Caffeic acid phenethyl ester (CAPE) analogues: potent nitric oxide inhibitors from the Netherlands propolis

The MeOH and water extracts of the Netherlands propolis were tested for their inhibitory activity toward nitric oxide (NO) production in lipopolysaccharide (LPS)-activated murine macrophage-like J774.1 cells. Both of the extract possessed significant NO inhibitory activity with IC(50) values of 23.8 and 51.5 microg/ml, respectively. Then 13 phenolic compounds obtained from the MeOH extract showing stronger NO inhibition were examined on their NO inhibitory activities. Caffeic acid phenethyl ester (CAPE) analogues, i.e., benzyl caffeate, CAPE and cinnamyl caffeate, possessed most potent NO inhibitory activities with IC(50) values of 13.8, 7.64 and 9.53 microM, respectively, which were two- to four-fold stronger than the positive control N(G)-monomethyl-L-arginine (L-NMMA; IC(50), 32.9 microM). Further study on the synthetic analogues of CAPE revealed that both of 3-phenylpropyl caffeate (18; IC(50), 7.34 microM) and 4-phenylbutyl caffeate (19; IC(50), 6.77 microM) possessed stronger NO inhibitory activity than CAPE (10) and that elongation of alkyl side chain of alcoholic parts of caffeic acid esters enhance the NO inhibitory activity. In addition, it was found that CAPE analogues having longer carbon chain (>C(5)) in alcoholic part showed toxic effects toward J774.1 cells. This NO inhibitory effect may directly correlate with antiinflammatory properties of the Netherlands propolis.

Inhibition of NO production by highly-oxygenated diterpenes of Orthosiphon stamineus and their structure-activity relationship

Nitric oxide (NO) has been implemented in various pathological processes. In the present study, 47 highly-oxygenated isopimarane-type and novel carbon framework staminane-type diterpenes isolated from Orthosiphon stamineus of Indonesia, Okinawa, Myanmar and Vietnam were evaluated for their inhibitory activity in NO production by lipopolysaccharide (LPS)-activated macrophage-like J774.1 cells. All the isolated diterpenes showed concentration-dependent inhibition of NO production in LPS-activated macrophage-like J774.1 cells, and based on the results, their structure-activity relationship were established.

Highly-oxygenated isopimarane-type diterpenes from Orthosiphon stamineus of Indonesia and their nitric oxide inhibitory activity

From the methanolic extract of Indonesian Orthosiphon stamineus, nine new highly-oxygenated isopimarane-type diterpenes [7-O-deacetylorthosiphol B (1), 6-hydroxyorthosiphol B (2), 3-O-deacetylorthosiphol I (3), 2-O-deacetylorthosiphol J (4), siphonols A-E (5-9)] have been isolated together with nine known diterpenes [orthosiphols H (10), K (11), M (12) and N (13); staminols A (14) and B (15); neoorthosiphols A (16) and B (17); norstaminol A (18)]. Their structures were determined based on the spectroscopic data. The isolated diterpenes inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)-activated macrophage-like J774.1 cells. Compounds 4-7, 9, 10, 14, and 17 showed inhibitory activities more potent (IC(50), 10.8-25.5 microM) than a positive control N(G)-monomethyl-L-arginine (L-NMMA; IC(50), 26.0 microM).

Nitric oxide inhibitory isopimarane-type diterpenes from Orthosiphon stamineus of Indonesia

A methanolic extract of Orthosiphon stamineus yielded six new highly oxygenated isopimarane-type diterpenes, orthosiphols U-Z (1-6), and 15 previously reported diterpenes. The isolated diterpenes all showed significant dose-dependent inhibitory effects on the nitric oxide (NO) production in lipopolysaccharide (LPS)-activated macrophage-like J774.1 cells. Orthosiphols A (7), B (8), D (9), and X (4) showed more potent inhibitory activities than a positive control, N(G)-monomethyl-l-arginine (l-NMMA), and 1 displayed the strongest activity with an IC(50) value of 6.4 microM.

