Indonesian medicinal plants. XXI. Inhibitors of Na+/H+ exchanger from the bark of Erythrina variegata and the roots of Maclura cochinchinensis

Phytochemistry and Pharmacology of Medicinal Plants Used by the Tenggerese Society in Java Island of Indonesia

The archipelagic country of Indonesia is inhabited by 300 ethnic groups, including the indigenous people of Tengger. Based on the reported list of medicinal plants used by the Tengger community, we have reviewed each of them for their phytochemical constituents and pharmacological activities. Out of a total of 41 medicinal plants used by the Tengerrese people, 33 species were studied for their phytochemical and pharmacological properties. More than 554 phytochemicals with diverse molecular structures belonging to different chemical classes including flavonoids, terpenoids, saponins and volatiles were identified from these studied 34 medicinal plants. Many of these medicinal plants and their compounds have been tested for various pharmacological activities including anti-inflammatory, antimicrobial, wound healing, headache, antimalarial and hypertension. Five popularly used medicinal plants by the healers were Garcinia mangostana, Apium graveolens, Cayratia clematidea, Drymocallis arguta and Elaeocarpus longifolius. Only A. graviolens were previously studied, with the outcomes supporting the pharmacological claims to treat hypertension. Few unexplored medicinal plants are Physalis lagascae, Piper amplum, Rosa tomentosa and Tagetes tenuifolia, and they present great potential for biodiscovery and drug lead identification.

Xanthones from the stems of Calophyllum membranaceum Gardn. et Champ. and their anti-inflammatory activity

Eighteen undescribed xanthones, including six pairs of xanthone enantiomers, three xanthones, and three xanthone glycosides, together with one pair of known xanthone enantiomers and 12 known xanthones, were isolated from the stems of Calophyllum membranaceum Gardn. et Champ. Their structures were elucidated by spectroscopic analysis, and the absolute configuration of the enantiomers was determined by using experimental and calculated electronic circular dichroism data. All compounds were screened for their anti-inflammatory effects on LPS-induced BV-2 microglial cells. Among them, six compounds showed remarkable activities with IC₅₀ values of 7.8-36.0 μM.

Macluracochinones A-E, antimicrobial flavonoids from Maclura cochinchinensis (Lour.) Corner

The phytochemical investigation of the fruit and leaf extracts of Maclura cochinchinensis (Lour.) Corner (Moraceae) resulted in the isolation and identification of four undescribed isoflavones (macluracochinones A-D) and one undescribed flavone (macluracochinone E), together with 24 known compounds. The structures of the undescribed compounds were elucidated using nuclear magnetic resonance (NMR) and high-resolution electrospray ionization time-of-flight mass spectrometry (HRESITOFMS) experiments. Gancaonin M, lupiwighteone, lupalbigenin, warangalone, auriculatin, and millexatin F displayed good antibacterial activities against Gram-positive bacteria with MIC values in the range of 1-8 μg/mL. Lupalbigenin showed strong activities against methicillin-resistant Staphylococcus aureus (MRSA) and S. aureus with the same MIC value of 1 μg/mL.

Structure Characterization and Biological Activity of 2-Arylbenzofurans from an Indonesian Plant, Sesbania grandiflora (L.) Pers

A new 2-arylbenzofuran, sesbagrandiflorain C (1), together with four known compounds, 2-(3,4-dihydroxy-2-methoxyphenyl)-4-hydroxy-6-methoxybenzofuran-3-carbaldehyde (2), 2-(4-hydroxy-2-methoxyphenyl)-5,6-dimethoxybenzofuran-3-carboxaldehyde (3), sesbagrandiflorain A (4) and sesbagrandiflorain B (5), have been isolated from the stem bark of an Indonesian plant, Sesbania grandiflora (L.) Pers. The chemical structure of compound 1 was elucidated by UV, IR, MS, and NMR spectroscopic techniques. The proton and carbon NMR resonances of 1 were also compared with the predicted chemical shifts obtained from DFT quantum mechanical calculations with Gaussian. None of the compounds showed antibacterial activity against Bacillus subtilis, Escherichia coli, Mycobacterium smegmatis, Pseudomonas aeruginosa, and Staphylococcus aureus in an agar diffusion assay. However, sesbagrandiflorains A (4) and B (5) exhibited moderate activity against Mycobacterium tuberculosis H37Rv. In addition, compounds 1 - 5 have moderate cytotoxicity against HeLa, HepG2, and MCF-7 cancer cell lines.

