Omer Caliskan

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.

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.

Effect of Salt Stress and Irrigation Water on Growth and Development of Sweet Basil (Ocimum basilicum L.)

Abstract This study was conducted to assess the influence of different salinity and irrigation water treatments on the growth and development of sweet basil (Ocimum basilicum L.). Five salinity levels (0.4, 1.00, 2.50, 4.00 and 8.00 dSm-1) and three different irrigation water regimes (80, 100, 120% of full irrigation) were applied in a factorial design with three replications. Dry root weight, aerial part dry weight and aerial part/root ratio were determined and evaluated as experimental parameters at the end of growing period. Results revealed significant decreases in yields with increasing salinity levels. However, basil managed to survive high salt stress. With increasing salinity levels, decreases in growth were higher in roots than in leaves. Changes in the amount of irrigation water also significantly affected the evaluated parameters.

DETERMINA TION OF REFLECTANCE VALUES OF HYPERICUM'S LEAVES UNDER STRESS CONDITIONS USING ADAPTIVE NETWORK BASED FUZZY INFERENCE SYSTEM

The effects of water stress and salt levels on hypericums leaves were examined on greenhouse-grown plants of Hypericum perforatum L. by spectral reflectance. Salt levels and irrigation levels were applied 0, 1, 2.5 and 4 deci Siemens per meter (dS/m), 80%, 100% and 120% respectively. Adaptive Network based Fuzzy Inference System (ANFIS) was performed to estimate the effects of water stress and salt levels on spectral reflectance. As a result of ANFIS, it was found that there was close relationship between actual and predicted reflectance values in Hypericum perforatum L. leaves. Performance of ANFIS was examined under different numbers of epoch and rules. On the other hand, RMSE, correlation and analysis time values were found as outputs. Correlation was 99%. The estimation of optimal ANFIS model was determined in 3*3*3 number of rules with 400 epochs.

Comparision of some models for estimation of reflectance of hypericum leaves under stress conditions

Lack of water resources and high water salinity levels are among the most important growth-restricting factors for plants species of the world. This research investigates the effect of irrigation levels and salinity on reflectance of Saint John’s wort leaves (Hypericum perforatum L.) under stress conditions (water and salt stress) by multiple linear regression (MLR), artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS). Empirical and heuristics modeling methods were employed in this study to relate stress conditions to leaf reflectance. It was found that the constructed ANN model exhibited a high performance than multiple regression and ANFIS in estimating leaf reflectance accurately.