Research Progress of Polycyclic Polyprenylated Acylphloroglucinols

Garcioblons A-F, Polycyclic Polyprenylated Acylphloroglucinols with Diverse Rearranged Skeletons from Garcinia oblongifolia

Garcioblons A-F (1-6), six unprecedented polycyclic polyprenylated acylphloroglucinols (PPAPs) formed via intramolecular Diels-Alder (IMDA) reactions from monocyclic polyprenylated acylphloroglucinols (MPAPs), were isolated from Garcinia oblongifolia. Their structures were elucidated through spectroscopic analysis and quantum calculations. Structurally, compound 1 is the first PPAP characterized by an unprecedented 6/6/5/7/6/5/6/5 octacyclic ring system with a 11-oxatetracyclo[8.5.1.01,12.05,10]hexadecane motif, while 2-4 are its biogenetically related analogues. Compound 5 possesses a caged 6-oxatetracyclo[7.3.1.12,10.02,7]tetradecane new carbon skeleton, while compound 6 features a 4-oxatricyclo[7.4.0.01,5]tridecane structure. Additionally, compound 1 demonstrated notable antitumor activities by inhibiting autophagic flux and stimulating oxidative stress, which collectively resulted in reduced cell proliferation and induced apoptosis.

Hyperwightianols A-H, monoterpenoid demethylated acylphloroglucinol derivatives from Hypericum wightianum

Twelve undescribed optically pure monoterpenoid demethylated acylphloroglucinol derivatives, named hyperwightianols A-H (1-8), were isolated from the dried whole herb of Hypericum wightianum, along with ten structurally related known compounds (9-18). The structures of the new compounds were elucidated using UV spectroscopy, HRMS, and extensive 1D & 2D NMR experiments. Absolute configurations of the new compounds were determined via chiral HPLC resolution and electronic circular dichroism (ECD) calculations. Brewster's rule, experimental and computed NMR chemical shift analyses, and conformational studies were collectively employed to validate the configuration of the C-1 2-methylbutanoyl moiety. Compounds 4 and (±)-14 exhibited potent inhibitory activity against NO release in LPS-induced RAW264.7 cells, with IC50 values of 9.56 ± 0.47 and 8.55 ± 1.10 μM, respectively.

Bicyclic polyprenylated acylphloroglucinol-related meroterpenoids as potent DRAK2 inhibitors from Hypericum patulum

As a both edible and medicinal plant, Hypericum patulum (Hypericaceae) is used as a natural herbal tea, scented tea, and folk medicine. In this study, eight undescribed bicyclic polyprenylated acylphloroglucinol-related meroterpenoids named hyperpatins A-H, along with eight known ones, were isolated from this plant. Their structures were elucidated on the basis of spectroscopic techniques, chemical method, X-ray crystallographic experiments, and electronic circular dichroism analyses. Hyperpatins A-H possess a characteristic pyran ring system diversely fused with the bicyclo[3.3.1]nonane-2,4,9-trione core, and hyperpatins C and D incorporate a unique α,β-unsaturated aldehyde moiety. Some of the isolates exhibited potent inhibitory effects on death-associated protein kinase-related apoptosis-inducing kinase 2 with IC50 values ranging from 2.60 ± 0.29 to 17.93 ± 3.08 μM. This is the first report of DRAK2 inhibitory activity for acylphloroglucinol-related meroterpenoids. The most active molecule hyperpatins C showed binding affinity with DRAK2 by hydrogen-bond and hydrophobic interactions in molecular docking and promoted the glucose-stimulated insulin secretion ability of primary islets.

Total Synthesis of (-)-Elodeoidins A and B

Biomimicry has long been a valuable approach for designing efficient synthetic strategies in complex natural product synthesis. However, abiotic yet powerful transforms can significantly streamline the synthesis by introducing greater convergence to the synthetic route. Herein, we delineate a convergent total synthesis of elodeoidins A and B, enabled by a cross-dehydrogenative coupling (CDC) reaction between an aldehyde and an electron-deficient olefin. The CDC reaction operating under the newly discovered reaction conditions proceeds via distinct concerted deprotonation within the formal Cu(III) catalytic complex. Furthermore, the total synthesis of both structural candidates of elodeoidin B revealed that the natural product exists as a mixture of epimers at the C8 stereocenter.

Meroterpenoids with bicyclic polyprenylated acylphloroglucinol scaffold and anti-inflammatory activity from Hypericum lancasteri

Twelve undescribed meroterpenoids possessing bicyclic polyprenylated acylphloroglucinol (BPAP) scaffold, (±)-lancasternoids A-D and lancasternoids E-H, together with fourteen known analogues, were isolated from Hypericum lancasteri (Hypericaceae) and structurally characterized. (±)-Lancasternoids A-D are the first examples of bicyclo[3.2.1]octane-type BPAP meroterpenoids present as enantiomeric pairs, while (±)-lancasternoids A-C incorporate an unprecedented 5-oxatetracyclo[7.5.1.04,9.01,11]pentadecane system. Lancasternoids E-H are two pairs of epimers with [3.3.1]-type BPAP scaffold. Some of the isolates showed inhibition in hypoxia-inducible factor-1α (HIF-1α) responsive element (HRE) luciferase assay, and uraloidin A further decreased the lipopolysaccharide (LPS)-induced pro-inflammatory factor IL-1β expression level in RAW 264.7 cells.

Xerophenone H, a naturally-derived proteasome inhibitor, triggers apoptosis and paraptosis in lung cancer

BACKGROUND

Polycyclic polyprenylated acylphloroglucinols (PPAPs) characterized by unique chemical architectures, exhibit diverse pharmacological activities. Xerophenone H (XeH) is a PPAP extracted from the plant Garcinia multiflora Champ. ex Benth. (Clusiaceae) with a novel and unique chemical structure. Although in vitro screening has revealed the anti-cancer activity of XeH, whose in vivo effectiveness and mechanistic basis required systematic investigation.

