Inhibition of mitochondrial electron-transport systems by nor-isoguaiacin

Biochemical parameters, oxidative stress biomarkers, and anatomopathological changes in Wistar rats treated with 3'-demethoxy-6-O-demethylisoguaiacin and norisoguaiacin

Artemisia cina (Ac) is a plant with anthelmintic compounds such as 3'-demethoxy-6-O-demethylisoguaiacin (D) and norisoguaiacin (N). Three major objectives were proposed: (1) To evaluate biochemical parameters in blood (2) to determine the tissue oxidative stress by biomarkers as TBARS and glutathione peroxidase activity, and (3) to evaluate anatomopathological changes in organs such as the brain, liver, kidney, and lung after oral administration of n-hexane extract of Ac and D and N. D and N were administrated following the OECD guides for acute oral toxicity evaluation (Guide 420). Fifty Wistar rats were distributed into ten groups as follows: Group 1 (G1): 4 mg/Kg; G2: 40 mg/Kg; G3: 240 mg/Kg; G4: 1600 mg/Kg of n-hexane extract of Ac. G5: 2 mg/Kg; G6: 20 mg/Kg; G7: 120 mg/Kg; G8: 800 mg/Kg of D and N, G9: water and G10: polyvinylpyrrolidone at 2000 mg/Kg. At 14 days, the rats were euthanized, and the blood, liver, brain, kidney, and lung were taken for biochemical analysis, anatomopathological changes, and TBARS and GSH evaluation. Glucose, cholesterol, and phosphorus were altered. Histopathological analysis showed multifocal neuronal degeneration in the brain (G2). The kidney and lungs had changes in G7. The GSH and TBARS increased in G6 and G7. The TBARS activity was higher in G1 and G2. In conclusion, extract and D and N of Ac did not have damage at therapeutic doses. D, N, and n-hexane extract of A. cina do not cause histopathological damage at pharmaceutical doses. Still, the brain, kidney, and liver are related to biochemical parameters at higher doses. However, compounds are proposed as antioxidant agents.

3'-Demethoxy-6-O-Demethylisoguaiacin and Norisoguaiacin Nematocidal Lignans from Artemisia cina against Haemonchus contortus Infective Larvae

Artemisia cina is a plant used in traditional Chinese medicine as a remedy for parasitic diseases. This study describes the isolation and chemical characterization of anthelmintic compounds of A. cina against Haemonchus contortus infective larvae (L₃) through lethal testing. Previously, three extracts-n-hexane (HexAc), ethyl acetate (EtOAc) and methanol (MeOAc)-were evaluated at concentrations of 4 to 0.5 mg/mL, resulting in the HexAc extract with the greatest effect of 76.6% mortality of the larvae at 4 mg/mL. Then, this was chemically fractioned by polarity, obtaining seven fractions (C1F1-C1F7), and, when evaluated at concentrations from 2 to 0.25 mg/mL, the 2 mg/mL C1F5 fraction produced an effect against the nematode H. contortus of 100% mortality of the larvae. Thus, this fraction was fractionated again by column chromatography, obtaining twelve subfractions (C2F1-C2F12) which were evaluated from 1 to 0.125 mg/mL, with the C2F5 subfraction causing a nematicidal effect of 100% mortality. NMR analysis of one (¹H, ¹³C and DEPT) and two dimensions (COSY, HSQC and HMBC) and mass spectrometry of this fraction allowed us to identify the mixture of 3'-demethoxy-6-O-demethylisoguaiacin and norisoguaiacin. Therefore, it can be assumed that the mixture of these compounds is responsible for the anthelmintic effect. These results indicate that A. cina containing anthelmintic compounds and might be used as an antiparasitic drug against H. contortus.

