Bioavailability and activity of p...
Copyright �� 2009 Thorne Research, Inc. All Rights Reserved. No Reprint Without Written Permission. Alternative Medicine Review Volume 14, Number 3 2009 Page 226 Environmental Medicine Review Article Page 226 Abstract Plant-derived polyphenols are increasingly receiving attention as dietary supplements for the homeostatic management of inflammation, to support detoxification, and for anticancer, weight loss, and other benefits. Their pro-homeostatic effects on genes, transcription factors, enzymes, and cell signaling pathways are being intensively explored, but the poor bioavailability of some polyphenols likely contributes to poor clinical trial outcomes. This review covers four polyphenol preparations with poor bioavailability and their complexation into phytosomes to bypass this problem. Silybin and the other silymarin flavonolignans from milk thistle conserve tissue glutathione, are liver-protective, and have anticancer potential. Curcumin and its related diphenolic curcuminoids have potent antioxidant, anti-inflammatory, and anti-carcinogenic properties. The green tea flavan-3-ol catechins have antioxidant, anti-inflammatory, cardio- and neuro-protective effects, and anti-carcinogenic benefits, with fat oxidation effects coupled to weight loss. The complex grape seed proanthocyanidin mix (including catechin and epicatechin monomers and oligomers) counters oxidative stress and protects the circulatory system. For each of these preparations, conversion into phytosomes has improved efficacy without compromising safety. The phytosome technology creates intermolecular bonding between individual polyphenol molecules and one or more molecules of the phospholipid, phosphatidylcholine (PC). Molecular imaging suggests that PC molecule(s) enwrap each polyphenol upon oral intake the amphipathic PC molecules likely ���usher��� the polyphenol through the intestinal epithelial cell outer membrane, subsequently accessing the bloodstream. PC itself has proven clinical efficacy that contributes to phytosome in vivo actions. As a molecular delivery vehicle, phytosome technology substantially improves the clinical applicabilities of polyphenols and other poorly absorbed plant medicinals. (Altern Med Rev 2009 14(3):226-246) Introduction Medicinal nutrients derived from plants have been used for health maintenance and disease manage- ment since the dawn of history. One class of phytomedi- cines currently receiving increased scrutiny is the poly- phenols. These number in the thousands and include, but are not limited to, the various flavonoid subclasses. But many polyphenols are very poorly absorbed when taken orally, posing the greatest obstacle to routine clini- cal application.1 Where possible, the conversion of poly- phenols to phytosome forms improves oral bioavailabil- ity without compromising safety. This review focuses on the four most widely studied polyphenol phytosome preparations for anti-inflammatory, anti-neoplastic, de- toxification, and weight loss applications: Bioavailability and Activity of Phytosome Complexes from Botanical Polyphenols: The Silymarin, Curcumin, Green Tea, and Grape Seed Extracts Parris M. Kidd, PhD Parris M. Kidd, PhD ��� Cell biology University of California, Berkeley contributing editor, Alternative Medicine Review health educator biomedical consultant to the dietary supplement industry Correspondence address: 10379 Wolf Drive, Grass Valley, CA 95949 Email: email@example.com
Copyright �� 2009 Thorne Research, Inc. All Rights Reserved. No Reprint Without Written Permission. Alternative Medicine Review Volume 14, Number 3 2009 Phytosomes Page 227 X silymarin flavonolignans, most specifically silybin (silibinin, silymarin I), which enhance systemic antioxidant status, are liver protectants, support liver detoxification, and have anticancer potential X curcuminoid polyphenols, which have potent antioxidant, anti-inflammatory, and anticancer properties X green tea flavan-3-ol catechins, which have antioxidant, anti-inflammatory, and anticancer benefits, and have demonstrated fat oxidation effects coupled to weight loss X grape seed catechin and epicatechin complex, including monomeric and oligomeric proanthocyanidins, which counters oxidative stress, protects circulation, and has anti-inflammatory and anticancer effects Background to Phytosome Technology Phytosome technology emerged in 1989.2 Based on a histochemical observation that certain poly- phenols had strong bonding affinity for phospholipids in their intact plant tissue, a group of Italian researchers focused on polyphenol preparations known to be poorly bioavailable when taken orally. These were typically mix- tures of polyphenols extracted from single plant species, and their conversion into phytosome forms markedly increased their bioavailability.3 To make phytosomes, the polyphenol mix is chemically reacted with a phos- pholipid preparation, consisting mainly of phosphati- dylcholine (PC), which is also the major phospholipid of living tissues. The resulting phytosome molecular complex is tested for bioavailability and efficacy, usually in direct comparison to its non-phytosome form. For the four phytosome