Effective attenuation of atrazine-induced histopathological changes in testicular tissue by antioxidant N-phenyl-4-aryl-polyhydroquinolines.

Some of the environmental toxicants acting as endocrine disruptors have been associated with health hazards in human and wildlife by modulating hormonal actions. Atrazine, a strong endocrine disruptor, induces detrimental effects on gonads in male and female, and causes impairment of fertility and developmental problems as well as sex alterations. Atrazine decreases the activities of antioxidant enzymes and thus responsible for oxidative stress. Natural antioxidants have shown ability to reduce/slow down the apoptotic effect of atrazine on testicular tissue. In the present study, some N-phenyl-4-aryl-polyhydroquinolines bearing phenolic or/and alkoxy group(s) (6a-6g) were synthesized and evaluated for antioxidant activity in four different assays. Three best compounds (6e-6g) were studied for their ameliorative effect on testicular tissue supplemented with atrazine in vitro.

Benzophenones and flavonoids from Hypericum maculatum and their antioxidant activities.

The occurrence of three known benzophenones, namely annulatophenonoside, acetylannulatophenonoside and annulatophenone as well as a flavonol O-glycoside guajaverin in the aerial parts of Hypericum maculatum Crantz was established. In addition, hyperoside, isoquercitrin and miquelianin were isolated from this plant, as well. Radical scavenging and antioxidant activities of the isolated compounds were examined using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) free radicals, ferric reducing antioxidant power (FRAP) assay and inhibition of lipid peroxidation in linoleic acid system by the ferric thiocyanate method. Isoquercitrin demonstrates the highest DPPH radical scavenging (96.6 ± 0.3%), FRAP (23.8 ± 0.2 Trolox equivalent, TE mol⁻¹) and antioxidant activity in linoleic acid system. Guajaverin and acetylannulatophenonoside show significantly strong ABTS radical scavenging activity (93.9 ± 0.4% and 93.4 ± 0.6%, respectively), which is comparable to that of ascorbic acid (96.2 ± 0.4%).

Elegaphenone and 7-epi-clusianone, the major cytotoxic constituents of Hypericum elegans.

Two cytotoxic constituents, namely elegaphenone and 7-epi-clusianone, were isolated from the aerial parts of Hypericum elegans Stepan ex Willd. Elegaphenone was identified as (E)-(2-(3,7-dimethylocta-2,6-dienyloxy)-4,6-dihydroxyphenyl)(phenyl)methanone by means of spectral evidence. Both compounds showed prominent cytotoxicity on HD-MY-Z, K-562 and KE-37 tumour cell lines. The IC(50) values for elegaphenone were 15.9 (HD-MY-Z), 13.9 (K-562) and 16.9 (KE-37) µmol while those of 7-epi-clusianone were 9.8 (HD-MY-Z), 11.8 (K-562) and 13.6 (KE-37) µmol. The established oligonucleosomal deoxyribonucleic acid (DNA) fragmentation of genomic DNA following short-term (6 h) or long-term (24 h) exposure to the tested compounds clearly indicates that the induction of apoptotic cell death is an important component for their cytotoxic mode of action.

Radical scavenging and antioxidant activities of methanolic extracts from Hypericum species growing in Bulgaria.

Thirteen Hypericum species growing in Bulgaria were investigated for free radical-scavenging activity, antioxidant activity, total tannins and total flavonoids contents. Methanolic extracts from the Hypericum species were analyzed for radical scavenging and antioxidant activities using DPPH-, ABTS- free radicals, total antioxidant activity and inhibition of lipid peroxidation by ferric thiocyanate (FTC) method. Butylated hydroxytoluene and ascorbic acid were used as positive controls. Methanolic extracts from H. cerastoides, H. perforatum and H. maculatum demonstrate the highest antioxidant activities and are potential sources of natural antioxidant compounds. The quantification of tannins and flavanoids were determined in Hypericum species using Folin-Chiocalteu reagent and AlCl3, respectively. The amounts of the tannins ranged from 1.30 +/- 0.01 mg/100 g dw in H. elegans to 8.67 +/- 0.02 g/100 g dw in H. perforatum. The highest concentration of flavonoids was found in H. cerastoides (1.22 +/- 0.02 g/100g dw), and the lowest amount was established in H. olympicum (0.20 +/- 0.03 g/100g dw).

Benzophenone O-glycosides from Hypericum elegans.

Elegaphenonoside, a new benzophenone O-rhamnoside, together with two known benzophenone O-glycosides, namely hypericophenonoside and neoannulatophenonoside, were isolated from the aerial parts of Hypericum elegans Stephan ex Willd. The structure of the new compound was established as 3',5',6-trihydroxy-4-methoxybenzophenone-2-O-alpha-L-rhamnopyranoside by means of chemical and physical evidence. In addition, the presence of kaempferol, quercetin, isoquercitrin, norathyriol, I-3,II-8-biapigenin, quercitrin, hyperoside and rutin were established in this plant.

