Ana Jérsia Araújo

Cytotoxic, Trypanocidal Activities and Physicochemical Parameters of nor-β-Lapachone-based 1,2,3-Triazoles

The cytotoxicities of five nor-²-lapachone-based 1,2,3-triazoles and the precursor azidonaphthoquinone were assayed against six neoplasic cancer cell lines: SF-295 (central nervous system), HCT-8 (colon), MDAMB-435 (melanoma), HL-60 (leukaemia), PC-3 (prostate) and B-16 (murine melanoma). IC50 values ranging from 0.43 to 9.48 µM were obtained. 3-(4-(1-hydroxycyclohexyl)-1H-1,2,3-triazol-1yl)-2,2-dimethylnaphtho[1,2-b]furan-4,5-dione proved highly cytotoxic to MDAMB-435, with IC50 even lower than the one from doxorubicin (positive control). In an attempt to correlate physicochemical parameters (reduction potentials and calculated log P) with cytotoxic activity, electrochemical studies were conducted in acetate buffer, pH 4.5, using a vitreous carbon electrode and calculated log P values were obtained. Despite the absence of a structural conjugative interaction between the two systems (quinone and triazole), the heterocyclic group was found to influence the voltammetric behaviour, as indicated by anodic shifts in the reduction potentials. No correlation was found between EpIc and cytotoxicity. In contrast, a comparison of EpIc with previously reported trypanocidal activities reconfirmed the trend for higher activity coupled with better quinone electrophilicity (> EpIc).A leading term in the correlation of cytoxicity, despite the absence of a linear correlation, was the calculated log P: the lower the lipophilicity, the lower the cytoxicity (> IC50).

Cytotoxic activity of naphthoquinones with special emphasis on juglone and its 5-O-methyl derivative

The cytotoxicity of nine naphthoquinones (NQ) was assayed against HL-60 (leukaemia), MDA-MB-435 (melanoma), SF-295 (brain) and HCT-8 (colon), all human cancer cell lines, and peripheral blood mononuclear cells (PBMC), as representatives of normal cells, after 72h of incubation. 5-Methoxy-1,4-naphthoquinone was the most active compound, showing IC(50) values in the range of 0.31 (1.7microM) in HL-60 to 0.88microg/mL (4.7microM) in SF-295 and IC(50) of 0.69microg/mL (3.7microM) against PBMC. With the introduction of a bromo-substituent in position 2 or 3 of juglone, the IC(50) significantly decreased, regardless of the position on the NQ moiety. However, compared with juglone methyl ether, the halogen substitution decreased the activity. To further understand the mechanism underlying the cytotoxicity of 5-methoxy-1,4-naphthoquinone, studies involving DNA fragmentation, cell cycle analysis, phosphatidyl serine externalization, mitochondrial depolarization and activation of caspases 8 and 3/7 were performed in HL-60 cell line, using doxorubicin as a positive control. The results indicate that the cytotoxic 5-methoxy-1,4-naphthoquinone activates caspases 8 and 3/7 and thus induces apoptosis independent of mitochondria.

Synthesis and anticancer activities of some novel 2-(benzo[d]thiazol-2-yl)-8-substituted-2H-pyrazolo[4,3-c]quinolin-3(5H)-ones.

A series of 2-(benzo[d]thiazol-2-yl)-8-substituted-2H-pyrazolo[4,3-c]quinolin-3(5H)-ones (3a-g) have been synthesized and evaluated for their in vitro antiproliferative activities against four human cancer cell lines: MDA-MB-435 (breast), HL-60 (leukemia), HCT-8 (colon) and SF-295 (central nervous system). The results showed that the compounds 3b (2-(benzo[d]thiazol-2-yl)-8-methyl-2H-pyrazolo[4,3-c]quinolin-3(5H)-one) and 3c (2-(benzo[d]thiazol-2-yl)-8-bromo-2H-pyrazolo[4,3-c]quinolin-3(5H)-one) exhibited good cytotoxicity for three cell lines with IC(50) values lower than 5 μg/mL. Analysis of theoretical toxicity risks have shown medium tumorigenic and irritant risks related to 3b and 3c in contrast to doxorubicin, the positive control.

Oxidative stress induction by (+)-cordiaquinone J triggers both mitochondria-dependent apoptosis and necrosis in leukemia cells

(+)-Cordiaquinone J is a 1,4-naphthoquinone isolated from the roots of Cordia leucocephala that has antifungal and larvicidal effects. However, the cytotoxic effects of (+)-cordiaquinone J have never being explored. In the present study, the effect of (+)-cordiaquinone J on tumor cells viability was investigated, showing IC(50) values in the range of 2.7-6.6muM in HL-60 and SF-295 cells, respectively. Studies performed in HL-60 leukemia cells indicated that (+)-cordiaquinone J (1.5 and 3.0muM) reduces cell viability and 5-bromo-2-deoxyuridine incorporation after 24h of incubation. (+)-Cordiaquinone J showed rapid induction of apoptosis, as indicated by phosphatidylserine externalization, caspase activation, DNA fragmentation, morphologic changes, and rapid induction of necrosis, as indicated by the loss of membrane integrity and morphologic changes. (+)-Cordiaquinone J altered the redox potential of cells by inducing the depletion of reduced GSH intracellular content, the generation of reactive oxygen species and the loss of mitochondrial membrane potential. However, pre-treatment of cells with N-acetyl-l-cysteine abolished most of the observed effects related to (+)-cordiaquinone J treatment, including those involving apoptosis and necrosis induction.

