Absolute Structure Determination and Kv1.5 Ion Channel Inhibition Activities of New Debromoaplysiatoxin Analogues.

Potassium channel Kv1.5 has been considered a key target for new treatments of atrial tachyarrhythmias, with few side effects. Four new debromoaplysiatoxin analogues with a 6/6/12 fused ring system were isolated from marine cyanobacterium Lyngbya sp. Their planar structures were elucidated by HRESIMS, 1D and 2D NMR. The absolute configuration of oscillatoxin J (1) was determined by single-crystal X-ray diffraction, and the absolute configurations of oscillatoxin K (2), oscillatoxin L (3) and oscillatoxin M (4) were confirmed on the basis of GIAO NMR shift calculation followed by DP4 analysis. The current study confirmed the absolute configuration of the pivotal chiral positions (7S, 9S, 10S, 11R, 12S, 15S, 29R and 30R) at traditional ATXs with 6/12/6 tricyclic ring system. Compound 1, 2 and 4 exhibited blocking activities against Kv1.5 with IC50 values of 2.61 ± 0.91 µM, 3.86 ± 1.03 µM and 3.79 ± 1.01 µM, respectively. However, compound 3 exhibited a minimum effect on Kv1.5 at 10 µM. Furthermore, all of these new debromoaplysiatoxin analogs displayed no apparent activity in a brine shrimp toxicity assay.

Maculosin, a non-toxic antioxidant compound isolated from Streptomyces sp. KTM18.

CONTEXT: Streptomyces species are prolific sources of bioactive secondary metabolites known especially for their antimicrobial and anticancer activities. OBJECTIVE: This study sought to isolate and characterize antioxidant molecules biosynthesized by Streptomyces sp. KTM18. The antioxidant potential of an isolated compound and its toxicity were accessed. MATERIALS AND METHODS: The compound was purified using bioassay-guided chromatography techniques. Nuclear magnetic resonance (NMR) experiments were carried out for structure elucidation. The antioxidant potential of the isolated compound was determined using DPPH free radical scavenging assay. The toxicity of the isolated compound was measured using a brine shrimp lethality (BSL) assay. RESULTS: Ethyl acetate extract of Streptomyces sp. KTM18 showed more than 90% inhibition of DPPH free radical at 50 µg/mL of the test concentration. These data were the strongest among 13 Streptomyces isolates (KTM12-KTM24). The active molecule was isolated and characterized as maculosin (molecular formula, C14H16N2O3 as determined by the [M + H]+ peak at 261.1259). The DPPH free radical scavenging activity of pure maculosin was higher (IC50, 2.16 ± 0.05 µg/mL) than that of commercial butylated hydroxyanisole (BHA) (IC50, 4.8 ± 0.05 µg/mL). No toxicity was observed for maculosin (LD50, <128 µg/mL) in brine shrimp lethality assay (BSLA) up to the compound's antioxidant activity (IC50) concentration range. The commercial standard, berberine chloride, showed toxicity in BSLA with an LD50 value of 8.63 ± 0.15 µg/mL. CONCLUSIONS: Maculosin may be a leading drug candidate in various cosmetic and therapeutic applications owing to its strong antioxidant and non-toxic properties.

In vitro cytotoxic, genotoxic, and antityrosinase activities of Clitoria macrophylla root.

Clitoria macrophylla Wall. (Leguminosae), locally known as Non-tai-yak or An-chan-pa, commonly distributed in tropical nations and Southeast Asia. Regarding traditional Thai medical system, C. macrophylla roots carry out a potential in dermatology. Its roots are also used as insecticide in agriculture and animal farming. Moreover, clitoriacetal is the major component that can be detected in C. macrophylla root. This research aimed to assess the efficacy of C. macrophylla root extract and clitoriacetal for its anticancer and antityrosinase activities as well as to assess in vitro safety potential for its cytotoxic and genotoxic effects. C. macrophylla root and clitoriacetal were tested by brine shrimp lethality, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, comet assay, and antityrosinase activity. C. macrophylla root, clitoriacetal, and rotenone demonstrated the toxicity against brine shrimp nauplii with LC50 of 332.15, 136.54, and 0.15 µg/mL, respectively. C. macrophylla root and clitoriacetal showed cytotoxic potential against breast ductal carcinoma (BT-474), liver hepatoblastoma (Hep-G2), and colon adenocarcinoma (SW-620). At 100 µg/mL, the percent DNA damage of C. macrophylla root and clitoriacetal was 37.84% and 36.01%, respectively. C. macrophylla root and clitoriacetal were able to inhibit the tyrosinase enzyme with IC50 of 12.27 and 7.30 mg/mL, respectively, which less effective than glutathione (positive control). The present study revealed the in vitro biological activities of C. macrophylla root and its clitoriacetal constituent which proposed the scientific evidences in efficacy and safety evaluation including in vitro cytotoxicity, DNA damage as well as antityrosinase activities.

