Tricyclic Polyprenylated Acylphloroglucinols from St John's Wort, Hypericum perforatum

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.

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.

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.

Cytotoxic and Antibacterial Prenylated Acylphloroglucinols from Hypericum olympicum L

Two new bicyclo[3.3.1]nonane type bicyclic polyprenylated acylphloroglucinol derivatives (BPAPs), olympiforin A and B as well as three known prenylated phloroglucinols, were isolated from the aerial parts of Hypericum olympicum L. The structures of the isolated compounds were established by means of spectral techniques (HRESIMS and 1D and 2D NMR). All compounds were tested on a panel of human tumor (MDA-MB-231, EJ, K-562, HL-60 and HL-60/DOX) and non- tumorigenic (HEK-293 and EA.hy926) cell lines using the MTT assay. All tested compounds exerted significant in vitro cytotoxicity with IC₅₀ values ranging from 1.2 to 24.9 μM and from 0.9 to 34 μM on tumor and non-cancerous cell lines, respectively. Most of the compounds had good selectivity and were more cytotoxic to the tumor cell lines than to the normal ones. A degradation of the precursor caspase 9 for some of the compounds was observed; therefore, the intrinsic pathway of apoptosis is the most likely mechanism of cytotoxic activity. The BPAPs were examined for antibacterial and antibiofilm activity through the broth microdilution method and the protocol of Stepanović. They showed a moderate effect against Enterococcus faecalis and Streptococcus pyogenes but a very profound activity against Staphylococcus aureus with minimum inhibitory concentrations (MIC) in the range of 0.78-2 mg/L. Olympiforin B also had a great effect against methicillin-resistant S. aureus (MRSA) with an MIC value of 1 mg/L and a very significant antibiofilm activity on that strain with a minimum biofilm inhibition concentration (MBIC) value of 0.5 mg/L. The structures of the isolated compounds were in silico evaluated using ADME and drug likeness tests.

Photoactivity of hypericin: from natural product to antifungal application

Considering the multifaceted and increasing application of photodynamic therapy (PDT), in recent years the antimicrobial employment of this therapy has been highlighted, because of the antiviral, antibacterial, antiparasitic, and antifungal activities that have already been demonstrated. In this context, research focussed on antimycological action, especially for treatment of superficial infections, presents promising growth due to the characteristics of these infections that facilitate PDT application as new therapeutic options are needed in the field of medical mycology. Among the more than one hundred classes of photosensitizers the antifungal action of hypericin (Hyp) stands out due to its ability to permeate the lipid membrane and accumulate in different cytoplasmic organelles of eukaryotic cells. In this review, we aim to provide a complete overview of the origin, physicochemical characteristics, and optimal alternative drug deliveries that promote the photodynamic action of Hyp (Hyp-PDT) against fungi. Furthermore, considering the lack of a methodological consensus, we intend to compile the best strategies to guide researchers in the antifungal application of Hyp-PDT. Overall, this review provides a future perspective of new studies and clinical possibilities for the advances of such a technique in the treatment of mycoses in humans.

Structurally diverse polycyclic polyprenylated acylphloroglucinols with protective effect on human vein endothelial cells injured by high-glucose from Hypericum acmosepalum N. Robson

Hyperacmotone A, a polycyclic polyprenylated acylphloroglucinol (PPAP) with an unprecedented skeleton, along with five undescribed congeners and eleven reported ones, was isolated from Hypericum acmosepalum. Hyperacmotone A possesses a unique monocyclic ring skeleton based on a cyclopent-4-ene-1,3-dione acylphloroglucinol core. Their structures were elucidated by extensive analysis of HRESIMS, NMR, biogenetic pathway, and quantum-chemical calculations. In addition, hypercohone G exhibited significant protective effects on high-glucose-injured HUVECs.

Polycyclic polyprenylated acylphloroglucinols from Hypericum beanii and their hepatoprotective activity

Twenty-seven polycyclic polyprenylated acylphloroglucinols (PPAPs) with diverse skeletons, including seven previously undescribed ones (hyperbeanins A-G), were isolated from the aerial parts of Hypericum beanii. Their structures were established by comprehensive analysis of NMR, HRESIMS, and experimental electronic circular dichroism (ECD) spectra. Hyperbeanin A was a monocyclic polyprenylated acylphloroglucinols (MPAPs) with an unusual spiro-fused cyclopropane ring. Four of the isolated compounds showed obvious hepatoprotective activity against paracetamol-induced HepG2 cell damage at 10 μM. The present results suggested that these compounds would be potential hepatoprotective agents. In addition, the plausible biogenetic pathways of hyperbeanins A-G were proposed, which gave an insight for future biomimetic synthesis of them.

