Novel and anti-inflammatory constituents of Garcinia subelliptica

The ethanol extract of Garcinia subelliptica Merr. induces autophagy

Background

Garcinia subelliptica Merr. is a multipurpose coastal tree, the potential medicinal effects of which have been studied, including cancer suppression. Here, we present evidence that the ethanol extract of G. subelliptica Merr. (eGSM) induces autophagy in human lung adenocarcinoma cells.

Methods

Two different human lung adenocarcinoma cell lines, A549 and SNU2292, were treated with varying amounts of eGSM. Cytotoxicity elicited by eGSM was assessed by MTT assay and PARP degradation. Autophagy in A549 and SNU2292 was determined by western blotting for AMPK, mTOR, ULK1, and LC3. Genetic deletion of AMPKα in HEK293 cells was carried out by CRISPR.

Results

eGSM elicited cytotoxicity, but not apoptosis, in A549 and SNU2292 cells. eGSM increased LC3-II production in both A549 and, more extensively, SNU2292, suggesting that eGSM induces autophagy. In A549, eGSM activated AMPK, an essential autophagy activator, but not suppressed mTOR, an autophagy blocker, suggesting that eGSM induces autophagy by primarily activating the AMPK pathway in A549. By contrast, eGSM suppressed mTOR activity without activating AMPK in SNU2292, suggesting that eGSM induces autophagy by mainly suppressing mTOR in SNU2292. In HEK293 cells lacking AMPKα expression, eGSM increased LC3-II production, confirming that the autophagy induced by eGSM can occur without the AMPK pathway.

Conclusion

Our findings suggest that eGSM induces autophagy by activating AMPK or suppressing mTOR pathways, depending on cell types.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03454-4.

Structural Revision of Garcinielliptin Oxide and Garcinielliptone E

Previously, Lin et al. reported the isolation and structural determination of two triterpenoids, garcinielliptin oxide (GO) and garcinielliptone E (GE). Their unusual structural features, which remained unparalleled in subsequent decades despite the intervening discovery of hundreds of other polycyclic polyprenylated acylphloroglucinols (PPAPs), caused us to question the originally assigned structures, so GO was reisolated from Garcinia subelliptica, and its NMR spectra were reacquired. In this Note, we revise the structures of GO and the related GE via NMR analysis, biosynthetic considerations, and chemical conversion. Garcinielliptone T, a new PPAP, was also isolated and characterized. GO exhibited weak inhibitory activity against acetylcholinesterase with an IC₅₀ value of 20.7 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.

Acylphloroglucinol Derivatives from Garcinia multiflora with Anti-Inflammatory Effect in LPS-Induced RAW264.7 Macrophages

Two new acylphloroglucinol derivatives, 13,14-didehydroxygarcicowin C (1) and 13,14-didehydroxyisoxanthochymol (2), have been isolated from the stems of Garcinia multiflora, together with seven known compounds (3⁻9). The structures of new compounds 1 and 2 were elucidated by MS and extensive 1D/2D NMR spectroscopic analyses. Among the isolates, 13,14-didehydroxy-isoxanthochymol (2) and sampsonione B (3) exhibited inhibition against lipopolysaccharide (LPS)-induced NF-κB activation in macrophages at 30 μM with relative luciferase activity values (inhibitory %) of 0.75 ± 0.03 (24 ± 4%) and 0.12 ± 0.03 (88 ± 4%), respectively. Additionally, sampsonione B (3) reduced LPS-induced nitric oxide (NO) production in murine RAW264.7 macrophages and did not induce cytotoxicity against RAW 264.7 cells after 24 h treatment. Compound 3 is worth further investigation and may be expectantly developed as an anti-inflammatory drug candidate.

