Research Progress of Polycyclic Polyprenylated Acylphloroglucinols

Novel Targets for Stroke Therapy: Special Focus on TRPC Channels and TRPC6

Stroke remains a leading cause of death, disability, and medical care burden worldwide. However, transformation from laboratory findings toward effective pharmacological interventions for clinical stroke has been unsatisfactory. Novel evidence has been gained on the underlying mechanisms and therapeutic potential related to the transient receptor potential (TRP) channels in several disorders. The TRP superfamily consists of a diverse group of Ca²⁺ permeable non-selective cation channels. In particular, the members of TRP subfamilies, TRP canonical (TRPC) channels and TRPC6, have been found in different cell types in the whole body and have high levels of expression in the central nervous system (CNS). Notably, the TRPCs and TRPC6 channel have been implicated in neurite outgrowth and neuronal survival during normal development and in a range of CNS pathological conditions. Recent studies have shown that suppression of TRPC6 channel degradation prevents ischemic neuronal cell death in experimental stroke. Accumulating evidence supports the important functions of TRPC6 in brain ischemia. We have highlighted some crucial advancement that points toward an important involvement of TRPCs and TRPC6 in ischemic stroke. This review will make an overview of the TRP and TRPC channels due to their roles as targets for clinical trials and CNS disorders. Besides, the primary goal is to discuss and update the critical role of TRPC6 channels in stroke and provide a promising target for stroke prevention and therapy.

Congenetic Hybrids Derived from Dearomatized Isoprenylated Acylphloroglucinol with Opposite Effects on Cav3.1 Low Voltage-Gated Ca2+ Channel

A hybrid of dearomatized isoprenylated acylphloroglucinol (DIAP) and monoterpenoid, hypatone A (1), together with its biosynthetic analogues 2-4 is characterized from Hypericum patulum. Structurally, 1 possesses an unprecedented spiro[bicyclo[3.2.1]octane-6,1'-cyclohexan]-2',4',6'-trione core as elucidated by extensive spectroscopic and X-ray crystallographic analyses. Biological studies reveal that compounds 1 and 2-4 produce opposite effects on Ca_v3.1 low voltage-gated Ca²⁺ channel, with 1 and 4, respectively, being the most potent Ca_v3.1 agonist and antagonist from natural products. Further studies suggest that compound 1 and its biogenetical precursor, 2, have the same binding site on Ca_v3.1 and that the rigid cagelike moiety at C-5 and C-6 is a key structural feature responsible for 1 being an agonist. Furthermore, 1 can normalize the pathological gating of a mutant Ca_v3.1 channel found in spinocerebellar ataxia 42 (SCA42), a hereditary neurodegenerative disorder with no available therapy. Collectively, our findings provide valuable tools for future studies on Ca_v3.1 physiology and pathophysiology, as well as afford possible leads for developing new drugs against SCA42, epilepsy, and pain.

Dearomatized Isoprenylated Acylphloroglucinol Derivatives with Potential Antitumor Activities from Hypericum henryi

A series of dearomatized isoprenylated acylphloroglucinols derivatives, hyperhenols A-E (1-5), as well as seven known analogues (6-12), were characterized from Hypericum henryi. Their structures were determined by combination of NMR, ECD spectroscopy, and X-ray diffraction analysis. Compounds 1 and 6-8 were tested to exhibit potential antitumor properties, of which 6 and 7 inhibited cell growth through inducing apoptosis and cell cycle arrest. In addition, these compounds could induce autophagy and PINK1/Parkin-mediated mitophagy in cancer cell lines, as well as suppress lung cancer A549 cells metastasis in vitro.

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.

Programmable meroterpene synthesis

The bicyclo[3.3.1]nonane architecture is a privileged structural motif found in over 1000 natural products with relevance to neurodegenerative disease, bacterial and parasitic infection, and cancer among others. Despite disparate biosynthetic machinery, alkaloid, terpene, and polyketide-producing organisms have all evolved pathways to incorporate this carbocyclic ring system. Natural products of mixed polyketide/terpenoid origins (meroterpenes) are a particularly rich and important source of biologically active bicyclo[3.3.1]nonane-containing molecules. Herein we detail a fully synthetic strategy toward this broad family of targets based on an abiotic annulation/rearrangement strategy resulting in a 10-step total synthesis of garsubellin A, an enhancer of choline acetyltransferase and member of the large family of polycyclic polyprenylated acylphloroglucinols. This work solidifies a strategy for making multiple, diverse meroterpene chemotypes in a programmable assembly process involving a minimal number of chemical transformations.

