1. Introduction
Adulteration of authentic natural ingredients is a serious problem. The plant active ingredients are
mostly complex mixtures rather than single ingredients, it is hard to standardize and affected by changes in the natural environment. Recently, various analytical methods developed to identify plant extracts based on chromatography, spectroscopy and even DNA technology. Saw Palmetto (Serenoa repens) is a common herbal supplement widely used for the treatment of urinary system problems related to benign prostatic hyperplasia (BPH). Saw Palmetto berry is endemic to the subtropical wild growing in swampy areas of southeastern United States, unfavorable climatic conditions and difficulty of artificial picking lead to high harvesting cost. Therefore, Saw Palmetto oil is an expensive natural ingredient and the cheaper edible oils (palm oil, pumpkin seed oil, olive oil and etc.) are often used to be replaced or diluted in the market. The USP identifies Saw Palmetto oil by evaluating fatty acids composition and concentration of specific fatty acids relative to lauric acid. With continuous development of nuclear magnetic technology especially the 1H NMR spectrum which has the advantages of damage less to the sample, fast speed, high sensitivity and ability to measure a wide range of sample information in one 1H NMR spectrum. Thus, NMR is very effective in identifying complex natural products and determine the authenticity and origin.
We found a convenient, fast and effective method to identify the Saw Palmetto oil by establishing the 1H NMR spectrum database of various plant oils and combining with multivariate statistical.
2. Experiment
2.1 Sample Collection
Saw Palmetto oil and 7 kinds of edible oils on sale, three samples for each, total 24 samples were used to establish the 1HNMR spectrum database.
2.2 NMR Data Processing: Bruker TopSpin3.5
2.3 Data Analysis
Data processing was performed on SPSS 18.0 software, establish 12 variables before input normalized 1H NMR data and then use 6 discriminant functions for discriminant analysis.
3.Results and Discussion
3.1 Principal Component and 1H NMR Spectrogram Analysis of Plant Oil
We listed structural formulas of the mainly free fatty acids and their glycerides, then, calculated chemical shift of H in each structural formula combining with the empirical formula and put the results into 1H NMR spectra to identify all kinds of H. Confirm the corresponding structures of chemical shift in 1HNMR spectrum on the basis of total correlation spectrum analysis.