From plant selection by elephants to human and veterinary pharmacopeia of mahouts in Laos

ETHNOPHARMACOLOGICAL RELEVANCE

To what extent has animal observation contributed to the development of human pharmacopeias? We approach this question here through the study of mahouts' knowledge regarding the responses by elephants to their health problems, and the human medicinal uses of plants and the care of domestic animals that result from their observations.

MATERIALS AND METHODS

32 mahouts were interviewed in Thongmyxay district and 28 at the Elephant Conservation Center in the province of Xayabury. Interviews focused on the elephants' diet, health problems, plant items they consume in particular physiological or pathological contexts and the treatments that mahouts provide them. For each plant mentioned, the part of the plant consumed and mode of preparation and administration if used by mahouts were recorded. Species samples were then collected and later identified by specialists.

RESULTS

114 species were recorded as being consumed by elephants during interviews with mahouts and forest outings with them to collect samples. Twenty species were identified as used by elephants in particular pathological conditions or physiological states. According to interviewed mahouts, the consumption of certain plants improves the health of the elephant. We observed clear convergences between the observations interpreted by the mahouts as self-medication behaviour from elephants and their own medicinal practices (for human and veterinary purposes).

CONCLUSION

Beyond a mere reproduction of elephant self-medication behaviours observed, the human or veterinary medicinal cares derived from these observations are the result of complex arrangements integrating all available medicinal and conceptual resources into elaborate preparations. We recommend that mahouts' knowledge about traditional medicinal care given to elephants be further compiled, as it could have a beneficial impact on veterinary health care provided in elephant resorts and elephants' well-being.

Two new xanthones and cytotoxicity from the bark of Garcinia schomburgkiana

Two new xanthone derivatives, named schomburgones A (1) and B (2), along with eight known compounds, including xanthones (3–8) and anthraquinones (9–10) were isolated from the bark of Garcinia schomburgkiana. Their structures were determined by spectroscopic analysis especially 1D and 2D NMR spectroscopies. All isolated compounds were evaluated for their cytotoxicity against five cancer cell lines (KB, HeLa S-3, HT-29, MCF-7 and HepG-2). Compounds 3–6 and 8 showed good cytotoxicity against all the five cancer cell lines with IC₅₀ values in the range of 1.45–9.46 µM.

Prenylated Xanthones from the Roots of Cudrania tricuspidata as Inhibitors of Lipopolysaccharide-Stimulated Nitric Oxide Production

Investigation of the CH₂ Cl₂ and EtOAc-soluble fractions of the roots of Cudrania tricuspidata afforded 31 compounds. The structures of the isolated compounds were determined on the basis of spectroscopic data interpretation such as 1D and 2D NMR analysis and elucidated as xanthones with prenyl moieties including four simple xanthones (1-4), five prenylated xanthones with one prenyl moiety (5-7, 20, and 21), and 22 prenylated xanthones with two prenyl moieties (8-19 and 22-31). Among them, three diprenylated xanthones named cudracuspixanthones E-G (16, 29, and 31) were first isolated in nature. Xanthones 2, 5, 6, 12, 19, 21, 22, 25, 27, and 28 showed moderate inhibition of lipopolysaccharide-stimulated nitric oxide production in RAW 264.7 cells, with IC₅₀ values ranging from 16.1 to 24.8 µM.

