Hypersampones A-C, Three Nor-Polycyclic Polyprenylated Acylphloroglucinols with Lipid-Lowering Activity from Hypericum sampsonii

(±)-Hypernumqulins A-H: Eight pairs of unexpected [2+2] cycloaddition sesquiterpenoid alkaloid with 6/6/6/4/10 ring system from Hypericum monogynum L

(±)-Hypernumqulins A-H (1-8), eight pairs of enantiomeric quinoline alkaloids fused with an isopentenyl and a germacrane-type sesquiterpenoid, featuring an unprecedented skeleton with 6/6/6/4/10 ring system, were isolated from Hypericum monogynum L. under the guidance of molecular networking strategy. Their structures including absolute configuration were elucidated by NMR spectroscopy analysis, X-ray crystallography and quantum chemical calculation. The proposed [2+2] cycloaddition may play a key biogenic step in building the unexpected skeleton. Most of the isolates exhibited cytotoxicity with IC50 values ranging from 2.82 ± 0.03 to 45.25 ± 1.26 μM against MCF-7, A549 or SGC7901 cells. Furthermore, compounds (±)-1 and (-)-1 could induce apoptosis by upregulating the protein expression level of Bax and downregulating of Bcl-2 in MCF-7 cells. These findings provided the first example of germacrane sesquiterpene quinoline alkaloids, and supported the possibilities for the development of new anti-tumor agents.

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.

Discovery from Hypericum elatoides and synthesis of hyperelanitriles as α-aminopropionitrile-containing polycyclic polyprenylated acylphloroglucinols

The search for lead compounds with anti-neuroinflammatory activity from structurally 'optimized' natural products is a crucial and promising strategy in the quest to discover safe and efficacious agents for treating neurodegenerative diseases. A phytochemical investigation on the aerial portions of Hypericum elatoides led to the isolation of five nitrogenous polycyclic polyprenylated acylphloroglucinols (PPAPs), hyperelanitriles A-D (1-4) and hyperelamine A (5). Their structures were determined by spectroscopic analysis, ECD and NMR calculations, and X-ray crystallography. To the best of our knowledge, compounds 1-4 represent the first examples of acylphloroglucinols featuring an α-aminonitrile moiety, while 5 is a rare enamine-containing PPAP. Further, the synthesis of these naturally occurring PPAP-based nitriles or amines was accomplished. Compound 5 exhibited inhibitory activity against LPS-activated NO production in BV-2 cells, potentially through the suppression of TLR-4/NF-κB signaling. Here we show the isolation, structural elucidation, synthesis, and bioactive evaluation of compounds 1-5.

Three rare nor-sesquiterpenoids with lipid-lowering activity from Belamcanda chinensis

Belchinoids A-C (1-3), three unusual nor-sesquiterpenoids, along with a new isoflavone (4), were isolated from the roots of Belamcanda chinensis, a traditional Chinese medicine. To the best of our knowledge, compound 1 represents the first C13 nor-sesquiterpenoid with a five membered carbon ring. Compounds 2 and 3 are rare C14 chained nor-sesquiterpenoids. Their structures were fully characterized based on extensive spectroscopic data and quantum chemistry calculation. Three compounds (1, 2, and 4) showed potent inhibitory effects on lipid accumulation in an oleic acid-treated HepG2 cell model. In particular, compound 2 exhibited the most potent inhibitory effect on triglyceride accumulation at a low concentration of 2.5 μM, better than the positive control atorvastatin. The plausible biosynthetic pathway of the three nor-sesquiterpenoids (1-3) is also proposed.

Hyperipersions A-C, three new acylphloroglucinols from the branches and leaves of Hypericum perforatum L. with antiangiogenic activities

Three new acylphloroglucinols were isolated from the branches and leaves of Hypericum perforatum L., named as hyperipersions A-C (1-3), together with three known compounds which were identified as elegaphenone (4), 2,6-dihydroxy-3,4-dimethylbenzoic acid methyl ester (5) and 2,3-methylenedioxyxanthone (6), respectively. The structures of isolated compounds were determined by UV, IR, HR-ESI-MS, NMR analysis. Their antiangiogenic activities were studied against HUVECs. The IC50 value of compound 3 was 2.39 ± 0.21 μM against HUVECs, which was stronger than vatalanib, and other compounds had moderate antiangiogenic 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.

Bioassay-guided isolation of α-Glucosidase inhibitory constituents from Hypericum sampsonii

This study employed the α-glucosidase inhibitory activity model as an anti-diabetic assay and implemented a bioactivity-guided isolation strategy to identify novel natural compounds with potential therapeutic properties. Hypericum sampsoniiwas investigated, leading to the isolation of two highly modified seco-polycyclic polyprenylated acylphloroglucinols (PPAPs) (1 and 2), eight phenolic derivatives (3-10), and four terpene derivatives (11-14). The structures of compounds 1 and 2, featuring an unprecedented octahydro-2H-chromen-2-one ring system, were fully characterized using extensive spectroscopic data and quantum chemistry calculations. Six compounds (1, 5-7, 9, and 14) exhibited potential inhibitory effects against α-glucosidase, with IC₅₀ values ranging from 0.050 ± 0.0016 to 366.70 ± 11.08 μg·mL^-1. Notably, compound 5 (0.050 ± 0.0016 μg·mL^-1) was identified as the most potential α-glucosidase inhibitor, with an inhibitory effect about 6900 times stronger than the positive control, acarbose (IC₅₀ = 346.63 ± 15.65 μg·mL^-1). A docking study was conducted to predict molecular interactions between two compounds (1 and 5) and α-glucosidase, and the hypothetical biosynthetic pathways of the two unprecedented seco-PPAPs were proposed.

Hyperpatone A, a polycyclic polyprenylated acylphloroglucinol with a rare 8/6/5/6/5 pentacyclic skeleton from Hypericum patulum

Hyperpatone A (1), a highly oxidated polycyclic polyprenylated acylphloroglucinol (PPAP), along with a biosynthesized related PPAP (2) was isolated from Hypericum patulum under the guidance of LC-MS investigation. Architecturally, compound 1 represents the first PPAP with an unprecedented 8/6/5/6/5 pentacyclic skeleton and an intramolecular peroxy bridge, which might be derived from the [3.3.1]-type bicyclic polyprenylated acylphloroglucinol via the critical Baeyer-Villiger oxidation, decarboxylation, and intramolecular cyclization. The structures were established by extensive spectroscopic analysis, ACD software calculation, and quantum chemical computations. A plausible biogenetic pathway of 1 and 2 was also proposed. Importantly, both compounds exhibited moderate cytotoxic activities against the HEL cell line with the IC₅₀ values ranging from 10.2 to 19.2 μM. Moreover, compound 1 showed an inhibitory effect on NO production in lipopolysaccharide-stimulated RAW264.7 cells at a lower concentration of 5 or 1 μM.

Hot off the Press

A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as hyjapone A from Hypericum japonicum.