Dioxasampsones A and B, Two Polycyclic Polyprenylated Acylphloroglucinols with Unusual Epoxy-Ring-Fused Skeleton from Hypericum sampsonii

Filicinic acid based meroterpenoids from Hypericum elodeoides and their anti-Alzheimer's disease effects

(±)-Elodeoidileons A-L (1-12), 12 pairs of previously undescribed filicinic acid based meroterpenoids were isolated from Hypericum elodeoides with unique linear or angular 6/6/6 ring core. Modern spectroscopic techniques, modified Mosher's method and quantum chemical calculations were used to identify the planner structures and configurations of 1-12. Additionally, the potential biosynthetic pathways for 1-12 were anticipated. Moreover, biological activity assessments suggested that 1a, 5a, and 11b could activate Retinoid X receptor-α (RXRα) transcription and enhance the ATP-binding cassette transporter A1 (ABCA1) protein's expression. Fluorescence titration assay suggested that 1a might have a direct interaction with the RXRα-LBD protein, with an estimated Kd value of 5.85 μM. Moreover, molecular docking study confirmed the binding of 1a to RXRα and further validated by cellular thermal shift assay (CETSA). Thus, compound 1a may promote β-amyloid (Aβ) clearance by targeting RXRα and upregulating the expression of the ABCA1 protein, showing promise as anti-Alzheimer's agent.

Discovery of bioactive polycyclic polyprenylated acylphloroglucinols with adamantine/homoadamantane skeletons from Hypericum wilsonii

In this work, nine previous undescribed polycyclic polyprenylated acylphloroglucinols with adamantine/homoadamantane skeletons, cumilcinols A-I (1-9), along with six known analogues, were isolated and identified from the stems, leaves and flowers of Hypericum wilsonii. Their structures were determined by HRESIMS, NMR spectroscopic analysis, single-crystal X-ray crystallography as well as electronic circular dichroism calculations and comparisons. Compound 2 formed a unique furan ring bearing a rare acetal functionality. In bioassays, hyperacmosin G (13) could significantly inhibit the production of NO in LPS-stimulated RAW264.7 cell (IC50 = 4.350 ± 1.146 μM), and increased expression of related transcription factors at the gene level, inhibit the nuclear translocation of NF-κBp65, and reduce the protein expression of COX-2. Additionally, compound 5 showed significant inhibitory activity on Con A-induced T-lymphocyte proliferation (IC50 = 4.803 ± 3.149 μM), and treatment of 5 could reduce the increased ratio of CD4 and CD8 subpopulations induced by Con A in vitro. Those results indicated 13 possesses potential anti-inflammatory activity, and 5 exhibits a certain degree of immunosuppressive activity.

Hypericum sampsonii Hance: a review of its botany, traditional uses, phytochemistry, biological activity, and safety

Ethnopharmacological relevance: Hypericum sampsonii Hance, also known as Yuanbao Cao in Chinese, is a traditional medicinal herb from the Guttiferae family and has been widely used in China to treat various conditions, including dysentery, enteritis, mastitis, scrofula, and contusion. Aim of the review: This review aims to provide a comprehensive overview of the botany, traditional uses, phytochemistry, biological activity and safety of H. sampsonii and to highlight its potential for medical application and drug development. Materials and methods: We searched several databases, i.e., Web of Science, SciFinder, PubMed, CBM, CNKI, Google Scholar, etc., for relevant information on H. sampsonii. Additionally, we also consulted some books on Chinese medicine. Results: To date, 227 secondary metabolites have been isolated from H. sampsonii, including polycyclic polyprenylated acylphloroglucinols (PPAPs), benzophenones, xanthones, flavonoids, naphthodianthrones, anthraquinones and aromatic compounds. These metabolites exhibit various biological activities such as anti-inflammatory, anti-tumor, anti-depressant, anti-oxidant, anti-viral and anti-bacterial effects. PPAPs are considered the main active metabolites with rich biological activities. Despite being known as rich source of PPAPs, the full extent of H. sampsonii biological activities, including their potential as PDE4 inhibitors, remained unclear. Since, previous studies have mainly been based on structural identification of metabolites in H. sampsonii, and efficacy evaluations of these metabolites based on clinical applications of H. sampsonii lack sufficient data. However, current evidence suggest that PPAPs are the most likely material basis for efficacy. From the limited information available so far, there is no evidence of potential safety issues and the safety data are limited. Conclusion: Collectively, this review provides a comprehensive overview of the botany, traditional uses, phytochemistry, pharmacology, and safety of H. sampsonii, a valuable medicinal plant in China with various pharmacological activities. Based on pharmacological studies, H. sampsonii shows potential for treating gastrointestinal and gynecological disorders as well as traumatic injuries, which aligns with traditional medicinal use due to the presence of PPAPs, benzophenones, xanthones, and flavonoids. Therefore, further studies are needed to evaluate the pharmacological effects and elucidate the pharmacological mechanisms. In addition, pharmacological mechanisms and safety evaluation of PPAPs on animal models need to be clarified. Yet, further comprehensive studies are required to elucidate the phytochemical constituents, pharmacological mechanisms, structure-activity relationships, safety evaluation, and quality standards of this plant. Takentogether, this review highlights the potential of H. sampsonii for medical application and drug development.