A new isocoumarin from Hypericum annulatum.

A new isocoumarin, annulatomarin (1), together with the known physcion and beta-sitosterol were isolated from the aerial parts of Hypericum annulatum. The structure of the new compound was established as 6,8-dihydroxy-7-methoxy-3-phenyl-3,4-dihydro-1H-isochromen-1-one on the basis of detailed spectroscopic analysis. Annulatomarin exhibited a modest growth-inhibitory activity in vitro against human chronic myeloid leukaemia LAMA-84 cells with an IC(50) = 111 microM.

Cytoprotective effects of 5 benzophenones and a xanthone from Hypericum annulatum in models of epirubicin-induced cytotoxicity: SAR-analysis and mechanistic investigations.

A new benzophenone O-glucoside neoannulatophenonoside (1) together with the known pinocembrin-7-O-glucoside were isolated from the aerial parts of Hyperium annulatum Moris (Guttiferae). The former was identified as 3',5',6-trihydroxy-4-methoxybenzophenone-2-O-beta-D-glucopyranoside by means of chemical and physical evidence. The cytoprotective effects of the new compound together with the previously isolated from this species hypericophenonoside (2), annulatophenone (3), annulatophenonoside (4), acetylannulatophenonoside (5) and 1,3,7-trihydroxyxanthone (6) were evaluated in a model of epirubicin-induced cellular toxicity in K-562 cells. While the benzophenone O-glycosides 1, 2, 4 and 5 exerted substantial cytoprotective effects against the epirubicin cytotoxicity in K-562 cells the aglycones 3 and 6 lacked any significant cytoprotective activity. Biochemical investigations aimed at evaluating the free-radical scavenging activity of the tested compounds as well as their effects on the cellular glutathione stores were carried out as well, aiming at unravelling the mechanisms of cytoprotection. Finally, the ability of 1, 4 and 5 to ameliorate epirubicin-induced anticlonogenic effects on bone marrow cells colony forming units, in vitro were also evaluated. Taken together, the experimental data indicate that the benzophenone glycosides isolated from H. annulatum have a substantial cytoprotective potential against the toxic effects induced by epirubicin and necessitates further detailed pharmacological evaluation of these compounds as possible chemoprotective/radioprotective agents.

Effect of benzophenones from Hypericum annulatum on carbon tetrachloride-induced toxicity in freshly isolated rat hepatocytes.

Five benzophenones and a xanthone, isolated from Hypericum annulatum Moris, were investigated for their protective effect against carbon tetrachloride toxicity in isolated rat hepatocytes. The benzophenones and the xanthone gentisein were administered alone (100 microM) and in combination with CCl4 (86 microM). CCl4 undergoes dehalogenation in the liver endoplasmic reticulum. This process leads to trichlormethyl radical (*CCl3) formation, initiation of lipid peroxidation, and measurable toxic effects on the hepatocytes. The levels of thiobarbituric acid reactive substances (TBARS) were assayed as an index of lipid peroxidation (LPO). Lactate dehydrogenase (LDH) leakage, cell viability and reduced glutathione (GSH) depletion were used as signs of cytotoxicity. CCl4 significantly decreased hepatocyte viability, GSH level and increased TBARS level and LDH leakage as compared to the control. Our data indicate that 2,3',5',6-tetrahydroxy-4-methoxybenzophenone, 2-O-alpha-L-arabinofuranosyl-3',5',6-trihydroxy-4-methoxybenzophenone and 2-O-alpha-L-3'-acetylarabinofuranosyl-3',5',6-trihydroxy-4-methoxybenzophenone showed weaker toxic effects compared to CCl4 and in combination showed statistically significant protection against the toxic agent.

Two benzophenone O-arabinosides and a chromone from Hypericum annulatum.

Two benzophenone O-arabinosides, annulatophenonoside (1) and acetylannulatophenonoside (2) were isolated from the methanol extract of the herb of Hypericum annulatum. The structures of the benzophenones were established as 2-O-alpha-L-arabinofuranosyl-3',5',6-trihydroxy-4-methoxybenzophenone (1) and 2-O-alpha-L-3"-acetylarabinofuranosyl-3',5',6-trihydroxy-4-methoxybenzophenone (2) based on spectral and chemical evidence. A chromone, 5,7-dihydroxy-3-methylchromone (3) was isolated from the chloroform extract. Although it has been previously synthesized it is encountered in a plant source for the first time. Co-occurrence of the two new benzophenone O-arabinosides along with the biogenetically related 1,5,7-trihydroxy-3-methoxyxanthone was not found.