Four new polyprenylated acylphloroglucinol derivatives from Hypericum beanii

Two new polycyclic polyprenylated acylphloroglucinols (PPAPs), hyperbeanins P-Q (1-2), and two new biosynthetic precursors, hyperbeanins R-S (3-4), were isolated from Hypericum beanii, together with three known analogs (5-7). Compound 1 was one of type A PPAPs featured with unusual bicyclo[5.3.1]hendecane core. The structures of isolates were established by NMR spectroscopic methods, experimental electronic circular dichroism (ECD) spectra and comparisons with known compounds. Compounds 5 and 6 showed obvious hepatoprotective activity at 10 µM against paracetamol-induced HepG2 cell damage.

Hypericum Genus as a Natural Source for Biologically Active Compounds

Hypericum L. genus plants are distributed worldwide, with numerous species identified throughout all continents, except Antarctica. These plant species are currently used in various systems of traditional medicine to treat mild depression, wounds and burns, diarrhea, pain, fevers, and their secondary metabolites previously shown, and the in vitro and/or in vivo cytotoxic, antimicrobial, anti-inflammatory, antioxidant, antihyperglycemic, and hepatoprotective activities, as well as the acetylcholinesterase and monoamine oxidase inhibitory activities. We conducted a systematic bibliographic search according to the Cochrane Collaboration guidelines to answer the question: "What is known about plants of Hypericum genus as a source of natural products with potential clinical biological activity?" We documented 414 different natural products with confirmed in vitro/in vivo biological activities, and 58 different Hypericum plant species as sources for these natural products. Phloroglucinols, acylphloroglucinols, xanthones, and benzophenones were the main chemical classes identified. The selective cytotoxicity against tumor cells, cell protection, anti-inflammatory, antimicrobial, antidepressant, anti-Alzheimer's, and adipogenesis-inhibition biological activities are described. Acylphloroglucinols were the most frequent compounds with anticancer and cell-protection mechanisms. To date, no work has been published with a full descriptive list directly relating secondary metabolites to their species of origin, plant parts used, extraction methodologies, mechanisms of action, and biological activities.

Hyperacmosin R, a New Decarbonyl Prenylphloroglucinol with Unusual Spiroketal Subunit from Hypericum acmosepalum

Two previously undescribed polycyclic polyprenylated acylphloroglucinols, hyperacmosins R-S (1–2), were obtained from the aerial parts of Hypericum acmosepalum. Their structures were elucidated by extensive spectroscopic analysis and electronic circular dichroism calculation (ECD). Compound 1 featured an unprecedented 5,8-spiroketal subunit as well as the loss of C-2′ carbonyl in the phloroglucinol ring. In addition, compounds 1 and 4 showed weak hepatoprotective activity against paracetamol-induced HepG2 cell damage at 10 μm. The plausible biosynthetic pathway of 1 was proposed via a retro-Clasisen reaction and decarboxylation.

(±)-Hyperpyran A: Terpenoid-based bicyclic dihydropyran enantiomers with hypoglycemic activity from Hypericum perforatum (St. John's wort)

(±)-Hyperpyran A (1a/1b), a pair of new terpenoid-based bicyclic dihydropyran enantiomers, were isolated from the aerial parts of Hypericum perforatum (St. John's wort). Their structures and absolute configurations were elucidated by NMR spectroscopic analyses, ECD comparison, and X-ray crystal diffraction. Compounds 1a/1b possess hexahydrocyclopenta[c]pyran ring system and a plausible biosynthetic pathway was also proposed. In addition, compound 1a exhibited a moderate promotion of glucose uptake activity in hepatocytes.