METHODS

Cytotoxic effects were evaluated through MTT and colony formation assays. A subcutaneous xenograft model was established to assess in vivo anti-cancer efficacy. To elucidate the underlying mechanism of the anti-cancer effect of XeH, RNA-sequencing and western blotting were performed. A proteasome activity assay was conducted to quantify the effect of XeH. Molecular docking and cellular thermal shift assays were conducted to identify the potential molecular target for XeH.

RESULTS

XeH demonstrated concentration-dependent cytotoxicity in A549 cells (IC₅₀ = 12.16 μM at 48 h). Intratumoral administration (10 mg/kg triweekly) achieved 38.6 % tumor growth inhibition. XeH simultaneously triggered apoptosis and paraptosis in A549 and H460 cells. Mechanistically, XeH promoted the formation of protein aggregates and induced significant endoplasmic reticulum stress in lung cancer cells by directly interacting with PSMB5 and inhibiting proteasome activity.

CONCLUSIONS

XeH, a novel PPAP, was identified as a novel proteasome inhibitor. It effectively downregulated proteasome activity, and induced both apoptosis and paraptosis in lung cancer cells.

Computable properties of selected monomeric acylphloroglucinols with anticancer and/or antimalarial activities and first-approximation docking study

CONTEXT

Malaria and cancer tend to become drug-resistant a few years after a drug is introduced into clinical use. This prompts the search for new molecular structures that are sufficiently different from the drugs for which resistance has developed. The present work considers eight selected acylphloroglucinols (ACPLs) with proven antimalarial and/or anticancer activities. ACPLs are compounds of natural origin structurally derivative from 1,3,5-trihydroxybenzene and characterized by the presence of an acyl group R-C = O. The selected ACPLs contain only one acylphloroglucinol moiety and are, therefore, monomeric ACPLs (also occasionally called "simple" ACPLs). They were studied computationally in vacuo and in-three-solvents with different polarities, using different levels of theory. The findings on molecular properties relevant to the understanding of biological activities align with previous studies, enhancing the reliability of predictions for molecules of the same class and providing insights into their behaviour in different environments. Structure-based virtual screening was used to study the interactions between these molecules and selected proteins known as relevant drug targets for antimalarial and anticancer activities; the screening showed that most of these ACPLs bind well with the selected proteins, thus being interesting for further studies. The results also suggest that most of these ACPLs have the potential for dual therapeutic applications (antimalarial and anticancer), offering a cost-effective drug development option. Furthermore, the ADME-T predictions indicated favourable pharmacokinetic properties for these ACPLs.

METHODS

Computational studies of the selected ACPLs were performed using Gaussian-09, in vacuo and in-three-solvents with different polarities. Three different levels of theory were used - Hartree Fock (HF), Density Functional Theory (DFT) with the B3LYP functional, and second order Møller-Plesset Perturbation Theory (MP2). HF and MP2 used a 6-31G(d,p) basis set, while DFT used a 6-31G + (d,p), for consistency with previous studies on ACPLs. The investigated molecular properties include conformational preferences, intramolecular hydrogen bonding patterns, HOMO-LUMO energy gap, dipole moments, as well as the solvent effect for the three considered solvents. Virtual screening was conducted using the Schrödinger suite, including Maestro 9.3 with GLIDE for docking and GlideScore for evaluating binding affinities. In addition, the QikProp tool provided ADME-T predictions for pharmacokinetic properties.

Hyperhelianthemones A-D: Polycyclic polyprenylated benzoylphloroglucinols from Hypericum helianthemoides

Phytochemical investigation of the n-hexane-soluble fraction of the aqueous ethanol extract of the aerial parts of Hypericum helianthemoides (Spach) Boiss. (Hypericaceae), furnished four undescribed polycylic polyprenylated benzoylphloroglucinols (PPBPs) 1-4, together with phytyl formate (5) and thirteen previously reported prenylated phloroglucinol derivatives, including yezo'otogirin C (6), hyperibrins A (7) and F (8), hyperibones G (9), J (10), La (11a)/Lb (11b), 7-epi-clusianone a (12a)/7-epi-clusianone b (12b), and hypermongones A (13), C (14), E (15), G (16), H (17), and sampsonione L (18). The structures of 1-4 were established by extensive 1D and 2D NMR spectral analysis as well as HREI-MS. The absolute configurations of the stereogenic carbons in 1 were established by X-ray crystallographic analysis, while the stereochemistry of 2 was assigned by quantum chemical calculation of its 1H and 13C NMR chemical shift values using DP4+ probability analysis. The isolated compounds were assayed for antileishmanial activity on Leishmania tropica and L. major parasites. Compounds 9 and 16 displayed activities against L. tropica, with IC50 values of 17.7 and 31.5 μM, respectively. Moreover, 9 was only active against L. major, with IC50 value of 34.2 μM.

Transannular Acylation Facilitates C5-C9 Bond Formation in Hyperforin Total Synthesis

Hyperforin is considered the flagship congener among polycyclic polyprenylated acylphloroglucinols due to its compelling and complex molecular architecture, coupled with remarkable biological activity, thus rendering it an appealing synthetic target for chemists over the past two decades. Herein, an innovative linear total synthesis of hyperforin is reported. Our synthesis relies on the formation of the bicyclo[3.3.1]nonane-2,4,9-trione framework via transannular acylation of a decorated eight-membered ring, followed by late stage bridgehead substitution.

