The preliminary SAR analysis with assistance of molecular modeling approach revealed 6j (IC50=0.59µM) as the most potent PTP1B inhibitor among all derivatives.

Synthesis and biological evaluation of novel marine-derived indole-based 1,2,4-oxadiazoles derivatives as multifunctional neuroprotective agents.

Phidianidines (1), isolated from the marine opisthobranch mollusk Phidiana militaris, present the first example of natural products possessing an 1,2,4-oxadiazole ring system and show various bioactivities. However, the structure-activity relationship study related to 1 has not been reported yet. As our ongoing effect toward marine-derived potential neuroprotective agents, a series of phidianidine-based derivatives have been synthesized and evaluated for neuroprotective effects against amyloid-ß25-35 (Aß25-35)-, hydrogenperoxide (H2O2)-, and oxygen-glucose deprivation (OGD)-induced neurotoxicity in SH-SY5Y cells. The bioassay results indicated that some of analogs, especially 2q and 2r, exhibited good in vitro neuroprotective effects in the above three screening models. The preliminary SAR study indicated that substituent groups introduced to the benzene ring play a crucial role in their bioactivity. In particular, the linear alkoxy group at 4-position favors the neuroprotective activity, while a bulky group could lead the activity decrease or loss. These findings could provide an alternative strategy for the development of novel indole-based 1,2,4-oxadiazole derivatives for the treatment of Alzheimer's disease.

The first synthesis of natural disulfide bruguiesulfurol and biological evaluation of its derivatives as a novel scaffold for PTP1B inhibitors.

Bruguiesulfurol (1), a cyclic 4-hydroxy-dithiosulfonate isolated from mangrove plant Bruguiera gymnorrhiza, was concisely synthesized for the first time in four steps, and a series of its synthetic derivatives were evaluated for in vitro inhibitory effects on PTP1B and related PTPs. Some derivatives were found to have improved pharmacological profile compared with hit 1. Among them, 5a showed the potent selectivity towards PTP1B over other PTPs, including TCPTP, and 7j exhibited the strongest PTP1B inhibitory activity with an IC50 value of 4.54 µM.

Marine natural product des-O-methyllasiodiplodin effectively lowers the blood glucose level in db/db mice via ameliorating inflammation.

AIM: des-O-methyllasiodiplodin (DML) from Cerbera manghas has shown antagonistic activity against mineralocorticoid receptor (MR). Considering the involvement of MR in the insulin tolerance, we attempted to investigate the potential of DML in the treatment of type 2 diabetes mellitus (T2DM). METHODS: Surface plasmon resonance (SPR) technology and reporter gene-based assays were used to study protein-small molecule interactions. HepG2 and 3T3-L1 cells were treated with H2O2 (0.2 mmol/L) or aldosterone (10 nmol/L) for 24 h. The expression of MR in the cells was downregulated with siRNA. The anti-inflammatory effect of the compound was evaluated, respectively. db/db mice were administered DML (30 mg·kg(-1)·d(-1)) for 4 weeks. Serum biochemical parameters and insulin sensitivity were examined. The expression levels of pro-inflammatory cytokines (MCP-1, TNF-α and IL-6) and ROS-related genes (NADPH p47 subunit and transcriptional factor PU.1) in adipose tissues and livers were analyzed using real-time RT-PCR. RESULTS: In HepG2 and 3T3-L1 cells, both H2O2 and aldosterone markedly stimulates the expression of MCP-1, TNFα, IL-6, p47 and PU.1 genes. Co-treatment with DML (10 µmol/L) significantly reduced the H2O2- or aldosterone-induced expression of these genes. SPR-based assay confirmed the antagonistic activity of DML against the interaction between SRC-1 and MR-LBD. Furthermore, DML decreased aldosterone-induced MR transcriptional activity in a dose-dependent manner. Downregulation of MR with siRNA in the cells prevented or significantly attenuated aldosterone-stimulated expression of these genes, whereas DML did no longer affect the expression of these genes except that of IL-6. Oral administration of DML effectively reduced the levels of blood glucose and glycosylated hemoglobin (HbA1c) in db/db mice. The treatment also rectified the expression of pro-inflammatory factor and ROS-related genes in db/db mice. CONCLUSION: DML effectively lowers the blood glucose level in db/db mice possibly via ameliorating the expression of obesity-related pro-inflammatory cytokines, highlighting the potential of the marine natural product as a drug lead for the treatment of metabolic disorders.

