Quorum quenching activity of Andrographis paniculata (Burm f.) Nees andrographolide compounds on metallo-ß-lactamase-producing clinical isolates of Pseudomonas aeruginosa PA22 and PA247 and their effect on lasR gene expression.

Andrographis paniculata (Burm f.) Nees is a tropical plant native to Southeast Asia that has been used as an effective remedy for a wide variety of illnesses in traditional Chinese and Ayurvedic medicine. The antimicrobial activity of its crude extract had been shown to be due to its quorum quenching activity. The study determined the effect of purified extracted compounds from the leaf of A. paniculata, namely: andrographolide, 14-deoxyandrographolide, 14-deoxy-12-hydroxyandrographolide and neoandrographolide on quorum sensing-mediated virulence mechanisms in clinical isolates of metallo-ß-lactamase (MßL)-producing Pseudomonas aeruginosa. Their effect on the expression of the lasR gene, which codes for LasR, a transcription activator protein of the quorum sensing system in P. aeruginosa was also determined using RT-qPCR. All the pure compounds significantly decreased the biofilm formation, protease production and swarming motility of the P. aeruginosa isolates compared to the untreated controls (p < 0.05). Results of the RT-qPCR assay showed that all compounds significantly downregulated the expression of lasR compared to the untreated control (p < 0.05), supporting the position that the lower virulence activities of the treated group were due to quorum quenching activity of the pure compounds. Multiple comparisons using Tukey's HSD analysis revealed that the means of the relative expression of lasR of the isolates treated with the different compounds were not significantly different from each other (p > 0.05), suggesting equal potencies. Results show the potential of the isolated pure compounds from A. paniculata for use as antimicrobial agents as a result of their quorum quenching activities.

Triterpenes from Euphorbia hirta and their cytotoxicity.

AIM: To investigate the chemical constituents of the stems, leaves and roots of Euphorbia hirta, and to test for the cytotoxic and antimicrobial potentials of the major constituents of the plant. METHODS: The compounds were isolated by silica gel chromatography and their structures were elucidated by NMR spectroscopy. The cytotoxicity tests were conducted using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, while the antimicrobial tests employed the agar well method. RESULTS: The air-dried stems of E. hirta afforded taraxerone 1, a mixture of 25-hydroperoxycycloart-23-en-3ß-ol (2a) and 24-hydroperoxycycloart-25-en-3ß-ol (2b) (sample 2) in a 2 : 1 ratio, and another mixture of cycloartenol (3a), lupeol (3b), α-amyrin (3c) and ß-amyrin (3d) (sample 3) in a 0.5 : 4 : 1 : 1 ratio. The air-dried leaves of E. hirta yielded sample 2 in a 3 : 2 ratio, sample 3 in a 2 : 3 : 1 : 1 ratio, phytol and phytyl fatty acid ester, while the roots afforded sample 2 in a 2 : 1 ratio, sample 3 in a 2 : 1 : 1 : 1 ratio, a mixture of cycloartenyl fatty acid ester 4a, lupeol fatty acid ester 4b, α-amyrin fatty acid ester 4c and ß-amyrin fatty acid ester 4d (sample 4) in a 3 : 2 : 1 : 1 ratio, linoleic acid, ß-sitosterol and squalene. Compound 1 from the stems, sample 2 from the leaves, and sample 3 from the stems were assessed for cytotoxicity against a human cancer cell line, colon carcinoma (HCT 116). Sample 2 showed good activity with an IC50 value of 4.8 µg·mL(-1), while 1 and sample 3 were inactive against HCT 116. Sample 2 was further tested for cytotoxicity against non-small cell lung adenocarcinoma (A549). It showed good activity against this cell line with an IC50 value of 4.5 µg·mL(-1). Antimicrobial assays were conducted on 1 and sample 2. Results of the study indicated that 1 was active against the bacteria: Pseudomonas aeruginosa and Staphylococcus aureus, but was inactive against Escherichia coli and Bacillus subtilis. Sample 2 was active against the bacteria: Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli and fungi: Candida albicans and Trichophyton mentagrophytes. It was inactive against Bacillus subtilis and Aspergillus niger. CONCLUSIONS: The triterpenes: 2a, 2b, 3a, 3b, 3c and 3d were obtained from the stems, roots and leaves of E. hirta. Taraxerol (1) was only isolated from the stems, the leaves yielded phytol and phytyl fatty acid esters, while the roots afforded 4a-4d, linoleic acid, ß-sitosterol, and squalene. Triterpene 1 and sample 2 were found to exhibit antimicrobial activities. Thus, these compounds are some of the active principles of E. hirta which is used in wound healing and the treatment of boils. The cytotoxic properties of sample 2 imply that triterpenes 2a and 2b contribute to the anticancer activity of E. hirta.

Chemical constituents of Cinnamomum cebuense.