Antiproliferative prenylated xanthones and benzophenones from the roots of Cudrania tricuspidata in HSC-T6 cells

Four new prenylated xanthones, cudracuspixanthones A-D (1-4), two new prenylated benzophenones, cudracuspiphenones A (5) and B (6), and 11 known xanthones (7-17) were isolated from the roots of Cudrania tricuspidata. The absolute configurations of compounds 2-4 were deduced by the comparison of the calculated optical rotation values with the measured data. Compounds 1, 5, and 6 showed moderate antiproliferative activity on HSC-T6 cells with IC50 values of 9.7, 3.3, and 7.1 μM, respectively. Compounds 2-4, 10, and 14-16 had weaker activity. Flow cytometric analysis suggested that compounds 1 and 5 inhibited HSC-T6 cell proliferation in part by inducing apoptosis.

A new auronol from Cudrania cochinchinensis

A new auronol, cudrauronol (1), was isolated from the roots of Cudrania cochinchinensis along with 10 known compounds, 1,3,5-trihydroxy-4-prenylxanthone (2), 1,3,7-trihydroxy-4-prenylxanthone (3), 3,4',5,7-tetrahydroxydihydroflavonol (4), kaempferol (5), 3,6-dihydroxy-1,5-dimethoxyxanthone (6), 2',4',5,7-tetrahydroxyflavanolol (7), 3,7-dihydroxy-1-methoxyxanthone (8), 1,3,5-trihydroxyxanthone (9), cudraflavone B (10), and 2'-oxyresveratrol (11). Compounds 1-8 were evaluated for anti-inflammatory activity on lipopolysaccharide-induced nitric oxide production in RAW 264.7 macrophages. Compounds 2-5 were more active than aminoguanidine, with IC(50) values of 8.8, 23.2, 27.1, and 11.9 μM, respectively.

Xanthone and benzophenone glycosides from the stems of Cratoxylum formosum ssp. pruniflorum

Two new xanthone glycosides, namely pruniflorosides A and B (1, 2), a new benzophenone glycoside, prunifloroside C (3), and a new xanthone, pruniflorone S (4) were isolated from the stems of Cratoxylum formosum ssp. pruniflorum, along with six known xanthones (5-10). Their structures were determined on the basis of extensive spectroscopic analysis. In addition, their retinoid X receptor α (RXRα) transcriptional activities were evaluated in vitro.

1,3,5-trihydroxy-4-prenylxanthone represses lipopolysaccharide-induced iNOS expression via impeding posttranslational modification of IRAK-1

Both high level of nitric oxide (NO) and its generating enzyme, inducible NO synthase (iNOS), play important roles in pathophysiological conditions such as inflammatory processes. We previously found that 1,3,5-trihydroxy-4-prenylxanthone (TH-4-PX) isolated from Cudrania cochinchinensis repressed lipopolysaccharide (LPS)-induced NO production in RAW264.7 macrophages. Here we further examined the underlying mechanisms using RT-PCR and Western blot analyses. Consistent with NO inhibition, suppression of LPS-induced iNOS expression by TH-4-PX through abolishing IκB kinase (IKK) phosphorylation, IκB degradation and nuclear factor-κB (NF-κB) nuclear translocation was observed. After LPS stimulation, the increased nuclear level of c-Fos and c-Jun (major components of activator protein-1, AP-1) and the phosphorylated level of upstream signal molecules, such as c-Jun NH2-terminal kinase (JNK) and extracellular signal-regulated kinase, (ERK) were all significantly suppressed by TH-4-PX, while p38 remained unaffected. A further experiment revealed that TH-4-PX inhibited the phosphorylation of transforming growth factor-β (TGF-β)-activated kinase 1 (TAK1), an upstream signaling molecule required for IKK and mitogen-activated protein kinases (MAPKs) activation. Stimulation with LPS also triggered the modification (phosphorylation and ubiquitination) and eventually the proteasomal degradation of membrane-associated interleukin (IL)-1 receptor-associated serine/threonine kinase 1 (IRAK-1), an essential signaling component to toll-like receptor (TLR)-mediated TAK-1 activation. Interestingly, the modified pattern of IRAK-1 in the presence LPS was significantly attenuated by TH-4-PX treatment. In conclusion, TH-4-PX inhibited LPS-induced NF-κB and AP-1 activations by interfering with the posttranslational modification (phosphorylation and/or ubiquitinylation) of IRAK-1 in the cell membrane to impede TAK1-mediated activation of IKK and MAPKs signal transduction.