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.

Hyperforones A–C, benzoyl-migrated [5.3.1]-type polycyclic polyprenylated acylphloroglucinols from Hypericum forrestii

Unprecedented benzoyl-migrated polycyclic polyprenylated acylphloroglucinols with a unique C-1 H-substituted bicyclo[5.3.1]hendecane framework, hyperforones A–C (1–3), were isolated from Hypericum forrestii.

Hypascyrins A-E, Prenylated Acylphloroglucinols from Hypericum ascyron

Six new prenylated acylphloroglucinols with menthane moieties, hypascyrins A-E (1-5) and ent-hyphenrone J (6), together with four known analogues, were isolated from Hypericum ascyron roots. Detailed spectroscopic data analyses resulted in the assignment of their structures. The absolute configuration of 1 was deduced by experimental and calculated ECD data, while those of 2-6 were assigned by ECD data analyses as well as chemical conversions. Hypascyrins A (1), C (3), and E (5) and ent-hyphenrone J (6) exhibited antimicrobial activity against MRSA (MIC₅₀ values of 4.0, 8.0, 2.0, and 4.0 μM, respectively) and Bacillus subtilis (MIC values of 4.0, 4.0, 2.0, and 4.0 μM, respectively).

Cytotoxic Xanthones from Hypericum stellatum, an Ethnomedicine in Southwest China

Hypericum stellatum, a species endemic to China, is used to treat hepatitis by several ethnic groups in Guizhou Province. This research was inspired by the traditional medicinal usage of H. stellatum, and aims to explore the phytochemistry and bioactivity of H. stellatum to explain why local people in Guizhou widely apply H. stellatum for liver protection. In this study, two new prenylated xanthones, hypxanthones A (8) and B (9), together with seven known compounds, were isolated from the aerial parts of the plant. Spectroscopic data as well as experimental and calculated ECD spectra were used to establish the structures of these compounds. Six xanthones isolated in this study, together with four xanthones previously isolated from H. stellatum, were evaluated for their growth-inhibitory activities against five human liver carcinoma cell lines to analyze the bioactivity and structure-activity relationship of xanthones from H. stellatum. Isojacareubin (6) showed significant cytotoxicity against five human liver carcinoma cell lines, with an IC₅₀ value ranging from 1.41 to 11.83 μM, which was stronger than the positive control cisplatin (IC₅₀ = 4.47–20.62 μM). Hypxanthone B (9) showed moderate cytotoxicity to three of the five cell lines. Finally, structure-activity analysis revealed that the prenyl and pyrano substituent groups of these xanthones contributed to their cytotoxicity.

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.

Phenolic constituents with neuroprotective activities from Hypericum wightianum

Five undescribed phenolic compounds, inclusing a depsidone derivative, hyperwightin A, a flavone derivative, hyperwightin B, and three benzophenone glycosides, hyperwightins C-E, along with four known ones were isolated from the 95% EtOH extract of the whole plants of Hypericum wightianum. Structures of the obtained compounds were elucidated by spectroscopic analyses. The protective effects of the isolates against corticosterone-induced PC12 cell injury were assessed. Hyperwightin E, petiolin G and hyperxanthone exhibited noticeable neuroprotection at 10 μM.

Chemical and Biological Aspects of Garcinol and Isogarcinol: Recent Developments

The natural polyisoprenylated benzophenone derivatives garcinol and isogarcinol are secondary plant metabolites isolated from various Garcinia species including Garcinia indica. This review takes stock of the recent chemical and biological research into these interesting natural compounds over the last five years. New biological sources and chemical syntheses are discussed followed by new insights into the activity of garcinol and isogarcinol against cancer, pathogenic bacteria, parasite infections and various inflammatory diseases.

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.

Regiodivergent Photocyclization of Dearomatized Acylphloroglucinols: Asymmetric Syntheses of (-)-Nemorosone and (-)-6-epi-Garcimultiflorone A

Regiodivergent photocyclization of dearomatized acylphloroglucinol substrates has been developed to produce type A polycyclic polyprenylated acylphloroglucinol (PPAP) derivatives using an excited-state intramolecular proton transfer (ESIPT) process. Using this strategy, we achieved the enantioselective total syntheses of the type A PPAPs (-)-nemorosone and (-)-6-epi-garcimultiflorone A. Diverse photocyclization substrates have been investigated leading to divergent photocyclization processes as a function of tether length. Photophysical studies were performed, and photocyclization mechanisms were proposed based on investigation of various substrates as well as deuterium-labeling experiments.