Polycyclic polyprenylated acylphloroglucinols from Hypericum sampsonii Hance and their anti-inflammatory activity

Phytochemical investigation of Hypericum sampsonii Hance resulted in the isolation of thirty-five polycyclic polyprenylated acylphloroglucinols including six new ones (1, 3, 5, and 15-17). Their structures were elucidated by UV, IR, NMR, HRESIMS, and calculated ECD analysis. Some compounds were evaluated for their anti-inflammatory effects in LPS-induced RAW264.7 cells. Compounds 1 and 26 showed significant inhibitory effects on LPS-induced NO production, and markedly suppressed the protein expression of iNOS and COX-2 in LPS-activated RAW264.7 cells.

A review on natural products with cage-like structure

Natural products with diverse structures and significant biological activities are essential sources of drug lead compounds, and play an important role in the research and development of innovative drugs. Cage-like compounds have various structures and are widely distributed in nature, especially caged xanthones isolated from Garcinia genus, paeoniflorin and its derivatives isolated from Paeonia lactiflora Pall, tetrodotoxin (TTX) and its derivatives, and so on. In recent years, the development and utilization of cage-like compounds have been a research hotspot in chemistry, biology and other fields due to their special structures and remarkable biological activities. In this review, we mainly summarized the cage-like compounds with various structures found and isolated from natural drugs since 1956, summarized its broad biological activities, and introduced the progress in the biosynthesis of some compounds, so as to provide a reference for the discovery of more novel compounds, and the development and application of innovative drugs.

Seco-polyprenylated acylphloroglucinols from Hypericum elodeoides induced cell cycle arrest and apoptosis in MCF-7 cells via oxidative DNA damage

Four undescribed seco-polyprenylated acylphloroglucinols (seco-PAPs), elodeoidesones A-D (1-4), were characterized from Hypericum elodeoides. Compound 1 represents the 1,6-seco-PAPs with fascinating 5/5 fused ring, while 2-4 possess a 1,2-seco-PAPs skeleton with a five-membered lactone core. Their structures including absolute configurations were established by spectroscopic analyses and quantum chemical computations. A possible biosynthetic pathway of 1-4 from normal PAPs was proposed. All the isolates were investigated for their cytotoxicity against tumor cells. Notably, 1 inhibited the proliferation of MCF-7 cells with the IC₅₀ value of 7.34 μM. Mechanism investigation indicated that 1 induced MCF-7 cells apoptosis by blocking cell cycle at S phase via inducing oxidative DNA damage.

Unprecedented Monoterpenoid Polyprenylated Acylphloroglucinols with a Rare 6/6/5/4 Tetracyclic Core, Enhanced MCF-7 Cells' Sensitivity to Camptothecin by Inhibiting the DNA Damage Response

(±)-Hypersines A-C (1-3), the three pairs of enantiomerically pure monoterpenoid polyprenylated acylphloroglucinols with an unprecedented 6/6/5/4 fused ring system, were isolated from Hypericum elodeoides. Their structures, including absolute configurations, were elucidated by comprehensive spectroscopic data, single-crystal X-ray diffraction, and quantum chemical calculations. The plausible, biosynthetic pathway of 1-3 was proposed. Moreover, the bioactivity evaluation indicated that 1a might be a novel DNA damage response inhibitor, and could enhance MCF-7 cell sensitivity to the anticancer agent, camptothecin.

