REVIEW | doi:10.20944/preprints202103.0598.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Camellia sinensis; tea polyphenols; gut microbiota; gastrointestinal bacteria; systematic review
Online: 24 March 2021 (16:18:03 CET)
A diet high in polyphenols is associated with a diversified gut microbiome. Tea is the second most consumed beverage in the world, after water. The health benefits of tea might be attributed to the presence of polyphenol compounds such as catechins, theaflavins, tannins, and flavonoids. Although many studies are on tea, little is known of its effects on trillions of gut microbiota. Hence, this review is aimed at systematically studying the effect of tea polyphenols on the stimulation or suppression of gut microbiota in humans and animals. It was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol. Articles were retrieved from PubMed and Scopus databases, and data were extracted from 6 human trials and 15 animal studies. Overall, huge variations were observed in terms of microbiota composition between humans and animals. A more consistent pattern of diversified microbiota was observed in animal studies. Tea alleviated the gut microbiota imbalance caused by high-fat diet-induced obesity, diabetes, and ultraviolet-induced damage. Overall changes in microbiota composition measured by beta diversity analysis showed that tea had shifted the microbiota from the pattern seen in animals that received tea-free intervention. In humans, the prebiotic-like effect was observed towards gut microbiota, but these results appear in lower-quality studies. Beta diversity in human microbiota remains intact despite tea intervention; supplementation with different teas affected different types of bacterial taxa in the gut. These studies suggest that tea polyphenols may have a prebiotic effect in disease-induced animals and in a limited number of human interventions. Further intervention is needed to identify the mechanisms of action underlying the effects of tea on gut microbiota.
ARTICLE | doi:10.20944/preprints201807.0433.v1
Subject: Biology, Plant Sciences Keywords: Near infrared reflectance spectroscopy; Camellia seeds kernel; Oil content; Moisture content
Online: 23 July 2018 (21:12:39 CEST)
A fast and effective determination method of different species of vegetable seeds oil is vital in the plant oil industry. The near-infrared reflectance spectroscopy (NIRS) method was developed in this study to massively analyze the oil and moisture contents of Camellia gauchowensis Chang and C. semiserrata Chi seeds kernels. In the prediction models of NIRS, the levels of accuracy obtained were sufficient for C. gauchowensis Chang and C. semiserrata Chi, the correlation coefficient of which oil were 0.983 and 0.962, respectively, while which of moisture were 0.937 and 0.907, respectively. The near infrared spectrum of crush seeds kernels was more precise compared to intact kernels. Based on the calibration models of the two Camellia species, the NIRS predictive oil contents of C. gauchowensis Chang and C. semiserrata Chi seeds kernels were 48.71 ± 8.94% and 31.71 ± 7.39%, respectively, and the NIRS predictive moisture contents were 4.39 ± 1.08% and 3.49 ± 0.71%, respectively. Compared with the traditional chemical measurement, the rapid, precise measurement of oil and moisture of C. gauchowensis Chang and C. semiserrata Chi seeds kernels can be actualized by NIRS method.
ARTICLE | doi:10.20944/preprints201806.0122.v1
Subject: Medicine & Pharmacology, Nutrition Keywords: Camellia oleifera cake; phenolic component; organic acid; antioxidant capacity; antimicrobial activity
Online: 7 June 2018 (12:34:19 CEST)
There is a great interest in finding antioxidants and products with antimicrobial activities from natural sources. The aim of this study was to obtain and identify the phenolic components and organic acids from Camellia oleifera cake. In addition, their antioxidant and antimicrobial activities were also investigated. The purity of phenolic components and organic acids obtained were 94.1 ± 0.5% w/w and 96.0 ± 0.3% w/w, respectively. There are 15 phenolic components have been detected and identified by HPLC-ESI-MS. Oxalic, citric, acetic, malic, and succinic acids are found to be major organic acids. The phenolic components and organic acids both had good antioxidant capacity, evaluated by 4 antioxidant activity assays (hydroxyl radical scavenging, superoxide radical scavenging, 1,1-diphenyl-2-picryl-hydrazyl radical scavenging and lipid peroxidation inhibition). In addition, the phenolic components and organic acids exhibited significant inhibitory activity against bacteria Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and fungi Mucor racemosus, Aspergillus oryzae, Rhizopus stolonifer. The phenolic components and organic acids from C. oleifera cake both showed good antioxidant capacity and exhibited antimicrobial activities. These results may be useful for the future use of phenolic components and organic acids from C. oleifera cake.
