Weseler and Bast Nutrition Journal (2017) 16:5 DOI 10.1186/s12937-016-0218-1 REVIEW Open Access Masquelier’s grape seed extract: from basic flavonoid research to a well-characterized food supplement with health benefits Antje R. Weseler* and Aalt Bast Abstract Careful characterization and standardization of the composition of plant-derived food supplements is essential to establish a cause-effect relationship between the intake of that product and its health effect. In this review we follow a specific grape seed extract containing monomeric and oligomeric flavan-3-ols from its creation by Jack Masquelier in 1947 towards a botanical remedy and nutraceutical with proven health benefits. The preparation’s research history parallels the advancing insights in the fields of molecular biology, medicine, plant and nutritional sciences during the last 70 years. Analysis of the extract’s flavanol composition emerged from unspecific colorimetric assays to precise high performance liquid chromatography - mass spectrometry and proton nuclear magnetic resonance fingerprinting techniques. The early recognition of the preparation’s auspicious effects on the permeability of vascular capillaries directed research to unravel the underlying cellular and molecular mechanisms. Recent clinical data revealed a multitude of favorable alterations in the vasculature upon an 8 weeks supplementation whichsummedupinahealthbenefitoftheextractin healthy humans. Changes in gene expression of inflammatory pathways in the volunteers’ leukocytes were suggested to be involved in this benefit. The historically grown scientific evidence for the preparation’shealth effects paves the way to further elucidate its metabolic fate and molecular action in humans. Keywords: Flavanols, Proanthocyanidins, Grape seed, Masquelier, Cardiovascular, Health, Inflammation, Oxidative stress, Nutraceutical, Food Introduction The authentic mixture of monomeric and oligo- In scientifically evaluating the health benefit of a meric flavan-3-ols extracted from the seeds of grapes food-derived product, three major rules have to be (Vitis vinifera L.) is commercially available as the followed: 1) The product for which a health claim is made herbal remedy Endotélon® and as Masquelier’s® should be well characterized; 2) the (claimed) effect should Original OPCs (Anthogenol®) in various food supple- be well defined and of physiological benefit; 3) a cause-and- ments. This plant extract forms an interesting effect relationship between the intake of the food product example of how product-specific research followed and the claimed effect on human health is substantiated by and contributed to the scientific evolution of botan- human (observational and intervention) studies. In this ical, biochemical and physiological insights during the review we will follow a specific botanical preparation, i.e. a post-WWII period. In this time, grape seed extracts mixture of monomeric and oligomeric flavan-3-ols from constantly remained at the forefront of successive in- the seeds of grapes, on its travel from its creation in 1947 novations in scientific investigation [1]. Applications towards a botanical remedy and nutraceutical with proven have been found in the treatment of chemo- and health benefits. radiotherapy-induced toxicity [2], in chemoprevention [3–5], in cardiovascular diseases [6] and neurodegen- erative diseases [7, 8], in oral health [9] or as cosme- * Correspondence: [email protected] ceutical [10]. In the early development some focus Department of Pharmacology and Toxicology; Faculty of Health, Medicine and Life Sciences, P.O. Box 6166200, MD, Maastricht, The Netherlands © The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Weseler and Bast Nutrition Journal (2017) 16:5 Page 2 of 19 was given to the effect of grape seed extracts as phle- plant pigments, the flavonoids (flavus (Latin) means botonics for venous insufficiency [11]. yellow). Research on the bioactive components of grape In 1947 the French researcher Jack Masquelier ex- seeds extracts, i.e. in flavonoids, started in the begin- tracted during his work for his PhD thesis a colorless ning of the 20th century, when nutritional scientists fraction from the red-brown skin of peanuts. He found were dedicated to the isolation and identification of this fraction to be responsible for the vitamin P effect compounds we came to define as “vitamins.” The in animals and proposed its major components as oligo- Hungarian