Vivien Yi Mian Jong

A new chromanone acid from the stem bark of Calophyllum teysmannii

A new chromanone acid, namely caloteysmannic acid (1), along with three known compounds, calolongic acid (2), isocalolongic acid (3) and stigmasterol (4) were isolated from the stem bark of Calophyllum teysmannii. All these compounds were evaluated for their cytotoxic and antioxidant activities in the MTT and DPPH assays, respectively. The structure of compound 1 was determined by means of spectroscopic methods including 1D and 2D NMR experiments as well as HR-EIMS spectrometry. The stereochemical assignment of compound 1 was done based on the NMR results and X-ray crystallographic analysis. The preliminary assay results revealed that all the test compounds displayed potent inhibitory activity against HeLa cancer cell line, in particular with compound 1 which exhibited the highest cytotoxic activity comparable to the positive control used, cisplatin. However, no significant antioxidant activity was observed for all the test compounds in the DPPH radical scavenging capacity assay.

A new xanthone from Garcinia nitida

A detailed chemical study on the stem bark of Garcinia nitida has led to the isolation of five xanthones. They are 1,6-dihydroxy-5-methoxy-6,6-dimethylpyrano[2′,3′:2,3]-xanthone (1), inophyllin B (2), osajaxanthone (3), 3-isomangostin (4) and rubraxanthone (5). The structures of these compounds were established using mainly 1-D and 2-D NMR spectroscopy (1H, 13C, DEPT, COSY, HMBC and HMQC) while molecular masses were determined via MS techniques; 1 is a new compound.

A new coumarin from stem bark of Mesua hexapetala

Abstract A new alkylated coumarin derivative, hexapetarin (1) along with three other xanthones, trapezifolixanthone (2), cudraxanthone G (3) and 1,3,7-trihydroxy-2,4-di (3-methyl-2-butenyl)xanthone (4), and four common triterpenoids, friedelin (5), stigmasterol (6), beta-sitosterol (7) and gamma-sitosterol (8) were isolated from the stem bark of Mesua hexapetala (Clusiaceae), a plant, native to Malaysia. The structures of these compounds were elucidated and determined using spectroscopic techniques such as NMR and MS. Anti-inflammatory activity assay indicated hexapetarin (1) to possess moderate anti-inflammatory activity, while 1,3,7-trihydroxy-2,4-di (3-methyl-2-butenyl)xanthone (4) gave very good activity. A new alkylated coumarin derivative, hexapetarin (1) along with three other xanthones, trapezifolixanthone (2), cudraxanthone G (3) and 1,3,7-trihydroxy-2,4-di (3-methyl-2-butenyl)xanthone (4) were isolated from the stem bark of Mesua hexapetala (Clusiaceae). The structures of these compounds were elucidated and determined using spectroscopic techniques such as NMR and MS.

The pyranoxanthone inophyllin A induces oxidative stress mediated-apoptosis in Jurkat T lymphoblastic leukemia cells☆

Inophyllin A (INO-A), a pyranoxanthone isolated from the roots of Calophyllum inophyllum represents a new xanthone with potential chemotherapeutic activity. In this study, the molecular mechanism of INO-A-induced cell death was investigated in Jurkat T lymphoblastic leukemia cells. Assessment of phosphatidylserine exposure confirmed apoptosis as the primary mode of cell death in INO-A-treated Jurkat cells. INO-A treatment for only 30 min resulted in a significant increase of tail moment which suggests that DNA damage is an early apoptotic signal. Further flow cytometric assessment of the superoxide anion level confirmed that INO-A induced DNA damage was mediated with a concomitant generation of reactive oxygen species (ROS). Investigation on the thiols revealed an early decrease of free thiols in 30 min after 50 μM INO-A treatment. Using tetramethylrhodamine ethyl ester, a potentiometric dye, the loss of mitochondrial membrane potential (MPP) was observed in INO-A-treated cells as early as 30 min. The INO-A-induced apoptosis progressed with the simultaneous activation of caspases-2 and -9 which then led to the processing of caspase-3. Taken together, these data demonstrate that INO-A induced early oxidative stress, DNA damage and loss of MMP which subsequently led to the activation of an intrinsic pathway of apoptosis in Jurkat cells.

