An Investigation into the Phytochemical Content and Antioxidant, Antidiabetic, and Wound-Healing Activities of Curculigo latifolia Found in Brunei Darussalam.

This present study aimed to investigate the phytochemical content and antioxidant and antidiabetic activities of Curculigo latifolia leaves (CL) and C. latifolia roots (CR) found in Brunei Darussalam. Phytochemical screening showed that CL and CR extracts contain saponins, tannins, glycosides, and terpenoids. CR showed higher total phenolic content (TPC), but lower total flavonoid content (TFC) when compared to CL. The high TPC in CR contributed to its potent radical scavenging activity (RSA) against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and strong ferric reducing antioxidant power (FRAP). Additionally, CR exerted significant inhibition of ∝-glucosidase and ∝-amylase, suggesting a potential link between the chemical compounds and its antioxidant and antidiabetic effects. In the animal study of antihyperglycemic activity, treatment with 250 mg/kg body weight (b.w.) of the CL extract normalised the blood glucose levels and improved body weight gain of alloxan-induced diabetic rats within 14 weeks. Furthermore, our investigation into the wound-healing effects of young C. latifolia leaves (YCL) and matured C. latifolia leaves (MCL) showed a significant reduction in wound size on Day 3, 5, and 7 of the experimental study, indicating its wound-healing potential. Based on our findings, C. latifolia can be consumed as part of a balanced diet due to its antioxidant and antidiabetic properties.

Chemical Constituents and Anticancer Activities of Marine-Derived Fungus Trichoderma lixii.

The fungal genus Trichoderma is a rich source of structurally diverse secondary metabolites with remarkable pharmaceutical properties. The chemical constituents and anticancer activities of the marine-derived fungus Trichoderma lixii have never been investigated. In this study, a bioactivity-guided investigation led to the isolation of eleven compounds, including trichodermamide A (1), trichodermamide B (2), aspergillazine A (3), DC1149B (4), ergosterol peroxide (5), cerebrosides D/C (6/7), 5-hydroxy-2,3-dimethyl-7-methoxychromone (8), nafuredin A (9), and harzianumols E/F (10/11). Their structures were identified by using various spectroscopic techniques and compared to those in the literature. Notably, compounds 2 and 5-11 were reported for the first time from this species. Evaluation of the anticancer activities of all isolated compounds was carried out. Compounds 2, 4, and 9 were the most active antiproliferative compounds against three cancer cell lines (human myeloma KMS-11, colorectal HT-29, and pancreas PANC-1). Intriguingly, compound 4 exhibited anti-austerity activity with an IC50 of 22.43 µM against PANC-1 cancer cells under glucose starvation conditions, while compound 2 did not.

Oridonin suppresses particulate-induced NLRP3-independent IL-1α release to prevent crystallopathy in the lung.

The human body is exposed to various particulates of industrial, environmental, or endogenous origin. Invading or intrinsic particulates can induce inflammation by aberrantly activating the immune system, thereby causing crystallopathies. When immune cells such as macrophages phagocytose the particulates, their phagolysosomal membranes undergo mechanical damage, eventually leading to pyroptotic cell death accompanied by the release of inflammatory cytokines, including interleukin (IL)-1α and IL-1ß. The nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is responsible for particulate-induced IL-1ß release and is therefore regarded as a potential therapeutic target for inflammation-mediated crystallopathies. However, IL-1α is released after particulate stimulation in an NLRP3 inflammasome-independent manner and plays a critical role in disease development. Therefore, drugs that exert potent anti-inflammatory effects by comprehensively suppressing particulate-induced responses, including IL-1ß release and IL-1α release, should be developed. Here, we found that oridonin, a diterpenoid isolated from Isodon japonicus HARA, strongly suppressed particulate-induced cell death, accompanied by the release of IL-1α and IL-1ß in mouse and human macrophages. Oridonin reduced particulate-induced phagolysosomal membrane damage in macrophages without affecting phagocytosis of particulates. Furthermore, oridonin treatment markedly suppressed the symptoms of silica particle-induced pneumonia, which was attributed to the release of IL-1α independently of NLRP3. Thus, oridonin is a potential lead compound for developing effective therapeutics for crystallopathies attributed to NLRP3-dependent as well as NLRP3-independent inflammation.

