Mangostanaxanthones I and II, new xanthones from the pericarp of Garcinia mangostana

Prenylated xanthones from mangosteen (Garcinia mangostana) target oxidative mitochondrial respiration in cancer cells

Mangosteen (Garcinia mangostana) is well-known for its nutritional value and health benefits. Breast cancer is the most common cancer and the leading cause of cancer-related mortality among females worldwide. Here we show that the prenylated xanthones, α-mangostin, γ-mangostin, 9-hydroxycalabaxanthone (9-HCX), and garcinone E from the mangosteen pericarp exhibit cytotoxicity against a panel of human cancer cell lines including lung adenocarcinoma (A549), cervical carcinoma (HeLa), prostatic carcinoma (DU 145), pancreatic carcinoma (MIA PaCa-2), hepatocellular carcinoma (Hep G2), bladder urothelial cancer (5637), as well as the triple-negative breast cancer cells MDA-MB-231. In line with its higher predicted bioactivity score compared to other prenylated xanthones, 9-HCX induced the strongest antiproliferative and proapoptotic effects in MDA-MB-231 breast cancer xenografts in vivo. In different in vitro models, we demonstrate that prenylated xanthones from G. mangostana target mitochondria in cancer cells by inhibition of the mitochondrial respiratory chain complex II (α-mangostin, γ-mangostin, and garcinone E) and complex III (9-HCX) as shown in isolated mitochondria. Accordingly, oxidative mitochondrial respiration (OXPHOS) was inhibited, mitochondrial proton leak increased, and adenosine triphosphate (ATP) synthesis decreased as analyzed by Seahorse assay in MDA-MB-231 cells. Hence, the prenylated xanthones increased mitochondrial superoxide levels, induced mitochondrial membrane permeabilization, and initiated caspase 3/7-mediated apoptosis in MDA-MB-231 triple-negative breast cancer cells. Thus, prenylated xanthones from Garcinia mangostana exhibit anticancer activity based on interference with the mitochondrial respiration.

In silico studies on the anti-acne potential of Garcinia mangostana xanthones and benzophenones

Garcinia mangostana fruits are used traditionally for inflammatory skin conditions, including acne. In this study, an in silico approach was employed to predict the interactions of G. mangostana xanthones and benzophenones with three proteins involved in the pathogenicity of acne, namely the human JNK1, Cutibacterium acnes KAS III and exo-β-1,4-mannosidase. Molecular docking analysis was performed using Autodock Vina. The highest docking scores and size-independent ligand efficiency values towards JNK1, C. acnes KAS III and exo-β-1,4-mannosidase were obtained for garcinoxanthone T, gentisein/2,4,6,3',5'-pentahydroxybenzophenone and mangostanaxanthone VI, respectively. To the best of our knowledge, this is the first report of the potential of xanthones and benzophenones to interact with C. acnes KAS III. Molecular dynamics simulations using GROMACS indicated that the JNK1-garcinoxanthone T complex had the highest stability of all ligand-protein complexes, with a high number of hydrogen bonds predicted to form between this ligand and its target. Petra/Osiris/Molinspiration (POM) analysis was also conducted to determine pharmacophore sites and predict the molecular properties of ligands influencing ADMET. All ligands, except for mangostanaxanthone VI, showed good membrane permeability. Garcinoxanthone T, gentisein and 2,4,6,3',5'-pentahydroxybenzophenone were identified as the most promising compounds to explore further, including in experimental studies, for their anti-acne potential.

Reversing the biofilm-inducing effect of two xanthones from Garcinia mangostana by 3-methyl-2(5H)-furanone and N-butyryl-D-L homoserine lactone

BACKGROUND

According to the WHO, 12 bacteria cause numerous human infections, including Enterobacteriaceae Klebsiella pneumoniae, and thus represent a public health problem. Microbial resistance is associated with biofilm formation; therefore, it is critical to know the biofilm-inducing potential of various compounds of everyday life. Likewise, the reversibility of biofilms and the modulation of persister cells are important for controlling microbial pathogens. In this work, we investigated the biofilm-inducing effects of xanthones from Garcinia mangostana on Klebsiella pneumoniae. Furthermore, we investigated the reversal effect of 3-methyl-2(5H)-furanone and the formation of persister cells induced by xanthones and their role in modulating the biofilm to the antibiotic gentamicin.

METHODS

To analyze the biofilm-inducing role of xanthones from Garcinia mangostana, cultures of K. pneumoniae containing duodenal probe pieces were treated with 0.1-0.001 μM α- and γ-mangostin, and the biofilm levels were measured using spectrophotometry. To determine biofilm reversion, cultures treated with xanthones, or gentamicin were mixed with 3-methyl-2(5H)-furanone or N-butyryl-DL-homoserine lactone. The presence of K. pneumoniae persister cells was determined by applying the compounds to the mature biofilm, and the number of colony-forming units was counted.

RESULTS

The xanthones α- and γ-mangostin increased K. pneumoniae biofilm production by 40% with duodenal probes. However, 3-methyl-2(5H)-furanone at 0.001 μΜ reversed biofilm formation by up to 60%. Moreover, adding the same to a culture treated with gentamicin reduced the biofilm by 80.5%. This effect was highlighted when 3-methyl-2(5H)-furanone was administered 6 h later than xanthones. At high concentrations of α-mangostin, persister K. pneumoniae cells in the biofilm were about 5 - 10 times more abundant than cells, whereas, with γ-mangostin, they were about 100 times more.

CONCLUSION

Two xanthones, α- and γ-mangostin from G. mangostana, induced biofilm formation in K. pneumoniae and promoted persister cells. However, the biofilm formation was reversed by adding 3-methyl-2(5H)-furanone, and even this effect was achieved with gentamicin. In addition, this compound controlled the persister K. pneumoniae cells promoted by α-mangostin. Thus, synthetic, and natural biofilm-inducing compounds could harm human health. Therefore, avoiding these substances and looking for biofilm inhibitors would be a strategy to overcome microbial resistance and recover antibiotics that are no longer used.