Siphonols A-E: novel nitric oxide inhibitors from Orthosiphon stamineus of Indonesia

From the methanolic extract of Orthosiphon stamineus, four novel highly oxygenated isopimarane-type diterpenes named siphonols A-D (1-4) and a novel biogenetically interesting norisopimarane-type diterpene named siphonol E (5) were isolated. The new compounds 1-3 and 5 showed more potent inhibitory effects on the nitric oxide (NO) production in lipopolysaccharide (LPS)-activated macrophage-like J774.1 cells than a positive control N(G)-monomethyl-L-arginine (L-NMMA). Siphonols A-E (1-5) represent the first examples of isopimaranes oxygenated at C-20.

Three new C-14 oxygenated taxanes from the wood of Taxus yunnanensis

Three new C-14 oxygenated taxane-type diterpenes, hongdoushans A-C (1-3), were isolated from the wood of Taxus yunnanensis together with four known diterpenes and two lignans. The absolute stereochemistry of the 2-methylbutyryloxy group attached at C-14 of the taxane skeleton was determined to be S by GC analysis of the methyl ester of 2-methylbutyric acid obtained after alkaline hydrolysis of 1 and 4 followed by treatment with CH(2)N(2). The complete stereostructure of the known compound 2alpha,5alpha,10beta-triacetoxy-14beta-[(S)-2-methylbutyryloxy]-4(20),11-taxadiene (4) was established for the first time. The isolates obtained were evaluated for their antiproliferative activity toward murine colon 26-L5 carcinoma and human HT-1080 fibrosarcoma cell lines.

Selective antiproliferative activity of caffeic acid phenethyl ester analogues on highly liver-metastatic murine colon 26-L5 carcinoma cell line

Caffeic acid phenethyl ester (CAPE, 2) and its twenty analogues (1, 3-21) were prepared. These esters were tested by MTT assay on growth of murine colon 26-L5 carcinoma, murine B16-BL6 malonoma, murine Lewis lung carcinoma, human HT-1080 fibrosarcoma, human lung A549 adenocarcinoma, and human cervix HeLa adenocarcinoma cell lines. It was found that CAPE analogues possessed selective antiproliferative activity toward highly liver-metastatic murine colon 26-L5 carcinoma cell line. Among them, 4-phenylbutyl caffeate (4), (Z)-8-phenyl-7-octenyl (10a) and (E)-8-phenyl-7-octenyl (10b) caffeate showed the most potent antiproliferative activity (EC50 value, 0.02 microM). In addition, CAPE (2) induced DNA fragmentation at concentrations of 1 to 10 microg/mL towards murine colon 26-L5 carcinoma cells.

Constituents of Chinese propolis and their antiproliferative activities

Two new flavonoids, 3-O-[(S)-2-methylbutyroyl]pinobanksin (1) and 6-cinnamylchrysin (2), were isolated from the EtOAc-soluble fraction of the MeOH extract of Chinese propolis, along with 12 known compounds (3-14). The structures of the isolated compounds were elucidated on the basis of spectroscopic and chemical analyses. The isolated compounds were tested for their antiproliferative activity toward five different cancer cell lines. Benzyl caffeate (13) and phenethyl caffeate (14) showed potent antiproliferative activity toward tested cell lines with a selective activity toward colon 26-L5 carcinoma cell line (EC(50) values: 13, 1.01; 14, 0.30 microM).

Antiproliferative activity of the Netherlands propolis and its active principles in cancer cell lines

The MeOH extract of the Netherlands propolis showed promising antiproliferative activity toward highly liver-metastatic murine colon 26-L5 carcinoma with an EC(50) value of 3.5 microg/ml. Further, antiproliferative activity-guided purification of the MeOH extract led us to isolate four flavonoids (1-4), seven cinnamic acid derivatives (5-11) and two new glycerol derivatives (12, 13), whose structures were elucidated on the basis of spectral analysis. The isolated compounds were tested for their antiproliferative activity against murine colon 26-L5, murine B16-BL6 melanoma, human HT-1080 fibrosarcoma and human lung A549 adenocarcinoma cell lines. The benzyl (9), phenethyl (10) and cinnamyl caffeates (11) possessed potent antiproliferative activities with EC(50) values of 0.288, 1.76 and 0.114 microM, respectively, toward colon 26-L5 carcinoma. These caffeates were considered to be active constituents of the Netherlands propolis in their antiproliferative activity. The antioxidative activity of these caffeates may play an important role in their antiproliferative activities.