AIM: To investigate the chemical constituents of Cinnamomum cebuense, an endemic and critically endangered tree found only in Cebu, Philippines. METHODS: The compounds were isolated by silica gel chromatography. The structures of the isolates were elucidated by NMR spectroscopy. RESULTS: The dichloromethane (DCM) extract of the bark of C. cebuense afforded a new monoterpene natural product 1 and a new sesquiterpene 2, along with the known compounds, 4-hydroxy-3-methoxycinnamaldehyde (3), 4-allyl-2-methoxyphenol (4), α-terpineol (5) and humulene (6). The DCM extract of the leaves of C. cebuense yielded 6, ß-caryophyllene (7), squalene (8), and a mixture of α-amyrin (9), ß-amyrin (10) and bauerenol (11). The structures of 1-7 were elucidated by extensive 1D and 2D NMR spectroscopy, while the structures of 8-11 were identified by comparison of their (13)C NMR data with those reported in the literature. CONCLUSION: The bark of C. cebuense afforded monoterpenes, sesquiterpenes and phenolics, while the leaves yielded sesquiterpenes and triterpenes.

Angio-suppressive triterpenoids from Ardisia cf. elliptica (subgenus Tinus) on duck (Anas platyrynchos L.) chorioallantoic membrane.

The dichloromethane extract of the air-dried leaves of Ardisia cf. elliptica (subgenus Tinus) afforded a mixture of bauerenol (1a), α-amyrin (1b) and ß-amyrin (1c). Their structures were identified by NMR spectroscopy. Mixtures of the triterpenes (1a-1c) at ratios of 2 : 2 : 1, 2 : 2 : 3 and 1 : 1 : 1 were tested for their angio-suppressive effects on duck chorioallantoic membrane (CAM). All three ratios were found to be effective in restricting inter-capillary length, while 1a-1c (2 : 2 : 1) was most effective in reducing branch point density with 100% CAM viability and embryo survivability, suggesting a high impact angio-suppressive potential of 1a-1c (2 : 2 : 1).

Cytotoxic cardenolide and sterols from Calotropis gigantea.

The dichloromethane extract from the leaves of Calotropis gigantea Linn. was strongly cytotoxic against non-small cell lung carcinoma (A549), colon carcinoma (HCT 116) and hepatocellular carcinoma (Hep G2), and non toxic to Chinese hamster ovary (AA8). The extract afforded uscharin (1), 3,5,8-trihydroxy-24-methylcholest-6,22-diene (2), a mixture of (24R)-3beta-hydroxy-24-ethylcholest-5-en-7-one (3a) and 6beta-hydroxy-24-ethylcholest-4,22-dien-3-one (3b), and another mixture of (24R)-24-ethylcholest-4-en-3-one (4a) and (24S)-24-ethylcholest-4,22-dien-3-one (4b). Cardenolide 1 exhibited extreme toxicity to A549, HCT 116 and Hep G2 with IC50 values of 0.003 microg/mL, 0.013 microg/mL, and 0.018 microg/mL, respectively, while sample 3 exhibited an IC50 of 1.35 microg/mL, 4.46 microg/mL, and 3.83 microg/mL, respectively.

A bioactive sesquiterpene from Bixa orellana.

A dichloromethane extract of the air-dried leaves of Bixa orellana afforded ishwarane 1, phytol 2, polyprenol 3, and a mixture of stigmasterol 4a and sitosterol 4b by silica gel chromatography. The structure of 1 was elucidated by extensive 1D and 2D NMR spectroscopy. Compound 1 at three doses (25, 50, and 100 mg/kg BW) was tested for prophylactic, gastrointestinal motility, analgesic, hypoglycemic, and antimicrobial potentials. Results of the prophylactic assay demonstrated the anti-toxic property of 1 at 100 mg/kg BW. A 50 mg/kg BW dose of 1 resulted in a more propulsive movement of the gastrointestinal tract (88.38 ± 13.59%) compared to the negative control (78.47 ± 10.61%). Tail flick and acetic acid writhing tests indicated that 100 mg/kg BW 1 had minimal analgesic activity. Compound 1 demonstrated no hypoglycemic potential on the animals tested. Compound 1 exhibited moderate antifungal activity against C. albicans, low activity against T. mentagrophytes, and low antibacterial activity against E. coli, S. aureus, and P. aeruginosa. It was inactive against B. subtilis and A. niger.

Hypoglycaemic effects of tea extracts and ent-kaurenoic acid from Smallanthus sonchifolius.

Hypoglycaemic activity was observed in normoglycaemic mice orally administered with the aqueous Smallanthus sonchifolius leaf tea extract, alloxan-induced diabetic mice orally administered with ent-kaurenoic acid (1), and normoglycaemic mice intraperitoneally administered with 1 from S. sonchifolius leaves. A single dose administration of 50 mg kg(-1) BW yacon leaf tea extract demonstrated immediate but relatively short hypoglycaemic activity, with significant effects observed during 1-2 h. Similarly, administration with 100 mg kg(-1) BW yacon leaf tea extract obtained by heavy stirring in hot water demonstrated a more potent activity compared to the positive control at 1.5-2.0 h. Oral administration of 1 did not affect the blood glucose level of the alloxan-induced diabetic mice, but a single intraperitonial injection of 10 mg kg(-1) BW in normoglycaemic mice had consistent percent blood glucose reduction persisting from 1 to 2 h observation periods.