Oblongifolin C suppresses lysosomal function independently of TFEB nuclear translocation

Lysosomes are the terminal organelles of the autophagic-endocytic pathway and play a key role in the degradation of autophagic contents. We previously reported that a natural compound oblongifolin C (OC) increased the number of autophagosomes and impaired the degradation of P62, most likely via suppression of lysosomal function and blockage of autophagosome-lysosome fusion. However, the precise mechanisms of how OC inhibits the lysosome-autophagy pathway remain unclear. In the present study, we investigated the effect of OC on transcription factor EB (TFEB), a master regulator of lysosomal biogenesis, lysosomal function and autophagy. We showed that treatment with OC (15 μM) markedly enhanced the nuclear translocation of TFEB in HeLa cells, concomitantly reduced the interaction of TFEB with 14-3-3 proteins. We further demonstrated that OC caused significant inhibition of mTORC1 along with TFEB nuclear translocation, and OC-mediated TFEB nuclear translocation was dependent on mTORC1 suppression. Intriguingly, this increased nuclear TFEB was accompanied by reduced TFEB luciferase activity, increased lysosomal pH and impaired cathepsin enzyme activities. In HeLa cells, treatment with OC (7.5 μM) resulted in about 30% of cell death, whereas treatment with hydroxycitrate, a caloric restriction mimetic (20 μM) did not affect the cell viability. However, cotreatment with OC and hydroxycitrate caused significantly great cytotoxicity (>50%). Taken together, these results demonstrate that inhibition of lysosome function is mediated by OC, despite evident TFEB nuclear translocation.

Diverse Polyphenols from Hypericum faberi

Six new polyphenols with different isoprenylated xanthones, isoprenylated acylphloroglucinols, and chromone architectures, hyperfaberols A-F (1-6), were isolated from the whole plants of Hypericum faberi along with seven other related known compounds. In which hyperfaberols A/B (1/2) and 12-13 were isoprenylated xanthones, hyperfaberols C-E (3-5) and 8-11 were seven isoprenylated acylphloroglucinol derivatives, while 6-7 were two chromones. Their structures were elucidated by comprehensive analysis of their spectroscopic data as well as detailed comparison with the literature data. Compounds 1 and 11 showed cytotoxities against the human esophageal cancer cell line (ECA-109) and the pancreatic tumor cell line (PANC-1) in vitro, respectively.

Polycyclic polyprenylated acylphloroglucinols from Hypericum choisianum

Twenty-one polycyclic polyprenylated acylphloroglucinols, including three new compounds named as hyperichoisins A (3), B (14) and C (21), were isolated from the aerial parts of Hypericum choisianum. The structures of those new compounds were elucidated by analysis of mass, NMR data, and chiroptical properties. A bioassay showed that otogirinin B had significant inhibitory effect on cell proliferation of A549.

Hypermongone C Accelerates Wound Healing through the Modulation of Inflammatory Factors and Promotion of Fibroblast Migration

The physiology of wound healing is dependent on the crosstalk between inflammatory mediators and cellular components of skin regeneration including fibroblasts and endothelial cells. Therefore, strategies to promote healing must regulate this crosstalk to achieve maximum efficacy. In light of the remarkable potential of natural compounds to target multiple signaling mechanisms, this study aims to demonstrate the potential of hypermongone C, a polycyclic polyprenylated acylphloroglucinol (PPAP), to accelerate wound closure by concurrently enhancing fibroblast proliferation and migration, promoting angiogenesis, and suppressing pro-inflammatory cytokines. This compound belongs to a family of plants (Hypericum) that traditionally have been used to treat injuries. Nevertheless, the exact biological evidence to support the claims is still missing. The results were obtained using a traditional model of cell scratch assay and endothelial cell tube formation, combined with the analysis of protein and gene expression by macrophages. In summary, the data suggest that hypermongone C is a multi-targeting therapeutic natural compound for the promotion of tissue repair and the regulation of inflammation.