Four highly oxygenated isopimarane-type diterpenes of Orthosiphon stamineus

Four highly oxygenated isopimarane-type diterpenes, named orthosiphols O, P and Q and nororthosiphonolide A, have been isolated from the aerial parts of Orthosiphon stamineus from Myanmar, together with three known diterpenes, orthosiphols D and E and orthosiphonone A. Their structures were determined on the basis of extensive spectral analysis. All the isolated compounds displayed mild antiproliferative activities against highly liver metastatic colon 26-L5 carcinoma and human HT-1080 fibrosarcoma cell lines.

Liquid chromatography-mass spectrometry analysis of propolis

The composition of propolis, a resinous hive product collected by honeybees from various plant sources, depends on various factors such as season and vegetation of the area. Based on standards (either isolated from Brazilian propolis or reported from propolis) including chromane, diterpenes and phenolic compounds, different Brazilian propolis were analysed by LC-MS in order to determine their chemical constituents. Dicaffeoylquinic acids were detected in almost all water extracts of Brazilian propolis, whereas diterpenes, flavonoids and prenylated phenolic compounds were found in their methanol extracts. Based on the identified chemical constituents and their biological activities, it was determined that the quality of Brazilian propolis could be directly related to the phenolic constituents. Moreover, Baccharis dracunculifolia was concluded to be an important source of Brazilian propolis. Propolis samples from Peru, China and the Netherlands were also studied.

An antiproliferative norditerpene dilactone, Nagilactone C, from Podocarpus neriifolius

An ethanolic extract of Podocarpus neriifolius D. Don (Podocarpaceae) showed antiproliferative activity against two major tumor cell lines, viz. human HT-1080 fibrosarcoma and murine color 26-L5 carcinoma. Bioassay guided fractionation showed the highest antiproliferative activity in chloroform-soluble fraction. Nagilactone C, the major constituent of this fraction was isolated and characterized by using NMR, IR and FAB-MS spectroscopic methods. Nagilactone C possessed potent antiproliferative activity against human fibrosarcoma and murine colon carcinoma tumor cell lines exhibiting ED50 values of 2.3 and 1.2 microg/ml, respectively. Hence, nagilactone C could be the active constituent present in this plant.

Recent progress in pharmacological research of propolis

Propolis is a resinous hive product collected by honeybees from various plant sources. It is a popular folk medicine possessing a broad spectrum of biological activities. It has also been used as a health drink in various Asian, European and American countries. Several groups of researchers have focused their attention on the biological activity of propolis and its active principles. Many scientific articles are published every year in different international journals related to the pharmacological properties of propolis. This review article compiles recent findings (since 1995) on the pharmacological properties of propolis focusing on its antihepatotoxic, antitumour, antioxidative, antimicrobial and antiinflammatory properties. The possible mechanism of action of propolis as well as the active compounds are discussed.

Screening of Chinese herbal drug extracts for inhibitory activity on nitric oxide production and identification of an active compound of Zanthoxylum bungeanum

Sixty-eight water and methanol extracts from 34 Chinese herbal drugs, most of which are used for inflammatory diseases, were screened for their inhibitory effects on nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated J774.1 macrophages and in LPS/interferon (IFN)-gamma-stimulated mouse peritoneal exudate macrophages. Among the extracts, methanol extracts of Myristica fragrans, Plantago asiatica, Rubia cordifolia, and Zanthoxylum bungeanum showed significant inhibition in J774.1 macrophages, while in mouse peritoneal exudate macrophages, water extracts of Ru. cordifolia and Scutellaria baicalensis and methanol extracts of Angelica megaphylla, My. fragrans, and Z. bungeanum inhibited the NO production. Among them, inhibition of water extract of Sc. baicalensis was found to be mainly due to direct scavenging of NO radicals, through an examination of its scavenging activity on PAPA NONOate-generated NO radicals, while water extract of Ru. cordifolia and methanol extracts of An. megaphylla, My. fragrans, P. asiatica, and Z. bungeanum showed inhibition on iNOS mRNA expression. At last, an inhibitory compound on iNOS mRNA expression was isolated from a methanol extract of Z. bungeanum and identified as 4-O-beta-D-glucopyranosyldihydroferulic acid by NMR spectral analyses and chemical synthesis.