Hypericum species in the Páramos of Central and South America: a special focus upon H. irazuense Kuntze ex N. Robson

Knowledge about members of the flowering plant family Clusiaceae occurring in the tropical mountain regions of the world is limited, in part due to endemism and restricted distributions. High altitude vegetation habitats (Páramos) in Central and South America are home to numerous native Hypericum species. Information related to the phytochemistry of páramo Hypericum, as well as ecological factors with the potential to influence chemical defenses in these plants, is briefly reviewed. Results of the phytochemical analysis of Hypericum irazuense, a species collected in the páramo of the Cordillera de Talamanca in Costa Rica, are presented. Lastly, guidelines for the viable and sustainable collections of plant material, to facilitate future investigations of these interesting plants, are given.

Four New Isoflavonoids from the Stem Bark of Erythrina variegata

Bioassay-directed fractionation of the stem bark extract of Erythrina variegata L. has resulted in the isolation of three new isoflavones: 5,4'-dihydroxy-8-(3,3-dimethylallyl)-2''-methoxyisopropylfurano[4,5:6,7]isoflavone (1), 5,7,4'-trihydroxy-6-(3,3-dimethylallyloxiranylmethyl)isoflavone (2), 5,4'-dihydroxy-8-(3,3-dimethylallyl)-2''-hydroxymethyl-2''-methylpyrano[5,6:6,7]isoflavone (3) and a new isoflavanone, 5,4'-dihydroxy-2'-methoxy-8-(3,3-dimethylallyl)-2'',2''-dimethylpyrano[5,6:6,7]isoflavanone (4) together with seven known compounds, euchrenone b10 (5), isoerysenegalensein E (6), wighteone (7), laburnetin (8), lupiwighteone (9), erythrodiol (10), and oleanolic acid (11). The structures were determined on the basis of spectroscopic analyses and chemical evidence. The effect of these compounds on the proliferation of rat osteogenic sarcoma (UMR106) is also reported.

Anti-nociceptive activity of the aqueous extract of Erythrina velutina leaves

Anti-nociceptive and anti-oedematogenic effects of the aqueous extract from the leaves of Erythrina velutina were tested through experimental models of nociception in mice and paw oedema induced by carrageenin in rats. The extract (300 and 600 mg/kg) did not change the carrageenin-induced paw oedema. In the hot plate test the extract also did not alter the latency time for mice liking the rear paws. Moreover, the extract (600 mg/kg) decreased by 96.5% the paw liking time in the second phase of the formalin test. This effect was antagonized by naloxone (5 mg/kg). In the acetic acid-induced writhing test, the extract (300 and 600 mg/kg) reduced the number of writhing by 88.8% and 96.4%, respectively. Our present results demonstrated that the crude extract from the leaves of E. velutina has anti-nociceptive but not anti-oedematogenic properties.

