Altitudinal changes in secondary metabolite contents of Hypericum androsaemum and Hypericum polyphyllum

The genus Hypericum (Hypericaceae) has attracted scientific interest as its members have yielded many bioactive compounds. In the present study we investigated the content of hypericin, pseudohypericin, hyperforin, adhyperforin, chlorogenic acid, neochlorogenic acid, caffeic acid, 2,4-dihydroxybenzoic acid, 13,II8-biapigenin, hyperoside, isoquercitrin, quercitrin, quercetin, avicularin, rutin, (+)-catechin and (−)-epicatechin in aerial parts of plants from populations of H. androsaemum L. and H. polyphyllum Boiss. & Bal. from Turkey growing at different altitudes. The plant materials were dried and subsequently assayed for chemical content by HPLC. All the tested compounds were detected in both species at varying levels depending upon the altitude the plants were growing, except for hypercins and rutin which did not accumulate in H. androsaemum. It was observed that overall the compounds were more abundant in plants from higher altitudes. The differences in the levels of the compounds could contribute to the ability of the plants to deal with the abiotic stress of lower temperature and higher ultraviolet (UV)-B radiation which would be greater at higher altitudes compared to lower altitudes.     

Palynological investigations on some Hypericum taxa (Hypericaceae) growing naturally in Turkey

This study examined the detailed pollen morphological structures of sixteen Hypericum taxa (four endemic, twelve non endemic) including eight sections showing the natural distribution in Turkey: H. sect. Ascyreia (H. calycinum L.), H. sect. Heterophyllum (H. heterophyllum Vent.), H. Sect. Taeniocarpium (Hypericum confertum Choisy subsp. confertum, H. venustum Fenzl, H. linaroides Bosse), H. sect. Drosocarpium (H. montbretii Spach, H. bithynicum Boiss.), H. sect. Crossophyllum (H. adenotrichum Spach, H. orientale L.), H. sect. Olympia (H. olympicum L. subsp. olympicum), H. sect. Origanifolia (H. origanifolium Willd., H. avicularifolium Jaub and Spach subsp. depilatum (Freyn and Bornm.) Robson var. depilatum, H. avicularifolium Jaub. and Spach subsp. byzantinum) and H. sect. Hypericum (H. tetrapterum Fries, H. perforatum L., H. triquetrifolium Tura). These taxa were studied under light microscope and scanning electron microscope for the first time. Of the taxa studied, H. tetrapterum has the smallest pollen grains (on average 15.85–17.20 × 15.45–16.05 μm); and H. olympicum subsp. olympicum the largest grains (on average 22.90–23.10 × 21.40–22.10 μm). The pollen grains of 15 taxa are subprolate and one taxon is prolate-spheroidal. The regular pollen grains of all 16 taxa are 3-zonocolporate. Ornamentation is microreticulate; lumina regularly spaced in eight taxa, tectum perforatum; tectal perforations regularly spaced in seven taxa and tectum perforatum; and tectal perforations grouped together in one taxon. Endoaperture is cruciform porus, with short lateral and meridional extensions in ten taxa, cruciform porus, transversally elongated, with very small lateral extensions in one taxon and lalongate colpus in five taxa. Basic pollen types are ten taxa in type X, five taxa in type IV and one taxon in type II.     

Comparison of chemical composition of Hypericum perforatum and H. maculatum in Estonia

Of numerous species belonging to the medicinally important genus Hypericum, only H. perforatum L. and H. maculatum Crantz grow widely in Estonia. A comparative biochemical systematics study of hypericins, hyperforins and other phenolics within Hypericum spp. growing in Estonia was performed. For comprehensive metabolomic investigation, 42 samples of H. perforatum and 16 samples of aerial parts of H. maculatum were collected in two consecutive years from various locations; methanolic extracts were prepared from airdried leaves and flowers. The concentrations of a quinic acid derivative, caffeic acid glucoside, vanillic acid glucoside, neochlorogenic acid, chlorogenic acid, catechin, epicatechin, myricetin glucoside, hyperoside, isoquercitrin, rutin, quercetin pentoside, quercitrin, kaempferol glucoside, kaempferol rutinoside, quercetin, hyperforin, adhyperforin, protopseudohypericin, pseudohypericin, and hypericin were determined by LC-DAD-MS/MS. All the aforementioned compounds were detected in both species, although some at very different levels – H. maculatum contained rutin and hyperforins only in trace amounts and overall tended to contain more phenolic compounds. The level of total hypericins was the same for both species. These results constitute a further contribution to the systematic knowledge about the Hypericum spp. Results of principal component analysis (PCA) demonstrated distinct between-years and between-species diversity in the chemical composition of the plants studied. Between-years diversity in Hypericum spp. has not been addressed before.     