NOD-like receptor protein 3 inhibitors in St. John's wort and their potential antidepressant effects

Depression is a chronic mental disorder characterized by persistent low mood and loss of interest, often associated with dysregulation of neuroinflammatory pathways. Inhibition of NOD-like receptor protein 3 (NLRP3), a key mediator of neuroinflammation, is a promising strategy for alleviating depressive symptoms by modulating inflammatory responses in the brain. Seven polycyclic polyprenylated acylphloroglucinols (PPAPs), including six new hyperioxides A-F (1-6) and furohyperforin (7) were isolated from St. John's wort and characterized via spectroscopic analyses. Compounds 2 and 7 exhibited neuroprotective effects at 10 μM in corticosterone (CORT)-injured SH-SY5Y cells. Furthermore, furohyperforin (7) was demonstrated potent antidepressant activity at 1.25 mg/kg in the forced swimming test (FST) of mice, which was equivalent to fluoxetine (10 mg/kg) and neurostan (78 mg/kg). Additionally, compound 7 was shown to reduce serum CORT levels in mice. Further studies highlighted its effects and potential mechanism through the NLRP3 inflammasome pathway and NLRP3 might be a protein target for the antidepressant effects of 7. Notably, this study provided the first evidence of furohyperforin (7)'s antidepressant properties in mice, highlighting its potential as a bioactive compound for antidepression.

Polycyclic Polyprenylated Acylphloroglucinols (PPAPs) from Garcinia Oblongifolia and their Antitumor Activity

Two new polycyclic polyprenylated acylphloroglucinols, along with four previously known compounds, were isolated and identified from the fruits of Garcinia oblongifolia. The structures of these compounds were elucidated through a combination of spectroscopic techniques, including MS, UV, IR, and 1D/2D NMR, as well as their chemical properties. Additionally, the cytotoxic activities of compounds 1-6 against the H134B cell line were evaluated using the MTT assay, revealing that compounds 1 and 2 exhibit promising antitumor activity.

Hypertums A-J, bioactive polycyclic polyprenylated acylphloroglucinols with diverse skeletons from Hypericum perforatum L. (St. John's wort)

Ten previously undescribed polycyclic polyprenylated acylphloroglucinols (PPAPs), hypertums A-J (1-10), together with eighteen known analogues (11-28), belonging to five subclasses of PPAPs, were isolated from the aerial parts of Hypericum perforatum L. (St. John's wort). The chemical structures and the absolute configurations of these compounds were elucidated by comprehensive analysis of NMR spectra, HR-ESI-MS data, quantum chemical calculations, chemical transformation, and X-ray crystallography. The carbon skeletons of compounds 1-5 were first characterized from H. perforatum. Compounds 6 and 7 were rare congeners assembled with two different polyprenylated acylphloroglucinol moieties through an ester bond. The plausible biosynthetic pathways for 1-10 were postulated. Compound 3, yezo'otogirin A (27) and yezo'otogirin B (28) exhibited weak acetylcholinesterase inhibitory activities at 50 μM. The isolated PPAPs were also evaluated for their anti-neuroinflammatory activity. Compound 3 inhibited nitric oxide (NO) production in LPS-stimulated BV-2 microglial cells with IC50 value of 34.34 μM and also suppressed the expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Moreover, anti-neuroinflammatory effect of 3 was also supported in zebrafish model.

Meroterpenes and prenylated acylphloroglucinol from the aerial parts of Hypericum erectum

Two previously undescribed specialized metabolites, erecricins F (1) and G (2), along with two known metabolites, erectumins A (3) and B (4), were isolated from the aerial parts of Hypericum erectum Thunb. (Hypericaceae). Detailed spectroscopic analyses revealed erecricin F (1) to be a C30 meroterpene with four isoprene units, and erecricin G (2) to be a prenylated acylphloroglucinol biogenetically related to 1. The relative configurations of erecricins F (1) and G (2) were assigned by NOESY analysis and GIAO NMR calculation, while their absolute configurations were deduced by comparison of the ECD spectra with TDDFT calculated spectra. The relative configurations of 3 and 4 were also elucidated by the similar method as for 1 and 2. Erecricins F (1) and G (2) and erectumins A (3) and B (4) were evaluated for their inhibitory effect against IL-1β release from LPS-stimulated murine microglial cells and anti-ferroptosis activity using human hepatoma Hep3B cells.

Polyprenylated acylphloroglucinols from Hypericum sampsonii with cytotoxicity against pancreatic carcinomas

Chemical investigation on the 80% EtOH extract of the air dried aerial parts of Hypericum sampsonii resulted in the isolation of two new polycyclic polyprenylated derivatives, hypersampines A and B (1 and 2). The structures of the new compounds were elucidated by spectroscopic data (NMR, IR, and UV) and high resolution mass analysis. The two isolated polyprenylated acylphloroglucinols were tested in vitro for cytotoxic activities against 6 pancreatic cell lines. As a result, compounds 1 and 2 possessed modest cytotoxic activities against all the tested tumor cell lines with IC50 values less than 40 μM.