Cytotoxic activity of cordycepin produced by marine-derived fungus Emericella sp. against HT29 human colon cancer cell lines.

Colorectal cancer accounted for the third most common cancer in the world. The search for new drug candidates that can be used for colorectal cancer treatment from marine-derived fungi, Emericella sp. The present study was performed to isolate the cytotoxic compound from Emericella sp. The isolation method was carried out by using a combination of chromatographic techniques to afford compound 1. The cytotoxic activity and the exosome production property were determined by using proliferation and luciferase assay against HT29 CD63 Nluc cells, respectively. The chemical structure of compound 1 was identified as cordycepin based on spectroscopy methods such as mass spectrometry and nuclear magnetic resonance (1D and 2D NMR) analyses and comparison with authentic spectral data. The biological activity assay showed that cordycepin exhibited cytotoxic activity with an IC50 value of 92.05 µM through proliferation assay, and also inhibited the exosome production by luciferase assay with an IC50 value of 86.47 µM. Cordycepin was isolated from culture broth Emericella sp., exhibiting moderate cytotoxic activity and inhibitory activity of exosome production. Thus, cordycepin is a potential compound to be investigated further for its exosome production inhibition activity for further use as an anticancer lead compound.

Single-step construction of an acetoxypyrroloindole skeleton via tandem iodocyclization/acetoxylation of indoles.

A method for the synthesis of C3a acetoxy hexahydropyrrolo[2,3-b]indole derivatives via a PhI(OAc)2/nBu4NI mediated tandem iodocyclization/acetoxylation has been developed. The newly developed synthetic strategy features the single-step assembly of various C3a acetoxylated tetrahydropyrrole-, tetrahydrofuran-, and lactone-fused indolines under mild reaction conditions, which enabled efficient asymmetric synthesis of (-)-protubonine B.

Gamma-Glutamylcysteine Production Using Phytochelatin Synthase-Like Enzyme Derived from Nostoc sp. Covalently Immobilized on a Cellulose Carrier.

Gamma-glutamylcysteine (γ-EC) is an intermediate generated in the de novo synthesis of glutathione (GSH). Recent studies have revealed that the administration of γ-EC shows neuroprotective effects against oxidative stress in age-related disorders and chronic diseases like Alzhiemer's disease in model animals, which is not expected function in GSH. A phytochelatin synthase-like enzyme derived from Nostoc sp. (NsPCS) mediates γ-EC synthesis from GSH. To achieve low-cost and stable commercial level supply, the availability of immobilized NsPCS for γ-EC production was investigated in this study. Among the tested immobilization techniques, covalent binding to the cellulose carrier was most effective, and could convert GSH completely to γ-EC without decreasing the yield. The stable conversion of γ-EC from 100 mM GSH was achieved by both batch repeated and continuous reactions using the immobilized NsPCS on cellulose sheet and column shape monolith, respectively. The immobilization of NsPCS on those carriers is promising alternative technique for high-yielding and cost-effective production of γ-EC on its commercial applications.

Synthesis and biological evaluation of cajaninstilbene acid and amorfrutins A-D as cytotoxic agents against human pancreatic carcinoma PANC-1 cells.

A concise synthesis of cajaninstilbene acid was achieved in 7 steps from (E)-3,5-dimethoxystilbene in 8.6% overall yield via the Claisen rearrangement of an aryl reverse-prenyl ether as the key step. Cytotoxic activities against human pancreatic carcinoma PANC-1 cells of cajaninstilbene acid and amorfrutins A-D were also evaluated.

Study of the Structure-Activity Relationship of an Anti-Dormant Mycobacterial Substance 3-(Phenethylamino)Demethyl(oxy)aaptamine to Create a Probe Molecule for Detecting Its Target Protein.

