Anti-Acanthamoeba activity of a semi-synthetic mangostin derivative and its ability in removal of Acanthamoeba triangularis WU19001 on contact lens.

Garcinia mangostana L., also known as the mangosteen tree, is a native medicinal plant in Southeast Asia having a wide variety of pharmacologically active compounds, including xanthonoid mangostin. In this study, we examined the pharmacological activities of the selected semi-synthetic mangostin derivative, namely, amoebicidal activity, encystation inhibition, excystation activity, and removal capacity of adhesive Acanthamoeba from the surface of contact lens (CL). Among the three derivatives, C1 exhibited promising anti-Acanthamoeba activity against Acanthamoeba triangularis WU19001 trophozoites and cysts. SEM images displayed morphological changes in Acanthamoeba trophozoites, including the loss of acanthopodia, pore formation in the cell membrane, and membrane damage. In addition, the treated cyst was shrunken and adopted an irregular flat cyst shape. Under a fluorescence microscope, acridine orange and propidium iodide (AO/PI) staining revealed C1 induced condensation of cytoplasm and chromatin with the loss of cell volume in the treated trophozoites, while calcofluor white staining demonstrated the leakage of cell wall in treated cysts, leading to cell death. Interestingly, at the concentration ranges in which C1 showed the anti-Acanthamoeba effects (IC50 values ranging from 0.035-0.056 mg/mL), they were not toxic to Vero cells. C1 displayed the highest inhibitory effect on A. triangularis encystation at 1/16×MIC value (0.004 mg/mL). While C1 demonstrated the excystation activity at 1/128×MIC value with a high rate of 89.47%. Furthermore, C1 exhibited the removal capacity of adhesive Acanthamoeba from the surface of CL comparable with commercial multipurpose solutions (MPSs). Based on the results obtained, C1 may be a promising lead agent to develop a therapeutic for the treatment of Acanthamoeba infections and disinfectant solutions for CL.

Phytochemical, anti-Acanthamoeba, and anti-adhesion properties of Garcinia mangostana flower as preventive contact lens solution.

Acanthamoeba keratitis infection extends due to the growing number of contact lens users. Indigenous plants including Garcinia mangostana play a vital role in human health and well being. Many species of this plant have been reported with myriads of potent medicinal properties. However, the aims of this study were, for the first time, to isolate compounds from the flower of G. mangostana and to test their anti-Acanthamoeba and anti-adhesion activity against Acanthamoeba triangularis. Powdered flowers of G. mangostana were extracted and chromatographed on a silica gel column. The structures of the compounds were established with the aid of 1H NMR. More so, the anti-Acanthamoeba and anti-adhesion properties were tested on a 96-well polystyrene microtiter plate and soft contact lenses. Scanning electron microscope (SEM) was used to determine the features of A. triangularis on contact lenses. Eight pure compounds were obtained, namely 9-hydroxycalabaxanthone, tovophillin A, garcinone E, garcinone B, α-mangostin, gartinin, 8-deoxygartinin and γ-mangostin. The extract and pure compounds exhibited anti-Acanthamoeba activity with MIC values in the range of 0.25-1 mg/mL. In addition, the extract and α-mangostin displayed significant activity against the adhesion of A. triangularis trophozoites both in polystyrene plate and in contact lenses at 0.5 × MIC (0.25 mg/mL). Furthermore, α-mangostin has the potential to remove A. triangularis adhesion in contact lenses similar to a commercial multipurpose solution (MPS). SEM study confirmed that crude extract and α-mangostin are effective as solutions for contact lenses, which removed A. triangularis trophozoites within 24 h. Alpha-mangostin was non-toxic to Vero cells at a concentration below 39 µM in 24 h. Crude extract of G. mangostana flower and its α-mangostin serve as candidate compounds in the treatment of Acanthamoeba infection or as lens care solution, since they can be used as a source of natural products against Acanthamoeba and virulence factor associated with the adhesion of A. triangularis.