Filicinic Acid-Based Meroterpenoids with Antiproliferative Activity against Prostate Cancer PC-3 Cells from Dryopteris wallichiana

Nine new structurally diverse filicinic acid-based meroterpenoids (1-9) with four kinds of carbon skeletons were isolated from the rhizomes of Dryopteris wallichiana. Their structures, including the absolute configurations, were elucidated by comprehensive analysis of spectroscopic data, quantum chemical calculations, and single-crystal X-ray diffraction. Structurally, compounds 1-4 feature an unprecedented 6/6/5/6/6/6 hexacyclic system with a rare oxaspiro[4.5]decane core linking the filicinic acid and ent-kaurane-type diterpene moieties. Compounds 5-6 are rare hybrids of filicinic acid and carotane-type sesquiterpene. Compound 7 is an unusual rearranged filicinic acid-carotane-type sesquiterpene meroterpenoid. Compounds 8-9 are two enantiomeric pairs of new meroterpenoids constructed by filicinic acid and a germarane-type sesquiterpene. A plausible biosynthetic pathway for the nine compounds was proposed. Notably, compounds 5, 6, (+)/(-)-8, and (+)/(-)-9 were discovered to possess antiproliferative activity against PC-3 cells based on virtual screening, and in vitro bioassay. An interactive preprint version of the article can be found at https://www.authorea.com/doi/full/10.22541/au.172666991.17272585/v1.

Asymmetric Total Synthesis of (+)-Hyperbeanol A

A bioinspired alkylation dearomatization reaction was developed to construct the 5/6/6 fused-spiro tricyclic core framework and spiro-quaternary carbon chiral center. The usage of this approach for assembling these natural products of spirocyclic polycyclic polyprenylated acylphloroglucinols with an octahydrospiro-[cyclohexan-1,5'-indene] core is demonstrated by the first asymmetric total synthesis of highly oxidized hyperbeanol A.

Isolation and Biomimetic Semisynthesis of Hyperzrones A and B, Two Nor-Polycyclic Polyprenylated Acylphloroglucinols with a Characteristic Cyclobutane Moiety, from Hypericum beanii

Hyperzrones A (1) and B (2), two unprecedented nor-polycyclic polyprenylated acylphloroglucinols with a characteristic cyclobutane moiety, were discovered from Hypericum beanii. Their structures were determined by extensive spectroscopic analysis, X-ray crystallography, and quantum chemical calculation methods. A bioinspired semisynthesis of 1 and 2 was achieved from the natural precursor hypercalin B (3), featuring a Favorskii-type rearrangement and a visible-light-mediated [2 + 2] photocycloaddition. Several diverse derivatives were also obtained, providing a compound library for biological studies.

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.

Specialized metabolism in St John's wort

The specialized metabolism of St. John's wort, Hypericum perforatum L., is a key focus in medicinal plant research due to its hallmark bioactive compounds hyperforin and hypericin. Known for its traditional medicinal uses dating back to ancient times, St. John's wort is currently used for mild depression therapy. Recent research works have shed light on the biosynthesis of various metabolites in this plant, such as flavonoids, xanthones, hyperforin, and hypericin. The elucidation of these pathways, along with the discovery of novel enzymes like hyperforin synthase, support the pharmaceutical research by enabling scalable production of bioactive compounds for the development of new drugs. Elucidation of the hyperforin biosynthesis based on single-cell RNA-seq is an approach that will be expanded and accelerate the gene discovery and full pathway reconstitution of plant specialized metabolites.

Three New Polyprenylated Benzophenone Derivatives Isolated from Clusia burle-marxii

Three new polyprenylated benzophenone derivatives named burlemarxiones G-I (1-3) were isolated from C. burle-marxii trunks (compound 1) and leaves (compounds 2 and 3), along with the known compound burlemarxione F. Burlemarxione G (1) was isolated after methylation with diazomethane and it is the keto-enol tautomeric pair of burlemarxione F. Burlemarxione H (2) derives from burlemarxiones F and G, but it has additional rings due to cyclization of the prenyl group attached to C-5 that establishes new single bonds between C-1 and C-23, as well as, between C-24 and C-29. Burlemarxione I (3) has two additional cyclizations: the first encompasses the cyclization of the former isopentenyl group into an 11,11-dimethyl-six-membered ring, whereas the second produces additional rings due to the cyclization of the prenyl group attached to C-5 that establishes new single bonds between C-1 and C-23, as well as, between C-24 and C-29. All three compounds showed moderate anti-glioma activity. These results show that C. burle-marxii is an important source of sophisticated polyprenylated benzophenone derivatives.

Bench-Stable Meisenheimer Complexes: Synthesis, Characterization, and Divergent Reactivity for Dearomatization

The chemistry of the Meisenheimer complexes is of fundamental interest in organic chemistry. While the nitro group has been extensively employed to facilitate the formation and stabilization of Meisenheimer complexes, the analogous application of more user-friendly ester groups has remained an unexplored frontier. Herein, we report ester-stabilized Meisenheimer complexes, which have remarkable air-, moisture-, and thermo-stability. Moreover, the isolable and well-defined Meisenheimer intermediates exhibit divergent reactivity for dearomatization reactions, including modular 1,4-additions, dearomative (2 + 3) cycloadditions, and even higher-order (4 + n) cycloadditions. These methodologies enabled rapid access to complicated cyclohexane derivatives with multiple all-carbon quaternary centers and interesting structure topologies.

Polyprenylated Benzoylphloroglucinols Isolated from Garcinia Species and Their Cytotoxic Effects on Cancer Cell Lines

Polyprenylated benzoylphloroglucinols (PPBPs) make up a group of complex natural products with anticancer potentials that are mainly distributed in Garcinia plants. As part of our intensive exploration on new bioactive substances from this genus, we report two undescribed PPBPs, picrorhizones I (1) and J (2), along with four known analogues (3-6) from the stem bark of Garcinia picrorhiza and Garcinia gracilis. The new structures were elucidated on the basis of spectroscopic analysis, particularly 1D and 2D NMR and HRESIMS, whereas the absolute configurations were determined by a combination of ECD and NMR calculations coupled with a DP4+ probability analysis. Being the least class in genus Garcinia, picrorhizone I possesses a type-A structure with the position of a benzoyl moiety attaching to one of the bridgehead carbons of a bicyclo[3.3.1]nonane skeleton, which differs from its major type-B counterparts. This work also represents the first report on the occurrence of PPBPs in G. gracilis. The cytotoxic evaluation of the isolated compounds revealed that isogarcinol (4) and garciyunnanin L (5) significantly inhibited the growth of KB and Hela S3 cancer cells with IC50 values lower than 10 μM, while 5 was also strongly active against the Hep G2 cancer cell line with an IC50 value of 8.02 μM. Among the B-class derivatives bearing a lavandulyl side chain, cyclization of the moiety in the bicyclic phloroglucinol skeleton enhanced the cytotoxic properties on cancer cells.