A Review of Malaysian Medicinal Plants with Potential Anti-Inflammatory Activity

This article aims to provide detailed information on Malaysian plants used for treating inflammation. An extensive search on electronic databases including PubMed, Google Scholar, Scopus, and ScienceDirect and conference papers was done to find relevant articles on anti-inflammatory activity of Malaysian medicinal plants. The keyword search terms used were "inflammation," "Malaysia," "medicinal plants," "mechanisms," "in vitro," and "in vivo." As a result, 96 articles on anti-inflammatory activity of Malaysian medicinal plants were found and further reviewed. Forty-six (46) plants (in vitro) and 30 plants (in vivo) have been identified to possess anti-inflammatory activity where two plants, Melicope ptelefolia (Tenggek burung) and Portulaca oleracea (Gelang pasir), were reported to have the strongest anti-inflammatory activity of more than 90% at a concentration of 250 µg/ml. It was showed that the activity was mainly due to the occurrence of diverse naturally occurring phytochemicals from diverse groups such as flavonoids, coumarins, alkaloids, steroids, benzophenone, triterpenoids, curcuminoids, and cinnamic acid. Hence, this current review is a detailed discussion on the potential of Malaysian medicinal plants as an anti-inflammatory agent from the previous studies. However, further investigation on the possible underlying mechanisms and isolation of active compounds still remains to be investigated.

Garcinia subelliptica Merr. (Fukugi): A multipurpose coastal tree with promising medicinal properties

In this short review, the current knowledge on the botany, ecology, uses, and medicinal properties of the multipurpose Garcinia subelliptica (Fukugi) is updated. As yet, there are no reviews on this indigenous and heritage coastal tree species of the Ryukyu Islands in Japan, which has ethnocultural, ecological, and pharmacological significance. Planted by the Okinawan people some 300 years ago, Fukugi trees serve as windbreaks and accord protection against the destructive typhoons. The species has become a popular ornamental tree, and its bark has been used for dyeing fabrics. It forms part of the food chain for mammals and insects and serves as nesting sites for birds. Endowed with bioactive compounds of benzophenones, xanthones, biflavonoids, and triterpenoids, G. subelliptica possesses anticancer, anti-inflammatory, anti-tyrosinase, trypanocidal, antibacterial, DNA topoisomerase inhibitory, DNA strand scission, choline acetyltransferase enhancing, hypoxia-inducible factor-1 inhibitory, and antiandrogenic activities. Fukugetin and fukugiside are two novel biflavonoids named after the species. The chemical constituents of Fukugi fruits when compared with those of mangosteen yielded interesting contrasts.

Garciyunnanimines A–C, novel cytotoxic polycyclic polyprenylated acylphloroglucinol imines from Garcinia yunnanensis

Novel cytotoxic PPAP imines from G. yunnanensis and the biomimetic synthesis of PPAP imines from corresponding PPAPs.

c-Jun N-terminal kinase-mediated anti-inflammatory effects of Garcinia subelliptica in macrophages

Garcinia plants have been traditionally used to treat inflammatory diseases, such as skin infections and pain, in many regions including South‑East Asia. Garcinia subelliptica, a plant of the Garcinia species widely distributed from Japan to Thailand, has been reported to contain components similar to other Garcinia plants that exhibit anti‑inflammatory effects. The present study aimed to explore the anti‑inflammatory effects of ethanol extracts of Garcinia subelliptica (EGS) in macrophages, as there are no previous systemic studies that have investigated the effects of Garcinia subelliptica on inflammation. Non‑cytotoxic concentrations of EGS (≤200 µg/ml) were observed to reduce nitric oxide production by modulating iNOS expression in lipopolysaccharide (LPS)‑stimulated RAW 264.7 macrophages. The expression of cyclooxygenase‑2, the enzyme responsible for the production of prostaglandin E2, was notably reduced by EGS. EGS treatment inhibited the production of pro‑inflammatory cytokines, including IL‑6 and IL‑1β, however, not TNF‑α. Reduced production of inflammatory mediators by EGS was followed by reduced phosphorylation of c‑Jun N‑terminal kinase (JNK) however, not of other mitogen‑activated protein kinases and nuclear factor‑κB. These results indicate that EGS selectively inhibits the excessive production of inflammatory mediators in LPS‑stimulated murine macrophages by reducing the activation of JNK, suggesting that EGS is a candidate for modulating severe inflammation.