A New Lignan and C(6)-Oxygenated Flavonoids from the Inflorescence of Ambrosia artemisiifolia

A new lignan (4,4',5'-trihydroxy-5,3'-dimethoxy-3-O-9',2-(7'R)-lignan, 1) and eight C(6)-oxygenated flavonoids (2-9), including a newly identified flavonoid (7,3',4'-trihydroxy-3,5,6-trimethoxyflavone, 2), were isolated from the inflorescence of Ambrosia artemisiifolia L. The structures of these isolates were determined using extensive spectroscopic analyses and comparison with data previously reported in the literature. The absolute configuration of compound 1 was established using electronic circular dichroism (ECD) spectrum. All the flavonoids (2-9) showed inhibitory effects on LPS-induced NO production in RAW264.7 cells, with the inhibition rate ranging from 24.51 % to 69.82 % at 50 μM. The in vitro cytotoxicity study showed that compounds 3-8 have a 60 % inhibition rate against SMMC-7721 at a concentration of 40 μM, while compounds 5 and 8 also exhibited inhibitory activity against HL-60 at 40 μM with the inhibition rate of 83.36 % and 52.01 %, respectively.

Regioisomers Salviprolin A and B, Unprecedented Rosmarinic Acid Conjugated Dinorditerpenoids from Salvia przewalskii Maxim

Salvia przewalskii Maxim is a perennial plant from the genus Salvia (family Lamiaceae). The roots of S. przewalskii were long used as a traditional herb to treat blood circulation related illnesses in China. As part of our continuing interest in polycyclic natural products from medicinal plants, two unprecedented adducts comprised of a dinor-diterpenoid and a 9'-nor-rosmarinic acid derivative, linked by a 1,4-benzodioxane motif (1 and 2), were isolated from the roots of S. przewalskii. Their structures were established by extensive spectroscopic approaches including 1D, 2D NMR, and HRFABMS. Their cytotoxic activities against five human tumor cell lines were evaluated.

Unprecedented polycyclic polyprenylated acylphloroglucinols with anti-Alzheimer's activity from St. John's wort

Hyperforones A–J (1–10), ten degraded and reconstructed polycyclic polyprenylated acylphloroglucinols (PPAPs) with six different types of unusual architectures, were isolated from Hypericum perforatum (St. John's wort). Compound 1 is characterized by an unprecedented 1,5-epoxyfuro[3′,4′:1,5]cyclopenta[1,2-c]oxecine ring system; compounds 2 and 3 represent the first PPAPs with a contracted B-ring leading to the unique 5/5 core skeletons; compound 4, a proposed biosynthetic precursor of 2, is defined by an oxonane-2,7-dione architecture; compound 5 features an unusual spiro[furo[3′,4′:1,5]cyclopenta[1,2-b]oxepine-3,2′-oxetane] ring system; compounds 6–8 possess a rare macrocyclic lactone ring in addition to the newly formed C-ring; and compounds 9 and 10 contain a newly formed six-membered C-ring, which constructed the unexpected 6/6 scaffold with the B-ring. Hypothetic biosynthetic pathways to generate these scaffolds starting from the classic [3.3.1]-type PPAPs helped to elucidate their origins and validate their structural assignments. Compounds 4 and 6 simultaneously displayed notable activation of PP2A (EC₅₀: 258.8 and 199.0 nM, respectively) and inhibition of BACE1 in cells (IC₅₀: 136.2 and 98.6 nM, respectively), and showed better activities than the positive controls SCR1693 (a PP2A activator, EC₅₀: 413.9 nM) and LY2811376 (a BACE1 inhibitor, IC₅₀: 260.2 nM). Furthermore, compound 6 showed better therapeutic effects with respect to the reduction of pathological and cognitive impairments in 3 × Tg AD mice than LY2811376. Compound 6 represents the first multitargeted natural product that could activate PP2A and simultaneously inhibit BACE1, which highlights compound 6 as a promising lead compound and a versatile scaffold in AD drug development.

Ten PPAPs with unusual skeletons were isolated from H. perforatum. 6 represents the first multitargeted natural product that could activate PP2A and simultaneously inhibit BACE1, which highlights 6 as a promising lead compound in AD drug development.