Design, synthesis, brine shrimp lethality and cytotoxicity of some novel 17a-aza-D-homo-androster-17-one derivatives.

In this work, twenty-eight novel 17a-aza-D-homo-androster-17-one derivatives, which divided into two categories, were synthesized with commercial available starting material (dehydroepiandrosterone) via oximation reaction, Beckmann rearrangement, hydroxyl protection, N-alkylation and deprotection. All compounds were characterized by 1H NMR, 13C NMR and HRMS. The structure of 14 g was also identified by X-ray single crystal diffraction. The bioactivities, brine shrimp toxicity and cytotoxicity, of all derivatives were tested. The results indicated that compounds 11 h, 11i, 11 m, 11 s, 14 b and 14 g exhibited excellent toxicity against brine shrimp with LC50 values ranging from 5.34 to 16.89 µg/mL, and compounds 11 s and 14 g displayed significant cytotoxicity against HT29 cells and A549 cells with IC50 values of 9.70 µM and 8.85 µM, respectively. Structure-activity relationships are discussed based on the results obtained from our research, and some important determinants for further modification of steroids towards the development of novel drug candidates are identified.

Chemical and Biological Study of Novel Aplysiatoxin Derivatives from the Marine Cyanobacterium Lyngbya sp.

Since 1970s, aplysiatoxins (ATXs), a class of biologically active dermatoxins, were identified from the marine mollusk Stylocheilus longicauda, whilst further research indicated that ATXs were originally metabolized by cyanobacteria. So far, there have been 45 aplysiatoxin derivatives discovered from marine cyanobacteria with various geographies. Recently, we isolated two neo-debromoaplysiatoxins, neo-debromoaplysiatoxin G (1) and neo-debromoaplysiatoxin H (2) from the cyanobacterium Lyngbya sp. collected from the South China Sea. The freeze-dried cyanobacterium was extracted with liquid-liquid extraction of organic solvents, and then was subjected to multiple chromatographies to yield neo-debromoaplysiatoxin G (1) (3.6 mg) and neo-debromoaplysiatoxin H (2) (4.3 mg). They were elucidated with spectroscopic methods. Moreover, the brine shrimp toxicity of the aplysiatoxin derivatives representing differential structural classifications indicated that the debromoaplysiatoxin was the most toxic compound (half inhibitory concentration (IC50) value = 0.34 ± 0.036 µM). While neo-aplysiatoxins (neo-ATXs) did not exhibit apparent brine shrimp toxicity, but showed potent blocking action against potassium channel Kv1.5, likewise, compounds 1 and 2 with IC50 values of 1.79 ± 0.22 µM and 1.46 ± 0.14 µM, respectively. Therefore, much of the current knowledge suggests the ATXs with different structure modifications may modulate multiple cellular signaling processes in animal systems leading to the harmful effects on public health.

Synthesis of Novel Fluorene Bisamide Derivatives via Ugi Reaction and Evaluation their Biological Activity against Mycobacterium species.

A series of new fluorene bisamide derivatives were synthesized through multi-component Ugi reaction and tested for their in-vitro anti-mycobacterial activity. The structures of the products 5a-w were deduced from their IR, 1H NMR, and 13C NMR spectra. Elemental analyses (CHN) for novel compounds (5a, 5d, 5f, 5h, 5k, 5l, 5p, 5s, 5t, 5v, 5w) was done. These compounds were evaluated as anti-bacterial agents against Mycobacterium bovis and M. tuberculosis, while their activity expressed as the minimum inhibitory concentration (MIC) in µg/mL. Among the twenty-three synthesized compounds, 5a was found to be the most active compound in vitro with MIC of 1.95 µg/mL against Mycobactrium bovis and compound 5k showed greatest potency against sensitive and resistant strains of M.tuberculosis (H37Rv, IHMT149/09, HPV115/08, and HPV65/08).

Antifungal, phytotoxic and toxic metabolites produced by Penicillium purpurogenum.

