A new 3,4-seco-isopimarane and three new isopimarane diterpenoids from Kaempferia champasakensis collected from Vietnam and their cytotoxic activities.

A phytochemical investigation of Kaempferia champasakensis rhizomes led to the isolation of a new 3,4-seco-isopimarane diterpene, kaempferiol A (1), and three new isopimarane diterpenes, kaempferiols B-D (2-4), together with six known isopimarane diterpenes (5-10). The structures of 1-4 were elucidated by extensive spectroscopic analyses, including HR-ESI-MS, UV, IR, and 1D and 2D NMR. The absolute configurations of 1, 3, and 4 were determined by ECD calculations, while that of 2 was established using the modified Mosher method. All isolated compounds were tested for cytotoxicity against three human cancer cell lines, lung cancer (A549), cervical cancer (HeLa), and breast cancer (MCF-7). Among them, 6 and 7 showed moderate cytotoxic activities against the three tested cell lines, with IC50 values ranging from 38.04 to 27.77 µM, respectively.

Phenolic Derivatives with Anti-Acetylcholinesterase Inhibitory Activities from Galeola nudifolia in Vietnam.

A new phenolic derivative, galeomalate A (1), together with five known structurally related compounds (2-6), was isolated from the ethyl acetate extract of Galeola nudifolia collected in Vietnam. The structures were elucidated by various spectroscopic methods, including 1D and 2D NMR, HR-ESI-TOF-MS, and CD data, and chemical conversion of the sugar moiety. All isolated compounds possessed acetylcholinesterase (AChE) inhibitory activities in a dose-dependent manner. Among them, compounds 2 and 3 exhibited the first and second highest inhibitory activity on AChE with IC50 values of 122.13 and 125.49 µM, respectively. Compounds 1 and 4-6 inhibited the AChE activity by mixed modes of action comprising competitive and non-competitive modes, whereas 2 and 3 exerted their inhibitory activities in a competitive manner. Molecular docking analyses suggested that the phenyl-ß-D-glucopyranoside unit of 2 and 3 bound to the active site of AChE for the competitive inhibitory activities, while the mixed inhibitory activity of 4 was due to the two binding patterns in the active-site and the active-site entrance of AChE. Furthermore, the docking studies indicated that 1, 5, and 6 would inhibit AChE in a mixed inhibitory manner by adopting three distinct binding patterns of the additional phenyl-ß-D-glucopyranoside unit at the active-site entrance.

Arginase inhibitory activities of guaiane sesquiterpenoids from Curcuma comosa rhizomes.

Arginases are bimanganese enzymes involved in many human illnesses, and thus are targets for disease treatments. The screening of traditional medicinal plants demonstrated that an ethanol extract of Curcuma comosa rhizomes showed significant human arginase I and II inhibitory activity, and further fractionation led to the isolation of three known guaiane sesquiterpenoids, alismoxide (1), 7α,10α-epoxyguaiane-4α,11-diol (2) and guaidiol (3). Tests of their inhibitory activities on human arginases I and II revealed that 1 exhibited selective and potent competitive inhibition for human arginase I (IC50 = 30.2 µM), whereas the other compounds lacked inhibitory activities against human arginases. To the best of our knowledge, this is the first demonstration of human arginase I inhibitory activity by a sesquiterpenoid. Thus, 1 is a primary and specific inhibitory molecule against human arginase I.

Novel insights into the antibacterial activities of cannabinoid biosynthetic intermediate, olivetolic acid, and its alkyl-chain derivatives.

Investigations of antibacterial activities revealed that the incorporation of longer alkyl chains to the C-6 position in resorcylic acid conferred antibacterial properties against Staphylococcus aureus and Bacillus subtilis. The resultant olivetolic acid (OA) derivatives with n-undecyl and n-tridecyl side-chains, even those lacking the hydrophobic geranyl moiety from their C-3 positions, exhibited strong antibacterial activities against B. subtilis at a MIC value of 2.5 µM. Furthermore, the study demonstrated that the n-heptyl alkyl-chain modification at C-6 of cannabigerolic acid (CBGA) effectively enhanced the activity against B. subtilis, demonstrating the importance of the alkyl side-chain in modulating the bioactivity. Overall, the findings in this study provided insight into further evaluations of the antibacterial activities, as well as other various biological activities of OA and CBGA derivatives, especially with optimized hydrophobicities at both the alkyl and prenyl side-chain positions of the core skeleton for the discovery of novel drug seeds.

Enzymatic formation of a prenyl ß-carboline by a fungal indole prenyltransferase.