Polycyclic polyprenylated acylphloroglucinols with immunosuppressive activity from Hypericum perforatum and absolute configurations assignment of previously reported analogues

Hyperformitins A-I (1-9), nine undescribed polycyclic polyprenylated acylphloroglucinols (PPAPs) with double-bond migration, along with four new isomers hyperformitins J-M (10-13), were isolated from Hypericum perforatum. Their structures and absolute configurations were determined by spectroscopic analyses including HRESIMS, IR, UV, NMR, and ECD, as well as optical rotation (OR) calculations. The absolute configurations of previously reported analogues, garsubellins D and C as well as garcinielliptones L and M, were assigned for the first time by NMR spectra and specific rotations analyses assisting with OR calculations. Selected compounds were tested for their immunosuppressive activities against lipopolysaccharide (LPS)-induced B lymphocyte proliferation. Compounds 1, 3, 4, 5, 7, and 11 showed inhibition activities against the proliferation of B lymphocyte with IC₅₀ values ranging from 4.1 to 9.7 μM. Furthermore, the neuroprotective activities of the isolates against corticosterone (CORT)-induced injury in PC12 cells were also tested, and compounds 1, 12, and 13 exhibited neuroprotective effects with cell viabilities of 68.0%, 71.3%, and 68.4%, respectively under the concentration of 10 μM.

Hyperacmosins K-M, three new polycyclic polyprenylated acylphloroglucinols from Hypericum acmosepalum

Hyperacmosins K-M (1-3), three new polycyclic polyprenylated acylphloroglucinol (PPAPs) derivatives, were isolated from the air-dried aerial parts of Hypericum asmosepalum. Compounds 1 and 2 both possessed a rare 5,5-spiroketal subunit with the loss of C-2' carbonyl in the phloroglucinal ring, while compound 3 featured an unusual 1,2-seco-bicyclo[3.3.1] PPAP skeleton. Their structures were confirmed by NMR, HRESIMS, and CD spectra. The plausible biogenetic pathways of 1-3 were proposed, which gave an insight for future biomimetic synthesis of the novel compounds.

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.

New Cyclic Diarylheptanoids from Platycarya strobilacea

Five new cyclic diarylheptanoids (platycary A–E, compounds 1–5) and three previously identified analogues (i.e., phttyearynol (compound 6), myricatomentogenin (compound 7), and juglanin D (compound 8)) were isolated from the stem bark of Platycarya strobilacea. The structures of these compounds were determined using NMR, HRESIMS, and electronic circular dichroism (ECD) data. The cytotoxicity of compounds 1–5 and their ability to inhibit nitric oxide (NO) production, as well as protect against the corticosterone-induced apoptosis of Pheochromocytoma (PC12) cells, were evaluated in vitro using the appropriate bioassays. Compounds 1 and 2 significantly inhibited the corticosterone-induced apoptosis of PC12 cells at a concentration of 20 μΜ.

Longisglucinols A-C, Structurally Intriguing Polycyclic Polyprenylated Acylphloroglucinols with Anti-inflammatory Activity from Hypericum longistylum

Longisglucinol A (1), a polycyclic polyprenylated acylphloroglucinol (PPAP) with a new skeleton, along with two new congeners, longisglucinols B (2) and C (3), were isolated from Hypericum longistylum. Compound 1 features an unparalleled 6/6/6/5 fused ring skeleton based on a unique 8-oxa-tetracyclo-[8.3.3.0^1,9.0^3,7]cetane core. Longisglucinol A showed remarkable anti-inflammatory activity by inducing macrophage M2 polarization through the suppression of NF-κB.

Chemical constituents with cytotoxic and anti-inflammatory activity in Hypericum sampsonii and the antitumor potential under the view of cancer-related inflammation

ETHNOPHARMACOLOGICAL RELEVANCE

Chronic inflammation has an important role in the development of cancers. Hypericum sampsonii, known as "Yuanbao Cao", is mainly distributed in the southwest of China. As a folk medicinal plant, "Yuanbao Cao" is traditionally used for treatment of various inflammation-related diseases including swelling, burns, arthritis, and dermatitis, etc. The plant is a promising anticancer herb. However, there is no research on the antitumor potential of this plant from the view of cancer-related inflammation strategy.

AIM OF THE STUDY

To explore the H. sampsonii in relation to cancer-related chemical constituents with anti-inflammatory and cytotoxic activity in cancer-related inflammation.

