Chapter 9
Systematic Investigation on Quality Management of Saw Palmetto Products 1,3
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Tang-Sheng Peng , William F. Popin , and Marlin Huffman 1
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Twinlab Utah Division, 600 East Quality Drive, American Fork, U T 84003 P l a n t a t i o n Medicinals, Inc., 1401 Country Road 830, Felda FL 33930 Current address: Pure World Botanicals, 375 Huyler Street, South Hackensack, NJ 07606 2
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A systematic investigation of botanical and fatty acid profiles of saw palmetto (Serenoa repens (Bartr.) Small) products was conducted. Different products were analyzed for the morphological identification and quantification of major fatty acid constituents. The investigation included seed, fruit, fruit powder, powder mixtures and oil extracts, as well as mixtures of saw palmetto and other plant extracts, including pumpkin (Cucurbita pepo) seed oil. Each product has a characteristic fatty acid profile that can be used for the identification and standardization of different saw palmetto products. Examples of questioned products are presented.
Saw palmetto (Serenoa repens (Bartr.) Small) is one of the most popular herbal products in the U.S. dietary supplement market. It has been contiguously listed on the top-ten lists of several surveys with the 1997 sales of more than $ 18 millions. It is also one of the most frequently prescribed phytomedicines in Germany with the 1996 retail sales of more than $24 millions (7-5). It has been © 2002 American Chemical Society
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118 estimated that 2.8 million pounds of saw palmetto fruit are shipped to Europe each year for preparation of saw palmetto products as phytomedicines or nutritional supplements (6). Saw palmetto has a long history of various applications (6-7). The primary therapeutic applications of saw palmetto products are for treatment of benign prostatic hyperplasia (BPH) and other related disorders, such as urinary tract inflammation (1-3,8-12). Treatment of B P H in the US exceeds $2 billion in costs, accounting for 1.7 million physician office visits and results in more than 300,000 prostatectomies a year (9). Many studies on the clinical applications of saw palmetto products have been published. A recent literature search revealed at least 58 clinical trials (//). Although more systematic studies are needed, many of these studies have showed that saw palmetto extracts (SPE) reduces B P H symptoms with fewer side effects than synthetic drugs like finasteride (Π Ι 5). The review article listed 10 mechanisms, including the inhibition of 5areductase, revealed by many studies to support the polypharmaceutical nature of saw palmetto products (//). Importantly, saw palmetto products have no effect on prostate specific antigen (PSA) levels and, therefore, will not mask prostatic carcinoma during a B P H medication. Most, if not all, of the reviewed clinic trials used lipophilic extract of dried saw palmetto fruit. These extracts can be obtained from saw palmetto fruits through different procedures such as press, solvent extraction, and supercritical carbon dioxide ( C 0 ) extraction. Most of the SPE suppliers we have worked with use supercritical C 0 extraction that produces SPE directly without further purification. Approximately 10% of SPE can be obtained from ripened dried saw palmetto fruit. These lipophilic extracts contain a broad brand of chemical components including free fatty acids, fatty alcohols, fatty acid esters, neutral fats, and phytosterols (12,16). Although more studies are needed to ascertain the correlation of the chemical components and the pharmaceutical properties of SPE, some researchers have revealed that the free fatty acids and phytosterols in saw palmetto products played active roles in B P H treatments (17-19). The major components of lipophilic SPE are fatty acids and their esters. It is reported that the lipid content of SPE consists of 75% free fatty acids and 25% free fats (20). Since other constituents are minor and more difficult to be quantified, total fatty acid content has been selected by the dietary supplement industry as one of the specifications for the quality control of saw palmetto products. In the US dietary supplement market, almost all SPE oils are labeled to contain 85-95% total fatty acids. We have analyzed numerous saw palmetto samples during our quality control process in our laboratories and have found that the fatty acids content specification is not only good for quality control of SPE, but also useful for testing the quality of other saw palmetto products such as saw palmetto fruit powder. During the saw palmetto price crisis in 1995, we received several samples from a supplier labeled as "saw palmetto powder". The 2
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119 consequent analysis showed fatty acid profiles very different from that of authentic saw palmetto fruit. This prompted us to set up a program to investigate systematically the major types of saw palmetto products in the dietary supplement market and the results are reported below. A part of the preliminary results has been communicated earlier (27).