Anti-Acanthamoeba synergistic effect of chlorhexidine and Garcinia mangostana extract or α-mangostin against Acanthamoeba triangularis trophozoite and cyst forms.

Acanthamoeba spp. can cause amoebic keratitis (AK). Chlorhexidine is effective for AK treatment as monotherapy, but with a relative failure on drug bioavailability in the deep corneal stroma. The combination of chlorhexidine and propamidine isethionate is recommended in the current AK treatment. However, the effectiveness of treatment depends on the parasite and virulence strains. This study aims to determine the potential of Garcinia mangostana pericarp extract and α-mangostin against Acanthamoeba triangularis, as well as the combination with chlorhexidine in the treatment of Acanthamoeba infection. The minimal inhibitory concentrations (MICs) of the extract and α-mangostin were assessed in trophozoites with 0.25 and 0.5 mg/mL, for cysts with 4 and 1 mg/mL, respectively. The MIC of the extract and α-mangostin inhibited the growth of A. triangularis trophozoites and cysts for up to 72 h. The extract and α-mangostin combined with chlorhexidine demonstrated good synergism, resulting in a reduction of 1/4-1/16 of the MIC. The SEM results showed that Acanthamoeba cells treated with a single drug and its combination caused damage to the cell membrane and irregular cell shapes. A good combination displayed by the extract or α-mangostin and chlorhexidine, described for the first time. Therefore, this approach is promising as an alternative method for the management of Acanthamoeba infection in the future.

Xanthones from the green branch of Garcinia dulcis.

Two new prenylated xanthones, namely dulcisxanthone H and dulcisxanthone I along with garciniaxanthone C, were isolated from the dichloromethane extract of the green branch of Garcinia dulcis. Their structures were elucidated by the analysis of 1-D and 2-D NMR spectral data. Their antibacterial activities were also examined.

Anti-Proliferation and Apoptosis Induction in Breast Cancer Cells by Cratoxylum cochinchinense Extract.

Background: Breast cancer is the most common invasive cancer in females worldwide. It was found about 37.5% in Thai females and is one of the leading causes of death-related cancers in women. Therefore, new finding of anti-cancer compound as a therapeutic candidate in breast cancer is necessary. Objective: To investigate the effect of Cratoxylum cochinchinense extract on anti-proliferation and apoptosis induction in breast cancer cells. Material and Method: Cell proliferation and cell viability assay were determined by MTT assay. Hoechst 33342 and JC-1 staining were used to determined nuclear morphological changes and mitochondrial membrane potential, respectively. Resu;ts: C. cochinchinense extract showed anti-proliferation in MDA-MB-468 treated cells in a time- and dose-dependent manner with IC50 value of 19.19+0.8 µg/ml. In addition, C. cochinchinense extract induced nuclear condensation and apoptotic bodies in MDA-MB-468 treated cells. JC-1 staining revealed that C. cochinchinense extract induced mitochondrial membrane dysfunction. Conclusion: C. cochinchinense extract showed anti-proliferation and apoptosis induction properties in MDA-MB-468 treated cells. These results suggested that C. cochinchinense extract may be a potential candidate for anti-cancer drug developing. The underlying mechanisms of apoptosis induction should be further studied.

Emilia sonchifolia extract activity against white spot syndrome virus and yellow head virus in shrimp cell cultures.

Emilia sonchifolia (L.) DC is a plant used in traditional medicine to treat several viral and bacterial diseases. The antiviral activities of selected Sephadex LH-20 column fractions and HPLC subfractions of an acetone extract of E. sonchifolia leaves were determined in shrimp Penaeus merguiensis primary lymphoid cells infected with either white spot syndrome virus (WSSV) or yellow head virus (YHV). WSSV and YHV replication was quantified using quantitative real-time PCR tests targeted to the VP19 and ORF1b gene transcripts, respectively. In lymphoid organ cells exposed to 100 µg ml⁻¹ of either the Sephadex fraction F14 or the HPLC F14 subfraction SF4, both fractions caused reduced replication, but YHV replication was reduced only by SF4. In the asthiazolyl blue mitochondrial enzyme activity assays to assess extract cytotoxicity, >60% of primary lymphoid organ cells remained viable following exposure to 100 µg ml⁻¹ of either F14 or SF4. GC-MS analysis of the HPLC F14 subfraction SF4 showed that it contained 2,4-di-tert-butylphenol. This study is the first to show that E. sonchifolia leaf extracts might be useful as bioactive agents to protect shrimp against viruses such as WSSV and YHV.

