New Application of an Old Drug: Anti-Diabetic Properties of Phloroglucinol.

Phloroglucinol (PHG), an analgesic and spasmolytic drug, shows promise in preventing high-fat-diet (HFD)-induced non-alcoholic fatty liver disease (NAFLD) and insulin resistance. In Wistar rats, 10 weeks of PHG treatment did not prevent HFD-induced weight gain but significantly mitigated fasting hyperglycemia, impaired insulin responses, and liver steatosis. This protective effect was not linked to hepatic lipogenesis or AMP-activated protein kinase (AMPK) activation. Instead, PHG improved mitochondrial function by reducing oxidative stress, enhancing ATP production, and increasing anti-oxidant enzyme activity. PHG also relaxed gastric smooth muscles via potassium channel activation and nitric oxide (NO) signaling, potentially delaying gastric emptying. A pilot intervention in pre-diabetic men confirmed PHG's efficacy in improving postprandial glycemic control and altering lipid metabolism. These findings suggest PHG as a potential therapeutic for NAFLD and insulin resistance, acting through mechanisms involving mitochondrial protection, anti-oxidant activity, and gastric motility modulation. Further clinical evaluation is warranted to explore PHG's full therapeutic potential.

Development of Phloroglucinol-Linked Tris-Quaternary Ammonium Salt Antimicrobial Peptide Mimics with Low Cytotoxicity and Broad-Spectrum Antibacterial Activity.

Encouraged by the significantly different toxicities and antibacterial activities of diverse linkers, such as alkyl and aromatic nuclei linkers, and the unique structure of phloroglucinol, we synthesized a series of tris-quaternary ammonium salt (tris-QAS) antibacterial peptide mimics based on the marketed drug phloroglucinol. Among them, 2f displayed excellent activity against Staphylococcus aureus (MIC = 0.5 µg/mL) and high selectivity (SI > 2560). Surprisingly, the cytotoxicity of 2f (CC50 = 152.7 µg/mL) was dramatically better than those of alkyl QAS I and hydroquinone QAS II. Additionally, 2f possessed rapid bactericidal capability, was not prone to inducing bacterial resistance, and also exhibited excellent activity against S. aureus biofilms and persistent bacteria. Mechanistic research and transcriptome analysis revealed that 2f can interfere with the normal metabolism of bacterial cells, and it can specifically bind with phosphatidylglycerol to destroy the cell membrane. Importantly, 2f exhibited potent in vivo antibacterial activity in a mouse subcutaneous methicillin-resistant S. aureus (MRSA) infection model.

Antifungal Activity of Phloroglucinol Derivatives against Botrytis cinerea and Monilinia fructicola.

Naturally derived compounds show promise as treatments for microbial infections. Polyphenols, abundantly found in various plants, fruits, and vegetables, are noted for their physiological benefits including antimicrobial effects. This study introduced a new set of acylated phloroglucinol derivatives, synthesized and tested for their antifungal activity in vitro against seven different pathogenic fungi. The standout compound, 3-methyl-1-(2,4,6-trihydroxyphenyl) butan-1-one (2b), exhibited remarkable fungicidal strength, with EC50 values of 1.39 µg/mL against Botrytis cinerea and 1.18 µg/mL against Monilinia fructicola, outperforming previously screened phenolic compounds. When tested in vivo, 2b demonstrated effective antifungal properties, with cure rates of 76.26% for brown rot and 83.35% for gray mold at a concentration of 200 µg/mL, rivaling the commercial fungicide Pyrimethanil in its efficacy against B. cinerea. Preliminary research suggests that 2b's antifungal mechanism may involve the disruption of spore germination, damage to the fungal cell membrane, and leakage of cellular contents. These results indicate that compound 2b has excellent fungicidal properties against B. cinerea and holds potential as a treatment for gray mold.

Polycyclic polyprenylated acylphloroglucinols from the pericarps of Garcinia multiflora champ. ex Benth. with cytotoxic property.

