Necdet Camas

Changes in the contents of main secondary metabolites in two Turkish Hypericum species during plant development.

Context: The genus Hypericum (Guttiferae) has received considerable scientific interest as a source of biologically active compounds. Objective: The study determined the morphogenetic and ontogenetic variation in the main bioactive compounds of two Hypericum species, namely, Hypericum aviculariifolium subsp. depilatum var. depilatum (Freyn and Bornm.) Robson var. depilatum and Hypericum orientale L. through HPLC analyses of whole plants as well as individual plant parts (stems, leaves, and reproductive tissues). Materials and methods: The plant materials were harvested at five phenological stages: vegetative, floral budding, full flowering, fresh fruiting, and mature fruiting; dried at room temperature, then assayed for chemical content. Results: In H. aviculariifolium, no kaempferol accumulation was observed and the highest level of hypericin, pseudohypericin, and quercitrin was reached at full flowering (0.71, 1.78, and 4.15 mg/g DW, respectively). Plants, harvested at floral budding produced the highest amount of rutin, hyperoside, and isoquercitrine (32.96, 2.42, 1.52 mg/g DW, respectively). H. orientale did not produce hypericin, pseudohypericin, or kaempferol. Rutin, hyperoside, and isoquercetine levels were the highest at floral development (1.76, 11.85, and 1.21 mg/g DW, respectively) and plants harvested at fresh fruiting produced the highest amount of quercitrine and quercetine (0.20 and 1.30 mg/g DW, respectively). Discussion: For the first time, the chemical composition of the Turkish species of Hypericum was monitored during the course of ontogenesis to determine the ontogenetic and morphogenetic changes in chemical content. Conclusions: Plant material should be harvested during flower ontogenesis for medicinal purposes in which the content of many bioactive substances tested reached their highest level.

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.

Chemical composition of Hypericum species from the Taeniocarpium and Drosanthe sections

The presence of several phytochemicals, namely naphthodianthrones hypericin and pseudohypericin, phloroglucinol derivatives hyperforin and adhyperforin, the phenolic acids as chlorogenic acid, neochlorogenic acid, caffeic acid and 2,4-dihydroxybenzoic acid, the flavonols, hyperoside, isoquercitrin, quercitrin, quercetin, avicularin, rutin, and flavanols (+)-catechin and (−)-epicatechin, as well as biflavonoid amentoflavone was investigated in seven Turkish species of Hypericum from Taeniocarpium and Drosanthe sections. Plants were harvested at flowering, dried at room temperature, dissected into different tissues and assayed for chemical contents by HPLC. All chemicals were detected at various levels depending on species and plant parts. Despite the observed quantitative variation in the chemical content of plant material, it was found that phytochemical profiles of the species from the same section were very similar. The present data could be helpful in selecting the future targets for phytochemical and biological studies as well as enriching our current chemical knowledge about Hypericum species. Such kind of data could also be useful for elucidation of the chemotaxonomical relationships among the sections of Hypericum genus.

Models of estimation of the content of secondary metabolites in some Hypericum species.

In the present study, models for estimation of the content of main secondary metabolites, namely hypericin, pseudohypericin, and hyperforin, were developed for Hypericum origanifolium Willd. (Guttiferae), Hypericum perfoliatum L., and Hypericum montbretii Spach., growing in Northern Turkey. Wild growing plants were harvested at vegetative, floral budding, full flowering, fresh fruiting, and mature fruiting stages and dissected into stem, leaf, and reproductive tissues. Actual secondary metabolite contents of plant materials were measured by a high performance liquid chromatography method. Multiple regression analysis using the Excel 2003 computer package was performed for each species and chemical separately to develop multiple regression models. The equation produced for predicting the content of secondary metabolites in different tissues of the species was formulized as: SMC = [a + (b1 × S) + (b2 × L) + (b3 × RP) + (b4 × S²) + (b5 × (1/RP))], where SMC is the secondary metabolite content of the whole plant, S is the secondary metabolite content of the stem, L is the secondary metabolite content of the leaf, RP is the secondary metabolite content of the reproductive parts, and a, b1, b2, b3, b4, and b5 are coefficients. The R2 coefficient values between predicted and observed contents of secondary metabolites were determined as 0.99 for H. origanifolium, 0.95–0.98 for H. perfoliatum, and 0.90–0.99 for H. montbretii. All R² values and standard errors were found to be significant at the p < 0.05 level.