New carvotanacetone derivatives from Sphaeranthus africanus.

The dichloromethane extract of the air-dried leaves of Sphaeranthus africanus afforded four new carvotanacetone derivatives (1, 2, 3A, and 3B). Their structures were elucidated by extensive 1D and 2D NMR spectroscopy. Compounds 1- 3 exhibited antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa and antifungal activity against Candida albicans, Trichophyton mentagrophytes and Aspergillus niger.

Secondary metabolites from Tectona philippinensis.

The air-dried leaves of Tectona philippinensis, an endemic and endangered Philippine medicinal plant, afforded 5-hydroxy-3,7,4'-trimethoxyflavone (1), 5,4'-dihydroxy-3,7-dimethoxyflavone (2), squalene (3), a mixture of lupeol (4a) and beta-amyrin (4b), chlorophyllide a (5), and hydrocarbons. Antimicrobial tests on 1 and 2 indicated low antifungal activity against the fungi, Candida albicans and Trichophyton mentagrophytes. Compound 1 was also found to have low antibacterial activity against Escherichia coli and Pseudomonas aeruginosa.

A new sesquiterpene from Artemisia vulgaris.

The dichloromethane extract of the air-dried leaves of Artemisia vulgaris afforded a new sesquiterpene 1, caryophyllene oxide, phytyl fatty acid esters, squalene, stigmasterol and sitosterol. The structure of 1 was elucidated by extensive one- and two-dimensional nuclear magnetic resonance spectroscopy.

Chromomoric acid derivatives from Tectona philippinensis.

The air-dried leaves of Tectona philippinensis, an endemic and endangered Philippine medicinal tree, afforded four new chromomoric acid derivatives ( 1, 2, 3a, and 3b). Their structures were elucidated by extensive 1D and 2D NMR spectroscopy. Antimicrobial testing was carried out on 1- 3 against a panel of bacteria and fungi.

Monoterpene lactones from the seeds of Nephelium lappaceum.

Dichloromethane extracts of the seeds of Nephelium lappaceum afforded two new diastereomeric monoterpene lactones, 1 and 2, and the known butenolide siphonodin (3), as well as kaempferol 3-O-beta-D-glucopyranoside-7-O-alpha-L-rhamnopyranoside. Compounds 1 and 2 represent a new monoterpene skeleton, and their structures were elucidated by extensive 1D and 2D NMR spectral data interpretation. Antimicrobial testing was carried out on 1 and 2 against a panel of bacteria and fungi.

Antifungal metabolites from Blumea balsamifera.

The leaves of Blumea balsamifera afforded icthyothereol acetate, cryptomeridiol, lutein, and beta-carotene. The structures of icthyothereol acetate (1) and cryptomeridiol (2) were elucidated by extensive 1D and 2D NMR spectroscopy, while those of lutein and beta-carotene were identified by comparison with literature data. Antimicrobial tests indicated that 1 has moderate activity against the fungi Aspergillus niger, Trichophyton mentagrophytes, and Candida albicans, while 2 has low activity against A. niger, T. mentagrophytes, and C. albicans. Both compounds have no antimicrobial activity against Psuedomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, and Escherichia coli.

New cycloartenol esters from Ixora coccinea.

The air-dried flowers of Ixora coccinea L. afforded two new cycloartenol esters (1a and 1b), lupeol fatty ester, lupeol, ursolic acid, oleanolic acid, and sitosterol. The structures of 1a and 1b were elucidated by extensive 1D and 2D NMR spectroscopy and MS.

A new furanoid diterpene from Caesalpinia pulcherrima.

A new cassane-type diterpene isovouacapenol E (1) was isolated from the leaves of Caesalpinia pulcherrima, together with the known compounds caesaldekarin A (3), spathulenol (4), caryophyllene oxide (5), phytol, and sitosterol. The structure of 1 was elucidated by spectral data interpretation.

New furanoid diterpenes from Caesalpinia pulcherrima.

Four new cassane-type furanoditerpenoids (1-4) were isolated from the air-dried leaves of Caesalpinia pulcherrima. Their structures were elucidated by spectral data interpretation. The exocyclic methylene compound 1 readily isomerized and oxidized to the benzofuran 4. Benzyl 2,6-dimethoxybenzoate (5) was also identified in this study. Antimicrobial tests on 1-5 indicated that they were active against several bacteria (S. aureus, E. coli, P. aeruginosa, and B. subtilis) and fungi (C. albicans and T. mentagrophytes).

Ionone derivatives from Alternanthera sessilis.

The chloroform extract of the air-dried leaves of Alternanthera sessilis afforded a mixture of diastereomers of a new ionone derivative 1 whose structures were elucidated by extensive 1D and 2D NMR spectroscopy and mass spectrometry. Oxidative cleavage of 1 to aldehyde 3 with manganese dioxide confirmed diastereoisomerism arose from a racemic side chain chiral centre. Antimicrobial tests on the mixture of diastereomers and the derivative indicated that they have low activities against Pseudomonas aeruginosa and Trichophyton mentagrophytes.