(±)-hyperzewalsins A-D, four pairs of nor-monocyclic polyprenylated acylphloroglucinols with immunosuppressive activity from hypericum przewalskii maxim

Three pairs of previously undescribed 2,3-nor-monocyclic polyprenylated acylphloroglucinols (MPAPs), (±)-hyperzewalsins A-C, a pair of 1,2,3,4-nor-MPAPs, (±)-hyperzewalsins D, along with one undescribed precursor, hyperzewalsin E, were isolated and identified from the aerial parts of Hypericum przewalskii Maxim. (Hypericaceae), and their structures were confirmed by extensive spectroscopic analyses, and quantum-chemical calculations including electronic circular dichroism calculations and NMR calculations with a DP4+ analysis. Significantly, (±)-hyperzewalsins A-D represented the first nor-MPAPs bearing carbon chain constitutions based on diverse highly degraded phloroglucinols. (±)-Hyperzewalsins A-C were the rare nor-MPAPs characterized by degradations of C-2 and C-3 in the core decorated by scissions of C-3/C-4 and C-1/C-2 bonds through Retro-Claisen reactions. (±)-Hyperzewalsins D were the first examples of naturally occurring MPAPs with the loss of C-1/2/3/4 in the phloroglucinol ring formed by cleavages of C-3/C-4 and C-1/C-6 bonds via Retro-Claisen and decarboxylation reactions. Plausible biogenetic pathways for the isolates were proposed. The isolates were evaluated for their immunosuppressive activity in lipopolysaccharide-stimulated murine splenocytes.

Unusual derivatives from Hypericum scabrum

Three new compounds (1-3) with unusual skeletons were isolated from the n-hexane extract of the air-dried aerial parts of Hypericum scabrum. Compound 1 represents the first example of an esterified polycyclic polyprenylated acylphloroglucinol that features a unique tricyclo-[4.3.1.11,4]-undecane skeleton. Compound 2 is a fairly simple MPAP, but with an unexpected cycloheptane ring decorated with prenyl substituents, and compound 3 has an unusual 5,5-spiroketal lactone core. Their structures were determined by extensive spectroscopic and spectrometric techniques (1D and 2D NMR, HRESI-TOFMS). Absolute configurations were established by ECD calculations, and the absolute structure of 2 was confirmed by a single crystal determination. Plausible biogenetic pathways of compounds 1-3 were also proposed. The in vitro antiprotozoal activity of the compounds against Trypanosoma brucei rhodesiense and Plasmodium falciparum and cytotoxicity against rat myoblast (L6) cells were determined. Compound 1 showed a moderate activity against T. brucei and P. falciparum, with IC50 values of 3.07 and 2.25 μM, respectively.

Norwilsonnol A, an immunosuppressive polycyclic polyprenylated acylphloroglucinol with a spiro[5-oxatricyclo[6.4.0.03,7]dodecane-6′,1-1′,2′-dioxane] system from Hypericum wilsonii

Norwilsonnol A (1), a structurally complex polycyclic polyprenylated acylphloroglucinol (PPAP) bearing an unprecedented scaffold, together with a new biosynthetic analogue, norwilsonnol B (2), were isolated from Hypericum wilsonii.

Cytotoxic polyprenylated phloroglucinol derivatives from Hypericum elodeoides Choisy modulating the transactivation of RXRα

Hyperelodione D (1), an undescribed polyprenylated phloroglucinol derivative possessing 6/6/5/5 fused tetracyclic core, together with hyperelodiones E-F (2-3), two unreported analogues bearing 6/5/5 fused tricyclic structure, were isolated from Hypericum elodeoides Choisy. Their planar structures were elucidated by spectroscopic analysis (HRESIMS, 1D and 2D NMR) and their absolute configurations were determined by comparison of experimental and calculated ECD data. The cytotoxicity and retinoid X receptor-α (RXRα) related activities of the isolates were evaluated and the plausible biogenetic pathways of 1-3 were proposed.

12-Deacetyl-12-epi-Scalaradial, a Scalarane Sesterterpenoid from a Marine Sponge Hippospongia sp., Induces HeLa Cells Apoptosis via MAPK/ERK Pathway and Modulates Nuclear Receptor Nur77

