Strictinin

Receptor tyrosine kinase-like orphan receptor 1 inhibitor strictinin exhibits anti-cancer properties against highly aggressive androgen-independent prostate cancer.[Pubmed:38213538]

Explor Target Antitumor Ther. 2023;4(6):1188-1209.

AIM: It is important to identify anti-cancer compounds that can inhibit specific molecular targets to eradicate androgen-receptor negative (AR(neg)), 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 (IC(50)) of 277.2 micromol/L], an AR(neg)-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 (GSK3beta) 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 AR(neg)-AI DU145 cells, Strictinin inhibited ROR1 expression and modulated downstream AKT-GSK3beta 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 (IC(50) of 658.5 micromol/L). Strictinin was further identified as synergistic with docetaxel [combination index (CI) = 0.311] and the combination therapy was found to reduce the IC(50) of Strictinin to 38.71 micromol/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 AR(neg)-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.[Pubmed:37175375]

Molecules. 2023 May 8;28(9):3961.

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.

High-throughput screening and investigation of the inhibitory mechanism of alpha-glucosidase inhibitors in teas using an affinity selection-mass spectrometry method.[Pubmed:37119598]

Food Chem. 2023 Oct 1;422:136179.

An affinity selection-mass spectrometry method was applied for high-throughput screening of alpha-glucosidase (AGH) inhibitors from teas. Fourteen out of nineteen screened AGH inhibitor candidates were clustered as galloylated polyphenols (GPs). "AGH-GPs" interaction studies, including enzyme kinetics, fluorescence spectroscopy, circular dichroism, and molecular docking, jointly suggested that GPs noncompetitively inhibit AGH activity by interacting with amino acid residues near the active site of AGH and inducing changes in AGH secondary structure. Representative GPs and white tea extract (WTE) showed comparable AGH inhibition effects in Caco2 cells and postprandial hypoglycemic efficacy in diabetic mice as acarbose. The area under the curve of oral sucrose tolerance test was lower by 8.16%, 6.17%, and 7.37% than control group in 15 mg/kg EGCG, 15 mg/kg Strictinin, and 150 mg/kg WTE group, respectively. Our study presents a high-efficiency approach to discover novel AGH inhibitors and elucidates a potential mechanism by which tea decreases diabetes risks.

Discovery and Flavor Characterization of High-Grade Markers in Baked Green Tea.[Pubmed:36985433]

Molecules. 2023 Mar 8;28(6):2462.

Green tea is a popular beverage around the world and possesses a unique flavor. The flavor qualities of green tea are closely related to its grade and this relationship has not yet been studied. Three baked green teas with similar flavor were studied, namely, Huangshan Maofeng, Taiping Houkui, and Shucheng Xiaolanhua. A total of 34 odor compounds were identified by solid phase microextraction (SPME) combined with two-dimensional comprehensive gas chromatography-olfactometry-mass spectrometry analysis (GCxGC-O-MS). The results of the clustering analysis showed that the content of D-limonene and linalool in the high-grade (Grade A) tea was much higher than the content in other grades, so they were identified as odor markers of Grade A baked green tea. The taste components of different grades of green tea infusion were analyzed by high-performance liquid chromatography-mass spectrometry (HPLC-MS) and HPLC. A combination of clustering analysis, principal component analysis (PCA), and orthogonal partial least squares discrimination analysis (OPLS-DA) indicated that galloylglucose, digalloylglucose, trigalloyglucose, Strictinin, and gallic acid could be used as taste markers of Grade A baked green tea. Therefore, the results in this paper reveal the substances responsible for the odor and taste markers of high-grade baked green tea.

The potential antidiabetic properties of green and purple tea [Camellia sinensis (L.) O Kuntze], purple tea ellagitannins, and urolithins.[Pubmed:36907477]

J Ethnopharmacol. 2023 Jun 12;309:116377.