Antagonism of human formyl peptide receptor 1 with natural compounds and their synthetic derivatives

Formyl peptide receptor 1 (FPR1) regulates a wide variety of neutrophil functional responses and plays an important role in inflammation and the pathogenesis of various diseases. To date, a variety of natural and synthetic molecules have been identified as FPR1 ligands. Here, we review current knowledge on natural products and natural product-inspired small molecules reported to antagonize and/or inhibit the FPR1-mediated responses. Based on this literature, additional screening of selected commercially available natural compounds for their ability to inhibit fMLF-induced Ca(2+) mobilization in human neutrophils and FPR1 transfected HL-60 cells, and pharmacophore modeling, natural products with potential as FPR1 antagonists are considered and discussed in this review. The identification and characterization of natural products that antagonize FPR1 activity may have potential for the development of novel therapeutics to limit or alter the outcome of inflammatory processes.

Garcimultiflorone G, a novel benzoylphloroglucinol derivative from Garcinia multiflora with inhibitory activity on neutrophil pro-inflammatory responses

A novel benzoylphloroglucinol derivative, garcimultiflorone G (1), was isolated from the fruits of Garcinia multiflora. The structure of 1 was determined through extensive 1D- and 2D-NMR, and MS analyses. Garcimultiflorone G (1) showed inhibitory effects against superoxide anion (O·2(-) generation and elastase release by human neutrophils in response to formyl-L-methionyl-L-leucyl-L-phenylalanine/cytochalasin B (fMLP/CB), with IC50 values of 6.97 ± 1.56 and 11.70 ± 1.58 μM, respectively.

A new benzoylphloroglucinol derivative with an adamantyl skeleton and other constituents from Garcinia multiflora: effects on neutrophil pro-inflammatory responses

A novel benzoylphloroglucinol derivative, garcimultiflorone D (1), with an unusual adamantyl-caged skeleton was isolated from the fruits of Garcinia multiflora, together with four known compounds. The structure of 1 was determined through extensive 1D/2D-NMR and mass-spectrometric analyses. Garcimultiflorone D (1) exhibited inhibitory activities with IC(50) values of 7.21±1.07 and 6.01±0.37 μg/ml against fMLP/CB-induced superoxide anion generation and elastase release, respectively.

Cytotoxic and antioxidant constituents from Garcinia subelliptica

Two new triterpenoids, garcinielliptones Q (1) and S (3), and a new phloroglucinol, garcinielliptone R (2), were isolated from the seed of Garcinia subelliptica. Their structures were established by analysis of their spectroscopic data. Phloroglucinol, garcinielliptone FC (4) from this plant exhibited a significant increase of antiproliferative effect, while 4 combined with cisplatin significantly caused decrease of cell inhibition induced by cisplatin in NTUB1. Exposure of NTUB1 cells to 4 cotreated with cisplatin for significantly decreased the amount of reactive oxygen species (ROS) than that of the total amount generated by 4 and cisplatin. These results suggested that 4 could protect the cisplatin toxicity through reduction of ROS in NTUB1. Phloroglucinols, garcinielliptones, A (5) and F (7), and garsubelline A (6), from this plant, revealed ABTS radical cation scavenging activity and 5 displayed an inhibitory effect on xanthine oxidase. These finding showed that 5-7 may be used as antioxidants.