12-Deacetyl-12-epi-scalaradial, a scalarane sesterterpenoid from a marine sponge Hippospongia sp, has been reported to possess cytotoxic activity on HepG2, MCF-7, and HCT-116 cells. However, there is no research to indicate that 12-deacetyl-12-epi-scalaradial exhibited anticancer effect on cervical cancer HeLa cells. The aim of this study was to investigate the anticancer activity of 12-deacetyl-12-epi-scalaradial against HeLa cells and to explore the mechanism. The results from a methylthiazolyldiphenyl-tetrazolium (MTT) assay suggested that 12-deacetyl-12-epi-scalaradial suppressed the proliferation of HeLa cells and flow cytometry analysis showed 12-deacetyl-12-epi-scalaradial could induce the apoptosis of HeLa cells in dose- and time-dependent manner. Western blotting analysis demonstrated that 12-deacetyl-12-epi-scalaradial triggered apoptosis via mediating the extrinsic pathway and was found to suppress MAPK/ERK pathway which was associate with cancer cell death. Nur77, a critical number of orphan nuclear receptors, plays diverse roles in tumor development as a transcription factor and has been considered as a promising anticancer drug target. The dual-luciferase reporter assays suggested that 12-deacetyl-12-epi-scalaradial could selectively enhance the trans-activation activity of Nur77. Furthermore, Western blotting analysis and fluorescence quenching showed that 12-deacetyl-12-epi-scalaradial could induce the phosphorylation of Nur77 and interact with the ligand-binding domain (LBD) of Nur77. Our research confirmed 12-deacetyl-12-epi-scalaradial as a potential agent for cervical cancer therapy and provided a view that 12-deacetyl-12-epi-scalaradial may be a modulator of Nur77.

Hypersonins A-D, Polycyclic Polyprenylated Acylphloroglucinols with a 1,2-seco-Homoadamantane Architecture from Hypericum wilsonii

Hypersonins A-D (1-4), four 1,2-seco-homoadamantane type polycyclic polyprenylated acylphloroglucinols (PPAPs) possessing a new bicyclo[4.3.1]decane-3-methoxycarbonyl architecture, were obtained from Hypericum wilsonii. The structures of hypersonins A-D were identified by spectroscopic data, electronic circular dichroism comparison, and X-ray crystallographic data. Hypersonins A-D are the first seco-homoadamantane-type PPAPs with cleavage at the C-1-C-2 bond. Hypersonin A (1) showed moderate inhibitory activity to anti-CD3/anti-CD28 monoclonal antibody-induced proliferation of murine splenocytes, with an IC₅₀ value of 8.3 ± 0.2 μM.

Hyperelodiones A-C, monoterpenoid polyprenylated acylphoroglucinols from Hypericum elodeoides, induce cancer cells apoptosis by targeting RXRα

Hyperelodiones A-C, three undescribed monoterpenoid polyprenylated acylphloroglucinols possessing 6/6/6 fused tricyclic core, were isolated from Hypericum elodeoides Choisy. Their gross structures were elucidated by HRESIMS and NMR data. The absolute configurations of hyperelodiones A-C were assigned by their calculated and compared electronic circular dichroism (ECD) spectra combined with their common biosynthetic origin. A fluorescence quenching assay suggested that hyperelodiones A-C could bind to RXRα-LBD, whereas hyperelodione C showed the strongest interaction with a K_D of 12.81 μΜ. In addition, hyperelodiones A-C dose-dependently inhibited RXRα transactivation and the growth of HeLa and MCF-7 cells. Among them, hyperelodione C showed the most potent inhibitory activities and dose-dependent PARP cleavage. Molecular docking results suggested that hyperelodione C showed a different interaction mode compared with hyperelodione A and hyperelodione B. Thus, hyperelodione C can be considered as a promising lead compound for cancer therapy, which can bind to RXRα-LBD and induce HeLa and MCF-7 cell apoptosis.

homo-Adamantane type polycyclic polyprenylated acylphloroglucinols from Hypericum hookerianum

Hookeriones I-Q (1-9), nine new homo-adamantane type polycyclic polyprenylated acylphloroglucinols (PPAPs), were isolated from Hypericum hookerianum, along with twenty known analogues. These structures were determined on the basis of comprehensive NMR and MS spectroscopic data. Comprehensive analysis of the NMR data revealed the correlations between the configuration of H-18 and H-28 and the chemical shifts of related signals. The cytotoxicity and anti-allergic activities of the new isolates were evaluated, and several ones exhibited moderate cytotoxicity against ECA-109 cell lines.

Structural diversity and biological activities of phloroglucinol derivatives from Hypericum species

Plants of the genus Hypericum (Hypericaceae) are used in folk medicine all over the world, H. perforatum being the most well-known species. Standardized extracts of this plant are commercially-available to treat mild to moderate depression cases. The present review summarizes the literature published up to 2016 concerning the phloroglucinol derivatives isolated from Hypericum species, together with their structural features and biological activities. These phytochemical studies led to the isolation of 101 prenylated phloroglucinols, chromanes and chromenes, 35 dimeric acylphloroglucinols, 235 polycyclic polyprenylated acylphloroglucinols, 25 simple benzophenones and 33 phloroglucinol-terpene adducts. These compounds show a diverse range of biological activities, such as antimicrobial, cytotoxic, antinociceptive and antidepressant-like effects.