Secondary metabolites of Hypericum orientale L. growing in Turkey: variation among populations and plant parts

The present study was conducted to determine the variation in the content of several plant chemicals, namely hyperforin, hypericin, pseudohypericin, chlorogenic acid, rutin, hyperoside, isoquercetine, kaempferol, quercitrine and quercetine among ten Hypericum orientale L. populations from Northern Turkey. The aerial parts representing a total of 30 individuals were collected at full flowering and dissected into floral, leaf and stem tissues. After dried at room temperature, the plant materials were assayed for chemical contents by HPLC. The populations varied significantly in chemical contents. Among different plant parts, the flowers were found to be the principle organ for hyperforin, hypericin, pseudohypericin and rutin accumulations while the rest of the chemicals were accumulated mainly in leaves in all growing localities. The chemical variation among the populations and plant parts is discussed as being possibly the result of different genetic, environmental and morphological factors.     

A comparative study of bioactive secondary metabolite production in diploid and tetraploid Echinacea purpurea (L.) Moench

The impact of the ploidy level on biomass accumulation and the production of high-value secondary metabolites was studied in Echinacea purpurea (L.) Moench. Tetraploid E. purpurea was obtained by treating diploid explants with colchicine. The morphology, biomass yield, the contents of caffeic acid derivatives and alkamides, and the activities of phenylalanine ammonia-lyase (PAL) and cinnamate 4-hydroxylase (C4H) were compared between diploid plants and tetraploid plants of E. purpurea. The total fresh root weight and total dry root weight of the tetraploid plants were 39.32 and 40.48 % higher than those of the diploid plants, respectively. The chemical profiles of the diploid and tetraploid E. purpurea plants were similar, as determined through a comparison of their FTIR spectra and second derivative spectra. The caffeic acid derivatives and alkamides in the diploid and tetraploid plants were determined by HPLC. The tetraploid plants had higher contents of both of these types of molecules. In addition, the tetraploid plants had higher PAL and C4H activities compared with the diploid plants. The enhancement in the PAL and C4H activities was accompanied with an increase in the cichoric acid content, which indicates that the induction of polyploidy in E. purpurea resulted in higher PAL and C4H expression and promoted the biosynthesis of cichoric acid. Therefore, the induction of polyploidy may be a valid strategy to achieve a higher yield of biomass and bioactive compounds in E. purpurea.     

Determination of phenolic compounds in flowers of Hypericum species native to South Brazil and Peruvian Páramos

The flowers constitute one of the main sites of accumulation of phenolic compounds in plants of the Hypericum genus. In addition to their important pharmacological activities, some metabolites found in species from the section Brathys and Trigynobrathys appear to have chemotaxonomic significance according to the literature. HPLC analyses were carried out to assess the pattern and accumulation of the dimeric phloroglucinols, benzophenones, benzopyrans, flavonoids and a phenolic acid in flowers of Hypericum species native to southern Brazil and Peruvian Páramos. Qualitative and quantitative differences are reported. Uliginosin B and hyperoside were the main components detected in all species and with maximum concentrations up to 0.188 % in H. caprifoliatum and 5.987 % in H. andinum, respectively. The content of japonicin A varied from 0.003 to 0.087 % in H. myrianthum, while the yield of hyperbrasilol B ranged from 0.006 % in H. laricifolium to 0.011 % in H. caprifoliatum. The major compounds in H. polyanthemum and H. carinatum were the benzopyrans 6-isobutyryl-5,7-dimethoxy-2,2-dimethyl-benzopyran (HP1 = 0.200 %), 7-hydroxy-6-isobutyryl-5-methoxy-2,2-dimethyl-benzopyran (HP2 = 0.225 %) and 5-hydroxy-6-isobutyryl-7-methoxy-2,2-dimethyl-benzopyran (HP3 = 0.327 %) and benzophenones cariphenone A (0.309 %) and cariphenone B (0.062 %), respectively. Maximum amounts of chlorogenic acid, isoquercitrin, quercitrin and guaijaverin were observed, respectively, in H. campestre (1.458 %), H. andinum (1.161 %), H. carinatum (0.231 %) and H. laricifolium (0.404 %). The results obtained support the taxonomic evidence of the dimeric phloroglucinol derivatives at the section level.     

