en Other Other Original Article Original Article <div style="text-align: justify;">Hypericum orientale L. that is growing in high altitudes is used traditionally for hemorrhoids in Turkish folk medicine. In the present study, models were developed to estimate the altitudinal variation in secondary metabolite contents of Hypericum orientale growing wild in &ldquo;G&uuml;ldağı&rdquo; mountain, Turkey. Aerial parts of 30 flowering individuals were collected at six different altitudes (500, 1150, 1650, 2100, 2720 and 3250 m). Actual secondary metabolite contents of plants were measured by high performance liquid chromatography method. Multiple regression analysis was performed for each altitude and chemical separately to develop multiple regression models. The R2 coefficient values between the predicted and observed contents of secondary metabolites were determined as 0.89 for hyperoside and neochlorogenic acid, 0.94 for rutin, 0.95 for avicularin, 0.97 for quercetin, 0.98 for hypericin, pseudohypericin, cholorogenic acid, and 0.99 for hyperforin, 2,4-dihydroxybenzoic acid, amentoflavone, isoquercitrin, quercitrin. catechin, and epicatechin. All R&sup2; values and standard errors were found to be significant at the P < 0.001 level and a very close relationship was found between the actual and estimated values of secondary metabolites, tested. Prediction of secondary metabolite composition by using simple equations may represent a complementary important topic for phytochemical and taxonomical studies.</div> Altitude, HPLC, Hypericum orientale, modeling, secondary metabolite 199 205 http://ibbj.org/browse.php?a_code=A-10-324-1&slc_lang=en&sid=1 Dursun Kurt dursun.kurt@omu.edu.tr 10031947532846003587 10031947532846003587 Yes Ondokuz Mayis University, Bafra Vocational School, Bafra, Samsun, Turkey. Omer Caliskan ocaliskan@omu.edu.tr 10031947532846003588 10031947532846003588 No Ondokuz Mayis University, Bafra Vocational School, Bafra, Samsun, Turkey. Mehmet Serhat Odabas mserhat@omu.edu.tr 10031947532846003589 10031947532846003589 No Ondokuz Mayis University, Faculty of Agriculture, Samsun, Turkey. Jolita Radusiene jolita.r@botanika.tl 10031947532846003590 10031947532846003590 No Nature Research Centre, Institute of Botany, Zaliuju ezeru 49, Vilnius LT-08406, Lithuania. Cuneyt Cirak cuneytc@omu.edu.tr 10031947532846003591 10031947532846003591 No Ondokuz Mayis University, Bafra Vocational School, Bafra, Samsun, Turkey.