Insights into the Chemical Composition and In Vitro Bioactive Properties of Mangosteen (Garcinia mangostana L.) Pericarp

The industrial processing of mangosteen (Garcinia mangostana L.) generates high amounts of waste, as ~60% of the fruit is formed by an inedible pericarp. However, its pericarp has been explored as a source of xanthones; nevertheless, studies addressing the recovery of other chemical compounds from such biomass are still scarce. Hence, this study intended to elucidate the chemical composition of the mangosteen pericarp, including fat-soluble (tocopherols and fatty acids) and water-soluble (organic acids and phenolic compound non-xanthones) compounds present in the following extracts: hydroethanolic (MT80), ethanolic (MTE), and aqueous (MTW). In addition, the antioxidant, anti-inflammatory, antiproliferative and antibacterial potentials of the extracts were assessed. The mangosteen pericarp showed a composition with seven organic acids, three tocopherol isomers, four fatty acids and fifteen phenolic compounds. Regarding the extraction of phenolics, the MT80 was the most efficient (54 mg/g extract), followed by MTE (19.79 mg/g extract) and MTW (4.011 mg/g extract). All extracts showed antioxidant and antibacterial activities; however, MT80 and MTE extracts were more efficient than MTW. Only MTW did not show anti-inflammatory properties, whereas MTE and MT80 showed inhibitory activities towards tumor cell lines. Notwithstanding, MTE showed cytotoxicity towards normal cells. Our findings support the idea that the ripe mangosteen pericarp is a source of bioactive compounds, although their recovery is dependent on the extraction solvent.

N-Containing α-Mangostin Analogs via Smiles Rearrangement as the Promising Cytotoxic, Antitrypanosomal, and SARS-CoV-2 Main Protease Inhibitory Agents

New N-containing xanthone analogs of α-mangostin were synthesized via one-pot Smiles rearrangement. Using cesium carbonate in the presence of 2-chloroacetamide and catalytic potassium iodide, α-mangostin (1) was subsequently transformed in three steps to provide ether 2, amide 3, and amine 4 in good yields at an optimum ratio of 1:3:3, respectively. The evaluation of the biological activities of α-mangostin and analogs 2-4 was described. Amine 4 showed promising cytotoxicity against the non-small-cell lung cancer H460 cell line fourfold more potent than that of cisplatin. Both compounds 3 and 4 possessed antitrypanosomal properties against Trypanosoma brucei rhodesiense at a potency threefold stronger than that of α-mangostin. Furthermore, ether 2 gave potent SARS-CoV-2 main protease inhibition by suppressing 3-chymotrypsinlike protease (3CL^pro) activity approximately threefold better than that of 1. Fragment molecular orbital method (FMO-RIMP2/PCM) indicated the improved binding interaction of 2 in the 3CL^pro active site regarding an additional ether moiety. Thus, the series of N-containing α-mangostin analogs prospectively enhance druglike properties based on isosteric replacement and would be further studied as potential biotically active chemical entries, particularly for anti-lung-cancer, antitrypanosomal, and anti-SARS-CoV-2 main protease applications.

Garcimckeans A-C, three new xanthones from the stems of Garcinia mckeaniana, and their cytotoxic activity

Three new xanthones, garcimckeans A-C (1-3) were isolated from the methanol extract of the stems of Garcinia mckeaniana (Clusiaceae). Their structures were established by extensive spectroscopic analysis (HR-ESI-MS and 1 D and 2 D NMR) and by comparison of the spectral data with those reported in the literature. Compounds 1-3 displayed weak cytotoxic activity toward KB, Lu, HepG2, and MCF7 cell lines using the MTT assay with IC₅₀ values ranging from 71.03 ± 2.93 to 90.40 ± 7.13 µM compared to that of the positive control compound, ellipticine (IC₅₀: 1.22 ± 0.10 ∼ 2.44 ± 0.2 µM).

A Review of the Influence of Various Extraction Techniques and the Biological Effects of the Xanthones from Mangosteen (Garcinia mangostana L.) Pericarps

Xanthones are significant bioactive compounds and secondary metabolites in mangosteen pericarps. A xanthone is a phenolic compound and versatile scaffold that consists of a tricyclic xanthene-9-one structure. A xanthone may exist in glycosides, aglycones, monomers or polymers. It is well known that xanthones possess a multitude of beneficial properties, including antioxidant activity, anti-inflammatory activity, and antimicrobial properties. Additionally, xanthones can be used as raw material and/or an ingredient in many food, pharmaceutical, and cosmetic applications. Although xanthones can be used in various therapeutic and functional applications, their properties and stability are determined by their extraction procedures. Extracting high-quality xanthones from mangosteen with effective therapeutic effects could be challenging if the extraction method is insufficient. Although several extraction processes are in use today, their efficiency has not yet been rigorously evaluated. Therefore, selecting an appropriate extraction procedure is imperative to recover substantial yields of xanthones with enhanced functionality from mangosteens. Hence, the present review will assist in establishing a precise scenario for finding the most appropriate extraction method for xanthones from mangosteen pericarp by critically analyzing various conventional and unconventional extraction methods and their ability to preserve the stability and biological effects of xanthones.

Mangosteen Metabolites as Promising Alpha-Amylase Inhibitor Candidates: In Silico and In Vitro Evaluations

Diabetes is a chronic metabolic disorder characterized by raised glucose levels in the blood, resulting in grave damage over time to various body organs, including the nerves, heart, kidneys, eyes, and blood vessels. One of its therapeutic treatment approaches involves the inhibition of enzymes accountable for carbohydrate digestion and absorption. The present work is aimed at evaluating the potential of some reported metabolites from Garcinia mangostana (mangosteen, Guttiferae) as alpha-amylase inhibitors. Forty compounds were assessed for their capacity to inhibit alpha-amylase using in silico studies as well as in vitro assays. Molecular docking was carried out to analyze their binding capacities in the 3D structure of alpha-amylase (PDB ID: 4GQR). Among the tested compounds, 6-O-β-D-glucopyranosyl-2,4,6,3',4',6'-hexahydroxybenzophenone (8), aromadendrin-8-C-glucoside (5), epicatechin (6), rhodanthenone (4), and garcixanthone D (40) had a high XP G.score and a Glide G.score of -12.425, -11.855, -11.135, and -11.048 Kcal/mol, respectively. Compound 8 possessed the XP and Glide docking score of -12.425 Kcal/mol compared to the reference compounds myricetin and acarbose which had an XP and Glide docking score of -12.319 and 11.201 Kcal/mol, respectively. It interacted through hydrogen bond formations between its hydroxyl groups and the residues His 101, Asp 197, Glu 233, Asp 300, and His 305, in addition to water bridges and hydrophobic interactions. Molecular mechanics-generalized born surface area (MM-GBSA) was used to calculate the binding free energy and molecular dynamic studies that indicated the stability of the alpha-amylase-compound 8 complex during the 100 ns simulation in comparison with myricetin- and acarbose-alpha-amylase complexes. Additionally, the in vitro alpha-amylase inhibition assay findings validated the in silico study's findings. This could further validate the potential of G. mangostana as a candidate for diabetes management.