ETHNOPHARMACOLOGICAL RELEVANCE: Tea (Camellia sinensis) has been consumed for centuries as traditional medicine for various diseases, including diabetes. The mechanism of action of many traditional medicines, including tea, often requires elucidation. Purple tea is a natural mutant of Camellia sinensis, grown in China and Kenya, and is rich in anthocyanins and ellagitannins. AIM OF THE STUDY: Here we aimed to determine whether commercial green and purple teas are a source of ellagitannins and whether green and purple teas, purple tea ellagitannins and their metabolites urolithins have antidiabetic activity. MATERIALS AND METHODS: Targeted UPLC-MS/MS was employed to quantify the ellagitannins corilagin, Strictinin and tellimagrandin I, in commercial teas. The inhibitory effect of commercial green and purple teas and purple tea ellagitannins was evaluated on alpha-glucosidase and alpha-amylase. The bioavailable urolithins were then investigated for additional antidiabetic effects, by evaluating their effect on cellular glucose uptake and lipid accumulation. RESULTS: Corilagin, Strictinin and tellimagrandin I (ellagitannins) were identified as potent inhibitors of alpha-amylase and alpha-glucosidase, with K(i) values significantly lower (p < 0.05) than acarbose. Commercial green-purple teas were identified as ellagitannin sources, with especially high concentrations of corilagin. These commercial purple teas, containing ellagitannins, were identified as potent alpha-glucosidase inhibitors with IC(50) values significantly lower (p < 0.05) than green teas and acarbose. Urolithin A and urolithin B were as effective (p> 0.05) as metformin in increasing glucose uptake in adipocytes, muscle cells and hepatocytes. In addition, similar (p > 0.05) to metformin, both urolithin A and urolithin B reduced lipid accumulation in adipocytes and hepatocytes. CONCLUSIONS: This study identified green-purple teas as an affordable widely available natural source with antidiabetic properties. Furthermore, additional antidiabetic effects of purple tea ellagitannins (corilagin, Strictinin and tellimagrandin I) and urolithins were identified.

Alleviation of Hyperuricemia by Strictinin in AML12 Mouse Hepatocytes Treated with Xanthine and in Mice Treated with Potassium Oxonate.[Pubmed:36829604]

Biology (Basel). 2023 Feb 17;12(2):329.

Hyperuricemia, an abnormally high level of blood uric acid, is a major risk factor for gout. Although xanthine oxidase inhibitors were clinically used to lower blood uric acid level, the concerned side effects restricted their utilization. In this study, Strictinin, an abundant polyphenol in Pu'er tea, was evaluated for its preventive effects on hyperuricemia. The results showed that the xanthine oxidase activity, uric acid production, and inflammation in AML12 mouse hepatocytes treated with xanthine were significantly reduced by the supplementation of Strictinin. Detailed analyses revealed that Strictinin inhibited xanthine-induced NLRP3 inflammasome activation. Consistently, the elevated blood uric acid level and the enhanced xanthine oxidase activity in mice treated with potassium oxonate were effectively diminished by Strictinin supplementation. Moreover, for the first time, Strictinin was found to promote healthy gut microbiota. Overall, Strictinin possesses a great potential to be utilized as a functional ingredient for the prevention of hyperuricemia.

Strictinin, a Major Ingredient in Yunnan Kucha Tea Possessing Inhibitory Activity on the Infection of Mouse Hepatitis Virus to Mouse L Cells.[Pubmed:36770747]

Molecules. 2023 Jan 21;28(3):1080.

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 beta-coronavirus serving as a surrogate for SARS-CoV. Treatment with Strictinin (100 muM), 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 muM) completely blocked MHV infection. In contrast, no significant effect on MHV infection was observed when cells were pre-treated with Strictinin (100 muM) 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.

Periodontal ligaments enhance neurite outgrowth in trigeminal ganglion neurons through Wnt5a production induced by mechanical stimulation.[Pubmed:36374171]

Am J Physiol Cell Physiol. 2022 Dec 1;323(6):C1704-C1719.

