Structurally Diverse Cytotoxic Polyphenols from Garcinia gracilis.

Thirty-five diverse polyphenols, belonging to seven structure classes, were isolated from Garcinia gracilis, a medicinal and edible plant sampled from Laos. The structures of nine new compounds, gargarcilones A-I (1-3, 5-7, 10, 12, and 17), were established using spectroscopic, X-ray diffraction, and experimental and calculated ECD methods. Additionally, we revised the stereochemical assignment of cochinchinoxanthone and cochinchinoxanthone C. The compounds were evaluated for antiproliferative activity against five human tumor cell lines (HL-60, A549, SMMC-7721, MDA-MB-231, and SW480). Compounds 1-4, 7, and 8 exhibited cytotoxic activity with IC50 values of 0.5-8.9 µM. Compound 3 significantly induced apoptosis in SMMC-7721 cells.

Protective Effects of Dipterocarpus tuberculatus in Blue Light-Induced Macular Degeneration in A2E-Laden ARPE19 Cells and Retina of Balb/c Mice.

Natural products with significant antioxidant activity have been receiving attention as one of the treatment strategies to prevent age-related macular degeneration (AMD). Reactive oxygen intermediates (ROI) including oxo-N-retinylidene-N-retinylethanolamine (oxo-A2E) and singlet oxygen-induced damage, are believed to be one of the major causes of the development of AMD. To investigate the therapeutic effects of methanol extracts of Dipterocarpus tuberculatus Roxb. (MED) against blue light (BL)-caused macular degeneration, alterations in the antioxidant activity, apoptosis pathway, neovascularization, inflammatory response, and retinal degeneration were analyzed in A2E-laden ARPE19 cells and Balb/c mice after exposure of BL. Seven bioactive components, including 2α-hydroxyursolic acid, ε-viniferin, asiatic acid, bergenin, ellagic acid, gallic acid and oleanolic acid, were detected in MED. MED exhibited high DPPH and ABTS free radical scavenging activity. BL-induced increases in intracellular reactive oxygen species (ROS) production and nitric oxide (NO) concentration were suppressed by MED treatment. A significant recovery of antioxidant capacity by an increase in superoxide dismutase enzyme (SOD) activity, SOD expression levels, and nuclear factor erythroid 2-related factor 2 (NRF2) expression were detected as results of MED treatment effects. The activation of the apoptosis pathway, the expression of neovascular proteins, cyclooxygenase-2 (COX-2)-induced inducible nitric oxide synthase (iNOS) mediated pathway, inflammasome activation, and expression of inflammatory cytokines was remarkably inhibited in the MED treated group compared to the Vehicle-treated group in the AMD cell model. Furthermore, MED displayed protective effects in BL-induced retinal degeneration through improvement in the thickness of the whole retina, outer nuclear layer (ONL), inner nuclear layer (INL), and photoreceptor layer (PL) in Balb/c mice. Taken together, these results indicate that MED exhibits protective effects in BL-induced retinal degeneration and has the potential in the future to be developed as a treatment option for dry AMD with atrophy of retinal pigment epithelial (RPE) cells.

Dipterocarpus tuberculatus as a promising anti-obesity treatment in Lep knockout mice.

Introduction: The therapeutic effects and mechanisms of Dipterocarpus tuberculatus (D. tuberculatus) extracts have been examined concerning inflammation, photoaging, and gastritis; however, their effect on obesity is still being investigated. Methods: We administered a methanol extract of D. tuberculatus (MED) orally to Lep knockout (KO) mice for 4 weeks to investigate the therapeutic effects on obesity, weight gain, fat accumulation, lipid metabolism, inflammatory response, and ß-oxidation. Results: In Lep KO mice, MED significantly reduced weight gains, food intake, and total cholesterol and glyceride levels. Similar reductions in fat weights and adipocyte sizes were also observed. Furthermore, MED treatment reduced liver weight, lipid droplet numbers, the expressions of adipogenesis and lipogenesis-related genes, and the expressions of lipolysis regulators in liver tissues. Moreover, the iNOS-mediated COX-2 induction pathway, the inflammasome pathway, and inflammatory cytokine levels were reduced, but ß-oxidation was increased, in the livers of MED-treated Lep KO mice. Conclusion: The results of this study suggest that MED ameliorates obesity and has considerable potential as an anti-obesity treatment.

