Antibacterial and laxative activities of strictinin isolated from Pu'er tea (Camellia sinensis)

Constituent analysis, laxative activity, and toxicological evaluation of methanol extract of noni fruit (Morinda citrifolia L., Rubiaceae)

Noni fruits have gained considerable popularity as dietary supplements. However, the major constituents, the laxative activity, and the toxicity of Noni fruit remains still unknown. The purpose of the present study was, therefore, to analyze the constituents of methanol extract of Noni fruit by UPLC-MS, and further evaluate laxative activity and safety aspects of this Noni fruit-derived products in mice. UPLC-MS analysis identified eleven major constituents from this Noni fruit extract. Administration of this extract obviously shortened the time of first fecal excrement, significantly increased the total number and the weight of stools, and remarkably restored the intestinal transit to normal level in the constipated mice, with low toxicity to liver and kidney, and meanwhile, the abundance, composition, and function of gut microbiota remained homeostasis. These results revealed the laxative activity of the methanol extract of Noni fruit with low toxicity and no influence on gut microbiota.

Receptor tyrosine kinase-like orphan receptor 1 inhibitor strictinin exhibits anti-cancer properties against highly aggressive androgen-independent prostate cancer

Aim

It is important to identify anti-cancer compounds that can inhibit specific molecular targets to eradicate androgen-receptor negative (ARneg), androgen-independent (AI) prostate cancer, which is an aggressive form of prostate cancer with limited treatment options. The goal of this study was to selectively target prostate cancer cells that have high levels of oncogenic protein Receptor tyrosine kinase-like orphan receptor 1 (ROR1) by using strictinin, a small molecule ROR1 inhibitor.

Methods

The methods performed in this study include western blots, methyl thiazolyl tetrazolium (MTT) proliferation assays, phosphatidylserine apoptosis assays, apoptosis flow cytometry (Annexin V, caspase 3/7), migration scratch assays, Boyden chamber invasion assays, and cell cycle flow cytometry.

Results

Strictinin was most lethal against PC3 [half-maximal drug inhibitory concentration (IC50) of 277.2 µmol/L], an ARneg-AI cell type that expresses the highest levels of ROR1. Strictinin inhibited ROR1 expression, downstream phosphatidylinositol 3-kinase (PI3K)-protein kinase B (AKT)-glycogen synthase kinase 3beta (GSK3β) pro-survival signaling, and epithelial-to-mesenchymal transition markers in PC3 cells. Additionally, strictinin decreased PC3 cell migration and invasion, while increasing S-phase cell cycle arrest. In ARneg-AI DU145 cells, strictinin inhibited ROR1 expression and modulated downstream AKT-GSK3β signaling. Furthermore, strictinin exhibited anti-migratory, anti-invasive, but minimal pro-apoptotic effects in DU145 cells likely due to DU145 having less ROR1 expression in comparison to PC3 cells. Throughout the study, strictinin minimally impacted the phenotype of normal prostatic epithelial cells RWPE-1 (IC50 of 658.5 µmol/L). Strictinin was further identified as synergistic with docetaxel [combination index (CI) = 0.311] and the combination therapy was found to reduce the IC50 of strictinin to 38.71 µmol/L in PC3 cells.

Conclusions

ROR1 is an emerging molecular target that can be utilized for treating prostate cancer. The data from this study establishes strictinin as a potential therapeutic agent that targets ARneg-AI prostate cancer with elevated ROR1 expression to reduce the migration, invasion, cell cycle progression, and survival of prostate cancer.

Strictinin: A Key Ingredient of Tea

Strictinin is a relatively tiny ellagitannin, which is found in many plants as a minor constituent. Catechins are known as the major constituents in the young leaves of most tea plants, while strictinin was found as a major constituent in the Pu'er tea plant. In some Pu'er tea varieties, strictinin was identified as the most abundant phenolic compound rather than catechins. In the past decade, strictinin was demonstrated to possess several functional activities, including antiviral, antibacterial, anti-obesity, laxative, anticaries, anti-allergic, antipsoriatic, antihyperuricemia, antidiabetic, and anticancer effects. These functional activities were in accordance with the therapeutic effects empirically perceived for Pu'er tea. Evidently, strictinin is the key ingredient in Pu'er tea that acts as a herbal medicine. In functionally-based applications, an instant powder of Pu'er tea infusion was formulated as an active raw material to be supplemented in food, cosmetics, and beverages; a new type of tea named Bitter Citrus Tzen Tea was developed by combining three teas empirically consumed to expel the cold, and new edible oral care products were designed for caries prevention by supplementation with Pu'er tea extract. More functional activities and practical applications of strictinin are scientifically anticipated in follow-up research.

