Phytochemistry, Modes of Action and Beneficial Health Applications of Green Tea (Camellia sinensis) in Humans and Animals

Tea's anti-obesity properties, cardiometabolic health-promoting potentials, bioactive compounds, and adverse effects: A review focusing on white and green teas

Tea is one of the most commonly consumed beverages in the world. Morocco, Japan, and China have consumed green tea for centuries. White tea, which is a variety of green teas, is very popular in China and is highly revered for its taste. Presently, both teas are consumed in other countries around the world, even as functional ingredients, and novel research is constantly being conducted in these areas. We provide an update on the health benefits of white and green teas in this review, based on recent research done to present. After a general introduction, we focused on tea's anti-obesity and human health-promoting potential, adverse effects, and new approaches to tea and its bioactive compounds. It has been found that the health benefits of tea are due to its bioactive components, mainly phenolic compounds. Of these, catechins are the most abundant. This beverage (or its extracts) has potential anti-inflammatory and antioxidant properties, which could contribute to body weight control and the improvement of several chronic diseases. However, some studies have mentioned the possibility of toxic effects; therefore, reducing tea consumption is a good idea, especially during the last trimester of pregnancy. Additionally, new evidence will provide insight into the possible effects of tea on the human gut microbiota, and even on the viruses responsible for SARS-CoV-2. A beverage such as this may favor beneficial gut microbes, which may have important implications due to the influence of gut microbiota on human health.

Bioassay-Guided Alkaloids Isolation from Camellia sinensis and Colchicum luteum: In Silico and In Vitro Evaluations for Protease Inhibition

Bioassay-guided isolation from Camellia sinensis (Theaceae) and Colchicum luteum (Liliaceae) utilizing an in vitro model of protease assay revealed colchicine (1) and caffeine (2) from chloroform fractions, respectively. Their structures were validated using spectral techniques. The purified compounds were further optimized with Gaussian software utilizing the B3LYP functional and 6-31G(d,p) basis set. The result files were utilized to determine several global reactivity characteristics to explain the diverse behavior of the compounds. Colchicine (1) showed a higher inhibition of protease activity (63.7 ± 0.5 %age with IC50 = 0.83 ± 0.07 mM), compared with caffeine (2) (39.2 ± 1.3 %age). In order to determine the type of inhibition, compound 1 was further studied, and, based on Lineweaver–Burk/Dixon plots and their secondary replots, it was depicted that compound 1 was a non-competitive inhibitor of this enzyme, with a Ki value of 0.690 ± 0.09 mM. To elucidate the theoretical features of protease inhibition, molecular docking studies were performed against serine protease (PDB #1S0Q), which demonstrated that compound 1 had a strong interaction with the different amino acid residues located on the active site of this understudied enzyme, with a high docking score of 16.2 kcal/mol.

Functional roles of taurine, L-theanine, L-citrulline, and betaine during heat stress in poultry

Heat stress (HS) is an important environmental stress factor affecting poultry production on a global scale. With the rise in ambient temperature and increasing effects of global warming, it becomes pertinent to understand the effects of HS on poultry production and the strategies that can be adopted to mitigate its detrimental impacts on the performance, health, welfare, immunity, and survival of birds. Amino acids (AAs) have been increasingly adopted as nutritional modifiers in animals to ameliorate the adverse effects of HS. They are essential for protein synthesis, growth, maintenance, reproduction, immunity, stress response, and whole-body homeostasis. However, HS tends to adversely affect the availability, transport, absorption, and utilization of these AAs. Studies have investigated the provision of these AAs to poultry during HS conditions, and variable findings have been reported. Taurine, L-theanine, and L-citrulline are non-essential amino acids that are increasingly gaining attention as nutritional supplements in HS animals. Similarly, betaine is an amino acid derivative that possesses favorable biological properties which contributes to its role as a functional additive during HS. Of particular note, taurine is negligible in plants, while betaine, L-theanine, and L-citrulline can be found in selected plants. These nutrients are barely found in feed ingredients, but their supply has been shown to elicit important physiological roles including anti-stress effects, anti-oxidative, anti-inflammatory, gut promoting, and immunomodulatory functions. The present review provides information on the use of these nutritionally and physiologically beneficial nutrients as functional additives to poultry diets during HS conditions. Presently, although several studies have reported on the positive effects of these additives in human and murine studies, however, there is limited information regarding their utilization during heat stress in poultry nutrition. Therefore, this review aims to expound on the functional properties of these nutrients, their potentials for HS alleviation, and to stimulate further researches on their biological roles in poultry nutrition.