A new approach for the synthesis of 3-substituted cytotoxic nor-β-lapachones

Several studies have demonstrated the cytotoxic potential of nor-β-lapachone derivative against cancer cells. Considering nor-β-lapachone as an important prototype, a set of new 3-substituted nor-β-lapachones was synthesized by a new synthetic route that involves the use of synthetic intermediate generated for coupling with several nucleophiles containing the carbohydrate and 2H-pyrazole substituent moieties. All the compounds were screened against four tumor cell lines. Two of the compounds showed moderate cytotoxicity, while the other compounds strongly inhibit all tested cancer cell lines.

The Resin from Protium heptaphyllum Prevents High-Fat Diet-Induced Obesity in Mice: Scientific Evidence and Potential Mechanisms.

Herbal compounds rich in triterpenes are well known to regulate glucose and lipid metabolism and to have beneficial effects on metabolic disorders. The present study investigated the antiobesity properties of resin from Protium heptaphyllum (RPH) and the possible mechanisms in mice fed a high-fat diet (HFD) for 15 weeks. Mice treated with RPH showed decreases in body weight, net energy intake, abdominal fat accumulation, plasma glucose, amylase, lipase, triglycerides, and total cholesterol relative to their respective controls, which were RPH unfed. Additionally, RPH treatment, while significantly elevating the plasma level of ghrelin hormone, decreased the levels of insulin, leptin, and resistin. Besides, HFD-induced increases in plasma levels of proinflammatory mediators TNF-α, IL-6, and MCP-1 were significantly lowered by RPH. Furthermore, in vitro studies revealed that RPH could significantly inhibit the lipid accumulation in 3T3-L1 adipocytes (measured by Oil-Red O staining) at concentrations up to 50 μg/mL. These findings suggest that the antiobese potential of RPH is largely due to its modulatory effects on various hormonal and enzymatic secretions related to fat and carbohydrate metabolism and to the regulation of obesity-associated inflammation.

Trachylobane and kaurane diterpenes from Croton floribundus spreng

A new trachylobane diterpene ent-trachyloban-18,19-diol (1) was isolated from root bark of Croton floribundus, along with known diterpenes ent-trachyloban-19-oic acid (2), 15b-hydroxy-ent-trachyloban-19-oic acid (3), ent-trachyloban-19-ol (4), ent-kaur-16-en-19-oic acid (5), ent-kaur-16-ene-6a,19-diol (6) and ent-16a-hydroxykaur-11-en-19-oic acid (7). ent-trachyloban-18,19-diol (1) was submitted to derivatization reactions affording four new compounds (8-11). Cytotoxic activity of diterpenes 1, 3, 4, 7-11 against three human cancer cell lines was evaluated. No compounds showed cytotoxic potential with IC50 values greater than 25 mg/mL. Compound 6 was evaluated against five human cancer cell lines, showing moderate effect against three cancer cell lines, MDA-MB-435, HCT-8 and HCT-116, with IC50 values of 14.32, 13.47 and 12.1 mg/mL, respectively.

Antifungal ether diglycosides from Matayba guianensis Aublet

Since the 1960s, fungal infections have become a major worldwide public health problem. Antifungal treatments have many limitations, such as toxicity and resistance. Matayba guianensis Aublet (Sapindaceae) was chemically investigated as part of our ongoing search for lead molecules against fungi in the Brazilian Cerrado biome. The ethanolic extract of M. guianensis root bark revealed the presence of two previously unreported ether diglycosides: matayoside E (1) and F (2) with anti Candida activity, along with two known compounds: cupanioside (3) and stigmasterol (4).

Spirostanol glucosides from the leaves of Cestrum laevigatum L.

Two new steroidal saponins, (25R)-spirost-5-ene-3β,26β-diol 3-O-α-L-rhamnopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 4)-[(1 → 2)-α-L-rhamnopyranosyl]-β-D-glucopyranoside (1) and (25R)-spirost-6-ene-3β,5β-diol 3-O-α-L-rhamnopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 4)-[(1 → 2)-α-L-rhamnopyranosyl]-β-D-glucopyranoside (2), along with the known diosgenin 3-O-α-L-rhamnopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 4)-β-D-glucopyranoside (3), chonglouoside SL-5 (4) and Paris saponin Pb (5) were isolated from the leaves of Cestrum laevigatum. The structures of the compounds were determined using spectroscopic analyses including HRESI-MS, 1D and 2D NMR data, followed by comparison with data from the literature. Among them, two are particularly unique, compound 1 is the first (6)Δ-spirostanol saponin and compound 2 has an unusual C-26 hydroxyl in the (5)Δ-spirostanol skeleton. Antifungal testing showed a potent activity to formosanin C against Candida albicans and Candida parapsilosis. Evaluation of the cytotoxic activity indicated that compound 1 has a moderate activity against HL-60 and SF-295 cell lines, while compound 2 were active only against HL-60.

New Terpenoids from Croton limae (Euphorbiaceae)

An asymmetrical dimer of kaurane diterpene and monoterpene and four novel diterpenes were isolated from the roots of Croton limae, along with kaempferol-3-O-glucoside, ombuin- 3-O-rutinoside and acetyl aleuritolic acid. The cytotoxic activity of the kaurane diterpene was evaluated against colorectal adenocarcinoma (HCT-116), ovarian carcinoma (OVCAR-8) and glioma (SF-295) cell lines, exhibiting IC50 values of 7.14, 8.19 and > 10 µg mL−1, respectively.