New spirostanol steroids and steroidal saponins from roots and rhizomes of Dracaena angustifolia and their antiproliferative activity

The MeOH extract of Nam ginseng (roots and rhizomes of Dracaena angustifolia) afforded nine new compounds, including three spirostanol sapogenins, named namogenins A-C (1-3), four spirostanol saponins, named namonins A-D (4-7), a furostanol saponin, named namonin E (8), and a pregnan glycoside, named namonin F (9), along with another eight known steroidal saponins (10-17). Their structures were determined on the basis of spectral analyses and chemical methods. All compounds were tested for their antiproliferative activity against murine colon 26-L5 carcinoma, human HT-1080 fibrosarcoma, and B-16 BL6 melanoma cells. Compounds 4, 5, and 10 showed potent antiproliferative activity against HT-1080 fibrosarcoma cells, having IC(50) values of 0.2, 0.3, and 0.6 microM, respectively, comparable to that of doxorubicin.

1-O-galloyl-6-O-(4-hydroxy-3,5-dimethoxy)benzoyl-beta-D-glucose, a new hepatoprotective constituent from Combretum quadrangulare

A new gallic acid derivative, 1-O-galloyl-6-O-(4-hydroxy-3,5-dimethoxy)benzoyl-beta-D-glucose (1) has been isolated from an H2O-fraction of MeOH extract of Combretum quadrangulare seeds. Compound 1 exhibited potent hepatoprotective activity against D-GalN/TNF-alpha-induced cell death in primary cultured mouse hepatocytes with an IC50 of 3.3 microM.

Antiproliferative activity of diarylheptanoids from the seeds of Alpinia blepharocalyx

The 95% EtOH extract of the seeds of Alpinia blepharocalyx (Zingiberaceae) showed significant antiproliferative activity towards human HT-1080 fibrosarcoma and murine colon 26-L5 carcinoma cells. Chemical investigation of the extract led to the isolation of forty-four new (1-44) and one known (45) diarylheptanoids, eleven phenolic compounds (46-56) together with beta-sitosterol glucoside (57). Almost all the isolated compounds showed significant antiproliferative activity in a concentration-dependent manner. Among the compounds, epicalyxin F (17) exhibited the most potent activity against the proliferation of colon 26-L5 carcinoma cells with an ED50 value of 0.89 microM, while calyxin B (2) exhibited the most potent activity against human HT-1080 fibrosarcoma cells with an ED50 value of 0.69 microM. Moreover, calyxins B (2) and K (11), epicalyxins F (17), I (20) and K (22), 6-hydroxycalyxin F (25), blepharocalyxin B (27) and mixtures of 7 and epicalyxin G (18) and of calyxin J (10) and epicalyxin J (21) possessed more potent activity than a clinically used anticancer drug, 5-fluorouracil, towards HT-1080 fibrosarcoma cells. Analysis of the structure activity relationship suggested that the position of the attachment of a chalcone or a flavanone moiety does not affect the activity, although their presence in association causes a substantial enhancement of the antiproliferative activity. Moreover, the conjugated double bond of the chalcone moiety and the phenolic hydroxyl group potentiate the antiproliferative activity of the compounds.

Five novel highly oxygenated diterpenes of Orthosiphon stamineus from Myanmar

Five novel highly oxygenated diterpenes, orthosiphols K (1), L (2), M (3), and N (4) and norstaminone A (5), were isolated from the aerial part of Orthosiphon stamineus, together with three known diterpenes, orthosiphols A (6) and B (7) and neoorthosiphol A (8). Orthosiphol L (2) is an isopimarane-type diterpene with a hydroxyl group at C-12, which supports the biogenesis of staminane-type diterpenes, i.e., migration of a vinylic group from C-13 of isopimarane to C-12. Norstaminone A (5) has a staminane carbon framework and supports the biosynthetic pathway from staminols to norstaminols via staminolactones. All the isolated compounds showed mild to weak antiproliferative activities toward highly liver metastatic colon 26-L5 carcinoma and human HT-1080 fibrosarcoma cell lines.