Green and white teas as health-promoting foods

Tea is one of the most consumed beverages around the world and as such, it is constantly the object of novel research. This review focuses on the research performed during the last five years to provide an updated view of the current position of tea regarding human health. According to most authors, tea health benefits can be traced back to its bioactive components, mostly phenolic compounds. Among them, catechins are the most abundant. Tea has an important antioxidant capacity and anti-inflammatory properties, which make this beverage (or its extracts) a potential aid in the fight against several chronic diseases. On the other hand, some studies report the possibility of toxic effects and it is advisable to reduce tea consumption, such as in the last trimester of pregnancy. Additionally, new technologies are increasing researchers' possibilities to study the effect of tea on human gut microbiota and even against SARS CoV-2. This beverage favours some beneficial gut microbes, which could have important repercussions due to the influence of gut microbiota on human health.

Non-targeted and targeted metabolomics profiling of tea plants (Camellia sinensis) in response to its intercropping with Chinese chestnut

BACKGROUND

Intercropping is often used in the tea producing areas where land resources are not so abundant, and the produced green tea is tasted more delicious through a tea-Chinese chestnut intercropping system according to the experience of indigenous farmers. The length and weight of tea leaf increase under this intercropping system and their root systems are stratified vertically and coordinate symbiosis. However, the delicacy mechanism under the intercropping is not fully understood.

RESULTS

Green tea from the Chinese chestnut-tea intercropping system established in the 1980s ranked highest compared with a pure tea plantation from the same region. Based on the non-targeted metabolomics, 100 differential metabolites were upregulated in the tea leaves from intercropping system relative to monoculture system. Twenty-one amino acids were upregulated and three downregulated in response to the intercropping based on the targeted metabolomics; half of the upregulated amino acids had positive effects on the tea taste. Levels of allantoic acid, sugars, sugar alcohols, and oleic acid were higher and less bitter flavonoids in the intercropping system than those in monoculture system. The upregulated metabolites could promote the quality of tea and its health-beneficial health effects. Flavone and flavonol biosynthesis and phenylalanine metabolism showed the greatest difference. Numerous pathways associated with amino acid metabolism altered, suggesting that the intercropping of Chinese chestnut-tea could greatly influence amino acid metabolism in tea plants.

CONCLUSIONS

These results enhance our understanding of the metabolic mechanisms by which tea quality is improved in the Chinese chestnut-tea intercropping system and demonstrate that there is great potential to improve tea quality at the metabolomic level by adopting such an intercropping system.

A Review of Medicinal Plants in Cardiovascular Disorders: Benefits and Risks

Many cultivated and wild plants are used for the management of various diseases, specifically renal and hepatic diseases and those of the immune and cardiovascular systems. In China, medicinal plants from ancient to modern history have been used in patients with angina pectoris, congestive heart failure (CHF), systolic hypertension, arrhythmia, and venous insufficiency for centuries. The latest increase in the fame of natural products and alternative medicine has revived interest in conventional remedies that have been consumed in the management of CVD. The cardio-protective properties of the various herbs are possibly due to their anti-oxidative, antihypercholesterolemic, anti-ischemic activities, and inhibition of platelet aggregation that reduce the risk of CVD. Ethno-pharmacological and biological properties of these plants are explored, based upon published scientific literature. Although a majority of medicinal plants having a biological mechanism that linked with CVD management, to date, published literature pertaining to their promising scientific properties are still poorly understood. Compared with synthetic medicines, alternative medicines do not need scientific studies before their formal approval from the government sector and due to this purpose; their safety, as well as efficacy, still remain elusive. Taken together, we addressed all accessible evidence on alternative medicines commonly consumed in CVD management. Our comprehensive analysis of the scientific literature indicated that many TCMs are available and valuable herbal medication would be the best alternative for the management of CVD as a complementary therapy. Furthermore, practitioners should always discuss possible benefits-risks of alternative medicines with patients so that they are aware of the consumption of alternative medications.