Xanthine oxidase inhibitory triterpenoid and phloroglucinol from guttiferaceous plants inhibit growth and induced apoptosis in human NTUB1 cells through a ROS-dependent mechanism

A known triterpenoid, β-amyrin (1), and a known and a new phloroglucinol, cohulupone (2) and garcinielliptone P (3), were isolated from the pericarp and heartwood and seed of Garcinia subelliptica, respectively. A new xanthonolignoid, hyperielliptone HF (4), was isolated from the heartwood of Hypericum geminiflorum. The new compounds were established by analysis of their spectroscopic data. Compounds 1-3 showed an inhibitory effect on xanthine oxidase (XO). Treatment of NTUB1, a human bladder cancer cell, with 1 or 1 cotreated with cisplatin for 24 h resulted in a decreased viability of cells. Exposure of NTUB1 to 1 or 1 cotreated with cisplatin for 24 h significantly increased the level of production of reactive oxygen species (ROS). Flow cytometric analysis indicated that treatment of NTUB1 with 1 or 1 cotreated with cisplatin led to the cell cycle arrest, accompanied by an increase in the extent of apoptotic cell death in 1 or 1 combined with cisplatin-treated NTUB1 after 24 h. These data suggested that the presentation of cell cycle arrest and apoptosis in 1 or 1 combined with cisplatin-treated NTUB1 for 24 h was mediated through an increased amount of ROS in cells exposed to 1 or 1 cotreated with cisplatin.

Cytotoxic polyisoprenyl benzophenonoids from Garcinia subelliptica

Six new polyisoprenyl benzophenonoids, (+/-)-garcinialiptone A (1, 2), garcinialiptone B (3), (-)-cycloxanthochymol (4), garcinialiptone C (5), and garcinialiptone D (6), along with three known compounds, xanthochymol (7), isoxanthochymol (8), and cycloxanthochymol (9), were isolated from the fruits of Garcinia subelliptica. The structures of 1-6 were elucidated by spectroscopic analysis. Biological evaluation showed that all compounds 1-9 exhibited cytotoxic activity against a small panel of human tumor cell lines (A549, DU145, KB, vincristine-resistant KB).

Benzophenone derivatives from the fruits of Garcinia multiflora and their anti-inflammatory activity

Five new benzophenone derivatives, 13,14-didehydoxyisogarcinol (1), garcimultiflorone A (2), garcimultiflorone B (3), 13-hydroxygarcimultiflorone B (4), and garcimultiflorone C (5), have been isolated from the fruits of Garcinia multiflora, together with seven known compounds (6-12). The structures of these new compounds were determined through spectroscopic and MS analyses. 13,14-Didehydoxyisogarcinol (1), garcimultiflorone A (2), garcimultiflorone B (3), and 13-hydroxygarcimultiflorone B (4) exhibited inhibition with an IC(50) range of 0.11-5.58 microM on superoxide anion generation and elastase release by human neutrophils in response to fMet-Leu-Phe/cytochalasin B (fMLP/CB).

DNA strand-scission by phloroglucinols and lignans from heartwood of Garcinia subelliptica Merr. and Justicia plants

Five 2,4,6-prenylated phloroglucinols, garcinielliptones HA (1), HB (2), HC (3), HD (4) and HE (5), were isolated from the heartwood of Garcinia subelliptica Merr. Their structures, including relative configurations, were elucidated by means of spectroscopic data analysis. The ability of phloroglucinols, 1-5 and lignans, tuberculatin (8), justicidin A (9), procumbenoside A (10) and ciliatosides A (11) and B (12), isolated from Justicia ciliata and Justicia procumbens, to induce DNA-cleavage activity was examined using pBR322, a supercoiled, covalently closed circular DNA, and it was analyzed by agarose gel electrophoresis. In the presence of Cu (II), compounds 3, 8, 10 and 11 caused significant breakage of supercoiled plasmid pBR322. The products were relaxed circles with no detectable linear forms. In the Cu(II)-mediated DNA damage of 3 and selective compound 8, Cu(I) was shown not to be an essential intermediate by using the Cu(I)-specific sequestering reagent neocuproine.