Novel role of Dipterocarpus tuberculatus as a stimulator of focal cell adhesion through the regulation of MLC2/FAK/Akt signaling pathway.

To investigate a novel function of Dipterocarpus tuberculatus on focal cell adhesion stimulation, alterations to the regulation of focal cell adhesion-related factors were analyzed in NHDF cells and a calvarial defect rat model after treatment with methanol extracts of D. tuberculatus (MED). MED contained gallic acid, caffeic acid, ellagic acid, and naringenin in high concentrations. The proliferation activity, focal cell adhesion ability, adhesion receptors-mediated signaling pathway in NHDF cells were increased by MED. Also, a dense adhered tissue layer and adherent cells on MED-coated titanium plate (MEDTiP) surfaces were detected during regeneration of calvarial bone. The results of the present study provide novel evidence that MED may stimulate focal cell adhesion in NHDF cells and a calvarial defect rat model.

Promoting Effects of Titanium Implants Coated with Dipterocarpus tuberculatus Extract on Osseointegration.

Titanium (Ti) is the most commonly used biomaterial for dental implants. When inserting Ti implants into jawbones, the main issue is the lack of strong bonding between the Ti implant and the host bone (osseointegration). Inspired by the outstanding adhesion performance of natural phenolic compounds on metal substrates and promoting effect for cell adhesion, we coated a natural plant extract, Dipterocarpus tuberculatus (MED), on Ti implants. We tested three groups of Ti plates and screw-shaped fixtures: nontreated Ti as commercially produced, ozone-treated Ti as commonly used surface modification for dental implants, and MED-coated Ti. Interestingly, the MED coating on the Ti plate preserved the surface wetting property for 20 days, whereas the hydrophilic wetting of ozone-treated Ti was readily transformed to hydrophobic within a day. Computerized tomography and histopathological analysis revealed that MED coating enhanced new bone tissue formation and regeneration. The gene expression level of integrin as a bone cell adhesion receptor and its downstream key regulators was significantly increased than that of ozone-treated Ti. Therefore, we suggest considering MED-mediated cell signaling pathways in screening natural products for cell adhesion and osseointegration, and MED as a suitable coating agent for improving Ti implantation.

Therapeutic Effects of Dipterocarpus tuberculatus with High Antioxidative Activity Against UV-Induced Photoaging of NHDF Cells and Nude Mice.

To investigate the therapeutic effects of methanol extracts of Dipterocarpus tuberculatus Roxb. (MED) against UV-induced photoaging, we assessed for alterations in the antioxidant activity, anti-apoptotic effects, ECM modulation, skin appearances, and anti-inflammatory response in normal human dermal fibroblast (NHDF) cells and nude mice orally treated with MED. High levels of tannin content and high free radical scavenging activity to DPPH were determined in MED, while seven active components, namely, gallic acid, bergenin, ellagic acid, ε-viniferin, asiatic acid, oleanolic acid, and 2α-hydroxyursolic acid, were identified using LC-MS analyses. UV-induced alterations in the NO concentration, SOD activity, and Nrf2 expression were remarkably recovered in MED-treated NHDF cells. Moreover, the decreased number of apoptotic cells and G2/M phase arrest were observed in the UV + MED-treated groups. Similar recoveries were detected for ß-galactosidase, MMP-2/9 expression, and intracellular elastase activity. Furthermore, MED treatment induced suppression of the COX-2-induced iNOS mediated pathway, expression of inflammatory cytokines, and inflammasome activation in UV-radiated NHDF cells. The anti-photoaging effects observed in NHDF cells were subsequently evaluated and validated in UV + MED-treated nude mice through skin phenotypes and histopathological structure analyses. Taken together, these results indicate that MED exerts therapeutic effects against UV-induced photoaging and has the potential for future development as a treatment for photoaging.