New acridone from the wood of Citrus reticulata Blanco.

A new acridone, named citruscridone (1) together with five known compounds were isolated from the wood of Citrus reticulata Blanco. Their structures were established based on spectroscopic evidence. The antibacterial and antifungal activities of the wood extracts and pure compounds were evaluated.

Morelloflavone, a biflavonoid inhibitor of migration-related kinases, ameliorates atherosclerosis in mice.

While macrophages take up modified LDL to form foam cells and multiply to develop fatty streaks, vascular smooth muscle cells (VSMC) migrate from the media to intima, secrete extracellular matrix, and increase the volume of atherosclerotic lesions. A medicinal plant Garcinia dulcis has been used in traditional Thai medicine for centuries to treat various chronic human diseases. Morelloflavone, a biflavonoid and an active ingredient of the plant, has been shown to inhibit VSMC migration through its inhibition of multiple migration-related kinases such as focal adhesion kinase, c-Src, ERK, and RhoA. However, the exact role of morelloflavone in atherosclerogenesis was unknown. We fed Ldlr(-/-)Apobec1(-/-) mice with either normal chow or chow containing 0.003% morelloflavone for 8 mo and assessed the extent of atherosclerosis by the en face and cross-sectional analyses. A cell composition analysis of atherosclerotic tissue was carried out using immunohistochemical staining. Oral morelloflavone therapy significantly reduced the atherosclerotic areas of the mouse aortas (a 26% reduction), without changing plasma lipid profiles or weights. Immunohistochemical analyses showed that morelloflavone reduced the number of VSMC in the atherosclerotic lesion while it did not change the density of macrophages in the lesion or the percentages of proliferating and apoptotic cells. Oral, low-dose, morelloflavone therapy retards atherosclerogenesis by limiting the migration of VSMC into the intima in the mouse model of human atherosclerosis. Upon further investigation, morelloflavone may be found to be a novel oral antiatherosclerotic agent and a viable addition to the conventional therapies such as statins in humans.

Tomentosones A and B, hexacyclic phloroglucinol derivatives from the Thai shrub Rhodomyrtus tomentosa.

Two phloroglucinols named tomentosones A and B (1 and 2) that each possess a novel hexacyclic ring system were isolated from the CH(2)Cl(2) extract of Rhodomyrtus tomentosa leaves. Their structures were elucidated from analyses of 2D NMR spectroscopic data. Tomentosone A inhibited the growth of chloroquine-resistant and -sensitive strains of the malaria parasite Plasmodium falciparum, with IC(50) values of 1.49 µM and 1.0 µM, respectively, while tomentosone B was significantly less active.

Morelloflavone from Garcinia dulcis as a novel biflavonoid inhibitor of HMG-CoA reductase.

Morelloflavone, a biflavonoid from Garcinia dulcis previously shown to have hypocholesterolemic activity, was examined for its effect on HMG-CoA reductase, the rate-limiting enzyme of the cholesterol biosynthetic pathway. By using the catalytic domain of house mouse HMG-CoA reductase, morelloflavone was found to inhibit the enzyme activity by competing with HMG-CoA whereas it was non-competitive towards NADPH. The inhibition constants (K(i)) with respect to HMG-CoA and NADPH were 80.87 ± 0.06 µm and 103 ± 0.07 µm, respectively. Both flavonoid subunits of this compound, naringenin and luteolin, equally competed with HMG-CoA with K(i) of 83.58 ± 4.37 µm and 83.59 ± 0.94 µm, respectively, and were also non-competitive with NADPH (K(i) of 182 ± 0.67 µm and 188 ± 0.14 µm, respectively). Due to these findings, we suggest that each subunit of morelloflavone would occupy the active site of the enzyme, thereby blocking access of its substrate. The present study thus demonstrates the ability of morelloflavone from G. dulcis to inhibit HMG-CoA reductase in vitro. As a result, this biflavonoid might serve as a new candidate for the future development of hypocholesterolemic agents.