The phytochemical investigation on the pericarps of Garcinia multiflora resulted in the isolation of 12 previously undescribed polycyclic polyprenylated acylphloroglucinols (PPAPs, 1-12) with a variety of skeletons. Their structures were determined by comprehensive spectroscopic analyses, ECD calculations, and single-crystal X-ray diffraction. Compounds 6-9 possess a rare bicyclo[4.3.1]decane skeleton. Additionally, the anti-tumor activity of the 12 isolates was evaluated. The results indicated that compounds 5, 9, and 12 exhibited significant cytotoxicity in a wide range of cancer cell lines, including the human breast cancer MDA-MB-231 cells, human lung cancer A549 cells, human colon cancer SW480 cells and human ovarian cancer HEY cells. Further studies indicated that compound 5 induced cell cycle arrest and apoptosis, to inhibit the growth of MDA-MB-231 cells. Taken together, these findings expand the chemical diversity of PPAPs and further demonstrate the potential of PPAPs as candidates for cancer treatment.

Acetylcholinesterase inhibitory phloroglucinols from tropic Rhodomyrtus tomentosa.

Four previously undescribed phloroglucinols, including three pairs of enantiomers, (±)-rhodotomentodimer F, (±)-rhodotomentodimer G, and (±)-rhodotomentomonomer E, and one phloroglucinol-sesquiterpene meroterpenoid, rhodotomentodione E, together with one previously reported congener, (±)-rhodomyrtosone A, were obtained from the leaves of Rhodomyrtus tomentosa. The structures including absolute configurations of previously undescribed isolates were elucidated by extensive spectroscopic analysis (HRESIMS and NMR), ECD calculations, and single-crystal X-ray diffraction. (±)-Rhodotomentodimer F is a rare phloroglucinol derivative conjugated by a ß-triketone moiety and an unprecedented resorcinol unit via the formation of a rare bis-furan ring system, whereas (±)-rhodotomentomonomer E shares a rearranged pentacyclic scaffold. Pharmacologically, (±)-rhodotomentomonomer E showed the strongest human acetylcholinesterase (hAChE) inhibitory effect with an IC50 value of 1.04 ± 0.05 µM. Molecular formula studies revealed that hydrogen bonds formed between hAChE residues Glu202, Ser203, Ala204, Gly121, Gly122, Tyr337, and His447 and (±)-rhodotomentomonomer E played crucial roles in its observed activity. These findings indicated that the leaves of Rhodomyrtus tomentosa can supply a rich source of hAChE inhibitors. These inhibitors might potentially be utilized in the therapeutic strategy for Alzheimer's disease, offering promising candidates for further research and development.

Formohyperins G-L, polycyclic prenylated benzoylphloroglucinols from the flowers of Hypericum formosanum.

Phytochemical study on the flowers of Hypericum formosanum Maxim. (Hypericaceae) led to the isolation of formohyperins G-L (1-6), whose structures were assigned by detailed spectroscopic analysis. Formohyperins G-L (1-6) are new benzoylphloroglucinols substituted by a C10 unit, a prenyl group, and a methyl group. Formohyperins G-J (1-4) possess a 6/6/6-tricyclic structure, while formohyperins K (5) and L (6) have a unique 6/6/5/4-tetracyclic structure consisting of cyclohexadienone, dihydropyrane, cyclopentane, and cyclobutane rings. The absolute configurations of 1-6 were deduced by analysis of the ECD spectra. Formohyperins G-J (1-4) and L (6) were found to show potent inhibitory activities against IL-1ß release from LPS-treated murine microglial cells with EC50 values of 5.0, 10.9, 6.3, 10.8, and 13.7 µM, respectively, without cytotoxicity. 6-O-Methylformohyperins G (1a) and I (3a) also exhibited the inhibitory activities with EC50 values of 4.7 and 2.7 µM, respectively, although they were cytotoxic against microglial cells.