CdpNPT from Aspergillus fumigatus is a fungal indole prenyltransferase (IPT) with remarkable substrate promiscuity to generate prenylated compounds. Our first investigation of the catalytic potential of CdpNPT against a ß-carboline, harmol (1), revealed that the enzyme also accepts 1 as the prenyl acceptor with dimethylallyl diphosphate (DMAPP) as the prenyl donor and selectively prenylates the C-6 position of 1 by the "regular-type" dimethylallylation to produce 6-(3-dimethylallyl)harmol (2). Furthermore, our X-ray crystal structure analysis of the C-His6-tagged CdpNPT (38-440) truncated mutant complexed with 1 and docking studies of DMAPP to the crystal structure of the CdpNPT (38-440) mutant suggested that CdpNPT could employ the two-step prenylation system to produce 2.

Marginols A‒H, unprecedented pimarane diterpenoids from Kaempferia marginata and their NO inhibitory activities.

Kaempferia marginata rhizomes are used as an herb in food and as traditional medicine for the treatment of inflammatory-related diseases in Asian countries. In contrast to the previously reported phytochemical investigation of Thai and Chinese K. marginata rhizomes, which demonstrated the presence of sandaracopimaradiene and ent-sandaracopimaradiene, our first investigation of Vietnamese K. marginata rhizomes led to the isolation of eight undescribed pimarane diterpenoids, marginols A‒H, along with 18 known pimarane diterpenoids. The structures of these compounds were elucidated by spectroscopic techniques, including 1D and 2D NMR, HRESIMS, and CD spectroscopy and/or by comparisons of their NMR data with previously reported data. Furthermore, evaluations of the NO production inhibitory activity against LPS-stimulated RAW264.7 cells revealed that the undescribed compounds, marginols B and D‒G, and the known compounds, sandaracopimaradien-6ß,9α-diol-1-one and 6-acetoxysandaracopimardien-9-ol-1-one, showed potent activities. These results provide insights into the chemodiversity of Vietnamese K. marginata rhizomes as well as their traditional usage from the viewpoint of their chemical constituents.

Flavanols and Flavanes from Crinum asiaticum and Their Effects on LPS Signaling Pathway Through the Inhibition of NF-κB Activation.

Three new flavanols, (2R,3S)-7-methoxy-flavan-3-ol (1: ), (2R,3S)-7-hydroxy-flavan-3-ol (2: ), and (2R,3S)-2'-hydroxy-7-methoxy-flavan-3-ol (3: ), together with two known flavans (4: and 5: ), were isolated from the chloroform extract of Crinum asiaticum. Their structures were elucidated by various spectroscopic methods, including 1D and 2D NMR, HR-ESI-MS, and CD data. The isolated compounds 1: and 3: -5: showed inhibitory activity toward LPS-induced nitric oxide (NO) production. Further investigation of the NF-κB pathway mechanisms indicated that 1: and 3: -5: inhibited the LPS-induced IL-6 production and p65 subunit phosphorylation of NF-κB in RAW264.7 cells, with an effective dose of 10 µM.

Anti-Vpr activities of sesqui- and diterpenoids from the roots and rhizomes of Kaempferia candida.

New copaene-type and nerolidol-type sesquiterpenoids, 7-hydroxymustakone (1) and 15-hydroxynerolidol (2), and a 15-norlabdane diterpenoid, kaempcandiol (3), together with four known compounds (4-7) were isolated from the chloroform extract of Kaempferia candida roots and rhizomes. The structures of the new compounds 1-3 were elucidated based on 1D and 2D NMR and HRESIMS spectroscopic analyses. The extract of the K. candida roots and rhizomes and all isolated compounds 1-7 possessed HIV-1 viral protein R (Vpr) inhibitory activities on the TREx-HeLa-Vpr cell line at a 5 µM concentration, without detectable cytotoxicity.

Shanpanootols A-F, diterpenoids from Kaempferia pulchra rhizomes collected in Myanmar and their Vpr inhibitory activities.

Six new isopimarane diterpenoids, shanpanootols A-F (1-6), along with two known analogues, were isolated from the ethyl acetate-soluble extract of Kaempferia pulchra rhizomes collected in Myanmar. The structures of these compounds were elucidated by extensive spectroscopic techniques such as 1D and 2D NMR and HRESIMS. The absolute configuration of 1 was determined by the modified Mosher method. The new isolates (1-6) were tested for their Vpr inhibitory activities against TREx-HeLa-Vpr cells. Shanpanootols C (3) and E (5) inhibited Vpr at doses of 2.5 and 5 µM, respectively.

Anti-Vpr activities of homodrimane sesquiterpenoids and labdane diterpenoids from Globba sherwoodiana rhizomes.

Two new homodrimane sesquiterpenoids, globbatones A and B (1 and 2), and one 16-norlabdane diterpenoid, globbatone C (3), together with two new naturally occurring, (E)-labda-8(17),12-diene-15,16-olide (4) and γ-bicyclohomofarnesen-12-ol (5), and one known homodrimane sesquiterpenoid (6), nine known labdane diterpenoids (7-15), and one isospongian diterpenoid (16), were isolated from the chloroform extract of Globba sherwoodiana rhizomes. The structures of the new compounds 1-3 were elucidated based on 1D and 2D NMR and HRESIMS spectroscopic analyses. The chloroform extract of G. sherwoodiana rhizomes and 10 µM concentrations of some of its constituents 1, 3, 4, 8, 9, 12, and 14 showed the moderate anti-Vpr activities, without cytotoxic effects on the TREx-HeLa-Vpr cell line.