Naphthoquinones, anthraquinones and naphthalene derivatives from the bulbs of Eleutherine americana.

A new naphthoquinone, named eleuthinone A ( 8), two new anthraquinones, named eleuthraquinone A and B ( 12, 13), a naphthalene derivative, named eleucanarol ( 14) were isolated from the bulbs of ELEUTHERINE AMERICANA, together with two new natural products previously synthesized, and nine known compounds. Their structures were established based on spectroscopic evidence. Their antibacterial activities against STAPHYLOCOCCUS AUREUS ATCC25923 and ATCC27664, an enterotoxin producing strain were investigated.

Assessment of antistaphylococcal activity of partially purified fractions and pure compounds from Eleutherine americana.

Ready-to-eat foods were investigated for contamination with methicillin-resistant Staphylococcus aureus (MRSA), and the partially purified fractions from the bulb of Eleutherine americana were evaluated for their anti-MRSA activity. Partially purified fractions Ea6.3 and Ea9 demonstrated good antibacterial activity with a MIC of 125 to 500 microg/ml and MBC of 250 to > or =1000 microg/ml against all the food isolates. Fraction Ea6.3 produced a MIC and MBC of 250 and 500 microg/ml, respectively, whereas fraction Ea9 yielded MIC and MBC of 125 and > or =1000 microg/ml, respectively, against the enterotoxin-producing reference strains. Growth curves in the presence of fraction Ea6.3 at 4 x MIC resulted in total elimination of all the test strains between 20 and 24 h, while fraction Ea9 reduced bacterial population by at least 6 log relative to the control. The partially purified fractions were further purified to obtain pure compounds identified as eleutherol, eleutherin, isoeleutherin, hongconin, two anthraquinones, and elecanacin. The antibacterial activities of these compounds were also investigated; they produced MICs ranging from 31.25 to > or =1000 microg/ml. This study suggests that E. americana crude extract or its partially purified fractions have potentials for application as natural food preservatives.

Rhodomyrtone: a new candidate as natural antibacterial drug from Rhodomyrtus tomentosa.

Rhodomyrtone [6,8-dihydroxy-2,2,4,4-tetramethyl-7-(3-methyl-1-oxobutyl)-9-(2-methylpropyl)-4,9-dihydro-1H-xanthene-1,3(2H)-di-one] from Rhodomyrtus tomentosa (Aiton) Hassk. displayed significant antibacterial activities against gram-positive bacteria including Bacillus cereus, Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Staphylococcus epidermidis, Streptococcus gordonii, Streptococcus mutans, Streptococcus pneumoniae, Streptococcus pyogenes, and Streptococcus salivarius. Especially noteworthy was the activity against MRSA with a minimum inhibitory concentration (MIC) and a minimum bactericidal concentration (MBC) ranging from 0.39 to 0.78 microg/ml. As shown for S. pyogenes, no surviving cells were detected within 5 and 6h after treatment with the compound at 8MBC and 4MBC concentrations, respectively. Rhodomyrtone displays no bacteriolytic activity, as determined by measurement of the optical density at 620 nm. A rhodomyrtone killing test with S. mutans using phase contrast microscopy showed that this compound caused a few morphological changes as the treated cells were slightly changed in color and bigger than the control when they were killed. Taken together, the results support the view that rhodomyrtone has a strong bactericidal activity on gram-positive bacteria, including major pathogens.

Effects of compounds from Garcinia mangostana on inflammatory mediators in RAW264.7 macrophage cells.