A new pyranoxanthone from Garcinia nervosa

Abstract Phytochemical studies on the stem bark of Garcinia nervosa has resulted in the discovery of one new pyranoxanthone derivative, garner xanthone (1) and five other compounds, 1,5-dihydroxyxanthone (2), 6-deoxyisojacareubin (3), 12b-hydroxy-des-D-garcigerrin A (4) stigmasterol (5), and β-sitosterol (6). The structures of these compounds were elucidated with the aid of spectroscopic techniques, such as NMR and MS. The crude extracts of the plant were assessed for their antimicrobial activity.

A new coumarin from stem bark of Calophyllum wallichianum

Abstract A phytochemical study carried out on the plant, Calophyllum wallichianum has led to the isolation of a new coumarin, wallimarin T (1) and a known coumarin, calanolide E (2) along with two common triterpenes, friedelin (3) and stigmasterol (4). The structures of these compounds were elucidated with the aid of spectroscopic analyses such as FT-IR, GC-MS, and NMR. MIC assay against the Bacillus bacteria were conducted on the extracts and this gave MIC values ranging from 0.313 to 1.25 mg/mL. Compound 2 was weakly inhibitory towards the Bacilli strains with MIC values ranging from 0.25–0.50 mg/mL. Wallimarin T (1) was not active towards all four bacteria. Overall, the extracts exhibited weak bactericidal properties whereas compound 2 was not bactericidal on the tested bacteria. The hexane and chloroform extracts of the plant were found to be inhibitors to the growth of Bacillus megaterium, Bacillus cereus, Bacillus pumilus and Bacillus subtilis.

Anti-obesity effect of phenylcoumarins from two Calophyllum spp in 3T3-L1 adipocytes

Purpose : To evaluate the anti-obesity effects of five compounds isolated from Calophyllum andersonnii and Calophyllum sclerophyllum, viz, friedelin (CP1), friedelinol (CP2), isodispar B (CP3), 5,7-dihydroxy-6-(3-methybutyryl)-4-phenylcoumarin (CP4) and 5,7-dihydroxy-6-(2-methybutyryl)-4-phenylcoumarin (CP5) in 3T3-L1 mouse pre-adipocytes. Methods: Maximum non-toxic doses (MNTDs) of CP1 - CP5 were obtained by conducting 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Intracellular lipid droplet accumulation was determined by Oil Red O (ORO) staining. The effects of CP1 - 5 on the expression of adipogenesis transcriptional factors, namely, C/ebpα, Pparγ1, aP2 and on cellular glucose uptake and adipokine (adiponectin, leptin, resistin) secretion were assessed by commercial colorimetric and ELISA kits, respectively. Results : MNTDs for CP1-CP5 were 3.0, 1.4, 1.0, 29.0 and 25.0 μM, respectively. 3T3-L1 cells treated with CP1 - CP3 showed increased lipid accumulation (p < 0.05) and decreased glucose uptake (p < 0.05), compared with untreated cells; cells treated with CP4 and CP5 had opposite effects. Cells treated with CP4 and CP5 also showed downregulated Pparγ1, C/ebpα and aP2 expression (p < 0.05), compared with untreated cells. The anti-adipogenic property exerted by CP4 and CP5 manifested as increased secretion of adiponectin as well as reduced leptin and resistin levels. Conclusion : CP4 and CP5 isolated from Calophyllum sclerophyllum show promising anti-obesity properties, and could serve as candidate hits for further investigation at in vivo level to provide additional mechanistic evidence. Keywords : Phenylcoumarin, Calophyllum, Adipogenesis, Adipocyte, Adipokine, Obesity

Effect of Solvents on Phytochemical Concentrations and Antioxidant Activity of Garcinia benthamiana Stem Bark Extracts

ABSTRACT The effect of solvents of various polarities (hexane, chloroform, ethyl acetate, and methanol) on phytochemical concentrations and antioxidant activities of stem bark of Garcinia benthamiana were examined. A medium polar solvent, ethyl acetate, was the most efficient in extracting the phenolic components from G. benthamiana, followed by methanol. The ethyl acetate extract had high total phenolic concentrations and scavenging activity against 2,2-diphenyl-1-picylhydrazyl (DPPH) free radicals. Both the ethyl acetate and methanol extracts had strong reducing power and moderate ferrous ion chelating ability and inhibition of β-carotene bleaching.