Botanical Characteristics of Saw Palmetto Plant and Fruit Saw palmetto plant (Serenoa repens (Bartr.) Small, family Palmae) is a dwarf palm commonly growing wild in Florida and along the southern Atlantic coast (7, 6-7). Plantation Medicinals, Inc. has set up an experimental program to cultivate saw palmetto in South America. The plants have been growing vigorously but have not reached the fruiting stage. Serenoa repens may attain a height of 2 meters and has creeping, horizontal stems from which asexual reproduction may occur (1,6-7). The common name for Serenoa repens, saw palmetto, is derived from the leaves which are fan shaped, stiff, and reminiscent of saw blades (1,6-7). The fleshy fruit of Serenoa repens occurs as single seeded drupes and both the fruit and seed are processed for use in pharmaceutical and nutraceutical preparations. The immature Serenoa repensfruitis green to mottled green-black and turns yellow-orange to black when mature. The fruit turns brown to black when dried. The dry, mature fruit from Serenoa repens is ovoid to ellipsoid, 1830 mm in length and 12-14 mm in width. Polygonal depressions occur in mature, dried Serenoa repens fruits. The immature Serenoa repens fruit is green and turns brown-black when dried. The shape of immature fruit is ovoid to ellipsoid, around 16.0 mm in length, 10 mm in width, and wrinkled. Deep polygonal depressions are absent in dried immature fruit. The seed of Serenoa repens is orange-brown. A photograph of immature, mid-season semi-mature, and fully mature Serenoa repens fruits is shown in Figure 1. These samples were collected by Plantation Medicinals Inc. in a colony approximately 3 meters in diameter near Punta Gorda, Florida, during the 1995 harvest season from August 18 to September 6 . The fresh fruit was separated by hand into three groups according to the maturity stages by color: immature (green), semi-mature (yellow), and fully mature (black). The grouped fruit was then dried in an oven at 55°C for 72 hours and then cooled in oven. The average physical data of Serenoa repens fruits were measured from 10 fruits randomly selected from a one (1) pound sample and are summarized in Table I. From the data in Table I, the average weight of fully mature fruit can be up to 1.5 times of that of immature fruit. However, the percentages of flesh and seed are almost identical. th
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Figure 1. Immature, mid-season, and mature fruits ofSerenoa repens. Reprinted with permission from reference 21. Encyclia 1996.
121 Table I. Average Physical Data of Saw Palmetto Fruits Sample Description Length (mm) Immature Fruit 16.1 Semi-mature Fruit 20.0 Full Mature Fruit 19.1
Width (mm) 9.9 11.7 13.6
Weight Flesh (mg) (%) 887 57.6 1099 53.1 57.4 1307
Seed (%) 42.4 46.9 42.6
Although the harvest season can vary from year to year depending on the weather conditions, most of the immature saw palmetto fruit on the market is harvested in late July or early August by collectors who want to make some quick money. Fruit collected earlier is too small to be commercially harvested. The saw palmetto fruit turns deep black and soft in early October when it is fully mature. This makes the harvesting and transportation processes more complicated. Therefore, most of the saw palmetto fruit products are harvested in the mid-season from late August to September when >75% of the fruit are yellow-orange or turning from brown to yellow. The hand-harvested fruit is transported from the wild to the processing plant and then dried at about 55°C for approximately 72 hours. The resulting product is whole dried fruit with a moisture content of 10% or less. The dried and cleaned fruits are stored in controlled conditions before further processing into saw palmetto powders or extracts.
Fatty Acid Profile of Saw Palmetto Fruit and Fruit Powders Based on the preceding results, Serenoa repensfruits,and their maturity at harvest, can be readily identified and distinguished from other "palmetto" species (see below) by the shape, size, weight, color, and external morphology of the fruits. Morphological analysis of whole palmetto fruits utilizing voucher specimens or herbarium sheet standards is a useful method for the preliminary identification of saw palmetto fruits, especially when the product is in the form of whole fruit. However, most of the commercial saw palmetto products are milled into powders or processed into extracts. Therefore, identification based on the chemical components of the products is necessary. Since fatty acids are the major components of the lipophilic extracts of saw palmetto fruit, we decided to set up a quality control protocol for saw palmetto products using fatty acid profiles. The gas chromatography (GC) method for fatty acid analysis was modified from the A O A C method for oils and fats (22). This modified method has been submitted to USP and published as a part of the official saw palmetto monograph (23).
122 Thus, the dried saw palmetto fruits were milled to powders (< 40 US mesh) with a Handi-Magic mill (Magic Mill). The fatty acids and fatty acid-containing esters were saponified with 0.5 Ν methanoiic NaOH solution and converted to methyl esters in the presence of BF «MeOH (12.5%, Aldrich). The resulting fatty acid methyl eaters were extracted with hexane and analyzed by G C with a 30 m HP-INNOWax capillary column using helium as carrier gas and FID detector. The oven temperature was set at 120°C for 3 minutes and then raised to 220°C in 2 minutes. The total analyzing time is about 15 minutes. Nonadecane (Aldrich) was used as an internal standard. A representative chromatogram is shown in Figure 2 and the fatty acid contents of the saw palmetto fruits at different maturity stages are shown in Table II and Figure 3. 3
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