Alpha-Mangostin as a New Therapeutic Candidate for Concanavalin A-Induced Autoimmune Hepatitis: Impact on the SIRT1/Nrf2 and NF-κB Crosstalk

Alpha-mangostin (α-MN) is a xanthone obtained from Garcinia mangostana that has diverse anti-oxidative and anti-inflammatory potentials. However, its pharmacological activity against autoimmune hepatitis (AIH) has not been investigated before. Concanavalin A (Con A) was injected into mice to induce AIH and two doses of α-MN were tested for their protective effects against Con A-induced AIH. The results demonstrated the potent hepatoprotective activity of α-MN evidenced by a remarkable decrease of serum indices of the hepatic injury and amendment of the histological lesions. α-MN significantly attenuated the level and immuno-expression of myeloperoxidase (MPO) indicating a decrease in the neutrophil infiltration into the liver. Additionally, the recruitment of the CD4+ T cell was suppressed in the α-MN pre-treated animals. α-MN showed a potent ability to repress the Con A-induced oxidative stress evident by the reduced levels of malondialdehyde (MDA), 4-hydroxynonenal (4-HNE), and protein carbonyl (PC), as well as the enhanced levels of antioxidants as the reduced glutathione (GSH), superoxide dismutase (SOD), and total antioxidant capacity (TAC). The ELISA, RT-PCR, and IHC analyses revealed that α-MN enhanced the sirtuin1/nuclear factor erythroid 2 related factor-2 (SIRT1/Nrf2) signaling and its downstream cascade genes concurrently with the inhibition of the nuclear factor kappa B (NF-κB) and the inflammatory cytokines (tumor necrosis factor-alpha and interleukine-6) signaling. Taken together, these results inferred that the hepatoprotective activity of α-MN could prevent Con A-induced AIH through the modulation of the SIRT1/Nrf2/NF-κB signaling. Hence, α-MN may be considered as a promising candidate for AIH therapy.

The Potential of α-Mangostin from Garcinia mangostana as an Effective Antimicrobial Agent-A Systematic Review and Meta-Analysis

This systematic review aims to evaluate the antimicrobial activity of α-mangostin derived from Garcinia mangostana against different microbes. A literature search was performed using PubMed and Science Direct until March 2022. The research question was developed based on a PICO (Population, Intervention, Control and Outcomes) model. In this study, the population of interest was microbes, α-mangostin extracted from Garcinia mangostana was used as exposure while antibiotics were used as control, followed by the outcome which is determined by the antimicrobial activity of α-mangostin against studied microbes. Two reviewers independently performed the comprehensive literature search following the predetermined inclusion and exclusion criteria. A methodological quality assessment was carried out using a scoring protocol and the risk of bias in the studies was analyzed. Reward screening was performed among the selected articles to perform a meta-analysis based on the pre-determined criteria. Case groups where α-mangostin extracted from Garcinia mangostana was incorporated were compared to groups using different antibiotics or antiseptic agents (control) to evaluate their effectiveness. A total of 30 studies were included; they were heterogeneous in their study design and the risk of bias was moderate. The results showed a reduction in microbial counts after the incorporation of α-mangostin, which resulted in better disinfection and effectiveness against multiple microbes. Additionally, the meta-analysis result revealed no significant difference (p > 0.05) in their effectiveness when α-mangostin was compared to commercially available antibiotics. α-mangostin worked effectively against the tested microbes and was shown to have inhibitory effects on microbes with antibiotic resistance.

Polycyclic Phenol Derivatives from the Leaves of Spermacoce latifolia and Their Antibacterial and α-Glucosidase Inhibitory Activity

Three new polycyclic phenol derivatives, 2-acetyl-4-hydroxy-6H-furo [2,3-g]chromen-6-one (1), 2-(1′,2′-dihydroxypropan-2′-yl)-4-hydroxy-6H-furo [2,3-g][1]benzopyran-6-one (2) and 3,8,10-trihydroxy-4,9-dimethoxy-6H-benzo[c]chromen-6-one (8), along with seven known ones (3–7, 9 and 10) were isolated for the first time from the leaves of Spermacoce latifolia. Their structures were determined by spectroscopic analysis and comparison with literature-reported data. These compounds were tested for their in vitro antibacterial activity against four Gram-(+) bacteria: Staphyloccocus aureus (SA), methicillin-resistant Staphylococcus aureus (MRSA), Bacillus cereus (BC), Bacillus subtilis (BS), and the Gram-(−) bacterium Escherichia coli. Compounds 1, 2, 5 and 8 showed antibacterial activity toward SA, BC and BS with MIC values ranging from 7.8 to 62.5 µg/mL, but they were inactive to MRSA. Compound 4 not only showed the best antibacterial activity against SA, BC and BS, but it further displayed significant antibacterial activity against MRSA (MIC 1.95 µg/mL) even stronger than vancomycin (MIC 3.9 µg/mL). No compounds showed inhibitory activity toward E. coli. Further bioassay indicated that compounds 1, 4, 5, 6, 8 and 9 showed in vitro α-glucosidase inhibitory activity, among which compound 9 displayed the best α-glucosidase inhibitory activity with IC₅₀ value (0.026 mM) about 15-fold stronger than the reference compound acarbose (IC₅₀ 0.408 mM). These results suggested that compounds 4, 8 and 9 were potentially highly valuable compounds worthy of consideration to be further developed as an effective anti-MRSA agent or effective α-glucosidase inhibitors, respectively. In addition, the obtained data also supported that S. latifolia was rich in structurally diverse bioactive compounds worthy of further investigation, at least in searching for potential antibiotics and α-glucosidase inhibitors.

Inhibition of Quorum-Sensing Regulator from Pseudomonas aeruginosa Using a Flavone Derivative

Quorum sensing (QS) is a cell-to-cell communication process that controls bacterial collective behaviors. The QS network regulates and coordinates bacterial virulence factor expression, antibiotic resistance and biofilm formation. Therefore, inhibition of the QS system is an effective strategy to suppress the bacterial virulence. Herein, we identify a phosphate ester derivative of chrysin as a potent QS inhibitor of the human pathogen Pseudomonas aeruginosa (P. aeruginosa) using a designed luciferase reporter assay. In vitro biochemical analysis shows that the chrysin derivative binds to the bacterial QS regulator LasR and abrogates its DNA-binding capability. In particular, the derivative exhibits higher anti-virulence activity compared to the parent molecule. All the results reveal the potential application of flavone derivative as an anti-virulence compound to combat the infectious diseases caused by P. aeruginosa.