The peripheral sensory nerve must be maintained to perceive environmental changes. Daily physiological mechanical stimulations, like gravity, floor reaction force, and occlusal force, influence the nerve homeostasis directly or indirectly. Although the direct axonal membrane stretch enhances axon outgrowth via mechanosensitive channel activation, the indirect mechanisms remain to be elucidated. In this study, we identified the indirect pathways where Wnt5a was a molecular cue released by mechanically stimulated rat periodontal ligament (rPDL) cells. qRT-PCR and ELISA showed that mechanically stimulated rPDL cells enhanced Wnt5a expression level and Wnt5a protein in a Ca(2+)-dependent manner. The inhibitors of PI3K (LY294002) and MEK1/2 (U0126) suppressed the Akt/PKB and ERK1/2 phosphorylation, respectively, in Western blotting analysis and consequently abolished the increase in Wnt5a expression. Similarly, PF573228, a focal adhesion kinase inhibitor, attenuated Akt- and ERK1/2-phosphorylation and Wnt5a expression. Importantly, the culture medium of stretched PDL cells enhanced neurite elongation, sprouting, and branching in trigeminal ganglion neurons that project to PDL. Moreover, treatment with an anti-Wnt5a antibody (to neutralize Wnt5a activity), AP7677a (anti-Ryk antibody, to block Ryk receptor activity), or Strictinin (Ror1 inhibitor) suppressed the morphological changes. These findings reveal the indirect mechanisms that Wnt5a, released from the connective tissues in response to mechanical stimulation, enhances the outgrowth of the peripheral nerves. Our study suggests that the peripheral connective tissues regulate peripheral nerve homeostasis and that Wnt5a signaling could be targeted for the treatment of peripheral nerve disorders.

Walnut Prevents Cognitive Impairment by Regulating the Synaptic and Mitochondrial Dysfunction via JNK Signaling and Apoptosis Pathway in High-Fat Diet-Induced C57BL/6 Mice.[Pubmed:36014555]

Molecules. 2022 Aug 20;27(16):5316.

This study was conducted to evaluate the protective effect of Juglans regia (walnut, Gimcheon 1ho cultivar, GC) on high-fat diet (HFD)-induced cognitive dysfunction in C57BL/6 mice. The main physiological compounds of GC were identified as pedunculagin/casuariin isomer, Strictinin, tellimagrandin I, ellagic acid-O-pentoside, and ellagic acid were identified using UPLC Q-TOF/MS analysis. To evaluate the neuro-protective effect of GC, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), 2',7'-dichlorodihydrofluorecein diacetate (DCF-DA) analysis were conducted in H(2)O(2) and high glucose-induced neuronal PC12 cells and hippocampal HT22 cells. GC presented significant cell viability and inhibition of reactive oxygen species (ROS) production. GC ameliorated behavioral and memory dysfunction through Y-maze, passive avoidance, and Morris water maze tests. In addition, GC reduced white adipose tissue (WAT), liver fat mass, and serum dyslipidemia. To assess the inhibitory effect of antioxidant system deficit, lipid peroxidation, ferric reducing antioxidant power (FRAP), and advanced glycation end products (AGEs) were conducted. Administration of GC protected the antioxidant damage against HFD-induced diabetic oxidative stress. To estimate the ameliorating effect of GC, acetylcholine (ACh) level, acetylcholinesterase (AChE) activity, and expression of AChE and choline acetyltransferase (ChAT) were conducted, and the supplements of GC suppressed the cholinergic system impairment. Furthermore, GC restored mitochondrial dysfunction by regulating the mitochondrial ROS production and mitochondrial membrane potential (MMP) levels in cerebral tissues. Finally, GC ameliorated cerebral damage by synergically regulating the protein expression of the JNK signaling and apoptosis pathway. These findings suggest that GC could provide a potential functional food source to improve diabetic cognitive deficits and neuronal impairments.

Medicinal Importance, Pharmacological Activities, and Analytical Aspects of Strictinin: A Mini-Review.[Pubmed:35770392]

Recent Adv Antiinfect Drug Discov. 2022;17(2):86-94.

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.

Unique distribution of ellagitannins in ripe strawberry fruit revealed by mass spectrometry imaging.[Pubmed:34841268]

Curr Res Food Sci. 2021 Nov 17;4:821-828.

Ellagitannins (ETs) are hydrolysable tannins composed of a polyol core, primarily glucose, which is esterified with hexahydroxydiphenic acid (HHDP), and in some cases, gallic acid. ETs are the major phenolic compounds found in strawberries and may contribute to the health-related properties of strawberries, because of their strong antioxidative activity. However, their distribution in the strawberry fruit remains unclear. In this study, matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) was used to visualize ETs in ripe strawberry fruits. Five peaks, corresponding to the m/z values of ET [M-H](-) ions detected in the MALDI-MS spectrum of strawberry extracts, were identified as Strictinin, pedunculagin, casuarictin, davuriicin M(1), and an unknown ET using MALDI-tandem MS (MS/MS). In addition, liquid chromatography-electrospray ionization-MS/MS of the extracts revealed the presence of pedunculagin isomers and the unknown ET. Ion images of these five ETs were reconstructed using MALDI-MSI. Strictinin was widely distributed in and around the achene seed coats, while the other ETs were dispersed in and around the seed coats, and at the bottom of the receptacle; pedunculagin was distributed in the epidermis and pith, whereas casuarictin, the unknown ET, and davuriicin M(1) were distributed in the pith. Moreover, MALDI-MSI of a casuarictin standard indicated that in-source fragmentation weakly affected the ion images. The results suggest that the distribution of ETs depends on the presence or absence of their constituents, namely galloyl units, HHDP, and bis-HHDP. To the best of my knowledge, this is the first report on the visualization of ETs in plant tissues using MSI, MALDI-MSI may be a useful tool for analyzing the distribution of ETs in the strawberry fruit.