Blepharocalyxins C--E, three new dimeric diarylheptanoids, and related compounds from the seeds of Alpinia blepharocalyx

Three novel diarylheptanoids, blepharocalyxins C--E (5--7), together with four new (1--4) and one known (8) diarylheptanoids bearing a tetrahydropyran ring were isolated from the residual fraction of an EtOH extract of the seeds of Alpinia blepharocalyx. The structures and the stereochemistry at the chiral centers of the new diarylheptanoids were elucidated by spectroscopic techniques including 2D NMR spectroscopy. Blepharocalyxins C--E (5--7) have a novel carbon framework and are dimeric diarylheptanoids consisting of two diarylheptanoid units. Blepharocalyxin D (6) showed potent antiproliferative activity against murine colon 26-L5 carcinoma cells (ED(50), 3.61 microM), while against human HT-1080 fibrosarcoma cells, blepharocalyxin E (7) showed potent activity (ED(50), 9.02 microM).

Three new triterpenes from the seeds of Combretum quadrangulare and their hepatoprotective activity

Three new triterpenes of the lupane type, 2alpha,6beta-dihydroxybetulinic acid (1) and 6beta-hydroxyhovenic acid (2), and an oleanane type, 6beta-hydroxyarjunic acid (3), together with several known compounds, have been isolated from the MeOH extract of the seeds of Combretum quadrangulare. The structures of these compounds were elucidated on the basis of spectroscopic analysis, and their hepatoprotective activities were tested for D-GalN/TNF-alpha-induced cell death in primary cultured mouse hepatocytes.

Six new diarylheptanoids from the seeds of Alpinia blepharocalyx

Chromatographic separation of part of an EtOH extract of the seeds of Alpinia blepharocalyx resulted in the isolation of six new (1-6) and two known (7, 8) diarylheptanoids together with 12 known compounds. The structures of the new compounds, including their absolute stereochemistry, were elucidated by spectroscopic and chemical methods as (3S,5S)- (1) and (3S,5R)-3-hydroxy-5-methoxy-1-(4-hydroxyphenyl)-7-phenyl-6E-heptene (2), (3S,5S)- (3) and (3S,5R)-3-hydroxy-5-ethoxy-1-(4-hydroxyphenyl)-7-phenyl-6E-heptene (4), (3S)-methoxy-1,7-bis(4-hydroxyphenyl)-6E-hepten-5-one (5), and 1,7-bis(4-hydroxyphenyl)hepta-4E,6E-dien-3-one (6). Among the isolated compounds, 5, (3S,5S)-3,5-dihydroxy-1,7-bis(4-hydroxyphenyl)heptane (8), 4'-hydroxy-5,6-dehydrokawain (14), and/or phloroglucinol (20) showed significant antiproliferative activity against murine colon 26-L5 carcinoma (ED(50): 5, 5.2 microM; 8, 12.8 microM; 14, 20.7 microM; 20, 26.4 microM) and human HT-1080 fibrosarcoma (ED(50): 5, 10.1 microM; 14, 20.1 microM; 20, 20.9 microM) cells.

Eleven novel diarylheptanoids and two unusual diarylheptanoid derivatives from the seeds of Alpinia blepharocalyx

An EtOH extract of the seeds of Alpinia blepharocalyx afforded 11 novel diarylheptanoids, named deoxycalyxin A (1), epicalyxin F (2), calyxin K (3), epicalyxin K (4), calyxin I (5), epicalyxin I (6), calyxin J (7), epicalyxin J (8), and calyxin L (9), an epimeric mixture of calyxin M (10) and epicalyxin M (11), and two unusual diarylheptanoid derivatives, named neocalyxins A (12) and B (13), together with four known calyxins, calyxins A (14), F (15), E (16), and G (17). Structures were elucidated by spectroscopic techniques including 2D NMR spectroscopy. All compounds were examined for cytotoxicity toward murine colon 26-L5 carcinoma and human HT-1080 fibrosarcoma cells. Diarylheptanoids 2, 3, and 5 were cytotoxic against both cell lines, while 4 and 6-8 were cytotoxic against human fibrosarcoma cells.