Antioxidant and cytotoxic activities of xanthones from Cudrania tricuspidata

The new catecholic xanthone, 1,3,7-trihydroxy-4-(1,1-dimethyl-2-propenyl)-5,6-(2,2-dimethylchromeno)-xanthone (1), was isolated from the root bark of Cudrania tricuspidata together with seven known xanthones. The structures were fully characterized by analysis of physical and spectral (UV, IR, mass, and NMR) data. Relationships between the structural characteristics of xanthones and their antioxidant activities (DPPH, superoxide, and hydroxyl radical) were studied. Among the range of catecholic xanthones, 6,7-dihydroxyl xanthones (3-8) exhibited a strong scavenging effect on the DPPH radical. When one of the catecholic hydroxyl groups was protected as in compounds 1 and 2, DPPH radical scavenging activity was markedly decreased (IC(50)>200microM). DPPH activities were consistent with electrochemical response by cyclic voltammetry. Interestingly, compounds (1, 2) which had the weak activities on DPPH, exhibited both potent superoxide and hydroxyl radical scavenging activities. The strong activity on the hydroxyl radical of compounds (1, 2) could be rationalized by their chelating effect with iron (Fe(2+)) due to a redshift of its complex. The catecholic xanthones (3-8), being able to convert quinone methide intermediate, showed potent cytotoxicities against human cancer cell lines (HT-29, HL-60, SK-OV3, AGS, and A549). In particular, compounds 3, 6, and 7 had strong cytotoxic activities against AGS (LD(50)<5microM). DNA fragmentation patterns induced by catecholic xanthones revealed that tumor cell death was due to apoptosis.

Antimalarial xanthones from Calophyllum caledonicum and Garcinia vieillardii

The antimalarial activity of 22 xanthones against chloroquino-resistant strains of Plasmodium falciparum was evaluated. Natural caloxanthone C (1), demethylcalabaxanthone (2), calothwaitesixanthone (3), calozeyloxanthone (4), dombakinaxanthone (5), macluraxanthone (6), and 6-deoxy-gamma-mangostin (7) were isolated from Calophyllum caledonicum. 1,6-dihydroxyxanthone (8), pancixanthone A (9), isocudraniaxanthone B (10), isocudraniaxanthone A (11), 2-deprenylrheediaxanthone B (12) and 1,4,5-trihydroxyxanthone (13) were isolated from Garcinia vieillardii. Moreover, synthetic compounds (14-22) are analogues or intermediates of xanthones purified from Calophyllum caledonicum (Oger J.M., Morel C., Helesbeux J.J., Litaudon M., Seraphin D., Dartiguelongue C., Larcher G., Richomme P., Duval O. 2003. First 2-Hydroxy-3-Methylbut-3-Enyl substituted xanthones isolated from Plants: structure elucidation, synthesis and antifungal activity. Natural Product Research 17(3), 195-199; Helesbeux J.J., Duval O., Dartiguelongue C., Seraphin D., Oger J.M., Richomme P., 2004. Synthesis of 2-hydroxy-3-methylbut-3-enyl substituted coumarins and xanthones as natural products. Application of the Schenck ene reaction of singlet oxygen with ortho-prenylphenol precursors. Tetrahedron 60(10), 2293-2300). The relationship between antimalarial activity and molecular structure of xanthones has also been explored. The most potent xanthones (2), (3) and (7) (IC50 = c.a. 1.0 microg/mL) are 1,3,7 trioxygenated and prenylated on the positions 2 and 8.

Central nervous system effects of the crude extract of Erythrina velutina on rodents

The aqueous extract (AE) of Erythrina velutina prolonged the sleep duration induced by sodium pentobarbital (control: 6.4 +/- 1.2 min; extract 10 mg/kg, 47.1 +/- 3.9 min; extract 100 mg/kg, 109.4 +/- 7.2 min; F = 243, P < 0.001). In the open field, the extract at the doses of 10 and 50 mg/kg did not changed the number of crossings, rearings nor groomings. On the other hand, at the dose of 200 mg/kg it reduced the number of crossings (q = 6.25, P < 0.05) and groomings (q = 3.91, P < 0.05). When exposed during three consecutive days to the open field, the control animals showed habituation for crossings (F = 17.56, P < 0.001) and rearings (F = 14.01, P < 0.001). The same was not true for animals treated with 10 mg/kg of the extract (crossings: F = 3.59, P > 0.05; rearings: F = 3.62, P > 0.05). At the same dose, the extract blocked the acquisition of foot shock memory (P = 0.9219) when compared to the control values (P = 0.0078). Our data showed that the crude extract of Erythrina velutina at lower doses interferes with mnemonic process for different tasks, while at higher doses, the sedative and neuromuscular blocking actions are the main effects.