Changes in the content of bioactive substances among Hypericum montbretii populations from Turkey

In the present study, we investigated the variation in the content of seventeen secondary metabolites among Hypericum montbretii Spach., Hypericaceae, populations from five different growing zones in Turkey for the first time.The plants were collected at full flowering, and after they were dried at room temperature, they were assayed for chemical contents by HPLC. Chemical constituents of plants varied significantly among populations except for 2,4-dihydroxybenzoic acid which was accumulated at similar levels. Plants from population - 1 yielded the highest amount of hypericin and pseudohypericin (1.27 and 2.97 mg/g, respectively) while hyperforin and adhyperforin accumulations were the highest in plants from population - 2 (6.64 and 1.24 mg/g, respectively). (+)-Catechin and (-)-epicatechin were accumulated at significantly higher levels by plants of population - 4 (1.54 and 4.35 mg/g, respectively). The highest accumulation level of the rest compounds namely, chlorogenic and neochlorogenic acids, amentoflavone, hyperoside, isoquercitrin, quercitrin, quercetin, avicularin and rutin was reached in plants from population-5 (2.64, 4.37, 2.35, 10.26, 3.52, 4.37, 1.55, 1.56 and 20.54 mg/g, respectively). The pronounced chemical diversity between populations is discussed to possibly be the result of different environmental, morphological and genetic factors.

Secondary Metabolites of Hypericum leptophyllum Hochst., an Endemic Turkish Species

In the present study, the presence of the phloroglucinol derivative hyperforin, the naphthodianthrones hypericin and pseudohypericin, the phenylpropane chlorogenic acid and the flavonoids rutin, hyperoside, kaempferol, isoquercetine, quercitrine, and quercetine was investigated in Hypericum leptophyllum Hochst., an endemic Turkish species for the first time. The aerial parts representing a total of 30 individuals were collected at full flowering and dissected into floral, leaf, and stem tissues. After being dried at room temperature, the plant materials were assayed for secondary metabolite concentrations by HPLC. Aerial plant parts accumulated chlorogenic acid, hyperoside, isoquercetine, quercitrine, and quercetine, but they did not accumulate hyperforin, hypericin, pseudohypericin, rutin, and kaempferol. Accumulation levels of the detected compounds varied with plant tissues. Such kind of data could be useful for elucidation of the chemotaxonomical significance of the corresponding compounds and phytochemical evaluation of this endemic species.

Secondary metabolites in Hypericum species and their distribution in different plant parts@@@Jonažolių rūšių antriniai metabolitai ir jų pasiskirstymas augalų dalyse

The genus Hypericum (Hypericaceae) has attracted remarkable scientific interest as its members accumulate significant amounts of various bioactive compounds. In the current study, we investigated accumulation of several bioactive compounds in various parts of Hypericum hircinum L. subsp. majus (Ainton) N. Robson, H. pallens Banks et Sol., H. russeggeri (Fenzl) R. Keller and H. lanuginosum Lam. The plant materials were harvested at flowering, dissected into different tissues and subsequently subjected to high performance liquid chromatography (HPLC) analyses. Accumulation level of the investigated compounds varied greatly depending on species and plant parts. Among different plant tissues, flowers were found to be superior to leaves with respect to accumulation of the chemicals tested except for neochlorogenic, caffeic and 2,4-dihydroxybenzoic acids which were accumulated mainly in leaves. H. hircinum did not produce quercitrin or avicularin, H. lanuginosum did not accumulate hyperforins and caffeic acid, rutin was detected only in H. pallens. For the first time, chemical profiles of these Turkish species of Hypericum were reported and the results are discussed from a phytochemical point of view. The present data could be helpful in selecting the future targets for phytochemical and biological studies on Hypericum genus as well as enriching our current knowledge about Hypericum chemistry.