A concise synthesis of xestospongic acid methyl ester with pancreatic lipase inhibitory activity.

Xestospongic acid methyl ester, a naturally brominated fatty acid with potent pancreatic lipase inhibitory activity in vitro, was synthesized from 5-hexynol in 30% total yield.

Synthesis and biological evaluation of 21-arylidenepregnenolone derivatives as neuroprotective agents.

A series of 21-arylidenepregnenolone derivatives and their corresponding epoxides were synthesized. The neuroprotective effects of these steroidal compounds against amyloid-ß(25-35) (Aß(25-35))- and hydrogen peroxide (H(2)O(2))-induced neurotoxicity in PC12 cells, and oxygen-glucose deprivation (OGD)-induced neurotoxicity in SH-SY5Y cells were evaluated. The bioassay results indicated that several 3ß-pregn-21-benzylidene-20-one derivatives displayed potent in vitro neuroprotective effects in different screening models, for example, compounds 2b, 3a, 3b, and 3s showing significant activities against Aß(25-35)-induced neurotoxicity in PC12 cells, 2b showing significant activities against H(2)O(2)-induced neurotoxicity in PC12 cells, and 2g, 3b, and 3e showing potent protection against OGD insult. The results suggested that introduction of an arylidene group into steroidal nucleus played an important role in neuroprotective activity, while the formation of epoxy group at C-5,6 could be also important for the neuroprotective activity in some degree. The pharmacological data reported here are helpful for the design of novel steroidal neuroprotective candidates.

Drug transporter-independent liver cancer cell killing by a marine steroid methyl spongoate via apoptosis induction.

Hepatocellular carcinoma (HCC) is inherently resistant to the majority of clinical anticancer drugs. To obtain drugs that can circumvent or evade such inherent drug resistance of HCC, we investigated the effect of the marinely derived steroid methyl spongoate (MESP) on HCC cells. MESP displayed potent cell killing against a panel of six HCC cell lines, independent of their expression of drug transporters. MESP did not change the function of the drug transporters, and its cell killing was not impaired in multidrug-resistant cancer cells overexpressing the transporters. The cell killing of MESP was irrelevant to estrogen or androgen signaling and was not associated with cell cycle progression, inhibition of microtubules, and topoisomerases. In contrast, MESP potently induced apoptosis via activation of a proapoptotic caspase cascade and relief of the suppression of antiapoptotic signal transducers and activators of transcription 3 (STAT3) signaling. MESP inhibited the phosphorylation of STAT3, a critical survival signaling factor that reduced the expression of the antiapoptotic protein x-linked inhibitor of apoptosis protein but enhanced the expression of the proapoptotic protein Bax, thus promoting caspase-dependent apoptosis. These data reveal that MESP may well serve as an important candidate drug lead for HCC therapy.

Synthesis, modification, and evaluation of (R)-de-O-methyllasiodiplodin and analogs as nonsteroidal antagonists of mineralocorticoid receptor.

Macrolide (R)-de-O-methyllasiodiplodin (1), discovered to be a potent nonsteroidal antagonist of the mineralocorticoid receptor (MR), was synthesized via an efficient method and evaluated for MR antagonistic activity together with its analogs. Among all the tested compounds, compounds 18a, 18b and 18c, exhibited more potent antagonistic activity against MR with IC(50) values ranging from 0.58 to 1.11 µM. Generally, it was obviously demonstrated that acetylation at phenolic hydroxyl groups and the ring size in analogs of 1 were very important for MR antagonist activity.

Synthesis and antitumor evaluation of methyl spongoate analogs.

A series of novel methyl spongoate (1) analogs has been synthesized and evaluated for their in vitro cytotoxic properties. It was found that the nature of the C-20 side chain had significant effects on their bioactivities and some analogs showed higher cytotoxicity than 1 against A549, HCT-116, HepG2, SW-1990, MCF-7 and NCI-H460 tumor cell lines. The pharmacological results confirmed that the α,ß-unsaturated carbonyl moiety, a Michael acceptor in ring A, plays a pivotal role in the cytotoxic effect of these derivatives. The compiled pharmacological data may be useful for the design of novel analogous anticancer drugs.