ETHNOPHARMACOLOGICAL RELEVANCE: The fruit hull of Garcinia mangostana Linn. has been used in Thai traditional medicine for treatment of abscess and skin infection. AIM OF THE STUDY: The mangosteen fruit hull and its compounds were carried out to investigate for anti-inflammatory activity. MATERIAL AND METHODS: The extract of Garcinia mangostana together with alpha- and gamma-mangostins were tested for anti-inflammatory effect against lipopolysaccharide (LPS)-induced nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor alpha (TNF-alpha) and interleukin-4 (IL-4) releases as well as their mechanisms in transcriptional levels using RAW264.7 macrophage cells. RESULTS: Mangosteen extract possessed potent NO inhibitory effect with an IC50 value of 1.0 microg/ml. The isolated compounds from the extract including alpha-mangostin and gamma-mangostin, possessed marked inhibitory effect against NO release with IC50 values of 3.1 and 6.0 microM, respectively. The extract exhibited potent inhibitory effect on PGE2 release (IC50=6.0 microg/ml), whereas those of alpha- and gamma-mangostins were 13.9 and 13.5 microM, respectively. However, mangostins possessed only moderate effects towards TNF-alpha and IL-4 releases with IC50 values ranging from 31.8 to 64.8 microM. Both extract and alpha-mangostin suppressed transcription of gene encoding inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in dose-dependent manners, whereas gamma-mangostin had only an inhibitory effect on transcription of iNOS. CONCLUSION: The present study may support the Thai traditional use of Garcinia mangostana fruit hull for treatment of inflammatory-related diseases through the inhibition of NO and PGE2 releases, but moderate effect through TNF-alpha and IL-4.

Morelloflavone blocks injury-induced neointimal formation by inhibiting vascular smooth muscle cell migration.

BACKGROUND: In-stent restenosis, or renarrowing within a coronary stent, is the most ominous complication of percutaneous coronary intervention, caused by vascular smooth muscle cell (VSMC) migration into and proliferation in the intima. Although drug-eluting stents reduce restenosis, they delay the tissue healing of the injured arteries. No promising alternative anti-restenosis treatments are currently on the horizon. METHODS: In endothelium-denudated mouse carotid arteries, oral morelloflavone-an active ingredient of the Thai medicinal plant Garcinia dulcis-significantly decreased the degree of neointimal hyperplasia, without affecting neointimal cell cycle progression or apoptosis as evaluated by Ki-67 and TUNEL staining, respectively. At the cellular level, morelloflavone robustly inhibited VSMC migration as shown by both scratch wound and invasion assays. In addition, morelloflavone prevented VSMCs from forming lamellipodia, a VSMC migration apparatus. Mechanistically, the inhibition by morelloflavone of VSMC migration was through its negative regulatory effects on several migration-related kinases, including FAK, Src, ERK, and RhoA. Consistently with the animal data, morelloflavone did not affect VSMC cell cycle progression or induce apoptosis. RESULTS: These data suggest that morelloflavone blocks injury-induced neointimal hyperplasia via the inhibition of VSMC migration, without inducing apoptosis or cell cycle arrest. GENERAL SIGNIFICANCE: We propose morelloflavone to be a viable oral agent for the prevention of restenosis, without compromising effects on the integrity and healing of the injured arteries.

Phenolic compounds from the seeds of Garcinia dulcis.

Dulcisxanthone G, 1,3,6-trihydroxy-2-(2,3-dihydroxy-3-methylbutyl)-7-methoxy-8-(3-methyl-2-butenyl)xanthone, together with 13 known compounds were isolated from the seeds of Garcinia dulcis. Their structures were determined by analysis of 1D and 2D NMR spectroscopic data. The activities on antibacterial and antioxidation of the isolated compounds were examined.

Prenylated xanthones as potential antiplasmodial substances.

Mangostin, the major xanthone of Garcinia mangostana, and a series of synthetic derivatives were investigated for their in vitro antiplasmodial activity against Plasmodium falciparum. Mangostin itself showed moderate activity, but prenylated xanthones containing alkylamino functional groups exhibited quite potent antiplasmodial activity. Some structure-activity relationships are proposed.