Radiolytic transformation of rotenone with potential anti-adipogenic activity

A computational study to probe the binding aspects of potent polyphenolic inhibitors of pancreatic lipase

Pancreatic lipase (PL) is a keen target for anti-obesity therapy that reduces dietary fat absorption. Here, we investigated the binding patterns of 220 PL inhibitors having experimental IC50 values, using molecular docking and binding energy calculations. Screening of these compounds illustrated most of them bound at the catalytic site (S1-S2 channel) and a few compounds are at the non-catalytic site (S2-S3 channel/S1-S3 channel) of PL. This binding pattern could be due to structural uniqueness or bias in conformational search. A strong correlation of pIC50 values with SP/XP docking scores, binding energies (ΔGMMGBSA) assured the binding poses are more true positives. Further, understanding of each class and subclasses of polyphenols indicated tannins preferred non-catalytic site wherein binding energies are underestimated due to huge desolvation energy. In contrast, most of the flavonoids and furan-flavonoids have good binding energies due to strong interactions with catalytic residues. While scoring functions limited the understanding of sub-classes of flavonoids. Hence, focused on 55 potent PL inhibitors of IC50 < 5 µM for better in vivo efficacy. The prediction of bioactivity, drug-likeness properties, led to 14 bioactive compounds. The low root mean square deviation (0.1-0.2 nm) of these potent flavonoids and non-flavonoid/non-polyphenols PL-inhibitor complexes during 100 ns molecular dynamics runs (MD) as well as binding energies obtained from both MD and well-tempered metadynamics, support strong binding to catalytic site. Based on the bioactivity, ADMET properties, and binding affinity data of MD and wt-metaD of potent PL-inhibitors suggests Epiafzelechin 3-O-gallate, Sanggenon C, and Sanggenofuran A shall be promising inhibitors at in vivo conditions.Communicated by Ramaswamy H. Sarma.

Inhibitory Effects of Thermolysis Transformation Products of Rotenone on Nitric Oxide Production

Rotenone, isolated from Derris, Lonchocarpus, and Tephrosia from the family Fabaceae, has been shown to have a variety of biological properties and is used in various agricultural industries as a potent biopesticide. However, recent reports have demonstrated that rotenone has the potential to cause several adverse effects such as a neurodegenerative disease. This study aimed to induce thermolysis of the biopesticide rotenone and enhance the functionality of the degraded products. Rotenone (1) was degraded after autoclaving for 12 h, and the thermolytic reactants showed enhanced anti-inflammatory capacity against nitric oxide (NO) production. The structures of the newly modified products were spectroscopically determined. The thermal reaction products included various isoflavonoid derivatives 2-6, whose structures were characterized as being produced via chemical reactions in rotenone at the C-12 positions. Among the degraded products, (-)-tubaic acid (6) exhibited significantly improved anti-inflammatory effects compared to the original rotenone. Quantitative LC-MS analysis of the major thermolysis products generated in Derris extract containing rotenone was performed using isolate 2-5 purified from autoclaved rotenone. These results suggest that the thermal transformation of rotenone can improve the functionality of anti-inflammatory agents.

A novel radiolytic rotenone derivative, rotenoisin A, displays potent anticarcinogenic activity in breast cancer cells

Chemotherapy for cancer treatment has therapeutic limitations, such as drug resistance, excessive toxic effects and undesirable adverse effects. Therefore, efforts to improve the safety and efficacy of chemotherapeutic agents are essential. Ionizing radiation can improve physiological and pharmacological properties by transforming structural modifications of the drug. In this study, in order to reduce the adverse effects of rotenone and increase anticancer activity, a new radiolytic rotenone derivative called rotenoisin A was generated through radiolytic transformation. Our findings showed that rotenoisin A inhibited the proliferation of breast cancer cells and increased the rate of apoptosis, whereas it had no inhibitory effect on primary epidermal keratinocytes compared with rotenone. Moreover, rotenoisin A-induced DNA damage by increasing reactive oxygen species (ROS) accumulation. It was also confirmed not only to alter the composition ratio of mitochondrial proteins, but also to result in structural and functional changes. The anticancer effect and molecular signalling mechanisms of rotenoisin A were consistent with those of rotenone, as previously reported. Our study suggests that radiolytic transformation of highly toxic compounds may be an alternative strategy for maintaining anticancer effects and reducing the toxicity of the parent compound.