Eryvarins F and G, two 3-phenoxychromones from the roots of Erythrina variegata

Two 3-phenoxychromones, eryvarins F and G, were isolated from the roots of Erythrina variegata. Their structures were established to be 3-(2,4-dihydroxyphenoxy)-7-hydroxy-6,8-di(3,3-dimethylallyl)chromen-4-one and 3-(2,4-dihydroxyphenoxy)-8-(3,3-dimethylallyl)-2,2-dimethylpyrano[5,6:6,7]chromen-4-one on the basis of spectroscopic and chemical evidence. Eryvarins F and G are unusual 3-phenoxychromone derivatives with two isoprenoid groups.

Antibacterial activity of isoflavonoids isolated from Erythrina variegata against methicillin-resistant Staphylococcus aureus

AIMS

To screen 16 isoflavonoids isolated from Erythrina variegata (Leguminosae) for their antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA).

METHODS AND RESULTS

The roots of E. variegata were macerated with acetone. The chloroform-soluble fraction of the residue was subjected to repeated silica gel column chromatography followed by elution with various solvents. Structures of the isolated compounds were determined by extensive spectroscopic studies. Each compound was dissolved in dimethyl sulphoxide and added to agar plates (final concentration 1.56-100 microg ml(-1) and suspensions of MRSA spotted onto the agar plates to determine the minimum inhibitory concentration (MIC). Repeated silica gel chromatography yielded 16 compounds and spectroscopic studies revealed that all were isoflavonoids. Whilst 14 compounds showed antibacterial activity in this concentration range, the MIC values varied significantly among them. Of the active compounds, 3,9-dihydroxy-2,10-di(gamma,gamma-dimethylallyl)-6a,11a-dehydropterocarpan (erycristagallin) and 9-hydroxy-3-methoxy-2-gamma,gamma-dimethylallylpterocarpan (orientanol B) exhibited the highest activity with MIC values of 3.13-6.25 microg ml(-1).

CONCLUSIONS

Erycristagallin and orientanol B showed the highest anti-MRSA activity (3.13-6.25 microg ml(-1).

SIGNIFICANCE AND IMPACT OF THE STUDY

Erycristagallin and orientanol B could be leading compounds for phytotherapeutic agents against MRSA infections.

Theoretical Studies on the Configuration of a Chalcanol Derivative

The relative configuration of a naturally occurring monobenzoylated diol was assigned to erythro by comparing the weighted average of calculated 1H NMR coupling constants with the experimental values.

Anti-herpes simplex virus component isolated from Maclura cochinchinensis

The powerful anti-herpes simplex virus (HSV) activity of Maclura cochinchinensis in vitro prompted us to carry out biologically-guided separation of the active component(s). Ethyl acetate and methanol extracts exhibited anti-HSV-2 activity at EC50 values of 38.5 micrograms/ml and 50.8 micrograms/ml, respectively. Although petroleum ether extract was inactive, a chloroform extract was too toxic to the test cell culture to perform the test. Biologically-guided chromatographic separation of the ethyl acetate extract yielded compound A, identified as morin using a spectroscopic method. Morin exhibited anti-HSV-2 activity at an EC50 value of 53.5 micrograms/ml. Morin pentaacetate was synthetized, but was inactive. This result suggested that free hydroxyl groups are required for anti-HSV-activity, as demonstrated previously for the antiviral activity of other flavonoids.