(2004). Oligomeric catechins: an enabling synthetic strategy by orthogonal activation and C(8) protection. Proceedings of the National Academy of Sciences of the United States of America 101: 12002–12007.22 Oyama, K.‐I., Kuwano, M., Ito, M., et al. (2008). Synthesis of procyanidins by stepwise‐ and self‐condensation using 3,4‐cis‐4‐acetoxy‐3‐O‐acetyl‐4‐dehydro‐5,7,3',4'‐tetra‐O‐benzyl‐(+)‐catechin and (–)‐epicatechin as a key building monomer. Tetrahedron Letters 49: 3176–3180.
23 Pomilio, A., Müller, O., Schilling, G. and Weinges, K. (1977). Zur kenntnis der proanthocyanidine, XXII. Über die konstitution der kondensationsprodukte von phenolen mit flavyliumsalzen. Justus Liebigs Annalen der Chemie 1977: 597–601.
24 Saito, A, Mizushina, Y., Tanaka, A. and Nakajima, N. (2009). Versatile synthesis of epicatechin series procyanidin oligomers, and their antioxidant and DNA polymerase inhibitory activity. Tetrahedron 65: 7422–7428.
25 Selenski, C., and Pettus, T.R. (2006). (+/–)‐Diinsininone: made nature's way. Tetrahedron 62: 5298–5307.
26 Sharma, P.K., Romanczyk, L.J., Jr., Kondaveti, L., et al. (2015). Total synthesis of proanthocyanidin A1, A2, and their stereoisomers. Organic Letters 17: 2306–2309.
27 Stadlbauer, S., Ohmori, K., Hattori, F., and Suzuki, K. (2012). A new synthetic strategy for catechin‐class polyphenols: concise synthesis of (–)‐epicatechin and its 3‐O‐gallate. Chemical Communications 48: 8425–8427.
28 Van Rooyen, P.H., and Redelinghuys, H.J.P. (1983). Crystal structure and molecular conformation of proanthocyanidin‐A2, a bitter substance in litchis (Litchi chinensis Sonn.). South African Journal of Chemistry 36: 49–53.
29 Weinges, K., Kaltenhäuser, W., Marx, H.‐D., et al. (1968). Zur kenntnis der proanthocyanidine, X. Procyanidine aus früchten. Justus Liebigs Annalen der Chemie 711: 184–204.
30 Weinges, K. and Theobald, H. (1971). Synthese des 6‐phenyl‐12H‐6.12‐methano‐dibenzo[d.g][1.3]‐dioxocins, einer modellsubstanz für die C30H24O12‐procyanidine. Justus Liebigs Annalen der Chemie 743: 203–206.
31 Xia, L., Cai, H., and Lee, Y.R. (2014). Catalyst‐controlled regio‐ and stereoselective synthesis of diverse 12H‐6,12‐methanodibenzo[d,g][1.3]dioxocines. Organic and Biomolecular Chemistry 12: 4386–4396.
32 Yang, Z., He, Y. and Toste, F.D. (2016). Biomimetic approach to the catalytic enantioselective synthesis of flavonoids. Journal of the American Chemical Society 138: 9775–9778.
33 Yano, T., Ohmori, K., Takahashi, H., et al. (2012). Unified approach to catechin hetero‐oligomers: first total synthesis of trimer EZ‐EG‐CA isolated from Ziziphus jujuba. Organic and Biomolecular Chemistry 10: 7685–7688.