Hypericum dubium Leers—New Data on Taxonomy and Biology

New data on the taxonomy, karyology, reproductive biology and secondary metabolites of Hypericum dubium Leers (=H. maculatum subsp. obtusiusculum (Tourlet) Hayek) are given. The neotypification of the name H. dubium by plants from the locus classicus near the town of Herborn in Germany is presented. Hypericum dubium is characterized by stems with slightly conspicuous subsidiary lines, sepals with a finely denticulate or rarely entire apex, petals with pale and black, linear to striiform laminar glands. Karyological data confirm that the taxon is tetraploid (2n?=?32). Reproduction by facultative apomixis was discovered using a flow cytometric seed screen. In the spectrum of secondary metabolites, flavonoids, naphtodianthrones and phloroglucinol derivatives were found. The previously described taxon H. carpaticum Mártonfi is reclassified here to the level of nothospecies as H. dubium × H. maculatum. For the epitheton balcanicum a new combination Hypericum ×carinthiacum nothosubsp. balcanicum (N. Robson) Mártonfi is proposed. Finally, this paper provides a revised scheme of relationships among taxa of the H. maculatum group.     

Acetic acid acts as an elicitor exerting a chitosan-like effect on xanthone biosynthesis in <Emphasis Type="Italic">Hypericum perforatum</Emphasis> L. root cultures

Key message

Acetic acid acts as a signal molecule, strongly enhancing xanthone biosynthesis in Hypericum perforatum root cultures. This activity is specific, as demonstrated by the comparison with other short-chain monocarboxylic acids.

Abstract

We have recently demonstrated that Hypericum perforatum root cultures constitutively produce xanthones at higher levels than the root of the plant and that they respond to chitosan (CHIT) elicitation with a noteworthy increase in xanthone production. In the present study, CHIT was administered to H. perforatum root cultures using three different elicitation protocols, and the increase in xanthone production was evaluated. The best results (550 % xanthone increase) were obtained by subjecting the roots to a single elicitation with 200 mg l^?1 CHIT and maintaining the elicitor in the culture medium for 7 days. To discriminate the effect of CHIT from that of the solvent, control experiments were performed by administering AcOH alone at the same concentration used for CHIT solubilization. Unexpectedly, AcOH caused an increase in xanthone production comparable to that observed in response to CHIT. Feeding experiments with ¹³C-labeled AcOH demonstrated that this compound was not incorporated into the xanthone skeleton. Other short-chain monocarboxylic acids (i.e., propionic and butyric acid) have little or no effect on the production of xanthones. These results indicate that AcOH acts as a specific signal molecule, able to greatly enhance xanthone biosynthesis in H. perforatum root cultures.

     

The hepatoprotective effects of Hypericum perforatum L. on hepatic ischemia/reperfusion injury in rats

Little is known about the effective role of Hypericum perforatum on hepatic ischemia–reperfusion (I/R) injury in rats. Hence, albino rats were subjected to 45 min of hepatic ischemia followed by 60 min of reperfusion period. Hypericum perforatum extract (HPE) at the dose of 50 mg/kg body weight (HPE₅₀) was intraperitonally injected as a single dose, 15 min prior to ischemia. Rats were sacrificed at the end of reperfusion period and then, biochemical investigations were made in serum and liver tissue. Liver tissue homogenates were used for the measurement of malondialdehyde (MDA), catalase (CAT) and glutathione peroxidase (GPx) levels. At the same time alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) were assayed in serum samples and compared statistically. While the ALT, AST, LDH activities and MDA levels were significantly increased, CAT and GPx activities significantly decreased in only I/R-induced control rats compared to normal control rats (p < 0.05). Treatment with HPE₅₀ significantly decreased the ALT, AST, LDH activities and MDA levels, and markedly increased activities of CAT and GPx in tissue homogenates compared to I/R-induced rats without treatment–control group (p < 0.05). In oxidative stress generated by hepatic ischemia–reperfusion, H. perforatum L. as an antioxidant agent contributes an alteration in the delicate balance between the scavenging capacity of antioxidant defence systems and free radicals in favour of the antioxidant defence systems in the body.