MATERIALS AND METHODS

The chemical constituents of H. sampsonii were isolated by repeated chromatography techniques, and their structures were identified mainly by spectroscopic methods and compared to published data. The chemical profile of the herb was analyzed using HPLC. The cytotoxicities of compounds against five cancer cell lines: human melanoma cell (A375), human breast cancer cell (MDA-MB-231), human gastric cancer cell (SGC-7901), human colon cancer cell (SiHa), and human bone marrow neuroblastoma cell (SHSY-5Y), were tested using MTT assay; their anti-inflammatory activities were evaluated by inhibition on NO production in LPS-stimulated RAW 264.7, THP-1 and BV-2 microglial cells.

RESULTS

Twenty-five compounds, including four phenols (1-4), two anthraquinonoids (5 and 6), six xanthones (7-12), one benzophenone (13), one phloroglucinol (14), nine flavonoids (15-23), one sterol (24) and one alkaloid (25), were isolated from the EtOH extract of H. sampsonii. Of them, compounds 3, 4, 6, 7, 10-14, 17, 19, 22 and 23 were reported in H. sampsonii for the first time. HPLC analysis showed that flavonoids were the main constituents in the herb. MTT assay revealed that compounds 1, 2, 5-14, 15, 17, 18, 20, 21, 22 and 25 had selective cytotoxic activities (IC₅₀: 7.52-158.90 μM) against tested cancer cells, in which compound 5, 6, 13 and 14 displayed high activities against A375, MDA-MB-231, SiHa and SHSY-5Y. In the screening experiment of anti-inflammatory activity, most compounds (1-2, 5-23) showed considerable high anti-inflammatory activities (IC₅₀: 10.59-42.75 μM), in which compounds 5, 6, 13, 14, and 15 exhibited high anti-inflammatory activities in LPS-stimulated RAW264.7, THP-1 and BV-2 microglial cells.

CONCLUSIONS

Compounds 3, 4, 6, 7, 10-14, 17, 19, 22 and 23 were isolated for the first time from H. sampsonii. Compound 5, 6, 13 and 14 displayed high cytotoxic activities against the tested cancer cell lines. Compounds (1-2, 5-23) showed anti-inflammatory activities, of them, compounds 5, 6, 13, 14 and 15 exhibited the high activity. From the view of cancer-related inflammation point, not only the compounds with high cytotoxicity, but those compounds with anti-inflammatory activities, especially the flavonoids, contribute to the antitumor potential of H. sampsonii. The results and viewpoint of present study provide a different insight to better understand the antitumor potential of H. sampsonii, and may also promote the reasonable usage of this folk medical herb.

New cytotoxic secondary metabolites against human pancreatic cancer cells from the Hypericum perforatum endophytic fungus Aspergillus terreus

Four new compounds, including two lovastatin analogues, terrstatins A and B (1 and 2), and a pair of butenolide derivatives, (±)-asperteretone F (3a/3b), along with eleven known compounds (4-14), were isolated from the Hypericum perforatum endophytic fungus Aspergillus terreus. Their structures and absolute configurations were determined based on extensive spectroscopic analysis, experimental and calculated electronic circular dichroism (ECD) analysis. All isolates were evaluated for cytotoxic activities against five human cancer cell lines, and compounds 3a/3b and 6 showed potential cytotoxic activities against human pancreatic cancer cells, including AsPC-1, SW1990 and PANC-1 cells, with IC₅₀ values ranging from 1.2 to 15.6 μM.

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.

Metabolomic fingerprinting and genetic discrimination of four Hypericum taxa from Greece

Hypericum perforatum has plenty of uses in traditional medicine and is the source of top-selling herbal drugs and food supplements. The secondary metabolite chemistry for most of the nearly 500 Hypericum taxa is still unknown, even though they are used interchangeably. In the present study, we characterized four Hypericum populations from Achaia, Greece, belonging to H. perforatum ssp. veronense, H. perfoliatum, H. triquetrifolium, and an uninvestigated taxon, H. empetrifolium ssp. empetrifolium, in terms of their essential oils and polar bioactives in methanolic extracts via GC-MS, LC-HRMS, LC-DAD-MS, and HPLC-DAD. We also performed sequence analysis of nrITS to explore the genetic profile of these taxa and to examine whether their genotype is correlated to the metabolome. Sixty-three non-volatile compounds, phloroglucinols in their majority, and over one hundred (113) volatiles, mostly sesqui- and mono- terpenes, were detected. The concentration of the major polar constituents varied greatly among samples. In particular, phloroglucinols' diversity and abundance in H. empetrifolium ssp. empetrifolium was remarkable. The PCA and Biplot analysis revealed the contribution of each compound to the total chemodiversity and also revealed certain compounds that contribute to the discrimination of the samples. Sequence analysis of nrITS revealed different genetic profiles and markers which can be used for the identification of the four Hypericum taxa. The Mantel test showed a relatively strong correlation between the genetic profile and the volatile compounds and low with the main polar metabolites.