Catalytic prenyl conjugate additions for synthesis of enantiomerically enriched PPAPs

Polycyclic polyprenylated acylphloroglucinols (PPAPs) are a class of >400 natural products with a broad spectrum of bioactivity, ranging from antidepressant and antimicrobial to anti-obesity and anticancer activity. Here, we present a scalable, regio-, site-, and enantioselective catalytic method for synthesis of cyclic β-prenyl ketones, compounds that can be used for efficient syntheses of many PPAPs in high enantiomeric purity. The transformation is prenyl conjugate addition to cyclic β-ketoesters promoted by a readily accessible chiral copper catalyst and involving an easy-to-prepare and isolable organoborate reagent. Reactions reach completion in just a few minutes at room temperature. The importance of this advance is highlighted by the enantioselective preparation of intermediates previously used to generate racemic PPAPs. We also present the enantioselective synthesis of nemorosonol (14 steps, 20% yield) and its one-step conversion to another PPAP, garcibracteatone (52% yield).

Anti-inflammatory bicyclic polyprenylated acylphloroglucinols with diverse architectures including an unprecedented 6/6/6 tricyclic core from Garcinia yunnanensis

Garciyunnanol A (1), an unprecedented 1,2-seco-bicyclic polyprenylated acylphloroglucinol (BPAP) possessing a unique 6/6/6 tricyclic core, was characterized from Garcinia yunnanensis together with 16 BPAPs, including eight new compounds (garciyunnanols B-I, 2-9). Biogenetically, the bicyclo[3.3.1]nonane-2,4,9-trione moiety of 12 reconstructed the bicyclic δ-lactone core of 2 through Norrish type Ⅰ cleavage and cyclization, followed by a cyclization of two side chains to form an intriguing 6/6/6 tricyclic core of 1. Their structures were elucidated through analysis of spectroscopic data, calculation and comparison of ECD spectra. Bioactivity evaluation manifested that compounds 1, 2, 5, 6 and 14 demonstrated superior inhibition of NO production compared to the positive control dexamethasone. Notably, compound 5 exhibited a dose-dependent inhibitory effect on NO production, with an IC50 value of 0.25 ± 0.87 µM. Furthermore, experiments involving ELISA, Western blotting, and immunofluorescence staining revealed that 5 effectively reduced the secretion of interleukin-1β in LPS plus nigericin-stimulated THP-1 macrophages by inhibiting the activation of the NLRP3 inflammasome.

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.

How did plants evolve the prenylation of specialized phenolic metabolites by means of UbiA prenyltransferases?

Prenylated phenolics occur in over 4000 species in the plant kingdom, most of which are known as specialized metabolites with high chemical diversity. Many of them have been identified as pharmacologically active compounds from various medicinal plants, in which prenyl residues play a key role in these activities. Prenyltransferases (PTs) responsible for their biosynthesis have been intensively studied in the last two decades. These enzymes are membrane-bound proteins belonging to the UbiA superfamily that occurs from bacteria to humans, and in particular those involved in plant specialized metabolism show strict specificities for both substrates and products. This article reviews the enzymatic features of plant UbiA PTs, including C- and O-prenylation, molecular evolution, and application of UbiA PTs in synthetic biology.

Polyphenol-Based Self-Assembled Nanomedicine for a Three-Pronged Approach to Reversing Tumor Immunosuppression

The challenges of multi-pathway immune resistance and systemic toxicity caused by the direct injection of immune checkpoint inhibitors are critical factors that compromise the effectiveness of clinical immune checkpoint blockade therapy. In this context, natural polyphenols have been employed as the primary component to construct a targeted and acid-responsive PD-L1 antibody (αPD-L1) delivery nanoplatform. This platform incorporates garcinol, an inhibitor of the Nuclear Factor Kappa-B (NF-κB) signaling pathway, to regulate pro-tumor immune escape cytokines and regulatory T cells. Additionally, the nanoplatform has been verified to induce immunogenic cell death (ICD), which promotes the maturation of dendritic cells and enhances the activity of cytotoxic T lymphocytes. In vivo and in vitro experimental results demonstrated that the nanoplatform can boost the immune response through a PD-L1 and NF-κB blocking/ICD inducing three-pronged strategy, thereby effectively combating tumor growth and metastasis.

Single-cell RNA sequencing facilitates the elucidation of the complete biosynthesis of the antidepressant hyperforin in St. John's wort

Hyperforin is the compound responsible for the effectiveness of St. John's wort (Hypericum perforatum) as an antidepressant, but its complete biosynthetic pathway remains unknown. Gene discovery based on co-expression analysis of bulk RNA-sequencing data or genome mining failed to discover the missing steps in hyperforin biosynthesis. In this study, we sequenced the 1.54-Gb tetraploid H. perforatum genome assembled into 32 chromosomes with the scaffold N50 value of 42.44 Mb. By single-cell RNA sequencing, we identified a type of cell, "Hyper cells", wherein hyperforin biosynthesis de novo takes place in both the leaves and flowers. Through pathway reconstitution in yeast and tobacco, we identified and characterized four transmembrane prenyltransferases (HpPT1-4) that are localized at the plastid envelope and complete the hyperforin biosynthetic pathway. The hyperforin polycyclic scaffold is created by a reaction cascade involving an irregular isoprenoid coupling and a tandem cyclization. Our findings reveal how and where hyperforin is biosynthesized, enabling synthetic-biology reconstitution of the complete pathway. Thus, this study not only deepens our comprehension of specialized metabolism at the cellular level but also provides strategic guidance for elucidation of the biosynthetic pathways of other specializied metabolites in plants.