Polyphenolic profile and ethno pharmacological activities of Callistemonsubulatus (Cheel) Craven leaves cultivated in Egypt.[Pubmed:34600075]

J Ethnopharmacol. 2022 Feb 10;284:114698.

ETHNOPHARMACOLOGICAL RELEVANCE: The genus Callistemon (syn. Melaleuca) of the myrtle family (Myrtaceae) has been documented as an integral part in the ethnobotanical system of the indigenous people of Australian mainland and many of its islands. Several Callistemons including the species subulatus were used by aboriginal Australians for making rafts, roofs for shelters, bandages, and food recipes, in addition to the management of wounds, infections, pain, cough, bronchitis, and gastrointestinal tract (GIT) disorders. AIM OF THE STUDY: The current study is designed to document the therapeutic effect of the aqueous methanolic extract (AME) of C. sabulatus Chell (syn. M. sabulata) leaves in the management of diarrhea and pain. Also, its influence on additional pharmacological modalities that are related to oxidative stress just as skin aging. Ultimately, the polyphenolic profile of the extract is disclosed and correlated to the aforementioned bioactivities. MATERIALS AND METHODS: The extract was fractionated using various chromatography techniques and the structures of the isolated compounds were determined based on their chemical and spectral data. The antioxidant activity was assessed using multiple models, including 2,2-diphenyl-picrylhydrazyl (DPPH), oxygen radical absorbance capacity (ORAC) and beta-carotene bleaching assays. The anti-skin aging effect was evaluated using different relevant enzymatic assays. The antinociceptive activity was investigated using acetic acid-induced writhing, hot plate test, and formalin-induced paw licking in mice models. The antidiarrheal activity was gauge using the castor oil induced diarrhea, enter pooling and gastrointestinal motility in vivo models. RESULTS: Diverse polyphenols, including quercetin-3-O-beta-D-glucuronopyranoside (1), kaempferol-3-O-beta-D-glucuronopyranoside (2), Strictinin (3), quercetin-3-O-(2;;-O-galloyl)-beta-D-glucuronopyranoside (4), afzelin (5), di-galloyl glucose (6), mono-galloyl glucose (7), acacetin (8), apigenin-6,7-dimethyl ether (9), kaempferol trimethyl ether (10), dimethoxy chrysin (11), quercetin (12), kaempferol (13), methyl gallate (14), and gallic acid (15) were identified. The extract exhibited as significant antioxidant activity even better than that of Trolox or BHT. Moreover, it exerts elastase, tyrosinase, and collagenase inhibition activities, in addition to the significant peripheral and central analgesic activity in a dose-dependent manner (P < 0.0001). In castor oil induced diarrhea model, AME significantly prolonged the diarrhea onset, decreased the frequency of defecation, and weight of feces. Likewise, it exhibited a significant reduction in the gastrointestinal motility in charcoal meal model (P < 0.0001) and a considerable inhibitory effect on gastrointestinal transit and peristaltic index with all investigated doses (P < 0.0001). CONCLUSION: Ethnobotanicals are versatile resources for the management of various ailments by indigenous people and the experimental research is utmost to validate and uncover their pharmacological relevance. C. sabulatus leaves have strong antioxidant, analgesic, anti-skin aging, and antidiarrheal activities which are validated for the first time by various in vitro and in vivo models. The metabolic profile of the unprecedented AME of C. sabulatus leaves compromises a wide array of bioactive polyphenolic metabolites including, flavonoids, tannins, and phenolic acids that are correlated to the observed bioactivities. Altogether, ethnobotanicals with high and diverse contents of polyphenols are potential candidates for the management of various human aliments including neuropathies, GIT disorders, and skin aging conditions.

