Scholarly Work - Health & Human Development
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Item White and Green Teas (Camellia sinensis var. sinensis): Variation in Phenolic, Methylxanthine, and Antioxidant Profiles(2010-08) Unachukwu, Uchenna J.; Ahmed, Selena; Kavalier, Adam; Lyles, James T.; Kennelly, Edward J.Recent investigations have associated white teas with anti‐carcinogenic, immune‐boosting, and antioxidative properties that may impact human health in a manner comparable to green teas. An in‐depth chemical analysis of white tea types was conducted to quantify polyphenols and antioxidant potential of 8 commercially available white teas, and compare them to green tea. Extraction and HPLC protocols were optimized and validated for the quantification of 9 phenolic and 3 methylxanthine compounds to examine inter‐ and intra‐variation in white and green tea types and subtypes. A sampling strategy was devised to assess various subtypes procured from different commercial sources. Variation in antioxidant activity and total phenolic content (TPC) of both tea types was further assessed by the 1‐1‐diphenyl‐2‐picrylhydrazyl (DPPH) and Folin–Ciocalteau (F–C) assays, respectively. Total catechin content (TCC) for white teas ranged widely from 14.40 to 369.60 mg/g of dry plant material for water extracts and 47.16 to 163.94 mg/g for methanol extracts. TCC for green teas also ranged more than 10‐fold, from 21.38 to 228.20 mg/g of dry plant material for water extracts and 32.23 to 141.24 mg/g for methanol extracts. These findings indicate that statements suggesting a hierarchical order of catechin content among tea types are inconclusive and should be made with attention to a sampling strategy that specifies the tea subtype and its source. Certain white teas have comparable quantities of total catechins to some green teas, but lesser antioxidant capacity, suggesting that white teas have fewer non‐catechin antioxidants present.Item Pu-erh Tea Tasting in Yunnan, China: Correlation of Drinkers’ Perceptions to Phytochemistry.(2010-10) Ahmed, Selena; Unachukwu, Uchenna J.; Stepp, John R.; Peters, Charles M.; Long, Chunlin; Kennelly, Edward J.Aim of the study: Pu-erh (or pu’er) tea tasting is a social practice that emphasizes shared sensory experience, wellbeing, and alertness. The present study examines how variable production and preparation practices of pu-erh tea affect drinkers’ perceptions, phytochemical profiles, and anti-oxidant activity. Materials and methods: One hundred semi-structured interviews were conducted in Yunnan Province to understand the cultural and environmental context of pu-erh tea tasting. The gong fu cha dao (‘way of tea’ with ‘effort,’ ‘work,’ or ‘skill’) method of brewing tea through multiple infusions was employed to evaluate green and black pu-erh samples from smallholder agro-forests and terrace plantations. Ranking interviews, High Performance Liquid Chromatography (HPLC), and the 1-1-diphenyl-2-picrylhydrazyl (DPPH) assay were conducted to characterize color and taste profiles, Total Catechin Content (TCC), Total Methylxanthine Content (TMC), and free radical scavenging capacity (IC50). Results: Significant variation was found among pu-erh samples based on: (1) agro-ecosystem mode of production by TCC (P < 0.0001) and TMC (P < 0.0265), (2) processing method for TCC (P < 0.0001), TMC (P < 0.0027), and free radical scavenging capacity (P < 0.0001), (3) infusion sequence for TMC (P < 0.0013), (4) taste rankings for TCC (P < 0.0001), TMC (P < 0.0001), and IC50 (P < 0.0059) and, (5) color rankings for TMC (P < 0.0009) and IC50 (P < 0.0001). Samples rated as bitter and bitter-sweet contained the greatest TCC and free radical scavenging capacity. Conclusions: This research demonstrated that production environment, processing methods, and infusion sequence in preparing tea are related to the phytochemical profile, free radical scavenging activity, and flavor of tea. Findings contribute to the ethnomedical literature by supporting previous studies that have hypothesized that the taste of plants, particularly bitterness, may guide societies in the search for medicinal plants and beneficial phytochemicals.Item The Role of Montane Forests for Indigenous Dongba Papermaking in the Naxi Highlands of Northwest Yunnan, China. Mountain Research and Development.(2011-11) Yang, Lixin; Stepp, John R.; Ahmed, Selena; Pei, Shengji; Xue, DayuanChina's rapid economic development is influencing cultural practices and natural resource management in indigenous mountain communities throughout the country. Numerous studies have documented loss and change of cultural practices and environmental degradation in indigenous communities with the expansion of roads, markets, tourism, and other infrastructure development. The present study focuses on papermaking, a socioecological practice that began in China, as a case study to examine the influence of development on cultural practices and natural resource management. The Naxi are an indigenous people who primarily inhabit the mountains of the eastern Himalaya in China's northwest Yunnan province. The Naxi people are unique in that they have the last remaining pictographic writing system in the world. The Naxi pictographic script is customarily learned and mastered by shaman priests known as Dongba (Dto'mba) who transmit their knowledge to their sons. Approximately 300,000 Naxi live in this area. The pictographic system is transmitted on paper sourced from montane forest resources, primarily Wisktroemia delavayi. This cultural tradition almost disappeared during the Cultural Revolution in China during the 1960s and 1970s but has recently seen a revival. Research involved both ethnographic interviews and ecological sampling. Semistructured interviews were conducted with 100 informants between 2002–2011 to understand the management and use of W. delavayi for Dongba papermaking and the impact of market integration on papermaking. Sample plots were surveyed for floristic composition and structure in the 3 vegetation types where W. delavayi grows. Density, height, diameter, and number of branches of W. delavayiplants were recorded within each plot. Ecological importance values were calculated based on relative density, relative dominance, and relative frequency to determine the habitat where W. delavayidemonstrates the greatest growth. Additional plots were surveyed to understand the regeneration of W. delavayi after the local harvest cycle.Item Commercial Teas Highlight Plant DNA Barcode Identification Successes and Obstacles.(2011-07) Stoeckle, Mark Y.; Gamble, Catherine C.; Kirpekar, Rohan; Young, Grace; Ahmed, Selena; Little, Damon P.Appearance does not easily identify the dried plant fragments used to prepare teas to species. Here we test recovery of standard DNA barcodes for land plants from a large array of commercial tea products and analyze their performance in identifying tea constituents using existing databases. Most (90%) of 146 tea products yielded rbcL or matKbarcodes using a standard protocol. Matching DNA identifications to listed ingredients was limited by incomplete databases for the two markers, shared or nearly identical barcodes among some species, and lack of standard common names for plant species. About 1/3 of herbal teas generated DNA identifications not found on labels. Broad scale adoption of plant DNA barcoding may require algorithms that place search results in context of standard plant names and character-based keys for distinguishing closely-related species. Demonstrating the importance of accessible plant barcoding, our findings indicate unlisted ingredients are common in herbal teas.Item Comparative homegarden medical ethnobotany of Naxi healers and farmers in Northwestern Yunnan, China(2014-01) Yang, Lixin; Ahmed, Selena; Stepp, John R.; Mi, Kai; Zhao, Yanqiang; Ma, Junzeng; Liang, Chen; Pei, Shengji; Huai, Huyin; Xu, Gang; Hamilton, Alan C.; Yang, Zhi-wei; Xue, DayuanBackground Homegardens are ecologically and culturally important systems for cultivating medicinal plants for wellbeing by healers and farmers in Naxi communities of the Sino Himalayan region. The cultivation of medicinal plants in Naxi communities and associated ethnomedical knowledge base for maintaining and utilizing these resources is at risk with expanded commercialization of natural resources, development policies and rapid socio-economic change in China. Research is needed to understand the medicinal plant species maintained in Naxi homegardens, their use and contribution to community wellbeing, and how these practices and knowledge base varies between Naxi healers and farmers in order to develop plans for biodiversity conservation and preservation of ethnomedical practices. The main objective of this study is to document and compare medicinal plant species in Naxi homegardens and associated ethnomedical knowledge between Naxi healers and farmers. Methods Ethnobotanical homegarden surveys were conducted with three Naxi healers and 28 farmer households in two Naxi communities in Lijiang Prefecture in Northwest Yunnan Province of China. Surveys included inventories of medicinal plants in homegardens and semi-structured interviews with homegarden managers to document traditional medicinal uses of inventoried plants. Inventoried plants were classified into 13 ‘usage categories’ of medical condition groupings that impact a system of the body. Finally, plant species richness was calculated for each homegarden and species richness was compared between healers and farmers as well as between study sites using a Least Square Means Tukey HSD function. Results Ethnobotanical surveys at the study sites found that 13% of households rely exclusively on traditional Naxi medicine, 26% exclusively use Western medicine and 61% use a combination of traditional Naxi and Western medicine. A total of 106 medicinal plants were inventoried in Naxi homegardens representing 50 botanical families. Over 85% of inventoried medicinal plants were herbaceous. The most represented families were Asteraceae (12.8%), Ranunculaceae (8.3%), Apiaceae (8.3%), and Polygonaceae (7.3%). The primary medical functions of inventoried plants were to treat inflammation (73 species), circulatory system disorders (62), nervous system disorders (41), detoxification (39), digestive system disorders (33), muscular-skeletal system disorders (26), genitourinary system disorders (26), skin conditions (23), respiratory systems disorders (22), and cold and flu (20). Local herbal experts maintained greater medicinal plant species richness in their homegardens compared to local farmers as