preparations under review, the findings from systematic bioavailability comparisons show that when administered orally, phy- tosome complexation enhances the blood levels of poly- phenol constituents by factors of at least 2-6 times.3-7 Phytosome technology has proven to be a breakthrough for the clinical applicability of botanical polyphenols, since improved bioavailability generally results in enhanced efficacy. The flavonoids and other polyphenol mol- ecules are multi-ring compounds generally too large to be absorbed by simple diffusion,1 nor are they subject to active intestinal uptake as occurs with some vitamins and minerals. They also tend to be poorly soluble in water or lipids. PC by contrast is an amphipathic mol- ecule, having a positively charged headgroup and two neutrally charged tailgroups,8 a rare molecular charac- teristic that renders PC miscible in both water and lipid environments. By complexing a polyphenol with PC to make a phytosome, the polyphenol comes to share some of PC���s versatile solubility properties. Direct demonstration of the phytosome action is not yet feasible, but from what is known of these mo- lecular constituents, it is inferred that the water-miscible PC molecules enhance the dispersion of the poorly wa- ter-soluble polyphenol molecules into the water-soluble environment of the gastrointestinal lumen. PC ostensi- bly further enhances transfer from the lumen into the lipid-soluble environment of the outer cell membrane of the epithelial absorptive cells (enterocytes). The entero- cyte outer membrane has a lipid molecular bilayer that consists largely of PC. It is feasible that the PC of the phytosome merges into this PC domain of the entero- cyte membrane, carrying the polyphenol with it and so ���ushering��� the polyphenol into the cell.2-4 Phytosomes Differ from Liposomes To appreciate the uniqueness of phytosomes it is necessary to differentiate them from liposomes. The unit phytosome is a molecular-level association involv- ing as few as two molecules (one PC plus one polyphe- nol). The unit liposome is an aggregate of hundreds of phospholipid molecules into a spherule, within which other molecules are compartmentalized but not specifi- cally bonded. Whereas, the liposome concept remains unproven as an oral delivery vehicle, the phytosome is known to dramatically enhance oral delivery. As schematized in Figure 1, it is believed that in the phytosome one or more PC molecules effec- tively enwrap a polyphenol molecule. This supposition comes from molecular-level imaging of formed phyto- somes (Figure 2). When a phytosome preparation was examined by carbon-13 nuclear magnetic resonance (13C-NMR), the signal from PC mostly obliterated the signal from the polyphenol. Similarly, spectra obtained by hydrogen-1 nuclear magnetic resonance (1H-NMR)
Copyright �� 2009 Thorne Research, Inc. All Rights Reserved. No Reprint Without Written Permission. Alternative Medicine Review Volume 14, Number 3 2009 Review Article Page 228 show a similar obliteration of the catechin pattern by the PC.3 Note in Figure 2 that in the blue phytosome spectrum, the spectrum from the polyphenol (red) is eclipsed by the orange spec- trum from phosphatidylcholine. This is consistent with a physical enwrapment of the polyphenol by the PC molecule, as configured in Figure 1. Using a different phyto- some model, that of glycyrrhetinic acid with PC, an infrared spectrum analysis yielded similar findings to the 13C- and 1H-NMR analyses of (+)-catechin with PC.3 The most reasonable interpretation from these molecular imaging spectra is that the polyphenol molecule is being shielded from the view of the imaging probes. A corollary of these results is that in the unit phytosome, the polyphenol (or other phytomedicinal molecule) is held close to the PC molecule(s) by some form of quasi-stable bonding. In effect, the phytosome is a hybrid molecule that resembles PC in being sub- stantially lipid-soluble and water-soluble. Once this hybrid molecule enters the intestinal tract, its largely amphipathic character facilitates its transition from the water-soluble environment of the in- testinal lumen to the lipid-soluble envi- ronment of the enterocyte cell membrane. Phosphatidylcholine Itself Has Clinical Efficacy Depending on the proportions of PC contained, and the doses ingested, phytosome preparations can deliver clini- cally significant amounts of PC. This is an important aspect of phytosome activ- ity because PC itself has important clini- cal applications.8 PC, the most significant dietary source of the essential nutrient choline, is an orthomolecule ubiquitous in known life forms.8 Besides being an Figure 1. Schematic of the Phytosome Molecular Complex3 Figure 2. Molecular Imaging (13C-NMR) of PC, the Polyphenol (+)-Catechin, and the Phytosome Combination 180 160 140 120 100 80 60 40 20 0 PPM Distearoyl- phosphatidylcholine in C6D6 (+)-Catechin in DMSO-D6 1-1 Molar complex in C6D6 Top spectrum (orange) represents distearoyl-phosphatidylcholine (PC). Middle spectrum (red) represents (+)-catechin, a flavan-3-ol. Bottom spectrum (blue) represents a 1:1 molar complex between PC and (+)-catechin. From: Indena SpA, Italy