Hyperacmosins H-J, three new polycyclic polyprenylated acylphloroglucinol derivatives from Hypericum acmosepalum

Three new polycyclic polyprenylated acylphloroglucinol derivatives, hyperacmosins H-J (1-3), with four known compounds (4-7), were isolated from the air-dried aerial parts of Hypericum acmosepalum. Especially, compounds 1 and 2 were identified as methylated polycyclic polyprenylated acylphloroglucinol derivatives (mPPAPs). Their structures were established by NMR, HRESIMS and experimental electronic circular dichroism (ECD) spectra. The hepatoprotective activity of seven compounds were evaluated. Compounds 1 and 5 exhibited hepatoprotective activity against paracetamol-induced HepG2 cell damage.[Formula: see text].

Unraveling Plant Natural Chemical Diversity for Drug Discovery Purposes

The screening and testing of extracts against a variety of pharmacological targets in order to benefit from the immense natural chemical diversity is a concern in many laboratories worldwide. And several successes have been recorded in finding new actives in natural products, some of which have become new drugs or new sources of inspiration for drugs. But in view of the vast amount of research on the subject, it is surprising that not more drug candidates were found. In our view, it is fundamental to reflect upon the approaches of such drug discovery programs and the technical processes that are used, along with their inherent difficulties and biases. Based on an extensive survey of recent publications, we discuss the origin and the variety of natural chemical diversity as well as the strategies to having the potential to embrace this diversity. It seemed to us that some of the difficulties of the area could be related with the technical approaches that are used, so the present review begins with synthetizing some of the more used discovery strategies, exemplifying some key points, in order to address some of their limitations. It appears that one of the challenges of natural product-based drug discovery programs should be an easier access to renewable sources of plant-derived products. Maximizing the use of the data together with the exploration of chemical diversity while working on reasonable supply of natural product-based entities could be a way to answer this challenge. We suggested alternative ways to access and explore part of this chemical diversity with in vitro cultures. We also reinforced how important it was organizing and making available this worldwide knowledge in an "inventory" of natural products and their sources. And finally, we focused on strategies based on synthetic biology and syntheses that allow reaching industrial scale supply. Approaches based on the opportunities lying in untapped natural plant chemical diversity are also considered.

Hypericum spp.: An Update on the Biological Activities and Metabolic Profiles

Plants from the genus Hypericum, one genus of the Hypericaceae family, have attracted a lot of attention for their potential pharmaceutical applications. Most of the studies in the literature focus on H. perforatum L. (common St. John's wort), whose complex spectrum of bioactive compounds makes this species one of the top herbal remedies and supplements in the world. It is also important to compare the studies on other Hypericum species, both from the phytochemical and biological point of view. The aim of this review was to provide an update of most recent studies about biological investigations of plants belonging to Hypericum genus. The metabolic profiles of Hypericum spp. were also discussed in order to present a spectrum of secondary metabolites not previously identified in this genus.

Wilsonglucinols A–C, homoadamantane-type polycyclic polyprenylated acylphloroglucinols with unusual fused epoxy ring skeletons from Hypericum wilsonii

Wilsonglucinols A–C (1–3), three new polycyclic polyprenylated acylphloroglucinols (PPAPs) possessing novel homoadamantane architectures based on unusual epoxy-ring-fused systems were isolated from Hypericum wilsonii.

Discovery of new polycyclic polyprenylated acylphloroglucinols with diverse architectures as potent cyclooxygenase-2 inhibitors

Cyclooxygenase-2 (COX-2) is a significant therapeutic target of chronic inflammatory diseases.