Design, synthesis, and examination of neuron protective properties of alkenylated and amidated dehydro-silybin derivatives.

A series of C7-O- and C20-O-amidated 2,3-dehydrosilybin (DHS) derivatives ((+/-)-1a-f and (+/-)-2), as well as a set of alkenylated DHS analogues ((+/-)-4a-f), were designed and de novo synthesized. A diesteric derivative of DHS ((+/-)-3) and two C23 esterified DHS analogues ((+/-)-5a and (+/-)-5b) were also prepared for comparison. The cell viability of PC12 cells, Fe(2+) chelation, lipid peroxidation (LPO), free radical scavenging, and xanthine oxidase inhibition models were utilized to evaluate their antioxidative and neuron protective properties. The study revealed that the diether at C7-OH and C20-OH as well as the monoether at C7-OH, which possess aliphatic substituted acetamides, demonstrated more potent LPO inhibition and Fe(2+) chelation compared to DHS and quercetin. Conversely, the diallyl ether at C7-OH and C20-OH was more potent in protection of PC12 cells against H(2)O(2)-induced injury than DHS and quercetin. Overall, the more lipophilic alkenylated DHS analogues were better performing neuroprotective agents than the acetamidated derivatives. The results in this study would be beneficial for optimizing the therapeutic potential of lignoflavonoids, especially in neurodegenerative disorders such as Alzheimer's and Parkinson's disease.

Total synthesis of gymnorrhizol, an unprecedented 15-membered macrocyclic polydisulfide from the Chinese mangrove Bruguiera gymnorrhiza.

[reaction: see text] The total synthesis of gymnorrhizol, a naturally occurring macrocyclic polydisulfide with a new skeleton and a potent proteintyrosinephosphatase 1B inhibitor, was prepared in three steps, starting from (R)-1-bromo-3-chloroisopropanol and 1,3-dichloropropan-2-ol.

Total synthesis and cytotoxicity evaluation of syrinenin-4-O-farnesylether and its analogues.

First synthesis of natural product, syrinenin-4-O-farnesylether (1), was carried out via two different paths. Four of its derivatives (9-12) were also prepared. Cytotoxicity screening of the selected compounds were performed on six tumour cell lines. Compound 12 exhibited prominent IC50 values of 1.9 microM and 0.8 microM on CNE and PC-3 cells, respectively.

Design, synthesis, and SAR analysis of cytotoxic sinapyl alcohol derivatives.

Five series totalling 51 of sinapyl alcohol derivatives were designed and synthesized. Their cytotoxicity analyses were performed on six human tumor cell lines such as PC-3, CNE, KB, A549, BEL-7404, and HeLa. Certain sinapyl alcohol derivatives showed significant cytotoxic activities. Compound 14d exhibited especially potent cytotoxicity against the BEL-7404 cell line with an IC50 value of 0.7 microM, which showed more cytotoxic activity than the positive control, cisplatin. The structure-cytotoxicity relationships were discussed and the CoMFA analysis was performed using the cytotoxic data against HeLa cells as a template.

Synthesis and biological evaluation of a natural ester sintenin and its synthetic analogues.

Synthesis of 3-(3,4-dimethoxyphenyl)propyl-3-(3,4-dimethoxyphenyl) propanoate (18), a cytotoxic natural ester, was carried out by a convenient synthetic path with a total yield of 49%. Sixteen of its analogues (19-34) were also prepared. Seventeen unsaturated derivatives of 18, compounds 1-17, were also synthesized to examine the structure-activity relationship of this type of ester. All of the synthetic compounds were passed through the cytotoxicity screenings on human tumor cell lines, such as PC-3, Hela, A549, BEL7404, CNE, and KB. Some of the esters exhibited moderate inhibitory effects on these tumor cell lines. The phenolic derivatives exhibited the highest cytotoxicity among these derivatives, while the unsaturated esters were more cytotoxic than the saturated analogues. Some of the compounds also exhibited inhibition on alpha-glucosidase.