Dexamethasone modified by gamma-irradiation as a novel anticancer drug in human non-small cell lung cancer

Dexamethasone (Dex) is widely used in the management of leukemia and lymphoma. While Dex is commonly used for hematological malignancies, the effects of Dex in solid cancer cells remain controversial. To develop a more effective anticancer drug for solid cancers, Dex was modified by ionizing radiation and the anticancer activity of ionizing-radiation-irradiated Dex (Dex-IR) was investigated in human lung cancer cells. Using the MTT assay, the proliferation of non-small cell lung cancer cells was significantly inhibited after treatment with Dex-IR compared with Dex. Furthermore, Dex-IR induced apoptotic cell death and cell cycle arrest of H1650 human lung cancer cells. The invasiveness of H1650 cells was significantly reduced and the matrix metalloproteinase activity was strongly suppressed. These results indicate that Dex-IR acts as a tumor suppressor by both inducing apoptosis and arresting the cell cycle. Although the structure of Dex-IR remains to be determined, our results suggest it may be useful as a novel anticancer agent for the treatment of solid cancers.

Degradation products of mangiferin by gamma irradiation with inhibitory effects on NO production

The xanthone glucoside mangiferin (1) was converted by γ-irradiation into three new compounds, mangiferdiol (2), mangiferinol (3), and isomangiferinol (4). The new compound 2 containing two hydroxymethyl groups instead of a ketone moiety exhibited significantly improved inhibitory activity against nitric oxide production in lipopolysaccharide-stimulated RAW264.7 cells with IC50 value 47.1 ± 1.7 μM, compared to the mother mangiferin.

Influence of plasma-activated compounds on melanogenesis and tyrosinase activity

Many organic chemists around the world synthesize medicinal compounds or extract multiple compounds from plants in order to increase the activity and quality of medicines. In this work, we synthesized new eugenol derivatives (ED) and then treated them with an N₂ feeding gas atmospheric pressure plasma jet (APPJ) to increase their utility. We studied the tyrosinase-inhibition activity (activity test) and structural changes (circular dichroism) of tyrosinase with ED and plasma activated eugenol derivatives (PAED) in a cell-free environment. Later, we used docking studies to determine the possible interaction sites of ED and PAED compounds with tyrosinase enzyme. Moreover, we studied the possible effect of ED and PAED on melanin synthesis and its mechanism in melanoma (B16F10) cells. Additionally, we investigated the structural changes that occurred in activated ED after plasma treatment using nuclear magnetic resonance (NMR). Hence, this study provides a new perspective on PAED for the field of plasma medicine.

Novel Radiolytic Rotenone Derivative, Rotenoisin B with Potent Anti-Carcinogenic Activity in Hepatic Cancer Cells

Rotenone, isolated from roots of derris plant, has been shown to possess various biological activities, which lead to attempting to develop a potent drug against several diseases. However, recent studies have demonstrated that rotenone has the potential to induce several adverse effects such as a neurodegenerative disease. Radiolytic transformation of the rotenone with gamma-irradiation created a new product, named rotenoisin B. The present work was designed to investigate the anticancer activity of rotenoisin B with low toxicity and its molecular mechanism in hepatic cancer cells compared to a parent compound, rotenone. Our results showed rotenoisin B inhibited hepatic cancer cells’ proliferation in a dose dependent manner and increased in apoptotic cells. Interestingly, rotenoisin B showed low toxic effects on normal cells compared to rotenone. Mitochondrial transmembrane potential has been decreased, which leads to cytochrome c release. Down regulation of anti-apoptotic Bcl-2 levels as well as the up regulation of proapoptotic Bax levels were observed. The cleaved PARP (poly ADP-ribose polymerase) level increased as well. Moreover, phosphorylation of extracellular signal regulated kinase (ERK) and p38 slightly up regulated and intracellular reactive oxygen species (ROS) increased as well as cell cycle arrest predominantly at the G₂/M phase observed. These results suggest that rotenoisin B might be a potent anticancer candidate similar to rotenone in hepatic cancer cells with low toxicity to normal cells even at high concentrations compared to rotenone.