Therapeutic Potential of Phenolic Compounds in Medicinal Plants-Natural Health Products for Human Health

Phenolic compounds and flavonoids are potential substitutes for bioactive agents in pharmaceutical and medicinal sections to promote human health and prevent and cure different diseases. The most common flavonoids found in nature are anthocyanins, flavones, flavanones, flavonols, flavanonols, isoflavones, and other sub-classes. The impacts of plant flavonoids and other phenolics on human health promoting and diseases curing and preventing are antioxidant effects, antibacterial impacts, cardioprotective effects, anticancer impacts, immune system promoting, anti-inflammatory effects, and skin protective effects from UV radiation. This work aims to provide an overview of phenolic compounds and flavonoids as potential and important sources of pharmaceutical and medical application according to recently published studies, as well as some interesting directions for future research. The keyword searches for flavonoids, phenolics, isoflavones, tannins, coumarins, lignans, quinones, xanthones, curcuminoids, stilbenes, cucurmin, phenylethanoids, and secoiridoids medicinal plant were performed by using Web of Science, Scopus, Google scholar, and PubMed. Phenolic acids contain a carboxylic acid group in addition to the basic phenolic structure and are mainly divided into hydroxybenzoic and hydroxycinnamic acids. Hydroxybenzoic acids are based on a C6-C1 skeleton and are often found bound to small organic acids, glycosyl moieties, or cell structural components. Common hydroxybenzoic acids include gallic, syringic, protocatechuic, p-hydroxybenzoic, vanillic, gentistic, and salicylic acids. Hydroxycinnamic acids are based on a C6-C3 skeleton and are also often bound to other molecules such as quinic acid and glucose. The main hydroxycinnamic acids are caffeic, p-coumaric, ferulic, and sinapic acids.

Strictinin, a Major Ingredient in Yunnan Kucha Tea Possessing Inhibitory Activity on the Infection of Mouse Hepatitis Virus to Mouse L Cells

Theacrine and strictinin of Yunnan Kucha tea prepared from a mutant variety of wild Pu'er tea plants were two major ingredients responsible for the anti-influenza activity. As the COVID-19 outbreak is still lurking, developing safe and cost-effective therapeutics is an urgent need. This study aimed to evaluate the effects of these tea compounds on the infection of mouse hepatitis virus (MHV), a β-coronavirus serving as a surrogate for SARS-CoV. Treatment with strictinin (100 μM), but not theacrine, completely eliminated MHV infection, as indicated by a pronounced reduction in plaque formation, nucleocapsid protein expression, and progeny production of MHV. Subsequently, a time-of-drug addition protocol, including pre-, co-, or post-treatment, was exploited to further evaluate the possible mechanism of antiviral activity mediated by strictinin, and remdesivir, a potential drug for the treatment of SARS-CoV-2, was used as a positive control against MHV infection. The results showed that all three treatments of remdesivir (20 μM) completely blocked MHV infection. In contrast, no significant effect on MHV infection was observed when cells were pre-treated with strictinin (100 μM) prior to infection, while significant inhibition of MHV infection was observed when strictinin was introduced upon viral adsorption (co-treatment) and after viral entry (post-treatment). Of note, as compared with the co-treatment group, the inhibitory effect of strictinin was more striking in the post-treatment group. These results indicate that strictinin suppresses MHV infection by multiple mechanisms; it possibly interferes with viral entry and also critical step(s) of viral infection. Evidently, strictinin significantly inhibited MHV infection and might be a suitable ingredient for protection against coronavirus infection.

Medicinal Importance, Pharmacological Activities, and Analytical Aspects of Strictinin: A Mini-Review

BACKGROUND

Plants and their derived products have been used in history as food and medicine. Plant materials are rich sources of fiber, minerals, vitamins, and bioactive phytochemicals, which are useful for human beings. Strictinin is an important phytoconstituent of green tea.

METHODS

Present work mainly focuses on the biological importance, therapeutic potential, and pharmacological activities of strictinin in medicine. Numerous scientific data have been collected from various literature databases such as Google Scholar, Science Direct, PubMed, and Scopus database in order to realize the health beneficial potential of strictinin. Pharmacological data has been collected and analyzed in the present work to find the effectiveness of strictinin against human disorders and complications. Analytical data of strictinin has been also collected and analyzed in the present work.

RESULTS

Scientific data analysis revealed the biological importance of strictinin in medicine. Scientific data analysis signified the therapeutic benefit of strictinin mainly due to its anticancer, antimicrobial, antibacterial, antiviral, and antioxidant activity. However, enzymatic activities, cytotoxicity, effectiveness on skin disorders, and osteogenic potential of strictinin have also been discussed. Analytical data revealed the importance of modern analytical techniques in medicine for the separation, identification, and isolation of strictinin.

CONCLUSION

Present work signified the biological importance and therapeutic benefits of strictinin in medicine and other allied health sectors.