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-1β 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.

The Total Synthesis of Hyperfirin via a Cyclooctadiene Strategy

Polycyclic polyprenylated acylphloroglucinols (PPAPs) combine compelling structural complexity with effective biological activity. The total synthesis of Hyperfirin is reported as one linear sequence. Key to this novel modular strategy is to access the bicyclo[3.3.1]nonane-2,4,9-trione framework via transannular acylation of a decorated eight-membered ring, followed by late stage bridgehead substitution. The described route adds flexibility to PPAP construction and broadens the scope of eight-membered ring chemistry.

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.

Asymmetric Synthesis of α-Arylcyclohexenones Catalyzed by Diphenylprolinol Silyl Ether

A general methodology for the asymmetric synthesis of α-arylcyclohexeneones from arylacetones and α,β-unsaturated aldehydes catalyzed by diphenylprolinol silyl ether followed by p-TSA-mediated cyclization is developed. A variety of arylacetones and α,β-unsaturated aldehydes were successfully converted to α-arylcyclohexeneones in 34-67% yield, 10:1-100:0 dr, and 81-99% ee. The scalability of this methodology by a gram-scale synthesis and their utility by converting the product to the corresponding epoxide, alcohol, and diol are demonstrated.

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.

Isogarcinol inhibits nasopharyngeal carcinoma growth through mitochondria-mediated autophagic cell death

BACKGROUND AND AIMS

Isogarcinol, a natural compound extracted from the fruits of Garcinia oblongifolia, has potential chemopreventive activity. This study aimed to elucidate the anti-tumor effects and mechanism of action of isogarcinol on nasopharyngeal carcinoma (NPC).

METHODS

Isogarcinol was isolated from Garcinia oblongifolia by using chromatographic separation. The anti-tumor effects of isogarcinol in NPC cells were tested by MTT assay, flow cytometry, wound healing assay, western blotting, transwell assay, colony formation assay, immunofluorescence, and transmission electron microscopy (TEM). The anti-tumor efficacy in vivo was evaluated in NPC cells xenograft models.

RESULTS

Functional studies revealed that isogarcinol inhibited the proliferation, colony formation, migration and invasion abilities of NPC cells in vitro. Isogarcinol caused mitochondrial damage to overproduce reactive oxygen species through reducing the mitochondrial membrane potential and ΔΨm. Isogarcinol also substantially inhibited NPC cells growth in a xenograft tumor model without any obvious toxicity when compared with paclitaxel (PTX). Mechanistic studies have illustrated that isogarcinol increased the Bax/Bcl-2 ratio, cleaved caspase-3, and cytoplasmic cytochrome C levels to induce mitochondrial apoptosis. The ROS overproduction by isogarcinol could suppress EMT pathway via decreasing the levels of p-Akt and Snail. Furthermore, isogarcinol promoted the conversion of LC3-Ⅰ to LC3-Ⅱ, but increased p62 level to block autophagic flux, resulting in the accumulation of damaged mitochondria to promote autophagic cell death in NPC cells.

CONCLUSION

This study provides a new theoretical foundation for the anti-tumor application of Garcinia oblongifolia and confirms that isogarcinol could be developed as a candidate drug for NPC treatment with low toxicity.

Antimicrobial Evaluation of Two Polycyclic Polyprenylated Acylphloroglucinol Compounds: PPAP23 and PPAP53

Polycyclic polyprenylated acylphloroglucinols (PPAPs) comprise a large group of compounds of mostly plant origin. The best-known compound is hyperforin from St. John's wort with its antidepressant, antitumor and antimicrobial properties. The chemical synthesis of PPAP variants allows the generation of compounds with improved activity and compatibility. Here, we studied the antimicrobial activity of two synthetic PPAP-derivatives, the water-insoluble PPAP23 and the water-soluble sodium salt PPAP53. In vitro, both compounds exhibited good activity against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium. Both compounds had no adverse effects on Galleria mellonella wax moth larvae. However, they were unable to protect the larvae from infection with S. aureus because components of the larval coelom neutralized the antimicrobial activity; a similar effect was also seen with serum albumin. In silico docking studies with PPAP53 revealed that it binds to the F1 pocket of human serum albumin with a binding energy of -7.5 kcal/mol. In an infection model of septic arthritis, PPAP23 decreased the formation of abscesses and S. aureus load in kidneys; in a mouse skin abscess model, topical treatment with PPAP53 reduced S. aureus counts. Both PPAPs were active against anaerobic Gram-positive gut bacteria such as neurotransmitter-producing Clostridium, Enterococcus or Ruminococcus species. Based on these results, we foresee possible applications in the decolonization of pathogens.

Total Synthesis of Hypersampsone M

We report the first total synthesis of hypersampsone M, an archetypal member of the homoadamantane polycyclic polyprenylated acylphloroglucinols (PPAPs). Commencing from cyclohexenone, a key cyclopentene annulation followed by ring-expansion results in an elusive hydrazulene that undergoes a series of unexpected late-stage transformations, ultimately enabling completion of the synthesis. The route detailed herein represents a potentially general strategy for the synthesis of related homoadamantane PPAPs.