Me2AlSEt-Promoted Domino Dieckmann Cyclization Enables the Total Synthesis of Polycyclic Polyprenylated Acylphloroglucinols

A bioinspired, Me₂AlSEt-promoted domino Dieckmann cyclization via an 8-membered ring intermediate to construct bicyclo[3.3.1]nonanes was developed, and the divergent syntheses of nine complex polycyclic polyprenylated acylphloroglucinols were achieved. This novel domino cyclization tolerates a series of congested substrates, providing a very efficient way to construct diverse polycyclic structures. The selectivity and the advantages of the domino cyclization were studied. Moreover, the structure-activity relationship study leads to the identification of three simplified potent antitumor agents.

Hyperforatins L-U: Prenylated acylphloroglucinols with a terminal double bond from Hypericum perforatum L. (St John's Wort)

Hyperforatins L-U, ten undescribed polycyclic polyprenylated acylphloroglucinols (PPAPs) bearing a terminal double bond, together with a known compound hypericumoxide J, were isolated from the aerial parts of Hypericum perforatum L. Their structures were elucidated by spectroscopic methods, including HRESIMS, IR, UV, and NMR (¹H, ¹³C, DEPT, HSQC, HMBC, ¹H-¹H COSY, and NOESY experiments). Their absolute configurations were determined by comprehensive analyses of their experimental ECD spectra in conjunction with a modified Mosher's method. Evaluation of their neuroprotective activities highlighted hyperforatin L, which displayed mild activity at a concentration of 10 μM.

Hyperpatulones A-F, polycyclic polyprenylated acylphloroglucinols from Hypericum patulum and their cytotoxic activities

Six new compounds, hyperpatulones A-F (1-6), along with ten additional known related derivatives (7-16), were isolated from Hypericum patulum (Guttiferae). Their structures were elucidated by extensive analysis of spectroscopic data (IR, UV, HRESIMS, 1D and 2D NMR), X-ray crystallography, electronic circular dichroism (ECD) spectroscopy and Rh2(OCOCF3)4-induced ECD. All compounds were tested for their cytotoxic activities on human HepG-2, HeLa, MCF-7, and A549 cell lines via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Compound 5 exhibited significant cytotoxicities against HepG-2, HeLa and A549 cell lines with IC50 values of 9.52 ± 0.27, 11.87 ± 0.22 and 12.63 ± 0.12 μM, respectively.

A new cytotoxic polycyclic polyprenylated acylphloroglucinol from Garcinia nujiangensis screened by the LC-PDA and LC-MS

A new polycyclic polyprenylated acylphloroglucinol (1), nujiangefolin D, together with five known analogues (2-6), were isolated from the fruits of Garcinia nujiangensis. Compound 1 was screened by the LC-MS and LC-PDA. The structure of 1 was elucidated on the basis of extensive spectroscopic techniques including 1 D and 2 D NMR and MS analyses. The compounds isolated were evaluated for their cytotoxic activities against three cancer cell lines, 1 showed moderate cytotoxic activity against Hela, PANC-1, and MDA-MB-231 cell lines with IC₅₀ values of 5.6 ± 0.1, 9.1 ± 0.2, and 8.3 ± 0.2 μM, respectively. The antitumor mechanism was explained via virtual docking of 1 to the main sites in the human serine/threonine-protein kinase mTOR (mTOR) crystal structure (PDB code: 4DRI). Furthermore, 1 may inhibit Hela cell proliferation through mTOR by the western blotting analysis. Taken together, 1 may be a potential mTOR inhibitor used for the treatment of cervical cancer.

The absolute configurations of hyperilongenols A–C: rare 12,13-seco-spirocyclic polycyclic polyprenylated acylphloroglucinols with enolizable β,β′-tricarbonyl systems from Hypericum longistylum Oliv

Three PPAPs were isolated from H. longistylum Oliv.

Highly functionalized cyclohexanone-monocyclic polyprenylated acylphloroglucinols from Hypericum perforatum induce leukemia cell apoptosis

Five degraded C-MPAP derivatives were isolated from the stems and leaves of Hypericum perforatum.