well as had greater knowledge of medicinal functions of plants. Healers maintained medicinal plants primarily for healing while farmer households maintained approximately 90% of the medicinal plants in their homegardens for commercialization and the remaining for household healthcare. Conclusions This study highlights the importance of biodiversity and traditional ecological and medical knowledge for human wellbeing and livelihoods in Naxi communities. Conservation efforts and policies are necessary to preserve the ecological and cultural base that maintains medicinal plant use by both healers and farmers in Naxi homegardens of the Sino Himalayan region.Item Effects of water availability and pest pressures on tea (Camellia sinensis) growth and functional quality(2014-02) Ahmed, Selena; Orians, Colin M.; Griffin, Timothy S.; Buckley, Sarabeth; Unachukwu, Uchenna J.; Stratton, Anne E.; Stepp, John R.; Robbat, Albert Jr.; Cash, Sean; Kennelly, Edward J.Extreme shifts in water availability linked to global climate change are impacting crops worldwide. The present study examines the direct and interactive effects of water availability and pest pressures on tea (Camellia sinensis; Theaceae) growth and functional quality. Manipulative greenhouse experiments were used to measure the effects of variable water availability and pest pressures simulated by jasmonic acid (JA) on tea leaf growth and secondary metabolites that determine tea quality. Water treatments were simulated to replicate ideal tea growing conditions and extreme precipitation events in tropical southwestern China, a major centre of tea production. Results show that higher water availability and JA significantly increased the growth of new leaves while their interactive effect was not significant. The effect of water availability and JA on tea quality varied with individual secondary metabolites. Higher water availability significantly increased total methylxanthine concentrations of tea leaves but there was no significant effect of JA treatments or the interaction of water and JA. Water availability, JA treatments or their interactive effects had no effect on the concentrations of epigallocatechin 3-gallate. In contrast, increased water availability resulted in significantly lower concentrations of epicatechin 3-gallate but the effect of JA and the interactive effects of water and JA were not significant. Lastly, higher water availability resulted in significantly higher total phenolic concentrations but there was no significant impact of JA and their interaction. These findings point to the fascinating dynamics of climate change effects on tea plants with offsetting interactions between precipitation and pest pressures within agro-ecosystems, and the need for future climate studies to examine interactive biotic and abiotic effects.Item Increased Market Integration, Value, and Ecological Knowledge of Tea Agro-forests in the Akha Highlands of Southwest China.(2010) Ahmed, Selena; Stepp, John R.; Toleno, Robban A. J.; Peters, Charles M.This study assesses the persistence and change of traditional land use patterns and ecological knowledge in response to expanded commercialization of tea (Camellia sinensis var. assamica (L.) Kuntze Theaceae in an indigenous Akha (Hani) community in the midlevel montane forests of southwest Yunnan, China. Surveys were conducted in 2005 and 2008, over a period corresponding to a regional tea market boom and bust cycle, to compare the valuation smallholders attribute to land use types and to determine the role that value systems play in shaping environmental behavior and knowledge. At the community level, increased market integration of tea agroforests is associated with reconfiguration of land use, intensified management, reorganization of labor structures, and generation of knowledge on tea resources. Akha have tapped into customary resources and forged new social networks with tea industry agents to take advantage of emerging market opportunities. They have resisted state reforms calling for the cultivation of high-intensity plantations and introduced cultivars. Consequently, they have benefited from price premiums through niche market networks for tea sourced from agroforests and proprietary landraces not available to other communities disempowered by market cycles. Subsistence agriculture, home gardening, and foraging persist for food security despite tea wealth. However, as traditional values are reoriented toward market-based ideologies, the community may risk a breakdown of the social institutions that support sustainability.Item Biodiversity and Phytochemical Quality in Indigenous and State-Supported Tea Management Systems of Yunnan, China.