Research Progress of Polycyclic Polyprenylated Acylphloroglucinols

Polycyclic polyprenylated acylphloroglucinols (PPAPs) are a class of hybrid natural products sharing the mevalonate/methylerythritol phosphate and polyketide biosynthetic pathways and showing considerable structure and bioactivity diversity. This review discusses the progress of research into the chemistry and biological activity of 421 natural PPAPs in the past 11 years as well as in-depth studies of biological activities and total synthesis of some PPAPs isolated before 2006. We created an online database of all PPAPs known to date at http://www.chem.uky.edu/research/grossman/PPAPs . Two subclasses of biosynthetically related metabolites, spirocyclic PPAPs with octahydrospiro[cyclohexan-1,5'-indene]-2,4,6-trione core and complicated PPAPs produced by intramolecular [4 + 2] cycloadditions of MPAPs, are brought into the PPAP family. Some PPAPs' relative or absolute configurations are reassigned or critically discussed, and the confusing trivial names in PPAPs investigations are clarified. Pharmacologic studies have revealed a new molecular mechanism whereby hyperforin and its derivatives regulate neurotransmitter levels by activating TRPC6 as well as the antitumor mechanism of garcinol and its analogues. The antineoplastic potential of some type B PPAPs such as oblongifolin C and guttiferone K has increased significantly. As a result of the recent appearances of innovative synthetic methods and strategies, the total syntheses of 22 natural PPAPs including hyperforin, garcinol, and plukenetione A have been accomplished.

Furanmonogones A and B: two rearranged acylphloroglucinols with a 4,5-seco-3(2H)-furanone core from the flowers of Hypericum monogynum

Rearranged acylphloroglucinols with an unprecedented 4,5-seco-3(2H)-furanone skeleton, furanmonogones A (1) and B (2), were isolated from the flowers of Hypericum monogynum.

Norsampsone E, an unprecedented decarbonyl polycyclic polyprenylated acylphloroglucinol with a homoadamantyl core from Hypericum sampsonii

Norsampsone E, an unprecedented polycyclic polyprenylated acylphloroglucinol from Hypericum sampsonii, featured a homoadamantyl skeleton with the loss of the C-4 carbonyl.

Chiral separation and absolute configurations of two pairs of racemic polyprenylated benzophenones from Hypericum sampsonii

(±) Sampsonins A-B (1-2), two pairs of racemic polyprenylated benzophenones, were isolated from the aerial parts of Hypericum sampsonii and successfully separated by chiral HPLC column. Their structures were elucidated by spectroscopic analyses, X-ray diffraction analysis, and quantum chemical calculation of ECD method. Besides, the plausible biogenetic pathways of 1-2 were proposed, and all of them were evaluated for RXRα transcriptional-inhibitory activities and cytotoxicity against HeLa cells.

Polycyclic polyprenylated acylphloroglucinols: natural phosphodiesterase-4 inhibitors from Hypericum sampsonii

Seven novel PPAPs and 23 known analogs were isolated from Hypericum sampsonii, some of which were identified as potent PDE4 inhibitors.

Sampbenzophenones A–G, prenylated benzoylphloroglucinol derivatives from Hypericum sampsonii

Seven prenylated benzoylphloroglucinol derivatives, named sampbenzophenones A–G (1–7), together with two known analogues (8 and 9), were isolated from the aerial parts of Hypericum sampsonii.

Hypersampsones S–W, new polycyclic polyprenylated acylphloroglucinols from Hypericum sampsonii

Five new polycyclic polyprenylated acylphloroglucinols (1–5) with a bicyclo[3.3.1]nonane skeleton, along with five known analogues (6–10), were isolated from the aerial parts of Hypericum sampsonii.

Two Unusual Polycyclic Polyprenylated Acylphloroglucinols, Including a Pair of Enantiomers from Garcinia multiflora

Two polycyclic polyprenylated acylphloroglucinols, garcimulins A and B ((±)-1 and 2), including a pair of enantiomers with the unique caged tetracyclo[5.4.1.1(1,5).0(9,13)]tridecane skeleton were isolated from Garcinia multiflora. Their structures and absolute configurations were determined by extensive analysis of spectroscopic data and electronic circular dichroism (ECD) calculations. Compounds 1 and 2 exhibited cytotoxic activities against five human cancer cell lines in vitro (IC50 3.42-13.23 μM). The acidification of lysosomes in HeLa cell was obviously affected by compound 2.

Hot off the press

A personal selection of 33 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as artesin A from Artemisia sieversiana.