Nine known metabolites, 6,8,1'-tri-O-methyl averantin (1), 6,8-di-O-methyl averufnin (2), 6,8-di-O-methyl averufanin (3), aversin (4), 1,3-dihydroxy-6,8-dimethoxy-9,10-anthraquinone (5), 6,8-di-O-methylnidurufin (6), 6,8-di-O-methyl versiconol (7), 5-methyoxysterigmatocystin (8) and (S)-ornidazole (9), were isolated from the extracts of Penicillium purpurogenum, and their structures were elucidated by using spectroscopic methods. The brine shrimp toxicity, anti-phytopathogenic and phytotoxic effects of these compounds were evaluated. Among them, compounds 1 and 8 exhibited the strongest toxicity against brine shrimp (Artemia salina), with lethality rates of 100% at a low concentration of 10 µM, comparable to the positive control toosendanin. Compounds 1, 4 and 7 moderately inhibited the growth of Botrytis cinerea. Moreover, 4 displayed moderate antifungal effects on Gibberella saubinettii. In addition, compounds 6, 7 and 9 produced the phytotoxic effects on radish seedlings at 100 µM. This is the first report on the isolation of these metabolites from this organism.

Estudos farmacognósticos, fitoquímicos, atividade antiplasmódica e toxicidade em Artemia salina de extrato etanólico de folhas de Montrichardia linifera (Arruda) Schott, Araceae / Pharmacognostics studies, phytochemicals, antiplasmodic activity and toxicity in Artemia salina of ethanolic extract from Montrichardia linifera (Arruda) Schott, Araceae leaves

O presente trabalho descreve os resultados do estudo farmacognóstico, estudo fitoquímico preliminar, toxicidade em Artemia salina e atividade antiplasmódica contra cepa de Plasmodium falciparum resistente a cloroquina (W2) do extrato etanólico obtido do pó das folhas de Montrichardia linifera (Arruda) Schott, Araceae. Para realização dos estudos farmacognósticos utilizou-se as metodologias descritas na Farmacopéia Brasileira. A prospecção fitoquímica foi realizada pelos métodos descritos por Mattos. No ensaio antiplasmódico foi utilizado o microteste tradicional e no ensaio de Artemia salina. Os resultados obtidos nos estudos farmacognósticos do pó das folhas de M. linifera demonstraram tratar-se de um pó moderadamente grosso, com teores de água e cinzas totais dentro dos limites aceitáveis, baixa densidade (0,324 e 0,339 g/mL), pH próximo de neutro (6,69±0,02). A análise fitoquímica preliminar evidenciou a presença de alcaloides, flavonoides, taninos, triterpenos e esteroides. O extrato etanólico das folhas de M. linifera apresentou moderada atividade antiplasmódica e baixa toxicidade para a Artemia salina.

The present paper describes results of a pharmacognostic, a preliminary phytochemical study, brine shrimp toxicity and antiplasmodic activity in a strain of Plasmodium falciparum that is resistant to chloroquine (W2) using ethanolic extract obtained from powder of the leaves of Montrichardia linifera (Arruda) Schott, Araceae. To perform the pharmacognostic studies methodologies employed in the Brazilian Pharmacopoea were utilized. The methods described by Mattos were utilized for phytochemical prospecting. In the antiplasmodic test the traditional microtest was employed, as well as in the test with brine shrimp. The results obtained in the pharmacognostic studies with the powder from M. linifera leaves showed that it was a moderate thick powder, with water and ash totals within acceptable limits, low density (0.324 and 0.339 g/mL), pH close to neutral (6.69 ± 0.02). Preliminary phytochemical analysis showed the presence of alkaloids, flavonoids, tannins, triterpenes and esters. The ethanolic extract from M. linifera leaves presented moderate antiplasmodic activity and low brine shrimp toxicity. To summarize, the powder used in preparing the extract presented good quality in pharmacognostic terms.

Anticonvulsant activity of Diospyros fischeri root extracts.

Diospyros fischeri Gurke (Ebenaceae) is used in traditional medicine for the treatment of epilepsy. Dichloromethane, ethylacetate, and ethanol extracts of the roots, at doses between 100 and 1600 mg/kg BW, inhibited convulsions induced by the gamma-aminobutyric acid type A (GABAa) receptor antagonist, pentylenetetrazole (PTZ), in a dose dependent manner. The extracts also exhibited low toxicity against brine shrimps giving LC(50) values between 45.4 and 95.4 microg/ml. These results provide evidence for the potential of D. fischeri extracts to treat absence seizures, especially given their seemingly innocuous nature.