The current tuberculosis treatment regimen is long and complex, and its failure leads to relapse and emergence of drug resistance. One of the major reasons underlying the extended chemotherapeutic regimen is the ability of Mycobacterium tuberculosis to attain a dormant state. Therefore, the identification of new lead compounds with chemical structures different from those of conventional anti-tuberculosis drugs is essential. The compound 3-(phenethylamino)demethyl(oxy)aaptamine (PDOA, 1), isolated from marine sponge of Aaptos sp., is known as an anti-dormant mycobacterial substance, and has been reported to be effective against the drug resistant strains of M. tuberculosis. However, its target protein still remains unclear. This study aims to clarify the structure-activity relationship of 1 using 15 synthetic analogues, in order to prepare a probe molecule for detecting the target protein of 1. We succeeded in creating the compound 15 with a photoaffinity group that retained antimicrobial activity, which proved to be a suitable probe molecule for identifying the target protein of 1.

Anti-Mycobacterial N-(2-Arylethyl)quinolin-3-amines Inspired by Marine Sponge-Derived Alkaloid.

The synthesis and evaluation of simplified analogs of marine sponge-derived alkaloid 3-(phenethylamino)demethyl(oxy)aaptamine were performed to develop novel anti-mycobacterial substances. Ring truncation of the tricyclic benzo[de][1,6]-naphthyridine skeleton effectively weakened the cytotoxicity of the natural product, and the resulting AC-ring analog exhibited good anti-mycobacterial activity. A structure-activity relationship (SAR) study, synthesizing and evaluating some analogs, demonstrated the specificity and importance of the N-(2-arylethyl)quinolin-3-amine skeleton as a promising scaffold for anti-mycobacterial lead compounds.

A New Tetracyclic Bromopyrrole-Imidazole Derivative through Direct Chemical Diversification of Substances Present in Natural Product Extract from Marine Sponge Petrosia (Strongylophora) sp.

Chemical diversification of substances present in natural product extracts can lead to a number of natural product-like compounds with a better chance of desirable bioactivities. The aim of this work was to discover unprecedented chemical conversion and produce new compounds through a one-step reaction of substances present in the extracts of marine sponges. In this report, a new unnatural tetracyclic bromopyrrole-imidazole derivative, rac-6-OEt-cylindradine A (1), was created from a chemically diversified extract of the sponge Petrosia (Strongylophora) sp. We also confirmed that 1 originated from naturally occurring (-)-cylindradine A (2) via a new reaction pattern. Moreover, (-)-dibromophakellin (3) and 4,5-dibromopyrrole-2-carboxylic acid (4), as well as 2, were reported herein for the first time in this genus. Studies on the possible reaction mechanism and bioactivities were also conducted. The results indicate that the direct chemical diversification of substances present in natural product extracts can be a speedy and useful strategy for the discovery of new compounds.

3-(Phenethylamino)demethyl(oxy)aaptamine as an anti-dormant mycobacterial substance: Isolation, evaluation and total synthesis.

3-(Phenethylamino)demethyl(oxy)aaptamine (1) was re-discovered from the marine sponge of Aaptos sp. as an anti-dormant mycobacterial substance through the bioassay-guided separation. Compound 1 showed potent anti-microbial activity against Mycobacterium bovis BCG with a minimum inhibitory concentration of 0.75 µg/mL under both aerobic conditions and hypoxic conditions inducing dormant state. Compound 1 was also effective against pathogenic M. tuberculosis strains including clinical multidrug-resistant strains. Furthermore, the successful total syntheses of 1 and its analog 3-aminodemethyl(oxy)aaptamine (2) afford sufficient quantities for further biological studies.

Mitochondrial Targeting in an Anti-Austerity Approach Involving Bioactive Metabolites Isolated from the Marine-Derived Fungus Aspergillus sp.

The tumor microenvironment is a nutrient-deficient region that alters the cancer cell phenotype to aggravate cancer pathology. The ability of cancer cells to tolerate nutrient starvation is referred to as austerity. Compounds that preferentially target cancer cells growing under nutrient-deficient conditions are being employed in anti-austerity approaches in anticancer drug discovery. Therefore, in this study, we investigated physcion (1) and 2-(2',3-epoxy-1',3',5'-heptatrienyl)-6-hydroxy-5-(3-methyl-2-butenyl) benzaldehyde (2) obtained from a culture extract of the marine-derived fungus Aspergillus species (sp.), which were isolated from an unidentified marine sponge, as anti-austerity agents. The chemical structures of 1 and 2 were determined via spectroscopic analysis and comparison with authentic spectral data. Compounds 1 and 2 exhibited selective cytotoxicity against human pancreatic carcinoma PANC-1 cells cultured under glucose-deficient conditions, with IC50 values of 6.0 and 1.7 µM, respectively. Compound 2 showed higher selective growth-inhibitory activity (505-fold higher) under glucose-deficient conditions than under general culture conditions. Further analysis of the mechanism underlying the anti-austerity activity of compounds 1 and 2 against glucose-starved PANC-1 cells suggested that they inhibited the mitochondrial electron transport chain.

