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SDpre is the standard deviation of prediction set data, Cip is the reference value of prediction set, and C?ip is the average value of prediction set. LS-SVM algorithms carried out by LS-SVM lab Toolbox 1.8 (Department of Electrical Engineering, Leuven-Heverlee, Belgium) [28] was also used to set up quantitative models. In order to obtain the LS-SVM model, two extra hyperparameters, gam and sig2, need to be tuned by leave-one-out cross validation. Gam is the regularization parameter, determining the tradeoff between http://www.selleckchem.com/products/r428.html the training error minimization and smoothness of the estimated function. Sig2 is the Gaussian RBF kernel function parameter. The performance of the LS-SVM model was evaluated in terms of chemometric indicators the same as PLS regression. 4. Results and Discussion 4.1. HPLC Determination of Cryptotanshinone and Tanshinone IIA For quantitative consideration, the calibration curves of cryptotanshinone and tanshinone IIA were established upon eleven consecutive injections of different concentrations. The concentration range is from 0.73 to 102.48?��g��mL?1 for cryptotanshinone and from 0.83 to 182.56?��g��mL?1 for tanshinone IIA. Regression equation calibrated for cryptotanshinone was y = 46.95x + 2.506 (R2 = 0.9999, n = 11) and y = 44.74x + 19.93 (R2 = 0.9999, n = 11) for tanshinone IIA. Seen in Table 3, it is obvious that contents of cryptotanshinone JQ1 in vitro and tanshinone IIA varied considerably among different samples. And large quality fluctuations could be observed among the commercial tanshinone extracts produced under the same specifications according to the Ch.P. 2010 [24]. For example, contents of cryptotanshinone in commercial extract powders varied from 2.8 to 88?mg��g?1, with the mean value of 12?mg��g?1 and the standard deviation of 28?mg��g?1. E-64 And, for tanshinone IIA in commercial extract powders, the contents were from 0.85 to 1.4 �� 102?mg��g?1 with the average value and standard deviation being 25 and 27?mg��g?1, respectively. The possible reasons could be attributed to different sources of Salvia miltiorrhiza, different preparation processes, and various storage conditions. Table 3 The contents of cryptotanshinone and tanshinone IIA of tanshinone extract powders. 4.2. Analysis of Physical Attributes The results of physical attributes tests are shown in Table 4. The relative standard deviations of all physical attributes were smaller than 0.5. It is clear that the variation coverage of physical properties were smaller than the contents of active pharmaceutical ingredients, whose relative standard deviations values were above than 1.0. Table 4 Results of physical attributes tests of tanshinone extract powders.