Hepatoprotective and anti-Helicobacter pylori activities of constituents from Brazilian propolis

Propolis is a resinous hive product collected by honeybees from various plant sources. It is extensively used in food, beverage and in folk medicine for treating various ailments and reported to have broad spectrum of biological activities. The hepatoprotective activity of propolis and constituents from its MeOH extract belonging to various classes were tested on D-galactosamine (D-GalN)/tumor necrosis factor-alpha (TNF-alpha)-induced cell death in primary cultured mouse hepatocytes. The result indicated that hepatoprotective activity of alcoholic extract of tropical Brazilian propolis is mainly due to phenolic compounds including flavonoids. All the four isolated flavonoids possessed stronger inhibitory activity (IC50, < 25 microM) than silibinin (IC50, 39.6 microM) on TNF-alpha-induced cell death. The labdane-type diterpenes isolated from the MeOH extract also exhibited significant hepatoprotective activity in the same experimental model. Moreover, the labdane-type diterpenes and some of the prenylated phenolic compounds possessed antibacterial activity against Helicobacter pylori.

Kinmoonosides A-C, three new cytotoxic saponins from the fruits of Acacia concinna, a medicinal plant collected in myanmar

Three genuine saponins, named kinmoonosides A-C (1-3), have been isolated, together with a new monoterpenoid (4), from a methanolic extract of the fruits of Acacia concinna. The structures of kinmoonosides A-C were elucidated on the basis of spectral analysis as 3-O-¿alpha-L-arabinopyranosyl(1-->6)-[beta-D-glucopyranosyl(1-->2) ]-b eta-D-glucopyranosyl¿-21-O-¿(6R, 2E)-2-hydroxymethyl-6-methyl-6-O-[4-O-(2'E)-6'-hydroxyl-2'-hydroxymet hyl-6'-methyl-2',7'-octadienoyl-beta-D-quinovopyranosyl]-2, 7-octadienoyl¿acacic acid 28-O-alpha-L-arabinofuranosyl(1-->4)-[beta-D-glucopyranosyl(1-->3)]-a lpha-L-rhamnopyranosyl(1-->2)-beta-D-glucopyranosyl ester (1); 3-O-¿alpha-L-arabinopyranosyl(1-->6)-[beta-D-glucopyranosyl(1-->2) ]-b eta-D-glucopyranosyl¿-21-O-¿(6S, 2E)-2-hydroxymethyl-6-methyl-6-O-[4-O-(2'E)-6'-hydroxyl-2'-hydroxymet hyl-6'-methyl-2',7'-octadienoyl-beta-D-quinobopyranosyl]-2, 7-octadienoyl¿acacic acid 28-O-alpha-L-arabinofuranosyl(1-->4)-[beta-D-glucopyranosyl(1-->3)]-a lpha-L-rhamnopyranosyl(1-->2)-beta-D-glucopyranosyl ester (2); and 3-O-¿alpha-L-arabinopyranosyl(1-->6)-[beta-D-glucopyranosyl(1-->2) ]-b eta-D-glucopyranosyl¿-21-O-[(2E)-6-hydroxyl-2-hydroxymethyl-6-methyl- 2,7-octadienoyl]acacic acid 28-O-alpha-L-arabinofuranosyl(1-->4)-[beta-D-glucopyranosyl(1-->3)]-a lpha-L-rhamnopyranosyl(1-->2)-beta-D-glucopyranosyl ester (3), respectively. The new monoterpenoid 4 was determined as 4-O-[(2E)-6-hydroxyl-2-hydroxymethyl-6-methyl-2, 7-octadienoyl]-D-quinovopyranose. Compounds 1-3 showed significant cytotoxicity against human HT-1080 fibrosarcoma cells.