(2013-02) Ahmed, Selena; Peters, Charles M.; Chunlin, Long; Meyer, Rachel; Unachukwu, Uchenna J.; Litt, Amy; Kennelly, Edward J.; Stepp, John R.The Chinese government initiated one of the world's largest conservation programs involving agricultural ecosystems with the implementation of the ‘Grain for Green’ (Tui Geng Huan Lin) forest policy between 1999 and 2003. This is the first study to systematically quantify multiple dimensions of biodiversity, phytochemical quality and economic benefits associated with (1) the Grain for Green's tea (Camellia sinensis; Theaceae) initiative; (2) the state's previous forest policy involving tea populations in protected areas and; (3) the indigenous tea agro‐ecosystems replaced or overlooked by this conservation program. There are several novel and unexpected findings. While forest populations contained the greatest ecological diversity, agro‐forests and mixed crop plots were associated with the greatest genetic diversity, phytochemical quality and economic benefits. Indigenous management practices should be incorporated into conservation in China in order to create policies that are more aligned towards biodiversity conservation and sustainable livelihoods while allowing local communities to maintain their cultural identity through agrarian practices.Item Effects of water availability and pest pressures on tea (Camellia sinensis) growth and functional quality(2014-01) Ahmed, Selena; Orians, Colin M.; Griffin, Timothy S.; Buckley, Sarabeth; Unachukwu, Uchenna J.; Stratton, Anne E.; Stepp, John Richard; Robbat, Albert Jr.; Cash, Sean; Kennelly, Edward J.Extreme shifts in water availability linked to global climate change are impacting crops worldwide. The present study examines the direct and interactive effects of water availability and pest pressures on tea (Camellia sinensis; Theaceae) growth and functional quality. Manipulative greenhouse experiments were used to measure the effects of variable water availability and pest pressures simulated by jasmonic acid (JA) on tea leaf growth and secondary metabolites that determine tea quality. Water treatments were simulated to replicate ideal tea growing conditions and extreme precipitation events in tropical southwestern China, a major centre of tea production. Results show that higher water availability and JA significantly increased the growth of new leaves while their interactive effect was not significant. The effect of water availability and JA on tea quality varied with individual secondary metabolites. Higher water availability significantly increased total methylxanthine concentrations of tea leaves but there was no significant effect of JA treatments or the interaction of water and JA. Water availability, JA treatments or their interactive effects had no effect on the concentrations of epigallocatechin 3-gallate. In contrast, increased water availability resulted in significantly lower concentrations of epicatechin 3-gallate but the effect of JA and the interactive effects of water and JA were not significant. Lastly, higher water availability resulted in significantly higher total phenolic concentrations but there was no significant impact of JA and their interaction. These findings point to the fascinating dynamics of climate change effects on tea plants with offsetting interactions between precipitation and pest pressures within agro-ecosystems, and the need for future climate studies to examine interactive biotic and abiotic effects.Item Effects of Extreme Climate Events on Tea (Camellia sinensis) Functional Quality Validate Indigenous Farmer Knowledge and Sensory Preferences in Tropical China(2014-10) Ahmed, Selena; Stepp, John Richard; Orians, Colin M.; Griffin, Timothy S.; Matyas, Corene; Robbat, Albert Jr.; Cash, Sean; Xue, Dayuan; Long, Chunlin; Unachukwu, Uchenna J.; Buckley, Sarabeth; Small, David; Kennelly, EdwardClimate change is impacting agro-ecosystems, crops, and farmer livelihoods in communities worldwide. While it is well understood that more frequent and intense climate events in many areas are resulting in a decline in crop yields, the impact on crop quality is less acknowledged, yet it is critical for food systems that benefit both farmers and consumers through high-quality products. This study examines tea (Camellia sinensis; Theaceae), the world's most widely consumed beverage after water, as a study system to measure effects of seasonal precipitation variability on crop functional quality and associated farmer knowledge, preferences, and livelihoods. Sampling was conducted in a major tea producing area of China during an extreme drought through the onset of the East Asian Monsoon in order to capture effects of extreme climate events that are likely to become more frequent with climate change. Compared to the spring drought, tea growth during the monsoon period was up to 50% higher. Concurrently, concentrations of catechin and methylxanthine secondary metabolites, major compounds that determine tea functional quality, were up to 50% lower during the monsoon while total phenolic concentrations and antioxidant activity increased. The inverse relationship between tea growth and concentrations of individual secondary metabolites suggests a dilution effect of precipitation on tea quality. The decrease in concentrations of tea secondary metabolites was accompanied by reduced farmer preference on the basis of sensory characteristics as well as a decline of up to 50% in household income from tea sales. Farmer surveys indicate a high degree of agreement regarding climate patterns and the effects of precipitation on tea yields and quality. Extrapolating findings from this seasonal study to long-term climate scenario projections suggests that farmers and consumers face variable implications with forecasted precipitation scenarios and calls for research on management practices to facilitate climate adaptation for sustainable crop production.