2,7-Phloroglucinol-6,6'-bieckol from Ecklonia cava ameliorates nanoplastics-induced premature endothelial senescence and dysfunction.

Nanoplastics (NPs), plastic particles ranging from 1 to 100 nm are ubiquitous environmental pollutants infiltrating ecosystems. Their small size and widespread use in various products raise concerns for human health, particularly their association with cardiovascular diseases (CVD). NPs can enter the human body through multiple routes, causing oxidative stress, and leading to the senescence and dysfunction of endothelial cells (ECs). Although there are potential natural compounds for treating CVD, there is limited research on preventing CVD induced by NPs. This study investigates the efficacy of Ecklonia cava extract (ECE) in preventing NPs-induced premature vascular senescence and dysfunction. Exposure of porcine coronary arteries (PCAs) and porcine coronary ECs to NPs, either alone or in combination with ECE, demonstrated that ECE mitigates senescence-associated ß-galactosidase (SA-ß-gal) activity induced by NPs, thus preventing premature endothelial senescence. ECE also improved NPs-induced vascular dysfunction. The identified active ingredient in Ecklonia cava, 2,7'-Phloroglucinol-6,6'-bieckol (PHB), a phlorotannin, proved to be pivotal in these protective effects. PHB treatment ameliorated SA-ß-gal activity, reduced oxidative stress, restored cell proliferation, and decreased the expression of cell cycle regulatory proteins such as p53, p21, p16, and angiotensin type 1 receptor (AT1), well known triggers for EC senescence. Moreover, PHB also improved NPs-induced vascular dysfunction by upregulating endothelial nitric oxide synthase (eNOS) expression and restoring endothelium-dependent vasorelaxation. In conclusion, Ecklonia cava and its active ingredient, PHB, exhibit potential as therapeutic agents against NPs-induced premature EC senescence and dysfunction, indicating a protective effect against environmental pollutants-induced CVDs associated with vascular dysfunction.

Phloroglucinol inhibited glycation via entrapping carbonyl intermediates.

Advanced glycation end products (AGEs) play an important role in the pathogenesis of age-linked disorders and diabetes mellitus. The aim of this study was to assess the repurposing potential of Phloroglucinol (PHL the antispasmodic drug), as an anti-glycation agent using Fructose-BSA model. The ability of PHL to inhibit AGE formation was evaluated using AGEs formation (Intrinsic fluorescence), fructosamine adduct (NBT) and free lysine availability (TNBSA) assays. The BSA protein conformation was assessed through Thioflavin-T, Congo-Red and Circular Dichroism assays. The lysine blockade and carbonyl entrapment were explored as possible mode of action. Our data showed that PHL significantly decreased the formation of AGEs with an IC50 value of 0.3mM. The fructosamine adducts and free lysine load was found to be reduced. Additionally, the BSA conformation was preserved by PHL. Mechanistic assays did not reveal involvement of lysine blockade as underlying reason for reduction in AGEs load. This was also supported by computational data whereby PHL failed to engage any catalytic residue involved in early fructose-BSA interaction. However, it was found to entrap the carbonyl moieties. In conclusion, the PHL demonstrated anti-glycation potential, which can be attributed to its ability to entrap carbonyl intermediates. Hence, the clinically available antispasmodic drug, presents itself as a promising candidate to be repurposed as anti-glycation agent.

New polycyclic polyprenylated acylphloroglucinols with antidepressant activities from Hypericum perforatum L.