New Alpha-Amylase Inhibitory Metabolites from Pericarps of Garcinia mangostana

Two new benzophenones: garcimangophenones A (6) and B (7) and five formerly reported metabolites were purified from the pericarps EtOAc fraction of Garcinia mangostana ((GM) Clusiaceae). Their structures were characterized by various spectral techniques and by comparing with the literature. The α-amylase inhibitory (AAI) potential of the isolated metabolites was assessed. Compounds 7 and 6 had significant AAI activity (IC50 9.3 and 12.2 µM, respectively) compared with acarbose (IC50 6.4 µM, reference α-amylase inhibitor). On the other hand, 5 had a moderate activity. Additionally, their activity towards the α-amylase was assessed utilizing docking studies and molecular dynamics (MD) simulations. The docking and predictive binding energy estimations were accomplished using reported crystal structure of the α-amylase (PDB ID: 5TD4). Compounds 7 and 6 possessed highly negative docking scores of −11.3 and −8.2 kcal/mol, when complexed with 5TD4, respectively while acarbose had a docking score of −16.1 kcal/mol, when complexed with 5TD4. By using molecular dynamics simulations, the compounds stability in the complexes with the α-amylase was analyzed, and it was found to be stable over the course of 50 ns. The results suggested that the benzophenone derivative 7 may be potential α-amylase inhibitors. However, further investigations to support these findings are required.

Antibacterial activities of plant-derived xanthones

The increasing threat to global health posed by antibiotic resistance remains a serious concern. This troublesome scenario has steered a need for the discovery and evaluation of novel antibacterial agents. Natural products are the main sources of antimicrobials used in clinical practice, serving as a rich reservoir for the discovery of new antibiotics. Pharmaceutical phenolics especially xanthones widely exist in the plant kingdom, and are important plant metabolites. They possess versatile biological activities, including antiviral, antibacterial, neurotrophic, and anticancer. In the present study, we focus on the antibacterial activities of phytoxanthones and summarize their structures and sources, categories and drug-likeness evaluations, and antibacterial activities. A total of 226 different plant xanthones are identified through the NETs screening, and most of them are distributed in Clusiaceae family. These phytoxanthones are divided into four groups according to the intrinsic structural properties, including the most common simple xanthones and the majority of biprenylated ones. Moreover, their physicochemical parameters are calculated and the structure-activity relationships are discussed as well. These results indicate that the biprenylated xanthone derivatives may be promising antibacterial candidates and that the natural products of plants may be a poorly understood repository for the discovery of novel antibacterial agents.

Mangostanaxanthone IV Ameliorates Streptozotocin-Induced Neuro-Inflammation, Amyloid Deposition, and Tau Hyperphosphorylation via Modulating PI3K/Akt/GSK-3β Pathway

Alzheimer's disease (AD), a progressive neurodegenerative disorder, is characterized by amyloid deposition and neurofibrillary tangles formation owing to tau protein hyperphosphorylation. Intra-cerebroventricular (ICV) administration of streptozotocin (STZ) has been widely used as a model of sporadic AD as it mimics many neuro-pathological changes witnessed in this form of AD. In the present study, mangostanaxanthone IV (MX-IV)-induced neuro-protective effects in the ICV-STZ mouse model were investigated. STZ (3 mg/kg, ICV) was injected once, followed by either MX-IV (30 mg/kg/day, oral) or donepezil (2.5 mg/kg/day, oral) for 21 days. Treatment with MX-IV diminished ICV-STZ-induced oxidative stress, neuro-inflammation, and apoptosis which was reflected by a significant reduction in malondialdehyde (MDA), hydrogen peroxide (H₂O₂), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) brain contents contrary to increased glutathione (GSH) content. Moreover, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase content and cleaved caspase-3 activity were reduced together with a marked decrement in amyloid plaques number and phosphorylated tau expression via PI3K/Akt/GSK-3β pathway modulation, leading to obvious enhancement in neuronal survival and cognition. Therefore, MX-IV is deemed as a prosperous nominee for AD management with obvious neuro-protective effects that were comparable to the standard drug donepezil.

Quorum Sensing Inhibitors: Curbing Pathogenic Infections through Inhibition of Bacterial Communication

Currently, most of the developed and developing countries are facing the problem of infectious diseases. The genius way of an exaggerated application of antibiotics led the infectious agents to respond by bringing a regime of persisters to resist antibiotics attacks prolonging their survival. Persisters have the dexterity to communicate among themself using signal molecules via the process of Quorum Sensing (QS), which regulates virulence gene expression and biofilms formation, making them more vulnerable to antibiotic attack. Our review aims at the different approaches applied in the ordeal to solve the riddle for QS inhibitors. QS inhibitors, their origin, structures and key interactions for QS inhibitory activity have been summarized. Solicitation of a potent QS inhibitor molecule would be beneficial, giving new life to the simplest antibiotics in adjuvant therapy.

Garcinoxanthones SV, new xanthone derivatives from the pericarps of Garcinia mangostana together with their cytotoxic and antioxidant activities

Xanthones (9H-xanthene-9-ones) are considered to be very promising compounds due to a variety of interesting biological and pharmacological activities. In this study, column chromatography of the methanol extract of the Garcinia mangostana L. pericarps resulted in the isolation of four new xanthones (garcinoxanthones SV, 1-4) and five known analogs including garcinone E (5), 11-hydroxy-1-isomangostin (6) mangostenone E (7), 1,3,6,7-tetrahydroxyxanthone (8), and α-mangostin (9). The structures of the new compounds were elucidated by NMR, HRESIMS, and ECD spectra. Compound 8 (1,3,6,7-tetrahydroxyxanthone) was found from the G. mangostana pericarps for the first time. All the isolated compounds (1-8) were evaluated for their 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging capacity and cytotoxicity in vitro against three human cancer cell lines including SK-LU-1, MCF7, and HT-29 cell lines. Compounds 3, 5, and 8 exhibited significant DPPH scavenging capacity with IC₅₀ values of 68.55, 63.05, and 28.45 μM, respectively, in comparison with ascorbic acid (IC₅₀ = 48.03 μM). Compounds 5 and 8 showed moderate cytotoxic effects against the three human cancer cell lines with IC₅₀ value ranges of 19.86-27.38 μM.