scientist Albert Szent-Györgyi isolated vi- mers of flavan-3-ol units (i.e. (+)-catechin or (-)-epicate- tamins C and P from citrus fruits. In contrast to chin; Fig. 1). Nowadays, these polyphenolic compounds vitamin C, the chemical characterization of vitamin are commonly classified as monomeric and oligomeric P appeared to be difficult. As a result, it was not flavan-3-ols. Condensed flavanols (oligomers and poly- possible to attribute the vitamin P effect to a specific mers) are also designated as proanthocyanidins. Oligo- compound or preparation. Moreover, the notion of mers of proanthocyanidins are well-known by the such a vitamin was abandoned since no deficiency abbreviation “OPCs.” As the name suggests, proantho- disease could be linked to Szent-Györgyi’scitrus cyanidins are the precursors (pro) of anthocyani(di)ns extract. However, the biological effect of “vitamin P”, (anthos (ancient Greek) means flower and kyanos (an- i.e. its influence on vascular permeability was estab- cient Greek) means blue), which are water-soluble pig- lished as well as its enforcing influence on the anti- ments being responsible for the blue, violet or red color scurvy effect of vitamin C. Efforts to identify this of many flowers and fruits. In plants, anthocyanins are putative vitamin P were directed to yellow colored usually present as glycosides, i.e. bound to one or several Fig. 1 Molecular structure of monomeric and oligomeric flavan-3-ols Weseler and Bast Nutrition Journal (2017) 16:5 Page 3 of 19 sugar moieties. Their color depends on the pH of their established pool of in vitro, in vivo and clinical data unravel- environment changing from red/pinkish at acidic condi- ling health benefits of monomeric and oligomeric flavanols tions to blue—purple at neutral conditions and yellowish (Fig. 2). at alkaline conditions. Many plant products originate from traditional use. In any case, the scientific journey in the field of extracts Historical findings and concepts that come with it are a consisting of monomeric and oligomeric flavanols begins valuable source to get insides into the origin and poten- in the early attempt to classify these compounds as a vita- tial health effects of these products. The data on Masque- min amidst all other vitamins that were discovered in lier’s flavanol preparation suggest a vitamin-like action those days. As nutrients that are essential to prevent on capillary function, which can be associated with the symptoms of deficiency, vitamins were realized to ensure monomeric and oligomeric flavanols present in this ex- and procure health. In this context, the first discovered tract. A closer look at the biosynthetic origin of flavanols health effects of Masquelier’s flavanol-preparations fitted in plants may help to better understand their chemical well in the, at that time, new WHO definition of health as nature and biological activity. “a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity” [12]. Flavanol biosynthesis in plants Besides developing synthetic routes [13] and improving Monomeric flavan-3-ols like (-)-epicatechin and (+)-cat- methods for the extraction of monomeric and oligomeric echin are enzymatically synthesized by plants via a com- flavanols from different plant sources, Jack Masquelier also bination of the shikimate and the acetate pathway [14]. directed much of his and his colleagues’ efforts to elucidate The first step towards the synthesis of shikimic acid con- the biological activities of the extracts produced. In recent sists of the condensation of phosphoenolpyruvate (PEP; years, quite some scientific data have been generated that produced in glycolysis) and D-erythrose-4-phosphate provide insights in the presumed effects of all sorts of more (produced in pentose phosphate cycle) to 3-deoxy-D- or less well defined grape seed extracts on human health. arabinose-heptulosonic acid-7-phosphate (DAHP; Fig. 3a). However, in contrast to drugs, which are mostly single Intramolecular aldol-type condensation and NADH- chemical compounds, the evaluation of the biological mediated redox reactions result in dephosphorylation and effects of phytochemicals produced by extraction is challen- cyclization to 3-dehydroquinic acid. Dehydration and ging. The fact that most plant extracts contain a wide reduction of the latter give shikimic acid which is eventu- variety of individual chemical entities bedevils the establish- ally converted to chorismic acid. Chorismic acid serves as ment of