Design, synthesis and molecular docking of new N-4-piperazinyl ciprofloxacin-triazole hybrids with potential antimicrobial activity.

New N-4-piperazinyl ciprofloxacin-triazole hybrids 6a-o were prepared and characterized. The in vitro antimycobacterial activity revealed that compound 6a experienced promising antimycobacterial activity against Mycobactrium smegmatis compared with the reference isoniazide (INH). Additionally, compound 6a exhibited broad spectrum antibacterial activity against all the tested strains either Gram-positive or Gram-negative bacteria compared with the reference ciprofloxacin. Also, compounds 6g and 6i displayed considerable antifungal activity compared with the reference ketoconazole. DNA cleavage assay of the highly active compounds 6c and 6h showed a good correlation between the Mycobactrium cleaved DNA gyrase assay and their in vitro antimycobactrial activity. Moreover, molecular modeling studies were done for the designed ciprofloxacin derivatives to predict their binding modes towards Topoisomerase II enzyme (PDB: 5bs8).

Identification of biosynthetic genes for the ß-carboline alkaloid kitasetaline and production of the fluorinated derivatives by heterologous expression.

ß-Carboline alkaloids exhibit a broad spectrum of pharmacological and biological activities and are widely distributed in nature. Genetic information on the biosynthetic mechanism of ß-carboline alkaloids has not been accumulated in bacteria, because there are only a few reports on the microbial ß-carboline compounds. We previously isolated kitasetaline, a mercapturic acid derivative of a ß-carboline compound, from the genetically modified Kitasatospora setae strain and found a plausible biosynthetic gene cluster for kitasetaline. Here, we identified and characterized three kitasetaline (ksl) biosynthetic genes for the formation of the ß-carboline core structure and a gene encoding mycothiol-S-conjugate amidase for the modification of the N-acetylcysteine moiety by using heterologous expression. The proposed model of kitasetaline biosynthesis shows unique enzymatic systems for ß-carboline alkaloids. In addition, feeding fluorotryptophan to the heterologous Streptomyces hosts expressing the ksl genes led to the generation of unnatural ß-carboline alkaloids exerting novel/potentiated bioactivities.

Target Identification of the Marine Natural Products Dictyoceratin-A and -C as Selective Growth Inhibitors in Cancer Cells Adapted to Hypoxic Environments.

Hypoxia-adapted cancer cells in tumors contribute to the pathological progression of cancer. The marine spongean sesquiterpene phenols dictyoceratin-A (1) and -C (2) have been shown to induce hypoxia-selective growth inhibition in cultured cancer cells and exhibit in vivo antitumor effects. These compounds inhibit the accumulation of hypoxia-inducible factor-1α (HIF-1α), which is a drug target in hypoxia-adapted cancer cells, under hypoxic conditions. However, the target molecules of compounds 1 and 2, which are responsible for decreasing HIF-1α expression under hypoxic conditions, remain unclear. In this study, we synthesized probe molecules for compounds 1 and 2 to identify their target molecules and found that both compounds bind to RNA polymerase II-associated protein 3 (RPAP3), which is a component of the R2TP/Prefoldin-like (PEDL) complex. In addition, RPAP3-knockdown cells showed a phenotype similar to that of compound-treated cells.

Structure-Activity Relationship of Biakamide, Selective Growth Inhibitors under Nutrient-Starved Condition from Marine Sponge.