Metabolomic and chemometric analyses of St. John's wort and related Asian Hypericum species linked to bioactivity

ETHNOPHARMACOLOGICAL RELEVANCE

Plants in the genus Hypericum (Hypericaceae), include more than 500 species worldwide, and many are valued for their medicinal properties, and are used as traditional herbal medicines. However, only H. perforatum is officially recognized as herbal drug in several pharmacopoeias, and used as an antidepressant clinically. Hypericum perforatum had been used as an herbal medicine since the Han Dynasty (206 B.C. -220 A.D.) in China. It taxonomically belongs to the section Hypericum in the genus Hypericum. There are about 42 species in the section Hypericum, with six species occurring in China. All six are recorded as traditional herbal medicines for treating aliments, including hepatitis, malaria, traumatic hemorrhage, irregular menstruation, wounds, and bruises.

AIM OF THE STUDY

The study aimed to characterize the chemical profiles of five phylogenetically related Hypericum species, and compare their metabolites with three H. perforatum products. Informed by ethnobotanical use, the extracts prepared from the five species were further investigated into anticancer, anti-inflammatory and antiplasmodial activity. This study tested the hypothesis that systematic metabolomic and bioactivity characterization of species in section Hypericum will help to validate their phytotherapeutic use and reveal potential drug lead compounds.

MATERIALS AND METHODS

Targeted and non-targeted metabolic analyses coupled with chemometrics were conducted on H. perforatum and four medicinal species, H. attenuatum, H. enshiense, H. erectum, and H. faberi, native to China from section Hypericum. UPLC-QTOF-MS/MS and UPLC-TQD-MS/MS were used for non-targeted and targeted metabolic analyses, respectively. Cytotoxicity bioassays on four cancer cell lines, anti-inflammation tests and anti-plasmodial activity on Plasmodium falciparum 3D7, selected based on traditional medicinal use, were evaluated on extracts from Hypericum species. Progenesis QI and EZinfo were used for chemometrics analysis to link the chemical profile and bioassay activity to aid in the identification of bioactive compounds.

RESULTS

In total, 58 compounds were identified from the five species, including compounds with well-characterized bioactivity. Hypericum attenuatum, H. erectum, and H. perforatum, displayed the highest cytotoxicity, and contain the cytotoxic compounds petiolin A, prolificin A, and hypercohin G, respectively. Hypericum faberi and H. perforatum showed the highest anti-inflammatory activity, with pseudohypericin, quercetin and chlorogenic acid being observed at higher concentrations. Hypericum perforatum and H. erectum showed anti-plasmodial activity, with higher hyperforin and xanthones in these species that may account for the anti-plasmodial activity.

CONCLUSIONS

This study characterized the chemical differences among five Hypericum species using metabolomics. These ethnomedically important species were tested for their biological activities in three distinct in vitro assays. The ethnobotanical data were useful for identifying bioactive Hypericum species. Hypericum attenuatum, H. erectum and H. faberi are promising phytotherapeutic species, although they are much less studied than H. perforatum, St. John's wort. Combining ethnobotanical surveys with chemometric analyses and bioactivity screening can greatly enhance the discovery of promising active constituents.

(±)-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.

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.

Total Synthesis of Strigolactones via Palladium-Catalyzed Cascade Carbonylative Carbocyclization of Enallenes

Here we report an efficient route for synthesizing strigolactones (SLs) and their derivatives. Our method relies on a palladium-catalyzed oxidative carbonylation/carbocyclization/carbonylation/alkoxylation cascade reaction, which involves the formation of three new C-C bonds and a new C-O bond while cleaving one C(sp3)-H bond in a single step. With our versatile synthetic strategy, both naturally occurring and artificial SLs were prepared.

Spirohypertones A and B as potent antipsoriatics: Tumor necrosis factor-α inhibitors with unprecedented chemical architectures

Tumor necrosis factor-α (TNF-α) is a promising target for inflammatory and autoimmune diseases. Spirohypertones A (1) and B (2), two unprecedented polycyclic polyprenylated acylphloroglucinols with highly rearranged skeletons, were isolated from Hypericum patulum. The structures of 1 and 2 were confirmed through comprehensive spectroscopic analysis, single-crystal X-ray diffraction and electronic circular dichroism calculations. Importantly, 2 showed remarkable TNF-α inhibitory activity, which could protect L929 cells from death induced by co-incubation with TNF-α and actinomycin D. It also demonstrated the ability to suppress the inflammatory response in HaCaT cells stimulated with TNF-α. Notably, in an imiquimod-induced psoriasis murine model, 2 restrained symptoms of epidermal hyperplasia associated with psoriasis, presenting anti-inflammatory and antiproliferative effects. This discovery positions 2 as a potent TNF-α inhibitor, providing a promising lead compound for developing an antipsoriatic agent.

Regiodivergent biosynthesis of bridged bicyclononanes

Medicinal compounds from plants include bicyclo[3.3.1]nonane derivatives, the majority of which are polycyclic polyprenylated acylphloroglucinols (PPAPs). Prototype molecules are hyperforin, the antidepressant constituent of St. John's wort, and garcinol, a potential anticancer compound. Their complex structures have inspired innovative chemical syntheses, however, their biosynthesis in plants is still enigmatic. PPAPs are divided into two subclasses, named type A and B. Here we identify both types in Hypericum sampsonii plants and isolate two enzymes that regiodivergently convert a common precursor to pivotal type A and B products. Molecular modelling and substrate docking studies reveal inverted substrate binding modes in the two active site cavities. We identify amino acids that stabilize these alternative binding scenarios and use reciprocal mutagenesis to interconvert the enzymatic activities. Our studies elucidate the unique biochemistry that yields type A and B bicyclo[3.3.1]nonane cores in plants, thereby providing key building blocks for biotechnological efforts to sustainably produce these complex compounds for preclinical development.