Tetra-O-Methyl Nordihydroguaiaretic Acid Broadly Suppresses Cancer Metabolism and Synergistically Induces Strong Anticancer Activity in Combination with Etoposide, Rapamycin and UCN-01

The ability of Tetra-O-methyl nordihydroguaiaretic acid (M₄N) to induce rapid cell death in combination with Etoposide, Rapamycin, or UCN-01 was examined in LNCaP cells, both in cell culture and animal experiments. Mice treated with M₄N drug combinations with either Etoposide or Rapamycin showed no evidence of tumor and had a 100% survival rate 100 days after tumor implantation. By comparison all other vehicles or single drug treated mice failed to survive longer than 30 days after implantation. This synergistic improvement of anticancer effect was also confirmed in more than 20 cancer cell lines. In LNCaP cells, M₄N was found to reduce cellular ATP content, and suppress NDUFS1 expression while inducing hyperpolarization of mitochondrial membrane potential. M₄N-treated cells lacked autophagy with reduced expression of BNIP3 and ATG5. To understand the mechanisms of this anticancer activity of M₄N, the effect of this drug on three cancer cell lines (LNCaP, AsPC-1, and L428 cells) was further examined via transcriptome and metabolomics analyses. Metabolomic results showed that there were reductions of 26 metabolites essential for energy generation and/or production of cellular components in common with these three cell lines following 8 hours of M₄N treatment. Deep RNA sequencing analysis demonstrated that there were sixteen genes whose expressions were found to be modulated following 6 hours of M₄N treatment similarly in these three cell lines. Six out of these 16 genes were functionally related to the 26 metabolites described above. One of these up-regulated genes encodes for CHAC1, a key enzyme affecting the stress pathways through its degradation of glutathione. In fact M₄N was found to suppress glutathione content and induce reactive oxygen species production. The data overall indicate that M₄N has profound specific negative impacts on a wide range of cancer metabolisms supporting the use of M₄N combination for cancer treatments.

Inhibition of tumoral cell respiration and growth by nordihydroguaiaretic acid

The effects of nordihydroguaiaretic acid (NDGA), best known as an inhibitor of lipoxygenase activities, on the culture growth, oxygen consumption, ATP level, viability, and redox state of some electron carriers of intact TA3 and 786A ascites tumor cells have been studied. NDGA inhibited the respiration rate of these two tumor cell lines by preventing electron flow through the respiratory chain. Consequently, ATP levels, cell viability and culture growth rates were decreased. NDGA did not noticeably inhibit electron flow through both cytochrome oxidase and ubiquinone-cytochrome b-c1 complex. Also, the presence of NDGA changed to redox state of NAD(P)+ to a more reduced level, and the redox states of ubiquinone, cytochrome b and cytochromes c + c1 changed to a more oxidized level. These observations suggest that the electron transport in the tumor mitochondria was inhibited by NDGA at the NADH-dehydrogenase-ubiquinone level (energy-conserving site 1). As a consequence, mitochondrial ATP synthesis would be interrupted. This event could be related to the cytotoxic effect of NDGA.

Toxicology of various pesticides and their decomposition products on mitochondrial electron transport

The effect of various pesticides and derivatives on mitochondrial electron transport systems was assessed. DDT, DDE, TDE, Kelthane, chlorobenzilate, chloropropylate and Acarol were found to be inhibitory towards both heavy beef heart mitochondrial (HBHM) NADH-oxidase and succinoxidase enzyme systems. Dichlorobenzophenone and p-chlorophenol were less inhibitory towards the HBHM NADH-oxidase and did not inhibit the succinoxidase enzyme system. DDA did not inhibit either of the electron transport systems. Carbaryl was not inhibitory towards both HBHM oxidase systems, whereas its degradative product dihydroxynaphthalene was inhibitory at the same concentration. Furadan, Matacil, Baygon and Dimetilan were only slightly inhibitory towards themitochondrial NADH-oxidase system and did not inhibit the succinoxidase system. Zectran was inhibitory towards the NADH-oxidase system and was not inhibitory towards the succinoxidase system. DDT, DDE and TDE, dihydroxynaphthalene and 1-naphthol inhibited the NADH-oxidase enzyme system onthe substrate side of cytochrome c, whereas Kelthane inhibited on the oxygen side.