Pu'er tea water extract protects against cognitive impairment in a mouse model of lipopolysaccharide-induced neuroinflammation

BACKGROUND

Pu'er tea, a type of post-fermented tea made from Camellia sinensis leaves, has long been widely used in East Asian countries. It is mainly produced in southern China and is effective in preventing obesity due to its ability to break down fat. However, the effects of Pu'er tea on cognitive impairment or neuroinflammation by endotoxin have not yet been studied.

PURPOSE

Here, we assessed the inhibitory activity of Pu'er tea hot water extract (PTW) on neuroinflammation and cognitive impairment and explored its mechanism.

STUDY DESIGN

The ability of PTW to inhibit cognitive impairment was investigated in a mouse model of lipopolysaccharide (LPS)-induced neuroinflammation and murine microglia BV2 cells.

METHODS

We examined whether oral administration of PTW prevented cognitive impairment and LPS-induced neuroinflammation using behavioral tests, Nissl staining, immunohistochemistry, western blotting, real-time reverse transcription-polymerase chain reaction (real-time RT-PCR), Griess assay, and enzyme-linked immunosorbent assay (ELISA).

RESULTS

First, Morris water maze (MWM) and passive avoidance (PA) tests demonstrated that oral administration of PTW effectively attenuated LPS-induced spatial memory loss and inhibited neuronal damage of mouse brains. Histopathological analysis showed that PTW repressed LPS-induced expression of the activation markers ionized calcium-binding adaptor molecule-1 (Iba-1) and glial fibrillary acidic protein (GFAP). Furthermore, PTW inhibited the expression of amyloidogenesis proteins such as amyloid-β precursor protein (APP), C99, and β-secretase-1 (BACE-1); production of inflammatory proteins such as Iba-1, GFAP, inducible nitric oxide synthase (iNOS), and cyclooxygenase (COX)-2; activation of inflammatory pathways; and expression of inflammatory mediator mRNAs in hippocampal tissue. In cultured microglia, PTW treatment inhibited the generation of various inflammatory factors activated by LPS.

CONCLUSION

Our results in vivo and in vitro demonstrate that PTW effectively prevents cognitive impairment caused by neuroinflammation and is, therefore, a potential candidate for the development of a therapeutic agent for neurodegenerative diseases.

Theacrine and strictinin, two major ingredients for the anti-influenza activity of Yunnan Kucha tea

ETHNOPHARMACOLOGICAL RELEVANCE

Kucha tea plant (Camellia assamica var. kucha Chang et Wang) is regarded as a mutant variety of wild Pu'er tea plant found in few mountain areas of Yunnan, China. Its fresh young leaves and shoots are picked by the indigenous aborigines in these local areas to prepare an herbal tea for the treatment of common cold empirically.

MATERIALS AND METHODS

Two extra compounds of relative abundance were detected in Kucha tea in comparison with Pu'er tea, and their chemical structures were identified as chlorogenic acid and theacrine. These two compounds as well as two major compounds, strictinin and caffeine, in Kucha tea were evaluated for their cytotoxicity and inhibitory effects on human influenza virus A/Puerto Rico/8/34 by analyzing viral protein expression and progeny production.

RESULTS

No or low cytotoxicity was detected for the four Kucha compounds when their concentrations were below 100 μM. Expression of viral NS1 protein was significantly inhibited by chlorogenic acid, theacrine or strictinin, but not caffeine at a concentration of 100 μM. The relative inhibitory potency was detected as chlorogenic acid < theacrine < strictinin, and both theacrine and strictinin displayed significant inhibition at a concentration of 50 μM. According to a plaque assay, viral progeny production was significantly reduced by theacrine or strictinin, but not by chlorogenic acid or caffeine under the same concentration of 100 μM.

CONCLUSION

It is suggested that theacrine and strictinin are two major ingredients responsible for the anti-influenza activity of Yunnan Kucha tea traditionally used for the treatment of common cold.