Mirabijalone E: a novel rotenoid from Mirabilis himalaica inhibited A549 cell growth in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

The roots of Mirabilis himalaica have been used in Tibetan folk medicine for treatment of uterine cancer, nephritis edematous, renal calculus and arthrodynia. In our previous work, the ethanol extract of roots had shown potent cytotoxicity against human cancer cells. However, no information is available on the antitumor effect of Mirabilis himalaica. The aim of the present study was to investigate the active constituents guided by bioassay and evaluate the related antitumor efficacy in vitro and in vivo.

MATERIALS AND METHODS

The active subextract (ethyl acetate) was subjected to successive chemical separation using a combination of silica gel, LH-20 chromatography and semi-preparative HPLC. The structures were determined by spectroscopic analysis techniques such as nuclear magnetic resonance (NMR) and mass spectrometry. Three human cancer cell lines, A549, HepG2 and HeLa were used for in vitro cytotoxicity evaluation of all isolated compounds by MTT-assay. Then, the potent and novel compound mirabijalone E was employed to the mechanism study againstA549 cells. BrdU immunofluorescence, soft agar assay and cell cycle analysis were employed to detect the cell proliferation effects. Annexin V-FITC/PI staining assay was used for examining apoptotic effects. Expression levels of apoptosis-related proteins were determined by western blot assay. in vivo tumorigenic assay was used to evaluate the xenograft tumor growth treated with mirabijalone E.

RESULTS

One new rotenoid compound, mirabijalone E, together with eight known rotenoids was isolated from Mirabilis himalaica. Mirabijalone E, 9-O-methyl-inone B, boeravinone C and boeravinone H exhibited cytotoxicity against A 549 and HeLa cells. Further study on mirabijalone E was carried out in vitro and in vivo. Mirabijalone E inhibited A549 cells growth in a time and dose-dependent manner, which arrested cell cycle in S phase. Mechanistically, mirabijalone E treatment resulted in the increase of Bax expression level, the decrease of Bcl-2 level and the activation of caspase-3, which suggested the activation of apoptosis cascades. Consequently, the xenograft treated with mirabijalone E showed markedly suppressed tumor growth.

CONCLUSIONS

The result suggested that mirabijalone E, together with active compounds, 9-O-methyl-4-hydroxyboeravinone B, boeravinone C and boeravinone H could be a promising candidate for cancer therapy.

Effect of atmospheric pressure dielectric barrier discharge plasma on the biological activity of naringin

The biological activity of naringin treated with atmospheric pressure plasma was evaluated to investigate whether exposure to plasma can be used as a method to improve the biological activity of natural materials. Naringin was dissolved in methanol (at 500 ppm) and transferred to a container. A dielectric barrier discharge (DBD) (250 W, 15 kHz, ambient air) was then generated. Treatment with the plasma for 20 min increased the radical-scavenging activity, FRAP value, and the total phenolic compound content of naringin from 1.45% to 38.20%, from 27.78 to 207.78 μM/g, and from 172.50 to 225.83 ppm, respectively. Moreover, the tyrosinase-inhibition effect of naringin increased from 6.12% to 83.30% upon plasma treatment. Naringin treated with plasma exhibited antimicrobial activity against foodborne pathogens, especially Salmonella Typhimurium; an activity that was absent before plasma treatment. Structural modifications induced in the naringin molecule by plasma might be responsible for improving the biological activity of naringin.

Degradation of cyanidin-3-rutinoside and formation of protocatechuic acid methyl ester in methanol solution by gamma irradiation

Anthocyanins are naturally occurring phenolic compounds having broad biological activities including anti-mutagenesis and anti-carcinogenesis. We studied the effects and the degradation mechanisms of the most common type of anthocyanins, cyanidin-3-rutinoside (cya-3-rut), by using gamma ray. Cya-3-rut in methanol (1mg/ml) was exposed to gamma-rays from 1 to 10kGy. We found that the reddish colour of cya-3-rut in methanol disappeared gradually in a dose-dependent manner and effectively disappeared (>97%) at 10kGy of gamma ray. Concomitantly, a new phenolic compound was generated and identified as a protocatechuic acid methyl ester by liquid chromatography, (1)H, and (13)C NMR. The formation of protocatechuic acid methyl ester increased with increasing irradiation and the amount of protocatechuic acid methyl ester formed by decomposition of cya-3-rut (20μg) at 10kGy of gamma ray was 1.95μg. In addition, the radical-scavenging activities were not affected by gamma irradiation.