Anti-Inflammatory, Antioxidant, and Anti-Nonalcoholic Steatohepatitis Acylphloroglucinol Meroterpenoids from Hypericum bellum Flowers

In this work, 26 methylated acylphloroglucinol meroterpenoids with diverse skeletons, including 18 new ones (bellumones A-R, 1-18), were identified from the flowers of Hypericum bellum. Their structures including absolute configurations were elucidated by detailed spectroscopic data, calculated electronic circular dichroism (ECD), and X-ray diffraction (XRD). Through methylation at C-5, prenylation with different chain lengths of the acylphloroglucinol-derived core, along with different types of secondary cyclization, type A bicyclic polyprenylated acylphloroglucinols (BPAPs) (1-5 and 19-24) and dearomatized isoprenylated acylphloroglucinols (DIAPs) (6-18 and 25-26) were obtained. The significant results of anti-inflammatory, antioxidant, and anti-nonalcoholic steatohepatitis (anti-NASH) activities suggest its usefulness in daily health care.

Effect of Sub-Minimum Inhibitory Concentrations of Tyrosol and EDTA on Quorum Sensing and Virulence of Pseudomonas aeruginosa

Introduction

Pseudomonas aeruginosa is considered a dangerous pathogen, as it causes many human diseases, besides that it is resistant to almost all types of antibacterial agents. So, new strategies to overcome P. aeruginosa infection have evolved to attenuate its virulence factors and inhibit its quorum-sensing (QS) activity.

Purpose

This study investigated the effect of tyrosol and EDTA as anti-quorum-sensing and antivirulence agents against P. aeruginosa PAO1.

Methods

Anti-quorum activity of sub-minimum inhibitory concentrations (sub-MICs) of tyrosol and EDTA was tested using Chromobacterium violaceum (CV 12,472) biosensor bioassay. Miller assay was used to assess the inhibition of QS signal molecules by β-galactosidase activity determination. Also, their effects on the production of protease, lipase, lecithinase, and motility were tested. The inhibitory effects of these molecules on QS regulatory genes and exotoxins genes expression were evaluated by real-time PCR.

Results

Tyrosol and EDTA at sub-MICs inhibited the production of violacein pigment. Both compounds inhibited QS molecules production and their associated virulence factors (protease, lipase, lecithinase, and motility) (P≤ 0.05). Besides, the expression levels of QS regulatory genes (lasI, lasR, rhƖI, rhIR, pqsA, and pqsR) and exotoxins genes (exoS and exoY) were significantly reduced (P≤ 0.05).

Conclusion

Both tyrosol and EDTA can be used to fight P. aeruginosa infection as anti-quorum-sensing and antivirulence agents at their sub-MICs.

Cytotoxicity and nitric oxide inhibitory activities of Xanthones isolated from Calophyllum hosei Ridl

Previous studies on Calophyllum species have shown the existence of a wide variety of bioactive xanthones and coumarins. Phytochemical investigations carried out on the plant, Calophyllum hosei led to the isolation of eleven known xanthones, ananixanthone (1), 9-hydroxycalabaxanthone (2), dombakinaxanthone (3), thwaitesixanthone (4), caloxanthone B (5), trapezifolixanthone (6), β-mangostin (7), osajaxanthone (8), caloxanthone A (9), calozeyloxanthone (10) and rubraxanthone (11). The structures of these compounds were identified and elucidated using spectroscopic techniques such as NMR and MS. The cytotoxicity and nitric oxide production inhibitory activities of selected xanthones as well as the extracts were tested against HL-60 cells and RAW 264.7 murine macrophages, respectively. Among all tested compounds, β-mangostin exhibited appreciable cytotoxicity against HL-60 cells with the IC₅₀ value of 7.16 ± 0.70 µg/mL and rubraxanthone exhibited significant nitric oxide inhibitory activity against LPS induced RAW 264.7 murine macrophages with the IC₅₀ value of 6.45 ± 0.15 µg/mL.

Xanthones and Cancer: from Natural Sources to Mechanisms of Action

Xanthones are a class of heterocyclic natural products that have been widely studied for their pharmacological potential. In fact, they have been serving as scaffolds for the design of derivatives focusing on drug development. One of the main study targets of xanthones is their anticancer activity. Several compounds belonging to this class have already demonstrated cytotoxic and antitumor effects, making it a promising group for further exploration. This review therefore focuses on recently published studies, emphasizing their natural and synthetic sources and describing the main mechanisms of action responsible for the anticancer effect of promising xanthones.

α-Mangostin reduced the viability of A594 cells in vitro by provoking ROS production through downregulation of NAMPT/NAD

α-Mangostin (MAN) is a bioactive compound isolated from the inedible pericarp of a tropical fruit mangosteen (Garcinia mangostana Linn). It exhibits notable therapeutic potentials on lung cancers, but the underlying mechanisms are still largely unknown. This study was designed to further explore the mechanisms involved in cytotoxicity of MAN on A549 cells. Apoptosis and cell cycle distribution were analyzed by flow cytometry methods. The fluorescent probes DCFH-DA and JC-1 were used to assess the intracellular reactive oxidative species (ROS) and mitochondrial membrane potential statuses, respectively. The regulation of MAN on relevant pathways was investigated by immunoblotting assays. The results obtained indicated that MAN caused significant apoptosis and cell cycle arrest in A549 cells, which eventually resulted in inhibition on cell proliferation in vitro. All these phenomena were synchronized with escalated oxidative stress and downregulation of nicotinamide phosphoribosyltransferase/nicotinamide adenine dinucleotide (NAMPT/NAD). Supplementation with nicotinamide mononucleotide (NMN) and N-acetylcysteine (NAC) efficiently eased MAN-induced ROS accumulation, and potently antagonized MAN-elicited apoptosis and cell cycle arrest. The pro-apoptotic effect of MAN was further confirmed by increased expressions of cleaved caspase 3, 6, 7, and 9, and its effect on cell cycle progression was validated by the altered expressions of p-p38, p-p53, CDK4, and cyclin D1. The immunoblotting assays also demonstrated that NAC/NMN effectively restored these molecular changes elicited by MAN treatment. Collectively, this study revealed a unique anti-tumor mechanism of MAN by provoking ROS production through downregulation of NAMPT/NAD signaling and further validated MAN as a potential therapeutic reagent for lung cancer treatment.

Mangostanaxanthone VII, a new cytotoxic xanthone from Garcinia mangostana

Garcinia mangostana L. (the queen of fruits, mangosteen, family Guttiferae) is a wealthy source of xanthones. The CHCl3 soluble fraction of the air-dried pericarps of G. mangostana provided a new xanthone: mangostanaxanthone VII (5), along with four known xanthones: mangostanaxanthones I (1) and II (2), gartanin (3) and γ-mangostin (4). The structural verification of these metabolites was achieved by different spectral techniques, including UV, IR, 1D and 2D NMR and HRESIMS. The new metabolite was assessed for cytotoxic potential, using sulforhodamine B (SRB) assay towards the A549 and MCF-7 cancer cell lines. Moreover, its antimicrobial effects were evaluated against various bacterial and fungal strains, using agar disc diffusion assay. Mangostanaxanthone VII showed moderate cytotoxic activity against the A549 and MCF7 cell lines with IC50s 26.1 and 34.8 μM, respectively, compared with doxorubicin (0.74 and 0.41 μM, respectively).