Asymmetric aza-Henry reaction toward trifluoromethyl β-nitroamines and biological investigation of their adamantane-type derivatives

Amino acid-derived quaternary ammonium salts were successfully applied in the asymmetric aza-Henry reaction of nitromethane to N-Boc trifluoromethyl ketimines. α-Trifluoromethyl β-nitroamines were synthesized in good to excellent yields with moderate to good enantioselectivities. This reaction is distinguished by its mild conditions, low catalyst loading (1 mol%), and catalytic base. It also proceeded on a gram scale without loss of enantioselectivity. The products were transformed to a series of adamantane-type compounds containing chiral trifluoromethylamine fragments. The potent anticancer activities of these compounds against liver cancer HepG2 and melanoma B16F10 were evaluated. Six promising compounds with notable efficacy have potential for further development.

Hyperatins A-D, highly oxidized polycyclic polyprenylated acylphloroglucinols from Hypericum perforatum L. with hypoglycemic potential in liver cells

Hyperatins A-D (1-4), four previously undescribed polycyclic polyprenylated acylphloroglucinols, were isolated from Hypericum perforatum L. (St. John's wort). Compound 1 possessed a unique octahydroindeno[1,7a-b]oxirene ring system with a rare 2,7-dioxabicyclo[2.2.1]heptane fragment. Compounds 2-4 had an uncommon decahydrospiro[furan-3,7'-indeno[7,1-bc]furan] ring system. Their structures were established by spectroscopic analyses and X-ray crystallography. Plausible biosynthetic pathways of 1-4 were also proposed. Compounds 1 and 2 exerted promising hypoglycemic activity by inhibiting glycogen synthase kinase 3 expression in liver cells.

Two aromatic acid derivatives and a xanthone from Hypericum hengshanense

Three previously undescribed compounds including two aromatic acid derivatives (1-2), and one xanthone (3), together with ten known compounds (4-13) were isolated from the aerial part of Hypericum hengshanense. The planar structures of three new compounds were established by 1 D and 2 D NMR and MS data. And the absolute configurations of compounds 1-2 were determined by the quantum chemical ECD calculations. Compounds 1-2 showed weak cytotoxicity against Hep-2 human cancer cell lines with IC50 values of 65.1 ± 2.7 and 78.0 ± 1.0 μg/mL, respectively.

Four new compounds from fruits of Hypericum patulum Thunb

A new naphthoquinone, patulumnaphthoquinone A (1) and three new glycosides, patulumside B (2), patulumside C (3) and patulumside D (4) were isolated from the 30% ethanol extract of the fresh ripe fruits of Hypericum patulum Thunb. using column chromatography techniques. The structures of these compounds including absolute configurations were elucidated on the basis of HRESIMS, NMR spectroscopic analyses, calculated electronic circular dichroism spectra and comparison with the literatures.

Antiproliferative polycyclic polyprenylated acylphloroglucinols from Garcinia paucinervis

Bioassay-guided isolation of the stems of Garcinia paucinervis led to one new adamantane-type polycyclic polyprenylated acylphloroglucinols (PPAPs), (-)-garpauvinin A (1), and four known analogues (2-5). The structure and absolute configuration of 1 was established via spectroscopic techniques and ECD method. All the isolates displayed moderate antiproliferative activity against HL-60, PC-3 and Caco-2 human cancer cell lines with IC50 values ranging from 0.81 to 19.92 μM, and exhibited low toxicity on WPMY-1 normal human cells, showing selectivity between normal and malignant prostate cells. The biosynthetic pathways of the isolated PPAPs were proposed.

Meroterpenes and prenylated benzoylphloroglucinol from the flowers of Hypericum formosanum

Formohyperins A-F, previously undescribed meroterpenes, and grandone, a prenylated benzoylphloroglucinol being considered to be one of their biogenetic precursors, were isolated from the flowers of a Hypericaceous plant, Hypericum formosanum Maxim. Detailed spectroscopic analyses showed that formohyperins A-D were meroterpenes with an enolized 3-phenylpropane-1,3-dione moiety. Formohyperins E and F were elucidated as meroterpenes having a 4-benzoyl-5-hydroxycyclopent-4-ene-1,3-dione moiety. Formohyperins A-C and E were optically active, and their absolute configurations were deduced by comparison of the experimental and TDDFT calculated ECD spectra. In contrast, formohyperin D was concluded to be a racemate. Formohyperins A-F and grandone were found to show inhibitory activities against LPS-stimulated IL-1β production from murine microglial cells with EC50 values of 13.2, 6.6, 8.5, 24.3, 4.1, 10.9, and 3.0 μM, respectively.

Antidepressant polyprenylated acylphloroglucinols from Hypericum ascyron

Phytochemical investigation on the 90% EtOH extract of the air-dried aerial parts of Hypericum ascyron resulted in the isolation of three new polycyclic polyprenylated derivatives ascyronines A-C (1-3). Structural elucidation of all the compounds was performed by spectral methods such as 1D and 2D (1H-1H COSY, HMQC, and HMBC) NMR spectroscopy. All the polycyclic polyprenylated acylphloroglucinols were evaluated for their antidepressant activity by inhibiting the reuptake of tritiated serotonin ([3H]-5-HT) and noradrenalinet ([3H]-NE) in rat brain synaptosomes. Compounds 2 and 3 exhibited weak antidepressant activities in the [3H]-5-HT mode.