Six new polycyclic polyprenylated acylphloroglucinols (PPAPs), hyperidiones A-F (1-6), were obtained from Hypericum perforatum L. Their structures were characterized via extensive spectroscopic analyses, the circular dichroism data of the in situ formed [Mo2(OCOCH3)4] complexes, the nuclear magnetic resonance calculation with DP4 + probability analysis, and the calculated electronic circular dichroism (ECD) spectra. Compounds 1-6 are bicyclic polyprenylated acylphloroglucinols with a major bicyclo[3.3.1]nonane-2,4,9-trione skeleton. Notably, compound 1 is a rare PPAP with a hydroperoxy group, and a plausible biosynthetic pathway for 1 was proposed. Compounds 4 and 6 exhibited significant neuroprotective effects under 10 µM against corticosterone (CORT)-injured SH-SY5Y cells. Furthermore, compound 4 demonstrated a noteworthy antidepressant effect at the dose of 5 mg/kg in the tail suspension test (TST) of mice, which was equivalent to 5 mg/kg of fluoxetine. And it potentially exerted an antidepressant effect through the hypothalamic-pituitary-adrenal (HPA) axis.

Hyperforin improves matrix stiffness induced nucleus pulposus inflammatory degeneration by activating mitochondrial fission.

OBJECTIVE: The continuously increasing extracellular matrix stiffness during intervertebral disc degeneration promotes disease progression. In an attempt to obtain novel treatment methods, this study aims to investigate the changes in nucleus pulposus cells under the stimulation of a stiff microenvironment. DESIGN: RNA sequencing and metabolomics experiments were combined to evaluate the primary nucleus pulposus and screen key targets under mechanical biological stimulation. Additionally, small molecules work in vitro were used to confirm the target regulatory effect and investigate the mechanism. In vivo, treatment effects were validated using a rat caudal vertebrae compression model. RESULTS: Our research results revealed that by activating TRPC6, hyperforin, a herbaceous extract can rescue the inflammatory phenotype caused by the stiff microenvironment, hence reducing intervertebral disc degeneration (IDD). Mechanically, it activates mitochondrial fission to inhibit PFKFB3. CONCLUSION: In summary, this study reveals the important bridging role of TRPC6 between mechanical stiffness, metabolism, and inflammation in the context of nucleus pulposus degeneration. TRPC6 activation with hyperforin may become a promising treatment for IDD.

Phloroglucinol ameliorated methylglyoxal induced harmful effects in rats.

Glycation is among the underlying mechanisms attributed to ageing and associated morbidities. There is no drug available to combat this deleterious phenomenon. The present study aimed to explore phloroglucinol (PHL) for its anti-glycation potential at preclinical level. The rats were treated with methylglyoxal (MGO, 17.25 mg/kg, i.p. for 14 days) to induce glvcative stress. The treatment groups received additional administration of test drug (PHL; 0.25mg/kg, 0.5mg/kg, and 1mg/kg) or standard aminoguanidine (AG, 50 mg/kg) or saline (control, 5ml/kg). During 14 days, the weight and food intake was noted. Afterwards, the cognitive function was evaluated using Morris Water Maze (MWM) while hepatic and renal functions were assessed through liver function test (bilirubin, alkaline phosphatase, SGPT, and SGOT) and creatinine respectively, using chemical analyzer. The carboxymethyllysine (CML) levels were quantified in the blood using ELISA technique. Histopathological study was performed on the brain, liver, and kidney using H&E staining. Additionally, the qPCR was used to quantify the expression of TNF-α, RAGE and BACE-1 (brain), RAGE, TNF-α, and glyoxalase-I (liver) and RAGE, TNF-α, and VEGF (kidney), while glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as a reference housekeeping gene. The data regarding weight and food intake did not reveal significant alterations. In MWM, the MGO treatment caused significant increase in the time to reach target quadrant, while decrease in the time spent in target quadrant and number of crossings through platform position. All these effects were inhibited by both AG and PHL. The navigation maps also exhibit that the retention of spatial memory. Additionally, the MGO-induced alteration in hepatic and renal function indicators was ameliorated by both AG and PHL treatments. The plasma CML levels were found to be elevated following MGO treatment, while the concomitant administration of AG and PHL has resisted this raise. Histopathological assessment revealed no specific pathology in liver kidney and brain tissues. The qPCR data revealed enhanced expression of all genes, especially TNF-α and BACE, which were found to be reduced following both AG and PHL treatments. PHL prevented the brain, hepatic, and renal impairments caused by MGO induced glycative stress. Hence, the PHL, a clinically used anti-spasmodic drug, presents itself as a potential candidate to be repurposed as anti-glycation drug.