REVIEW | doi:10.20944/preprints201609.0013.v1
Subject: Medicine & Pharmacology, General Medical Research Keywords: Camellia sinensis; tea ploysaccharides; chemical composition; antioxidant; antitumors; antihyperglycemia; anti-inflammation
Online: 5 September 2016 (10:19:33 CEST)
Tea (Camellia sinenesis) is a health beneficial beverage and is also a source for extracting bioactive components such as theanine, tea polyphenols (TPP) and tea polysaccharides (TPS). TPS is a group of hetero-polysaccharides bounded with proteins. There were tests showing that TPS had various bioactivities, such as antioxidant, antitumors, antihyperglycemia, anti-inflammation and improving immunity. However, inconsistent results concerning chemical composition and bioactivity of TPS were published in recent years. The advances in chemical composition and bioactivities of TPS were reviewed in the present paper. The inconsistent and controversial results regarding composition and bioactivities of TPS were also discussed.
REVIEW | doi:10.20944/preprints202011.0499.v1
Subject: Medicine & Pharmacology, Allergology Keywords: condensed tannins; proanthocyanidins; flavan-3-ols; periodontitis; gingivitis; gum disease; cranberry; Camellia sinensis; polyphenols
Online: 19 November 2020 (10:26:44 CET)
Flavan-3-ols and their oligomeric forms called proanthocyanidins are polyphenolic compounds occurring in several foodstuffs and in many medicinal herbs. Their consumption is associated with numerous health benefits. Their bioactivities include antioxidant, anti-inflammatory, cytoprotective, as well as antimicrobial. The latter property is important in prevention and treatment of periodontal diseases. Periodontitis is a multifactorial polymicrobial infection characterized by a destructive inflammatory process affecting the periodontium. Using non-toxic and efficient natural products such as flavanol derivatives can significantly contribute to alleviating of periodontitis symptoms and prevent the disease progress. In this paper, we systematically review the state-of-the art in antibacterial effects of these compounds from the viewpoint of gum health. There is a significant evidence supporting an importance of antibacterial action exerted by proanthocyanidins from edible fruits, tea and medicinal herbs in inhibition of periodontitis-causing pathogens.
REVIEW | doi:10.20944/preprints202011.0671.v1
Subject: Medicine & Pharmacology, Allergology Keywords: condensed tannins; proanthocyanidins; flavan-3-ols; periodontitis; gingivitis; gum disease; cranberry; Camellia sinensis; polyphenols; immunomodulatory
Online: 26 November 2020 (11:22:42 CET)
This paper continues the review study on antimicrobial properties relevant to the periodontal diseases. Inflammation as a major response of the periodontal tissues attacked by pathogenic microbes can significantly exacerbate the condition. However, the bidirectional activity of phytochemicals that simultaneously inhibit bacterial proliferation and proinflammatory signaling can provide a substantial alleviation of both cause and symptoms. The modulatory effects on various aspects of inflammatory and overall immune response has been covered, including confirmed and postulated mechanisms of action, structure activity relationships and molecular targets. Further, the clinical relevance of flavan-3-ols and available outcomes from clinical studies has been analyzed and discussed. Among the numerous natural sources of flavan-3-ols and proanthocyanidins the most promising are, similarly to antibacterial properties, constituents of various foods, such as fruits of Vaccinium species, tea leaves, grape seeds, and tannin-rich medicinal herbs. Despite a vast amount of in vitro and cell-based evidence of immunomodulatory there is still much less studies using animal models and only a few clinical studies. Most of the studies, regardless of the used model indicated efficiency of these phytochemicals from cranberries and other Vaccinium species and tea extracts (green or black). Other sources such as grape seeds and traditional medicinal plants, were seldom. In conclusion, the potential of flavan-3-ols and their derivatives in prevention and alleviation of periodontitis is remarkable but clinical evidence is urgently needed for issuing credible dietary recommendation and complementary treatments.