L-theanine: an astounding sui generis amino acid in poultry nutrition

L-theanine (γ-Glutamylethylamide) is a nonprotein water soluble amino acid (AA) mostly found in leaves of Camellia sinensis (green tea). This is a key component of green tea and is considered as the most abundant form of total AAs in green tea (i.e., about 50%). L-theanine is an exclusive taste ingredient of tea producing an attractive flavor and aroma in tea. It has biological effects such as antioxidant, growth promoter, immune booster, anti-stresser, hepatoprotective, antitumor, antiaging, antimicrobial, anti-inflammatory, and antianxiety activities that are worth noticing. It could reduce the oxidative impairment by reducing the synthesis of reactive oxygen species, oxidative parameters, and lipid damage as well as increasing the activity of antioxidant enzymes. The oral ingestion of L-theanine enhanced γδ T-cell proliferation. Therefore, it is being considered an essential compound of green tea that has the ability to improve immune function. The L-theanine can be used as a potential treatment for hepatic injury and immune-related liver diseases via the downregulation of the inflammatory response through the initiation of nitric oxide synthesis and glutathione production which are likely to be critical for the control of hepatic diseases as well as for the improvement of immune function. In addition, it could be used as a best natural feed additive with a potent antistressor by decreasing the levels of corticosterone, dopamine, and noradrenaline. After systematically reviewing the literature, it is noticed that most studies were carried out on mice, pig, human, and butterfly; while dietary supplementation studies of L-theanine in animal and poultry especially among broilers are very limited because of less awareness of this AA. So, the aim of this review is to encourage the veterinarian and poultry researchers to conduct more research at the molecular level about this AA to expose its more beneficial effects and its mechanism of absorption for potential use of this unique green tea AA in poultry nutrition.

Epigallocatechin-3-gallate activates the AMP-activated protein kinase signaling pathway to reduce lipid accumulation in canine hepatocytes

Epigallocatechin-3-gallate (EGCG) plays a crucial role in hepatic lipid metabolism. However, the underlying regulatory mechanism of hepatic lipid metabolism by EGCG in canine is unclear. Primary canine hepatocytes were treated with EGCG (0.01, 0.1, or 1 μM) and BML-275 (an AMP-activated protein kinase [AMPK] inhibitor) to study the effects of EGCG on the gene and protein expressions associated with AMPK signaling pathway. Data showed that treatment with EGCG had greater activation of AMPK, as well as greater expression levels and transcriptional activity of peroxisome proliferator activated receptor-α (PPARα) along with upregulated messenger RNA (mRNA) abundance and protein abundance of PPARα-target genes. EGCG decreased the expression levels and transcriptional activity of sterol regulatory element-binding protein 1c (SREBP-1c) along with downregulated mRNA abundance and protein abundance of SREBP-1c target genes. Of particular interest, exogenous BML-275 could reduce or eliminate the effects of EGCG on lipid metabolism in canine hepatocytes. Furthermore, the content of triglyceride was significantly decreased in the EGCG-treated groups. These results suggest that EGCG might be a potential agent in preventing high-fat diet-induced lipid accumulation in small animals.

Effects of dried okra fruit (Abelmoschus esculentus L.) powder on growth, carcass characteristics, blood indices, and meat quality of stored broiler meat