Isolated Compounds from Turpinia formosana Nakai Induce Ossification

Bone metabolism is a homeostatic process, imbalance in which leads to the onset of diseases such as osteoporosis and osteopenia. Although several drugs are currently available to treat such conditions, they are associated with severe side effects and do not enhance bone formation. Thus, identifying alternative treatment strategies that focus on enhancing bone formation is essential. Herein, we explored the osteogenic potential of Turpinia formosana Nakai using human osteoblast (HOb) cells. The plant extract was subjected to various chromatographic techniques to obtain six compounds, including one new compound: 3,3′-di-O-methylellagic acid-4-O-α-l-arabinofuranoside (1). Compounds 3,3′-di-O-methylellagic acid-4-O-α-l-arabinofuranoside (1), gentisic acid 5-O-β-d-(6′-O-galloyl) glucopyranoside (2), strictinin (3), and (-)-epicatechin-3-O-β-d-allopyranoside (6) displayed no significant cytotoxicity toward HOb cells, and thus their effects on various osteogenic markers were analyzed. Results showed that 1–3 and 6 significantly increased alkaline phosphatase (ALP) activity up to 120.0, 121.3, 116.4, and 125.1%, respectively. Furthermore, 1, 2, and 6 also markedly enhanced the mineralization process with respective values of up to 136.4, 118.9, and 134.6%. In addition, the new compound, 1, significantly increased expression levels of estrogen receptor-α (133.4%) and osteogenesis-related genes of Runt-related transcription factor 2 (Runx2), osteopontin (OPN), bone morphogenetic protein (BMP)-2, bone sialoprotein (BSP), type I collagen (Col-1), and brain-derived neurotropic factor (BDNF) by at least 1.5-fold. Our results demonstrated that compounds isolated from T. formosana possess robust osteogenic potential, with the new compound, 1, also exhibiting the potential to enhance the bone formation process. We suggest that T. formosana and its isolated active compounds deserve further evaluation for development as anti-osteoporotic agents.

Ripe and Raw Pu-Erh Tea: LC-MS Profiling, Antioxidant Capacity and Enzyme Inhibition Activities of Aqueous and Hydro-Alcoholic Extracts

Herein, we reported a detailed profiling of soluble components of two fermented varieties of Chinese green tea, namely raw and ripe pu-erh. The identification and quantification of the main components was carried out by means of mass spectrometry and UV spectroscopy, after chromatographic separation. The antioxidant capacity towards different radical species, the anti-microbial and the enzyme inhibition activities of the extracts were then correlated to their main constituents. Despite a superimposable qualitative composition, a similar caffeine content, and similar enzyme inhibition and antimicrobial activities, raw pu-erh tea extract had a better antioxidant capacity owing to its higher polyphenol content. However, the activity of raw pu-erh tea seems not to justify its higher production costs and ripe variety appears to be a valid and low-cost alternative for the preparation of products with antioxidant or antimicrobial properties.

Flavonoids and Other Phenolic Compounds from Medicinal Plants for Pharmaceutical and Medical Aspects: An Overview

Phenolic compounds as well as flavonoids are well-known as antioxidant and many other important bioactive agents that have long been interested due to their benefits for human health, curing and preventing many diseases. This review attempts to demonstrate an overview of flavonoids and other phenolic compounds as the interesting alternative sources for pharmaceutical and medicinal applications. The examples of these phytochemicals from several medicinal plants are also illustrated, and their potential applications in pharmaceutical and medical aspects, especially for health promoting e.g., antioxidant effects, antibacterial effect, anti-cancer effect, cardioprotective effects, immune system promoting and anti-inflammatory effects, skin protective effect from UV radiation and so forth are highlighted.

Relative content of gallic acid over 5-galloylquinic acid as an index for the baking intensity of oolong teas

Phenolic compounds in a series of old oolong teas prepared by baking annually were monitored and compared. The results showed that the relative content of gallic acid over 5-galloylquinic acid was subsequently elevated during this preparatory process. To reveal the effect was mainly resulted from baking or aging, two sets of oolong teas were collected and examined; one set was generated from fresh oolong tea via continually daily baking and the other set was composed of aged oolong teas with no or light baking in the storage period. The relative content of gallic acid over 5-galloylquinic acid was observed to be subsequently elevated when oolong tea was continually baked at 90, 100, 110, and 120 °C for 8 h day after day. In contrast, the relative contents of gallic acid over 5-galloylquinic acid in aged oolong teas with no or light baking were found to be similar to or slightly higher than that in fresh oolong tea. The results suggest that the relative content of gallic acid over 5-galloylquinic acid seems to be a suitable index for the baking intensity of oolong tea in different preparations.

In vitro assay to estimate tea astringency via observing flotation of artificial oil bodies sheltered by caleosin fused with histatin 3

Astringency, a sensory characteristic of food and beverages rich in polyphenols, mainly results from the formation of complexes between polyphenols and salivary proteins, causing a reduction of the lubricating properties of saliva. To develop an in vitro assay to estimate the astringency of oolong tea infusion, artificial oil bodies were constituted with sesame oil sheltered by a modified caleosin fused with histatin 3, one of the human salivary small peptides. Aggregation of artificial oil bodies was induced when they were mixed with oolong tea infusion or its major polyphenolic compound, (−)-epigallocatechin gallate (EGCG) of 100μM as observed in light microscopy. The aggregated artificial oil bodies gradually floated on top of the solution and formed a visible milky layer whose thickness was in proportion to the concentrations of tea infusion. This assay system was applied to test four different oolong tea infusions with sensory astringency corresponding to their EGCG contents. The result showed that relative astringency of the four tea infusions was correlated to the thickness of floated artificial oil bodies, and could be estimated according to the standard curve generated by simultaneously observing a serial dilution of the tea infusion with the highest astringency.