Chemical Predictive Modelling and Natural Product-based Divergent Synthesis - Design of Type B PPAPs with Nanomolar Activities against MRSA.

In response to the pressing global challenge of antibiotic resistance, time efficient design and synthesis of novel antibiotics are of immense need. Polycyclic polyprenylated acylphloroglucinols (PPAP) were previously reported to effectively combat a range of gram-positive bacteria. Although the exact mode of action is still not clear, we conceptualized a late-stage divergent synthesis approach to expand our natural product-based PPAP library by 30 additional entities to perform SAR studies against methicillin-resistant Staphylococcus aureus (MRSA). Although at this point only data from cellular assays are available and understanding of molecular drug-target interactions are lacking, the experimental data were used to generate 3D-QSAR models via an artificial intelligence training and to identify a common pharmacophore model. The experimentally validated QSAR model enabled the estimation of anti-MRSA activities of a virtual compound library consisting of more than 100,000 in-silico generated B PPAPs, out of which the 20 most promising candidates were synthesized. These novel PPAPs revealed significantly improved cellular activities against MRSA with growth inhibition down to concentrations less than 1 µm.

Effects of Phloroglucinol on Embryo Transfer: A Systematic Review and Meta-Analysis.

INTRODUCTION: Phloroglucinol may be able to improve embryo transfer outcomes. We aimed to systematically evaluate the effects of phloroglucinol on embryo transfer outcomes. METHODS: The databases searched were PubMed, Ovid MEDLINE, Web of Science, Wanfang, CQVIP, China National Knowledge Infrastructure, and ClinicalTrials.gov. The last search was on February 7, 2023. The included studies were written in English or Chinese. Randomized controlled trials and cohort studies aiming to assess the effect of phloroglucinol on embryo transfer outcomes were included. The studies reported at least one of the primary outcomes (biochemical pregnancy rate, clinical pregnancy rate, and live birth rate). The odds ratio (OR) and 95% confidence interval (CI) were calculated. A random-effects or fixed model was used where applicable to estimate the results. RESULTS: Seventeen articles reporting 5,953 cycles were included. Biochemical pregnancy rate (OR = 1.58, 95% CI = 1.20-2.08, I2 = 71%), clinical pregnancy rate (OR = 1.69, 95% CI = 1.35-2.10, I2 = 64%), and live birth rate (OR = 1.45, 95% CI = 1.23-1.71, I2 = 36%) were improved by phloroglucinol. Less miscarriage (OR = 0.46, 95% CI = 0.35-0.60, I2 = 0%), less ectopic pregnancy (OR = 0.45, 95% CI = 0.28-0.72, I2 = 0%), higher implantation rate (OR = 1.45, 95% CI = 1.24-1.71, I2 = 62%) but more multiple pregnancy rate (OR = 1.48, 95% CI = 1.13-1.94, I2 = 0%) were induced by phloroglucinol. Endometrial peristaltic waves were improved by phloroglucinol (OR = 22.87, 95% CI = 5.52-94.74, I2 = 72%). CONCLUSION: Phloroglucinol may improve the outcomes of embryo transfer, including biochemical pregnancy, clinical pregnancy, and live birth rates. Further studies are warranted.

Patumantanes A-D, seco-Polycyclic Polyprenylated Acylphloroglucinols with Diverse Carbon Skeletons from Hypericum patulum.