β-Sitosterol derived compound from onion husks non-polar fraction reduces quorum sensing controlled virulence and biofilm production

Quorum sensing is an important regulatory factor of P. aeruginosa virulence induction such as BF, motility, formations of proteases, pyocyanin, and some toxins. The aim of the current study is to detect the effect of the pet.ether extract from onion husk and compound drive from it on quorum sensing and virulence formations of P. aeruginosa. Quorum sensing inhibiting effect of the pet.ether extract of onion husk and a compound drive from it, was evaluated by C. violaceum reporter using dilution method as well as an antioxidant by using DPPH. The efficacious of: Quorum sensing inhibiting on pet.ether fraction and compound derived from it, were investigated for their activities toward biofilm and pyocyanin synthesis as well as motility from P. aeruginosa. The pet.ether fraction and compound derived from it of onion husk exhibited potent antimicrobial, antioxidant and Quorum sensing inhibiting effects. The pet.ether fraction and compound derived from it possesses significant reduction on pyocyanin and biofilm induction of P. aeruginosa. Moreover, they significantly inhibited swimming motilities of P. aeruginosa. For the first time, our study showed the medical importance of Allium cepa L. as antimicrobial, antioxidant as well as Quorum sensing inhibiting and virulence suppressors of P. aeruginosa. Thus, these might emphasized on Allium cepa L as a natural source for attenuating toxins of the Pseudomonas.

α-Amylase inhibition of xanthones from Garcinia mangostana pericarps and their possible use for the treatment of diabetes with molecular docking studies

Chromatographic separation of the methanol extract of Garcinia mangostana (mangosteen, Guttiferae) dried pericarps led to the isolation and structural characterization of a new xanthone, namely garcimangostin A (5), together with garcixanthone A (1), gartanin (2), normangostin (3), and garcinone C (4). Their structural characterization was achieved using various NMR spectroscopic tools as well as HRMS. Their α-amylase inhibitory (AAI) potential was assessed. It is noteworthy that 5 had the most potent inhibitory effect with % inhibition 94.1 compared to acarbose (96.7%). Moreover, the molecular modeling studies were estimated. The observed scoring results correlated to those results of the AAI assay. Interestingly, 5 was completely fitting with acarbose structure and a superimposition of acarbose complexed structure with 5 in the enzyme binding site was observed. The AAI activity of 5 could be attributed to the xanthone moiety insertion in the active site of the enzyme via H-bonds network and pi-pi interactions. PRACTICAL APPLICATIONS: Garcinia mangostana is a widely consumed fruit for its unique pleasant aroma and sweet taste. Also, it contains valuable nutritious compounds that are advantageous for human body. It is used as various traditional medicines for treating several ailments such as skin infection, hyperkeratosis, eczema, wounds, psoriasis, amebic dysentery, cholera, diarrhea, and suppuration. The findings of this work can demonstrate the significant AAI potential of G. mangostana xanthones. Therefore, mangosteen as a functional food could help in lowering the postprandial glucose absorption and identifying lead compounds from α-amylase inhibition for the treatment and/or prevention of diabetes and obesity.

Garcixanthone A, a new cytotoxic xanthone from the pericarps of Garcinia mangostana

A new prenylated xanthone, garcixanthone A (5), together with eight known compounds, mangostanaxanthones I (1) and II (2), garcinone E (3), β-mangostin (4), 8-hydroxycudraxanthone G (6), garcinone C (7), cudraxanthone G (8), and (-)-epicatechin (9) were isolated from the EtOAc-soluble fraction of the air-dried pericarps of Garcinia mangostana (family Clusiaceae). Their structures were verified on the basis of spectroscopic data interpretation as well as comparison with the literature. The cytotoxic and antimicrobial activities of the new compound were assessed using sulforhodamine B (SRB) and agar disk diffusion assays, respectively. Compound 5 showed significant cytotoxic potential against epithelial lung carcinoma (A549) and breast carcinoma (MCF7) cell lines with IC₅₀s 3.0 and 4.2 μM, respectively, compared to doxorubicin (0.74 and 0.41 μM, respectively).

Biotransformation of β-Mangostin by an Endophytic Fungus of Garcinia mangostana to Furnish Xanthenes with an Unprecedented Heterocyclic Skeleton

Biotransformation of β-mangostin (1) by the endophytic fungus Xylaria feejeensis GM06 afforded hexacyclic ring-fused xanthenes with an unprecedented hexacyclic heterocylic skeleton. β-Mangostin (1) was transformed to two diastereomeric pairs of enantiomers, mangostafeejin A [(-)-2a/(+)-2b)] and mangostafeejin B [(-)-3a/(+)-3b)]. The chemical structures of the transformation products were elucidated by analysis of NMR and MS data, and the structure of mangostafeejin A [(-)-2a/(+)-2b)] was confirmed by single-crystal X-ray diffraction analysis. The absolute configurations of 3a and 3b were established on the basis of calculated and measured ECD data using the ECD spectra of 2a and 2b as models. The fungal biotransformation described herein provides an effective method to convert an abundant achiral plant natural product scaffold into new chiral heterocyclic scaffolds representing expanded chemical diversity for biological activity screening.

Taib AZ, Mohd Noor N, Mohd Said MI, Abu Bakar M, Mackeen MM. From the Front or Back Door? Quantitative analysis of direct and indirect extractions of α-mangostin from mangosteen (Garcinia mangostana)

The pulp and pericarp of mangosteen (Garcinia mangostana) fruit are popular food, beverage and health products whereby 60% of the fruit consist of the pericarp. The major metabolite in the previously neglected or less economically significant part of the fruit, the pericarp, is the prenylated xanthone α-mangostin. This highly bioactive secondary metabolite is typically isolated using solvent extraction methods that involve large volumes of halogenated solvents either via direct or indirect extraction. In this study, we compared the quantities of α-mangostin extracted using three different extraction methods based on the environmentally friendly solvents methanol and ethyl acetate. The three solvent extractions methods used were direct extractions from methanol (DM) and ethyl acetate (DEA) as well as indirect extraction of ethyl acetate obtained via solvent partitioning from an initial methanol extract (IEA). Our results showed that direct extraction afforded similar and higher quantities of α-mangostin than indirect extraction (DM: 318 mg; DEA: 305 mg; IEA: 209 mg per 5 g total dried pericarp). Therefore, we suggest that the commonly used method of indirect solvent extraction using halogenated solvents for the isolation of α-mangostin is replaced by single solvent direct extraction using the environmentally friendly solvents methanol or ethyl acetate.