3 Answering the Call of the Wild: Polyphenols in Traditional Therapeutic Practice
Mary Ann Lila1 and Kriya Dunlap2
1 Plants for Human Health Institute, Department of Food Bioprocessing and Nutrition Sciences, North Carolina State University, Kannapolis, USA
2 Department of Biochemistry, University of Alaska Fairbanks, Fairbanks, USA
3.1 Introduction
Polyphenols, ubiquitous and exceptionally human health–relevant plant‐derived compounds, have had a central role in ethnomedicine (traditional herbal medicine) and subsistence diets throughout history, even prerecorded history (Buttriss 2012; Schmidt and Klaser Cheng 2017). Foraging wild edible plants for foods and therapeutic applications is an ancient tradition that was considered obsolescent by most modern urban consumers, but now is enjoying a resurgence in interest. Thanks to some new insights into the composition and resiliency of endemic wild plants, and the quest for novel flavors and textures—especially in niche, fine dining establishments—wild foraging has become “cool” again. Foraged cuisine and indigenous ingredients are coveted, trendy options in high‐end restaurants, where the tannic astringency of wildcrafted leaves and fruits can complement blander foods or flavor botanical‐infused gins and vodkas, and consumers are keen to experience new foods that they perceive as healthier, natural, and unadulterated (Reyes‐Garcia et al. 2015; Schatzker 2015; Soukand 2016; Sebag‐Montefiore 2017; Pinela et al. 2017). But what is the real history of human use for polyphenol‐rich biologically active edible wild plants? Where were they discovered and which species were preferentially targeted as medicinally relevant?
3.2 The Wildcrafting Tradition
Our hunter‐gatherer ancestors were opportunistic omnivores, combining indigenous plant‐based foods and ingredients and wild‐caught fish and game. Today, wildcrafted plant foods are still part of the cultural and genetic heritage in many nonurbanized regions of the world. They can form the mainstay of the traditional diet, complement staple agricultural foods, help to alleviate poverty, and provide food security, especially in rural villages during times when food is scarce (Soukand 2016; Pinela et al. 2017).
Historically, wild plants, including polyphenol‐rich berryfruits, were put to use as both food and medicines as well as for dyes and preservatives in the Americas, Europe, Africa, and Asia, and in most cases, responsibility for wildcrafting fell to the female villagers (Densmore 1974; Alarcomicronn et al. 2015; Soukand 2016; Pinela et al. 2017). Some of the earliest historic records from Native Americans and Alaska Natives not only describe the sources and preparation of polyphenol‐rich food sources, but also stress the importance of collecting the wild plants in proper season and stage of development, in order to ensure bioactive efficacy, palatability, and resource sustainability (Burns Kraft et al. 2008; Wapner 2012; Allkin 2017). Traditional ecological knowledge and folk medicine provide an ethnobotanical record that guides current discovery efforts (Joseph et al. 2014; Pinela et al. 2017).
Regular consumption of plant‐based diets supports health maintenance by regulating the balance between cellular (endogenous) and dietary (exogenous) antioxidants to maintain cell redox homeostasis, (Al‐Gubory and Laher 2018) whereas plant medicines are generally prepared by extraction and concentration of the active compounds from medicinal species prior to administration either orally or topically to humans (Moerman 1996; Allkin 2017; Pinela et al. 2017). Herbal teas, for example, were social/recreational beverages used without restriction, but more concentrated decoctions were taken only for a limited time to treat a health condition such as a digestive disorder or respiratory symptoms.
Phytotherapy, the integration of traditional practices and scientific method, supports the biological basis for traditional ecological medicines, and traditional knowledge is increasingly evolving as evidence‐based medicine. In the past, the generally potent antioxidant capacities of polyphenolic resources were credited with the multifaceted uses of these plants, however, research now suggests that the diverse health benefits coincident with plant polyphenol intake are more related to their anti‐inflammatory, prebiotic, vasodilation and signaling pathways’ influences (Cordova and Sumpio 2009; Margina et al. 2015). In each case, specific dosages and controlled periods of intake are recommended, often combined with cultural healing rituals (Pinela et al. 2017). Interestingly, Native Americans used only a small percentage of available polyphenol‐containing flora as medicines, and with the exception of several genera (i.e. Ribes, Vaccinium, Malus, Fragaria, Rubus, Crataegus, Prunus, and Arctostaphylos) the species used for medicines excluded those used for foods. This makes some sense, as medicines can be toxic and proper attention to homeopathy implies that the lowest possible effective doses should be used, as is the case for prescription synthetic drugs