Prenylated Acylphloroglucinols from Hypericum faberi

The isolation and structure elucidation of six new prenylated acylphloroglucinols, faberiones A-F, from the whole plant of Hypericum faberi is reported. Faberiones A-D (1-4) share a rare styrene substituent and may be biosynthetically generated via further acylation of the acylphloroglucinols. By analyzing the MS and NMR data, the structures of the new isolates were established. Faberiones B (2) and C (3) showed moderate cytotoxicity against the pancreatic cell line (PANC-1) with IC₅₀ values of 6.2 and 9.0 μM, respectively.

Hyperascyrins L - N, rare methylated polycyclic polyprenylated acylphloroglucinol derivatives from Hypericum ascyron

Seven natural compounds, including new compounds hyperascyrins L-N (1-3) and four known compounds (4-7), were acquired from the aerial parts of Hypericum ascyron, that were all identified as methylated polycyclic polyprenylated acylphloroglucinol derivatives (mPPAPs). The structures of these compounds were established by NMR spectroscopy, experimental and calculated electronic circular dichroism (ECD) data. The neuroprotective activities and hepatoprotective activity of these compounds (10 µM) were evaluated. Compounds 1, 2 and 3 exhibited neuroprotection activity. Compounds 1 and 3 show hepatoprotective activity.

Atropisomeric meroterpenoids with rare triketone-phloroglucinol-terpene hybrids from Baeckea frutescens

Baefrutones A-F (1-6), six new meroterpenoids with rare triketone-phloroglucinol-monoterpene/sesquiterpene frameworks, together with their biosynthetically related intermediate (±)-baeckenon B (7), were isolated from the aerial part of Baeckea frutescens under the guidance of HPLC-Q/TOF-MS2 investigation. Compounds 1-4 represent the first examples of natural meroterpenoids existing as four pairs of inseparable diastereomeric atropisomers (2 : 1, 1H NMR integration) caused by the restricted rotation around the C-6-C-7-C-1' bonds arising from the intramolecular hydrogen bond between C-1 carbonyl and 2'-OH. The discovery of these architectures not only largely enriched the chemodiversity of the meroterpenoid and atropisomer library, but also might be exciting and challenging for asymmetric organic synthesis. Their structures and absolute configurations were established by extensive spectroscopic analysis, X-ray diffraction, and ECD calculations. Compounds 5 and 6 were biomimetically synthesized from 7 and β-caryophyllene via a regioselective oxidative hetero-Diels-Alder reaction, thus providing access to the construction of the 6/6/9/4 tetracyclic ring system. The anti-inflammatory activities of these meroterpenoids were also discussed.

Polycyclic polyprenylated acylphloroglucinol and phenolic metabolites from the aerial parts of Hypericum elatoides and their neuroprotective and anti-neuroinflammatory activities

A phytochemical study on the aerial parts of Hypericum elatoides led to the isolation of a previously undescribed polycyclic polyprenylated acylphloroglucinol derivative, hyperelatone A, seven previously undescribed phenolic metabolites, hyperelatones B-H, along with ten known analogues. The structures of hyperelatones A-H were elucidated by 1D and 2D NMR spectroscopy, HRESIMS experiment, single-crystal X-ray diffraction and comparison of experimental and calculated ECD spectra, as well as chemical derivatization. All compounds were evaluated for their neuroprotective activity against hydrogen peroxide (H₂O₂)-induced cell injury in rat pheochromocytoma PC-12 cells and inhibitory effects on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in BV-2 microglial cells. Hyperelatones B-D and H, cinchonain Ib, and tenuiside A showed noticeable neuroprotection at concentrations of 1.0-100.0 μM. Hyperelatones D, G, and H, (-)-epicatechin, tenuiside A, and (Z)-3-hexenyl-β-D-glucopyranoside exhibited significant anti-neuroinflammatory activity with IC₅₀ values ranging from 0.75 ± 0.02 to 5.83 ± 0.23 μM.

Hyperbeanols F-Q, diverse monoterpenoid polyprenylated acylphloroglucinols from the flowers of Hypericum beanii

Hyperbeanols F-Q, which are twelve undescribed monoterpenoid polyprenylated acylphloroglucinols, and four known analogues were isolated from the dried flowers of Hypericum beanii. Their structures were elucidated by detailed HRESIMS and 1D and 2D NMR data analyses. The absolute configurations of hyperbeanols FH were established by the circular dichroism (CD) exciton chirality method. The plausible biosynthetic pathway speculation of hyperbeanols F-Q indicated that diverse reactions, including prenylation, 1,6-ene reaction, rearrangement, epoxidation and dehydration, contributed to their diverse skeletons. Hyperbeanols FI, O and hypercalin B exhibited moderate nitric oxide (NO) inhibitory activities in LPS-induced RAW 264.7 macrophages, with IC₅₀ values in the range of 17.11-28.74 μM.