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.

Structure-Activity Relationship and Prediction of the Electron-Transfer Potential of the Xanthones Series

The structure-activity relationships of 31 xanthones were analyzed by using the ferric reducing antioxidant power (FRAP) assay to determine their electron-transfer (ET) potential. It was proven that the ET potential of xanthones was dominated by four moieties (i.e. hydroquinone moiety, 5,6-catechol moiety, 6,7-catechol moiety, and 7,8-catechol moiety) and was only slightly affected by other structural features, including a single phenolic OH group, the resorcinol moiety, the transannular dihydroxy moiety, a methoxy group, a sugar residue, an isoprenyl group, a cyclized isoprenyl group, and an isopentanol group. The results could be used to predict the ET potentials of other antioxidant xanthones.

Bioactivity and pharmacological properties of α-mangostin from the mangosteen fruit: a review

INTRODUCTION

α-Mangostin (α-MG) is the most representative xanthone isolated from the pericarp of mangosteen, possessing extensive biological activities and pharmacological properties, considered as an antineoplastic agent, antioxidant, anti-proliferation and induces apoptosis.

AREAS COVERED

The bioactivity and pharmacological properties of α-MG are being actively investigated by various industrial and academic institutions. The bioactivities of α-MG have been summarized in several previous reviews, which were worthy of high compliment. However, recently, many new literatures about the bioactivities of α-MG have been further reported from 2016 to 2017. Herein, the activities of α-MG are supplemented and summarized in this text.

EXPERT OPINION

As previously said, α-MG possesses good bioactivities pharmacological properties. More recently, it found that α-MG has the effect of maintaining cardiovascular system and gastrointestinal health and controlling free radical oxidation. Furthermore, α-MG has more applications in cosmetics, with the effects of anti-aging, anti-wrinkle, acne treatment, maintenance of skin lubrication. The application of α-MG in treating rheumatoid arthritis has been disclosed and the MG-loaded self-micro emulsion (MG-SME) was designed to improve its pharmacokinetic deficiencies. As mentioned above, α-MG can be a promising drug, also worthy of developing, and further research is crucial for the future application of α-MG.

Usage, biological activity, and safety of selected botanical dietary supplements consumed in the United States

In view of the continuous growth of the botanical dietary supplement industry and the increased popularity of lesser known or exotic botanicals, recent findings are described on the phytochemical composition and biological activities of five selected fruits consumed in the United States, namely, açaí, noni, mangosteen, black chokeberry, and maqui berry. A review of the ethnomedicinal uses of these plants has revealed some similarities ranging from wound-healing to the treatment of fever and infectious diseases. Laboratory studies on açaí have shown both its antioxidant and anti-inflammatory activities in vitro, and more importantly, its neuroprotective properties in animals. Anthraquinones and iridoid glucosides isolated from noni fruit induce the phase II enzyme quinone reductase (QR), and noni fruit juice exhibited antitumor and antidiabetic activities in certain animal models. Antitumorigenic effects of mangosteen in animal xenograft models of human cancers have been attributed to its xanthone content, and pure α-mangostin was shown to display antineoplastic activity in mice despite a reported low oral bioavailability. Work on the less extensively investigated black chokeberry and maqui berry has focused on recent isolation studies and has resulted in the identification of bioactive secondary metabolites with QR-inducing and hydroxyl-radical scavenging properties. On the basis of the safety studies and toxicity case reports described herein, these fruits may be generally considered as safe. However, cases of adulteration found in a commercialized açaí product and some conflicting results from mangosteen safety studies warrant further investigation on the safety of these marketed botanical dietary supplements.

Anti-Quorum Sensing Natural Compounds

Increasing extent of pathogenic resistance to drugs has encouraged the seeking for new anti-virulence drugs. Many pharmacological and pharmacognostical researches are performed to identify new drugs or discover new structures for the development of novel therapeutic agents in the antibiotic treatments. Although many phytochemicals show prominent antimicrobial activity, their power lies in their anti-virulence properties. Quorum sensing (QS) is a bacterial intercellular communication mechanism, which depends on bacterial cell population density and controls the pathogenesis of many organisms by regulating gene expression, including virulence determinants. QS has become an attractive target for the development of novel anti-infective agents that do not rely on the use of antibiotics. Anti-QS compounds are known to have the ability to prohibit bacterial pathogenicity. Medicinal plants offer an attractive repertoire of phytochemicals with novel microbial disease-controlling potential, due to the spectrum of secondary metabolites present in extracts, which include phenolics, quinones, flavonoids, alkaloids, terpenoids, and polyacetylenes. They have recently received considerable attention as a new source of safe and effective QS inhibitory substances. The objective of this review is to give a brief account of the research reports on the plants and natural compounds with anti-QS potential.

Protective activity of tovophyllin A, a xanthone isolated from Garcinia mangostana pericarps, against acetaminophen-induced liver damage: role of Nrf2 activation

Tovophyllin A (TA) ameliorates APAP-induced hepatotoxicity by activating Nrf2 and inhibiting the NF-κB pathway.

A Comparative Study of Actinidia deliciosa and Garcinia mangostana in Ovariectomy-Induced Osteoporosis in Female Wistar Rats

The present study was designed to evaluate antiosteoporotic activity of the fresh juice mixtures obtained from Actinidia deliciosa and Garcinia mangostana as well as the pericarp extract of Garcinia mangostana on postmenopausal osteoporosis. 3-month-old female Wistar rats were ovariectiomized and the treatment began 14 days after ovariectomy and continued for 40 days. Statistically significant changes were noticed in body weight, ash weight, bone mineral content, and femur length and weight followed by serum evaluation and histopathology of femur bone. Administration of the fresh juice mixtures of the fruits of Actinidia deliciosa and Garcinia mangostana prevented ovariectomy-induced bone loss. The administration of the fresh juice mixtures resulted in an increase in the femur length and weight, followed by an increase in the body weight as well as the calcium content obtained from the ash of the femur bone. It is evident that the fresh juice mixtures can be used as a remedy as well as a prophylactic for the prevention of postmenopausal osteoporosis. The present study showed that the combined effect of the fruit juice mixtures of Actinidia deliciosa and Garcinia mangostana was found to be a better treatment for postmenopausal osteoporosis when compared to the pericarp extract of Garcinia mangostana.