Patumantanes A-D (1-4), four new seco-polycyclic polyprenylated acylphloroglucinols (PPAPs) were isolated from Hypericum patulum. Patumantane A (1) was an unprecedented 1,2-seco-homoadamantane-type PPAP bearing a new 3,7-dioxatetracyclo[7.7.0.01,6.111,15]heptadecane architecture based on a 6/7/5/6 ring system. Patumantane B (2) was a unique 1,9-seco-adamantane-type PPAP with a tricyclo[4.4.4.0.02,12]tridecane core formed by a 6/6/6 carbon skeleton, and the further breakage between C-5 and C-9 decorated patumantane C (3) with the 9-nor-adamantane skeleton. More importantly, compounds 2 and 3 exhibited moderate immunosuppressive activity on Con A-induced T-lymphocyte proliferation in vitro, with IC50 values of 5.6 ± 1.2 and 11.2 ± 1.2 µM, respectively.

Garciyunnanones A-R: Caged polycyclic polyprenylated acylphloroglucinols decorated with a lavandulyl substituent from Garcinia yunnanensis.

Garciyunnanones A-R (1-18), eighteen undescribed caged polycyclic polyprenylated acylphloroglucinols, two undescribed biogenetic congeners (19-20), and nineteen known analogues (21-39), were isolated from the stem barks of Garcinia yunnanensis Hu. All of these isolates are decorated with a C-5 lavandulyl substituent. Their structures and absolute configurations were confirmed by HRESIMS, 1D & 2D NMR spectroscopic analysis, quantum chemical calculations of electronic circular dichroism data, and single-crystal X-ray diffraction analysis. The X-ray crystallographic data of ten isolated caged compounds ascertained the absolute configuration of C-23 in the lavandulyl as S. The cytotoxicity on three cancer cell lines and the anti-nonalcoholic steatohepatitis activity of the isolates were tested. In a free fatty acid-induced L02 cell model, compounds 33 and 39 decreased intracellular lipid accumulation significantly.

St. John's wort extract with a high hyperforin content does not induce P-glycoprotein activity at the human blood-brain barrier.

St. John's wort (SJW) extract, a herbal medicine with antidepressant effects, is a potent inducer of intestinal and/or hepatic cytochrome P450 (CYP) enzymes and P-glycoprotein (P-gp), which can cause clinically relevant drug interactions. It is currently not known whether SJW can also induce P-gp activity at the human blood-brain barrier (BBB), which may potentially lead to decreased brain exposure and efficacy of certain central nervous system (CNS)-targeted P-gp substrate drugs. In this study, we used a combination of positron emission tomography (PET) imaging and cocktail phenotyping to gain a comprehensive picture on the effect of SJW on central and peripheral P-gp and CYP activities. Before and after treatment of healthy volunteers (n = 10) with SJW extract with a high hyperforin content (3-6%) for 12-19 days (1800 mg/day), the activity of P-gp at the BBB was assessed by means of PET imaging with the P-gp substrate [11C]metoclopramide and the activity of peripheral P-gp and CYPs was assessed by administering a low-dose phenotyping cocktail (caffeine, omeprazole, dextromethorphan, and midazolam or fexofenadine). SJW significantly increased peripheral P-gp, CYP3A, and CYP2C19 activity. Conversely, no significant changes in the peripheral metabolism, brain distribution, and P-gp-mediated efflux of [11C]metoclopramide across the BBB were observed following the treatment with SJW extract. Our data suggest that SJW does not lead to significant P-gp induction at the human BBB despite its ability to induce peripheral P-gp and CYPs. Simultaneous intake of SJW with CNS-targeted P-gp substrate drugs is not expected to lead to P-gp-mediated drug interactions at the BBB.

(±)-hypermonanones A-G, seven pairs of monoterpenoid polyprenylated acylphloroglucinol enantiomers from Hypericum monanthemum.