Methylated Polycyclic Polyprenylated Acylphloroglucinol Derivatives from Hypericum ascyron

Hyperascyrins A-H (1-11) and four known compounds (12-15) were acquired from the air-dried aerial parts of Hypericum ascyron and were all identified as methylated polycyclic polyprenylated acylphloroglucinol derivatives. Their structures were established by NMR spectroscopy, experimental and calculated electronic circular dichroism (ECD) data, and comparison with established compounds. Compounds 8 and 9 showed protection against paracetamol-induced HepG2 cell damage at 10 μM. The neuroprotective activities of all compounds (10 μM) were evaluated, and compounds 1 and 8 exhibited mild neuroprotection against glutamate-induced toxicity in SK-N-SH cells.

Polyketide and Prenylxanthone Derivatives from the Endophytic Fungus Aspergillus sp. TJ23

Eight secondary metabolites, including a new polyketide, named asperetide (1) and a new prenylxanthone derivative, called asperanthone (4), and six known compounds, (S)-3-butyl-7-methoxyphthalide (2), ruguloxanthone C (3), tajixanthone hydrate (5), tajixanthone methanoate (6), salimyxin B (7), and ergosterol (8), were isolated and identified from the medicinal plant-derived fungus, Aspergillus sp. TJ23. The new structures and their absolute configurations were elucidated via multiple methods, including 1D- and 2D-NMR, HR-ESI-MS, UV, IR, and the electronic circular dichroism (ECD) calculations. All of the isolates were characterized from the strain for the first time. The in vitro bioassay showed that compounds 3-5 and 8 exerted inhibitory activities against five cancer cell lines (B16, MDA-MB-231, 4T1, HepG2, and LLC) with IC₅₀ values ranging from 5.13 to 36.8 μm.

Protoilludane, Illudalane, and Botryane Sesquiterpenoids from the Endophytic Fungus Phomopsis sp. TJ507A

To explore the chemical diversity of metabolites from endophytic fungi, the strain Phomopsis sp. TJ507A, isolated from the medicinal plant Phyllanthus glaucus, was investigated. A 2,3- seco-protoilludane-type sesquiterpenoid (1), eight protoilludane-type sesquiterpenoids (2-9), four illudalane-type sesquiterpenoids (10a/10b, 11, and 12), and a botryane-type sesquiterpenoid (13) in addition to seven known sesquiterpenoids (14-20) were identified from the liquid culture of the fungus. Structures of the isolated compounds, including their absolute configurations, were elucidated based on extensive spectroscopic analyses, a modified Mosher analysis, electronic circular dichroism (ECD) calculations, and [Rh₂(OCOCF₃)₄]-induced ECD spectra as well as X-ray crystallographic analyses. Compound 1 represents the first example of a naturally occurring sesquiterpenoid containing the unusual 2,3- seco-protoilludane scaffold. Compounds 1 ( p < 0.001); 2-6, 15, and 18 ( p < 0.01); and 7, 9, and 20 ( p < 0.05) displayed β-site amyloid precursor protein cleaving enzyme 1 (BACE1) inhibitory activities ranging from 19.4% to 43.8% at the concentration of 40 μM. LY2811376 was used as the positive control with an inhibitory activity of 38.6% ( p < 0.01). Furthermore, none of these compounds showed obvious hepatotoxicity at concentration of 40 μM.

Hyperjaponol H, A New Bioactive Filicinic Acid-Based Meroterpenoid from Hypericum japonicum Thunb. ex Murray

Hyperjaponol H (1), a new filicinic acid-based meroterpenoid, with a 6/6/10 ring system trans-fused by hetero-Diels–Alder cycloaddition between a germacrane sesquiterpenoid and a filicinic acid moiety, was isolated from aerial parts of Hypericum japonicum. The elucidation of its structure and absolute configuration were accomplished by the analyses of extensive spectroscopic data and the comparison of Cotton effects of electron circular dichroism (ECD) with previously reported ones. The bioactivity assay showed that hyperjaponol H exhibited a moderate inhibitory efficacy on lytic Epstein-Barr virus (EBV) DNA replication in B95-8 cells.

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.

Bioactive polycyclic polyprenylated acylphloroglucinols from Hypericum perforatum

Fifteen new polycyclic polyprenylated acylphloroglucinols with dual-targeted inhibitory activities for Alzheimer's disease, were isolated from Hypericum perforatum.