The tumor microenvironment is considered as one of the important targets for anticancer drug discovery. In particular, nutrient deficiency may be observed in tumor microenvironment; biakamides A-D (1-4) isolated from marine sponge Petrosaspongia sp. as growth inhibitors against cancer cells adapted to glucose-deprived conditions have potential as new drugs and tools for elucidating adaptation mechanisms to these conditions. In this paper, we investigated structure-activity relationship (SAR) of biakamide to create easily accessible analog and gain insights about participation of the substructures to growth-inhibitory activity toward development of anticancer drug. This work revealed that 14,15-dinor-biakamide C (5), which is easily accessible, has similar activity to natural biakamide C (3). In addition, detailed SAR study showed the terminal acyl chain is important for interacting with target molecule and amide part including thiazole ring has acceptability to convert structures without losing activity.

Discovery of a new diol-containing polyketide by heterologous expression of a silent biosynthetic gene cluster from Streptomyces lavendulae FRI-5.

The genome of streptomycetes has the ability to produce many novel and potentially useful bioactive compounds, but most of which are not produced under standard laboratory cultivation conditions and are referred to as silent/cryptic secondary metabolites. Streptomyces lavendulae FRI-5 produces several types of bioactive compounds. However, this strain may also have the potential to biosynthesize more useful secondary metabolites. Here, we activated a silent biosynthetic gene cluster of an uncharacterized compound from S. lavendulae FRI-5 using heterologous expression. The engineered strain carrying the silent gene cluster produced compound 5, which was undetectable in the culture broth of S. lavendulae FRI-5. Using various spectroscopic analyses, we elucidated the chemical structure of compound 5 (named lavendiol) as a new diol-containing polyketide. The proposed assembly line of lavendiol shows a unique biosynthetic mechanism for polyketide compounds. The results of this study suggest the possibility of discovering more silent useful compounds from streptomycetes by genome mining and heterologous expression.

Biakamides A-D, Unique Polyketides from a Marine Sponge, Act as Selective Growth Inhibitors of Tumor Cells Adapted to Nutrient Starvation.

Biakamides A-D, novel unusually unique polyketides, were isolated from an Indonesian marine sponge (Petrosaspongia sp.) with a constructed bioassay using PANC-1 human pancreatic cancer cells. Through detailed analyses of the one- and two-dimensional NMR spectra of biakamides, planar chemical structures possessing a terminal thiazole, two N-methyl amides, a chloromethylene, and a substituted butyryl moiety were obtained. After elucidation of the configuration of the secondary alcohol moiety in biakamides A and B, the absolute stereostructures of the two secondary methyl groups in biakamides A-D were determined by the asymmetric total syntheses of all possible stereoisomers from the optically pure monoprotected 2,4-dimethyl-1,5-diol. Biakamides A-D showed selective antiproliferative activities against PANC-1 cells cultured under glucose-deficient conditions in a concentration-dependent manner. The primary mode of action of biakamides was found to be inhibition of complex I in the mitochondrial electron transport chain.

Furospinosulin-1, Marine Spongean Furanosesterterpene, Suppresses the Growth of Hypoxia-Adapted Cancer Cells by Binding to Transcriptional Regulators p54(nrb) and LEDGF/p75.

Hypoxia-adapted cancer cells in tumors contribute to the pathological progression of cancer. Cancer research has therefore focused on the identification of molecules responsible for hypoxia adaptation in cancer cells, as well as the development of new compounds with action against hypoxia-adapted cancer cells. The marine natural product furospinosulin-1 (1) has displayed hypoxia-selective growth inhibition against cultured cancer cells, and has shown in vivo anti-tumor activity, although its precise mode of action and molecular targets remain unclear. In this study, we found that 1 is selectively effective against hypoxic regions of tumors, and that it directly binds to the transcriptional regulators p54(nrb) and LEDGF/p75, which have not been previously identified as mediators of hypoxia adaptation in cancer cells.

Search for Anti-angiogenic Substances from Natural Sources.

As angiogenesis is critical for tumor growth and metastasis, potent and selective anti-angiogenic agents with novel modes of action are highly needed for anti-cancer drug discovery. In this review, our studies focusing on the search for anti-angiogenic substances from natural sources, such as bastadins, globostellatic acid X methyl esters and cortistatins from marine sponges, and pyripyropenes from marine-derived fungus, together with senegasaponins from medicinal plant, are summarized.