The present study investigated the impacts of dried okra fruit powder (DOFP), used as a natural feed supplement, on growth, carcass, blood, and meat quality parameters of broilers. A total of 240 unsexed, one-week-old chicks were randomly allotted to 4 equal groups with 6 replicates in each group (i.e., 10 birds/replicate). The dietary treatments consisted of the basal diet as control, and 3 DOFP groups, supplemented with 1.0, 2.0, and 3.0 g DOFP/kg feed, respectively. The results showed that the highest values of live body weight and body weight gain were observed in the group with 1.0 g of DOFP/kg of feed during the fifth week of age and between 1 and 5 wk of age, respectively. During 1 to 3 wk of age, daily feed consumption of chicks fed DOFP-supplemented diets increased numerically with increasing DOFP levels. Dietary treatments significantly depressed liver, thigh, and dressing fat percentages. Chicks fed the diet containing 1.0 g of DOFP/kg of feed had the lowest values for serum urea and creatinine compared with the other treatment group. In addition, the concentration of liver enzymes decreased with increasing DOFP levels, except for the groups fed 3.0 and 1.0 g of DOFP/kg of diet. Oxidative rancidity of broiler meat samples containing DOFP in their diets was lower than that of the control samples, throughout the storage period. It can be concluded that DOFP is a useful phytogenic additive, which can lower the percentage of abdominal fat of the carcass, as well as alanine aminotransferase, urea, and creatinine in the blood. Furthermore, all sensory characteristics of the meat were improved by the addition of DOFP to broiler diets. It could be concluded that DOFP can be used as a natural supplement in broiler diets for improving growth performance and reducing abdominal fat, blood creatinine, and urea.

Nutritional applications and beneficial health applications of green tea and l-theanine in some animal species: A review

Green tea (Camellia sinensis) is a popular herbal plant with abundant health benefits, and thus, it has been used as a potent antioxidant for a long time. Based on the available literature, the diversity and the availability of multifunctional compounds in green tea offer its noteworthy potential against many diseases such as liver and heart diseases, inflammatory conditions and different metabolic syndromes. Owing to its bioactive constituents including caffeine, amino acids, l-theanine, polyphenols/flavonoids and carbohydrates among other potent molecules, green tea has many pharmacological and physiological effects. The effects of green tea include anti-oxidative, anti-inflammatory, anti-arthritic, anti-stress, hypolipidaemic, hypocholesterolaemic, skin/collagen protective, hepatoprotective, anti-diabetic, anti-microbial, anti-infective, anti-parasitic, anti-cancerous, inhibition of tumorigenesis and angiogenesis, anti-mutagenic, and memory and bone health-improving activities. Apart from its utilization in humans, green tea has also played a significant role in livestock production such as in dairy, piggery, goatry and poultry industries. Supplementation of animal feeds with green tea and its products is in line with the modern concepts of organic livestock production. Hence, incorporating green tea or green tea by-products into the diet of poultry and other livestock can enhance the value of the products obtained from these animals. Herein, an effort is made to extend the knowledge on the importance and useful applications of green tea and its important constituents in animal production including poultry. This review will be a guideline for researchers and entrepreneurs who want to explore the utilization of feeds supplemented with green tea and green tea by-products for the enhancement of livestock production.

Green tea (Camellia sinensis) and l-theanine: Medicinal values and beneficial applications in humans-A comprehensive review

Green tea (Camellia sinensis) is a famous herb, and its extract has been extensively used in traditional Chinese medicinal system. In this context, several studies have revealed its health benefits and medicinal potentialities for several ailments. With ever increasing scientific knowledge, search for safer, potential and novel type of health-related supplements quest, scientists are re-directing their research interests to explore natural resources i.e. medicinal herbs/plant derived compounds. Green tea consumption has gained a special attention and popularity in the modern era of changing lifestyle. The present review is aimed to extend the current knowledge by highlighting the importance and beneficial applications of green tea in humans for safeguarding various health issues. Herein, we have extensively reviewed, analyzed, and compiled salient information on green tea from the authentic published literature available in PubMed and other scientific databases. Scientific literature evidenced that owing to the bioactive constituents including caffeine, l-theanine, polyphenols/flavonoids and other potent molecules, green tea has many pharmacological and physiological functions. It possesses multi-beneficial applications in treating various disorders of humans. This review also provides in-depth insights on the medicinal values of green tea which will be useful for researchers, medical professionals, veterinarians, nutritionists, pharmacists and pharmaceutical industry. Future research emphasis and promotional avenues are needed to explore its potential therapeutic applications for designing appropriate pharmaceuticals, complementary medicines, and effective drugs as well as popularize and propagate its multidimensional health benefits.