Targeting the Receptor Tyrosine Kinase ROR1 by Small Molecules.[Pubmed:34490515]

Handb Exp Pharmacol. 2021;269:75-99.

Receptor tyrosine kinases (RTKs) are frequently dysregulated in malignancies and important for the malignant characteristics of tumor cells. RTKs are attractive structures for drug targeting of cancer. The RTK ROR1 is of significance during embryogenesis but downregulated in post-partum tissues. However, ROR1 is overexpressed in several hematological and solid tumors and important for tumor cell proliferation, survival, migration, and metastasis. WNT5a is a main ligand for ROR1. Several clinical trials are ongoing using anti-ROR1 antibody based drugs directed against the external domain (monoclonal antibodies, BiTE, CAR-T). We have produced small molecules (KAN834/1571c) fitting to the ATP pocket of the intracellular tyrosine kinase (TK) domain of ROR1 (TK inhibitor, TKI). These inhibitors of ROR1 prevented ROR1 phosphorylation and inactivated the WNT/beta-catenin independent as well as WNT/beta-catenin dependent pathways. ROR1-TKI induced apoptosis of ROR1 positive fresh patient derived tumor cells and appropriate cell lines and a dose and time dependent tumor reduction in animal models. In combination with other clinically relevant targeting drugs as venetoclax a synergistic apoptotic effect was seen. Two other small molecules (ARI-1 and Strictinin) bound also to ROR1 and inhibited tumor growth. Development of small molecule ROR1 inhibitors is warranted to include this novel therapeutic approach for cancer therapy.

Pu'er tea rich in strictinin and catechins prevents biofilm formation of two cariogenic bacteria, Streptococcus mutans and Streptococcus sobrinus.[Pubmed:34484613]

J Dent Sci. 2021 Oct;16(4):1331-1334.

Cariogenic bacteria, such as Streptococcus mutans and Streptococcus sobrinus, are main pathogens responsible for human dental caries. Pu'er tea is empirically observed to prevent tooth decay. Besides caffeine and catechins commonly found in oolong tea, Strictinin is also found as an abundant phenolic compound in Pu'er tea. Infusion of Pu'er tea as well as single compound, Strictinin, caffeine or (-)-epigallocatechin gallate (EGCG) was examined for its inhibitory effects on S. mutans and S. sobrinus. Relatively weak inhibition of bacterial growth was observed for these Pu'er tea constituents. However, biofilm formation of S. mutans or S. sobrinus was strongly prevented by the infusion of Pu'er tea as well as by Strictinin or EGCG, but not caffeine. Relatively, Strictinin showed a higher potency than EGCG to prevent biofilm formation. Anti-caries effect of Pu'er tea seems to be resulted from the prevention of biofilm formation of cariogenic bacteria mainly by Strictinin and catechins.

Ellagitannin Digestion in Moth Larvae and a New Dimeric Ellagitannin from the Leaves of Platycarya strobilacea.[Pubmed:34299409]

Molecules. 2021 Jul 7;26(14):4134.

Ellagitannins (ETs) are plant polyphenols with various health benefits. Recent studies have indicated that the biological activities of ETs are attributable to their degradation products, including ellagic acid and its gut microflora metabolites, such as urolithins. Insect tea produced in the Guangxi region, China, is made from the frass of moth larvae that feed on the ET-rich leaves of Platycarya strobilacea. Chromatographic separation of the Guangxi insect tea showed that the major phenolic constituents are ellagic acid, brevifolin carboxylic acid, gallic acid, brevifolin, and polymeric polyphenols. Chemical investigation of the feed of the larvae, the fresh leaves of P. strobilacea, showed that the major polyphenols are ETs including pedunculagin, casuarictin, Strictinin, and a new ET named platycaryanin E. The new ET was confirmed as a dimer of Strictinin having a tergalloyl group. The insect tea and the leaves of P. strobilacea contained polymeric polyphenols, both of which were shown to be composed of ETs and proanthocyanidins by acid hydrolysis and thiol degradation. This study clarified that Guangxi insect tea contains ET metabolites produced in the digestive tract of moth larvae, and the metabolites probably have higher bioavailabilities than the original large-molecular ETs of the leaves of P. strobilacea.