Seven pairs of undescribed monoterpenoid polyprenylated acylphloroglucinol enantiomers [(±)-hypermonanones A-G (1-7)], together with three known analogues, were identified from the whole plant of Hypericum monanthemum Hook. The structures of these compounds were determined by analyses of their UV, HRESIMS, 1D/2D NMR spectroscopic data, and NMR calculations. The absolute configurations of these compounds were assigned by ECD calculations after chiral HPLC separation. Diverse monoterpene moieties were fused at C-3/C-4 of the dearomatized acylphloroglucinol core, which led to 3,4-dihydro-2H-pyran-integrated angular or linear type 6/6/6 tricyclic skeletons in 1-7. Compounds (-)-2 and (+)-2 exhibited significant NO inhibitory activity against LPS induced RAW264.7 cells with the IC50 values of 7.07 ± 1.02 µM and 11.39 ± 0.24 µM, respectively.

Phloroglucinol Derivatives Exert Anti-Inflammatory Effects and Attenuate Cognitive Impairment in LPS-Induced Mouse Model.

Neuroinflammation is an inflammatory immune response that arises in the central nervous system. It is one of the primary causes of neurodegenerative diseases, such as Alzheimer's disease and Parkinson's disease. Phloroglucinol (PG) is a natural product contained in extracts of plant, algae and microbe and has been reported to have antioxidant and anti-inflammatory properties. In this study, we synthesized PG derivatives to enhance antioxidant and anti-inflammatory activity. Among PG derivatives, 6 a suppressed pro-oxidative and inflammatory molecule nitric oxide (NO) production more effectively than PG. Moreover, 6 a dose-dependently reduced the expression of proinflammatory cytokines such as IL-6, IL-1ß, TNF-α, and NO producing enzyme iNOS in lipopolysaccharide (LPS)-stimulated BV-2 microglial cells. Additionally, we confirmed that 6 a alleviated cognitive impairment and glial activation in mouse model of LPS-induced neuroinflammation. These findings suggest that novel PG derivative, 6 a, is a potential treatment for neurodegenerative diseases.

Four New Polyprenylated Acylphloroglucinols from Hypericum perforatum L.

Hyperforatums A-D (1-4), four new polyprenylated acylphloroglucinols, together with 13 known compounds were isolated and identified from the aerial parts of Hypericum perforatum L. (St. John's wort). Their structures were confirmed with a comprehensive analysis comprising spectroscopic methods, including 1D and 2D NMR, HRESIMS, and electronic circular dichroism (ECD) calculations. Hyperforatum A featured an unusual chromene-1,4-dione bicyclic system, and hyperforatums B and C were two rare monocyclic PPAPs with five-membered furanone cores. Compound 1 exhibited a moderate inhibition effect on NO production in BV-2 microglial cells stimulated by LPS.

Discovery of PXR agonists from Hypericum japonicum: A class of novel nonaromatic acylphloroglucinol-terpenoid adducts.

Pregnane X receptor (PXR) has been considered as a promising therapeutic target for cholestasis due to its crucial regulation in bile acid biosynthesis and metabolism. To search promising natural PXR agonists, the PXR agonistic activities of five traditional Chinese medicines (TCMs) with hepatoprotective efficacy were assayed, and Hypericum japonicum as the most active one was selected for subsequent phytochemical investigation, which led to the isolation of eight nonaromatic acylphloroglucinol-terpenoid adducts including seven new compounds (1 - 4, 5a, 5b and 6). Their structures including absolute configurations were determined by comprehensive spectroscopic, computational and X-ray diffraction analysis. Meanwhile, the PXR agonistic activities of aplenty compounds were evaluated via dual-luciferase reporter assay, RT-qPCR and immunofluorescence. Among them, compounds 1 - 4 showed more potent activity than the positive drug rifampicin. Furthermore, the molecular docking revealed that 1 - 4 were docked well on the PXR ligand binding domain and formed hydrogen bonds with amino acid residues Gln285, Ser247 and His409. This investigation revealed that H. japonicum may serve as a rich source of natural PXR agonists.