Plicosepalin A, a new antioxidant catechin-gallic acid derivative of inositol from the mistletoe Plicosepalus curviflorus

Phytochemical investigation of the semi-parasitic plant, Plicosepalus curviflorus (Loranthaceae) growing in Saudi Arabia resulted in the isolation of a new catechin-gallic acid derivative of inositol, plicosepalin A (1) [(+) catechin-4'-O-(1″-O-galloyl-5″-O-methyl)-myo-inositol], along with seven known compounds: methyl gallate (2), catechin (3), quercetin (4), gallic acid (5), lupeol (6), β-sitosterol (7), and ursolic acid (8). Their structures were elucidated on the basis of spectroscopic analyses, including HRESIMS, ESIMS, 1H and 13C NMR, HSQC, and HMBC, as well as comparison with reported data. The antioxidant and antimicrobial activities of 1 were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and the disc diffusion assay, respectively. Compound 1 exhibited potent free radical scavenging activity with an IC50 value of 9.0 ± 0.27 μM. Moreover, significant activities against Staphylococcus aureus and Bacillus subtilis were recorded.

Scalemic Caged Xanthones Isolated from the Stem Bark Extract of Garcinia propinqua

Seven new caged xanthones, doitunggarcinones E-K (1-7), all as scalemic mixtures and 10 known compounds (8-17), were isolated from the stem bark extract of Garcinia propinqua. The structures were elucidated on the basis of spectroscopic methods. The separation of the enantiomers of 1-6 was achieved by semipreparative chiral HPLC. The absolute configuration of compound (+)-1 was determined by single-crystal X-ray crystallographic analysis using Cu Kα radiation. The absolute configurations of the other related compounds were determined from comparisons of their ECD spectra with that of compound (+)-1. Compounds (-)-6 and 7 showed cytotoxicity against a colon cancer cell line with IC₅₀ values of 14.23 and 23.95 μM, respectively.

Xanthones from the Pericarp of Garcinia mangostana

Mangosteen (Garcinia mangostana L.) is one of the most popular tropical fruits (called the "Queen of Fruits"), and is a rich source of oxygenated and prenylated xanthone derivatives. In the present work, phytochemical investigation has resulted in one new prenylated xanthone and 13 known xanthones isolated from the pericarp of G. mangostana. Their structures were established by spectroscopic data analysis, including X-ray diffraction. The new one was further tested for cytotoxic activity against seven cancer cell lines (CNE-1, CNE-2, A549, H490, PC-3, SGC-7901, U87), displaying the half maximal inhibitory concentration (IC₅0) values 3.35, 4.01, 4.84, 7.84, 6.21, 8.09, and 6.39 μM, respectively. It is noteworthy that the new compound can promote CNE-2 cells apoptosis in late stage, having a remarkable inhibition effect on the side population growth of CNE-2 at 1.26 μM. The bioactive compound was also detected in extract from fresh mangosteen flesh, which indicated that the popular fruit could have potential cytotoxic activity for cancer cell lines.

New xanthones and cytotoxic constituents from Garcinia mangostana fruit hulls against human hepatocellular, breast, and colorectal cancer cell lines

ETHNOPHARMACOLOGICAL RELEVANCE

Cancer has proceeded to surpass one of the most chronic illnesses to be the major cause of mortality in both the developing and developed world. Garcinia mangostana L. (mangosteen, family Guttiferae) known as the queen of fruits, is one of the most popular tropical fruits. It is cultivated in Southeast Asian countries: Malaysia, Indonesia, Sri Lanka, Burma, Thailand, and Philippines. Traditionally, numerous parts of G. mangostana have been utilized to treat various ailments such as abdominal pain, haemorrhoids, food allergies, arthritis, leucorrhoea, gonorrhea, diarrhea, dysentery, wound infection, suppuration, and chronic ulcer.

AIM OF STUDY

Although anticancer activity has been reported for the plant, the goal of the study was designed to isolate and characterize the active metabolites from G. mangostana and measure their cytotoxic properties. In this research, the mechanism of antiproliferative/cytotoxic effects of the tested compounds was investigated.

MATERIALS AND METHODS

The CHCl₃ fraction of the air-dried fruit hulls was repeatedly chromatographed on SiO₂, RP₁₈, Diaion HP-20, and polyamide columns to furnish fourteen compounds. The structures of these metabolites were proven by UV, IR, 1D, and 2D NMR measurements and HRESIMS. Additionally, the cytotoxic potential of all compounds was assessed against MCF-7, HCT-116, and HepG2 cell lines using SRB-U assay. Antiproliferative and cell cycle interference effects of potentially potent compounds were tested using DNA content flow cytometry. The mechanism of cell death induction was also studied using annexin-V/PI differential staining coupled with flow cytometry.

RESULTS

The CHCl₃ soluble fraction afforded two new xanthones: mangostanaxanthones V (1) and VI (2), along with twelve known compounds: mangostanaxanthone IV (3), β-mangostin (4), garcinone E (5), α-mangostin (6), nor-mangostin (7), garcimangosone D (8), aromadendrin-8-C-β-D-glucopyranoside (9), 1,2,4,5-tetrahydroxybenzene (10), 2,4,3`-trihydroxybenzophenone-6-O-β-glucopyranoside (11), maclurin-6-O-β-D-glucopyranoside (rhodanthenone) (12), epicatechin (13), and 2,4,6,3`,5`-pentahydroxybenzophenone (14). Only compound 5 showed considerable antiproliferative/cytotoxic effects with IC₅₀'s ranging from 15.8 to 16.7µM. Compounds 3, 4, and 6 showed moderate to weak cytotoxic effects (IC₅₀'s ranged from 45.7 to 116.4µM). Using DNA content flow cytometry, it was found that only 5 induced significant cell cycle arrest at G₀/G₁-phase which is indicative of its antiproliferative properties. Additionally, by using annexin V-FITC/PI differential staining, 5 induced cells killing effect via the induction of apoptosis and necrosis in both HepG₂ and HCT116 cells. Compound 3 produce necrosis and apoptosis only in HCT116 cells. On contrary, 6 induced apoptosis and necrosis in HepG₂ cells and moderate necrosis in HCT116 cells.

CONCLUSION

Fourteen compounds were isolated from chloroform fraction of G. mangostana fruit hulls. Cytotoxic properties exhibited by the isolated xanthones from G. mangostana reinforce the avail of it as a natural cytotoxic agent against various cancers. These evidences could provide relevant bases for the scientific rationale of using G. mangostana in anti-cancer treatment.