Garsubelone A, the First Dimeric Polycyclic Polyprenylated Acylphloroglucinols with Complicated Heptacyclic Architecture from Garcinia subelliptica

Garsubelone A (1), the first dimeric polycyclic polyprenylated acylphloroglucinols type metabolite featuring a complicated 6/6/6/6/6/6/6 heptacyclic architecture containing 10 stereogenic centers, was isolated from Garcinia subelliptica. Biogenetically, this compound was constructed by the plausible monomeric precursor, garsubelone B (2) and secohyperforin, via a key Diels-Alder cycloaddition to form an unique 2-oxabicyclo[3.3.1]nonane core. Their structures and absolute configurations were determined by comprehensive spectroscopic and X-ray diffraction techniques. The cytotoxic activities of these isolates were also evaluated.

Facile Synthesis of 2,2-Diacyl Spirocyclohexanones via an N-Heterocyclic Carbene-Catalyzed Formal [3C + 3C] Annulation

A novel strategy for the construction of 2,2-diacyl spirocyclohexanones 3 has been demonstrated on the basis of an NHC-catalyzed [3C + 3C] annulation of potassium 2-oxo-3-enoates with 2-ethylidene 1,3-indandiones. Furthermore, enantioenriched 3 was obtained in good to excellent yields with good enantioselectivities when chiral N-heterocyclic carbene (NHC) was employed. Notably, ring opening of the resulting 2,2-diacyl spirocyclohexanones 3 with hydrazine led to the formation of phthalazinones in good to excellent yields.

The Polycyclic Polyprenylated Acylphloroglucinol Antibiotic PPAP 23 Targets the Membrane and Iron Metabolism in Staphylococcus aureus

Recently, a series of endo-type B polycyclic polyprenylated acylphloroglucinols (PPAP) derivatives with high antimicrobial activities were chemically synthesized. One of the derivatives, PPAP 23, which showed high antimicrobial activity and low cytotoxicity, was chosen for further investigation of its bactericidal profiles and mode of action. PPAP 23 showed a better efficacy in killing methicillin resistant Staphylococcus aureus (MRSA) and decreasing the metabolic activity of 5-day-old biofilm cells than vancomycin. Moreover, S. aureus did not appear to develop resistance against PPAP 23. The antimicrobial mechanism of PPAP 23 was investigated by RNA-seq combined with phenotypic and biochemical approaches. RNA-seq suggested that PPAP 23 signaled iron overload to the bacterial cells because genes involved in iron transport were downregulated and iron storage gene was upregulated by PPAP 23. PPAP 23 affected the membrane integrity but did not induce pore formation; it inhibited bacterial respiration. PPAP 23 preferentially inhibited Fe–S cluster enzymes; it has a mild iron chelating activity and supplementation of exogenous iron attenuated its antimicrobial activity. PPAP 23 was more effective in inhibiting the growth of S. aureus under iron-restricted condition. The crystal structure of a benzylated analog of PPAP 23 showed a highly defined octahedral coordination of three PPAP ligands around a Fe (3+) core. This suggests that PPAPs are generally capable of iron chelation and are able to form defined stable complexes. PPAP 23 was found to induce reactive oxygen species (ROS) and oxidative stress. Fluorescence microscopic analysis showed that PPAP 23 caused an enlargement of the bacterial cells, perturbed the membrane, and dislocated the nucleoid. Taken together, we postulate that PPAP 23 interacts with the cytoplasmic membrane with its hydrophobic pocket and interferes with the iron metabolism to exert its antimicrobial activity in Staphylococcus aureus.

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.

Littordials A–E, novel formyl-phloroglucinol-β-caryophyllene meroterpenoids from the leaves of Psidium littorale

Littordials A–E (1–5), featuring unusual acyl phloroglucinol units, were isolated from the leaves of Psidium littorale. 2, 3 and 5 exhibited significant cytotoxic activities on MDA-MB-231 and B16 cell lines.

Adamantyl and homoadamantyl derivatives from Garcinia multiflora fruits

Nine undescribed caged polycyclic polyprenylated acylphloroglucinols (PPAPs), including adamantane type PPAPs (1–2) and homoadamantane type PPAPs (3–9), were isolated from the fruits of Garcinia multiflora.