Three new quassinoids isolated from the wood of Picrasma javanica and their anti-Vpr activities.

Three new quassinoids, javanicinols A and B (1 and 2) and 4-keto-(16S)-methoxyjavanicin B (3), together with three known quassinoids (4-6) were isolated from the chloroform-soluble fraction of the methanol extract of the Picrasma javanica wood. The structures of 1-3 were determined by spectroscopic analyses, including 1D and 2D NMR, HRESIMS, and CD. The anti-HIV-1 viral protein R (Vpr) assay revealed that 1 and 2 exhibited potent anti-Vpr activities at 1.25 µM. Furthermore, the assay also revealed the potent anti-Vpr activities of (16R)-methoxyjavanicin B (7) and (16S)-methoxyjavanicin B (8), which were previously isolated from the Picrasma javanica wood.

New cytotoxic polyacetylene amides from the Egyptian marine sponge Siphonochalina siphonella.

Four new polyacetylene amides, siphonellamides A-D (1-4), and one new fatty amide, siphonellamide E (5), together with a known indole fatty amide (6) and callyspongamide A (7), were isolated from the Red Sea marine sponge Siphonochalina siphonella. The structures of 1-5 were elucidated by extensive analyses of their 1D- and 2D-NMR spectra and MS. The isolated compounds were assessed for their cytotoxicity against HeLa, MCF-7, and A549 cancer cell lines. Compounds 1 and 2 exhibited cytotoxic activities with IC50 values ranging from 9.4 to 34.1 µM, while 5 was only cytotoxic to HeLa cells, with an IC50 value of 78.4 µM. Compound 7 showed moderate cytotoxicity against all tested cell lines.

Bis-iridoid and iridoid glycosides: Viral protein R inhibitors from Picrorhiza kurroa collected in Myanmar.

Four new bis-iridoid glycosides, saungmaygaosides A-D (1-4), and six known iridoid glycosides (5-10) were isolated from the n-butanol extract of the stems of Picrorhiza kurroa collected in Myanmar. Their structures were elucidated by extensive spectroscopic techniques. All of the isolates were assayed for anti-Vpr activity, using TREx-HeLa-Vpr cells. Among the isolates, saungmaygaoside D (4), sylvestroside IV dimethyl acetal (7), and sweroside (8) were the most potent inhibitors with effective doses of 5 and 10 µM, respectively, without showing any notable cytotoxicities.

2-Alkylquinolone alkaloid biosynthesis in the medicinal plant Evodia rutaecarpa involves collaboration of two novel type III polyketide synthases.

2-Alkylquinolone (2AQ) alkaloids are pharmaceutically and biologically important natural products produced by both bacteria and plants, with a wide range of biological effects, including antibacterial, cytotoxic, anticholinesterase, and quorum-sensing signaling activities. These diverse activities and 2AQ occurrence in vastly different phyla have raised much interest in the biosynthesis pathways leading to their production. Previous studies in plants have suggested that type III polyketide synthases (PKSs) might be involved in 2AQ biosynthesis, but this hypothesis is untested. To this end, we cloned two novel type III PKSs, alkyldiketide-CoA synthase (ADS) and alkylquinolone synthase (AQS), from the 2AQ-producing medicinal plant, Evodia rutaecarpa (Rutaceae). Functional analyses revealed that collaboration of ADS and AQS produces 2AQ via condensations of N-methylanthraniloyl-CoA, a fatty acyl-CoA, with malonyl-CoA. We show that ADS efficiently catalyzes the decarboxylative condensation of malonyl-CoA with a fatty acyl-CoA to produce an alkyldiketide-CoA, whereas AQS specifically catalyzes the decarboxylative condensation of an alkyldiketide acid with N-methylanthraniloyl-CoA to generate the 2AQ scaffold via C-C/C-N bond formations. Remarkably, the ADS and AQS crystal structures at 1.80 and 2.20 Å resolutions, respectively, indicated that the unique active-site architecture with Trp-332 and Cys-191 and the novel CoA-binding tunnel with Tyr-215 principally control the substrate and product specificities of ADS and AQS, respectively. These results provide additional insights into the catalytic versatility of the type III PKSs and their functional and evolutionary implications for 2AQ biosynthesis in plants and bacteria.

A kaempferol triglycoside from Tephrosia preussii Taub. (Fabaceae).

A phytochemical investigation of the MeOH extract of twigs and leaves of Tephrosia preussi was carried out to give a new kaempferol triglycoside, named tephrokaempferoside (1), together with five known compounds: tephrosin (2), betulinic acid (3), lupeol (4), ß-sitosterol (5) and 3-O-ß-d-glucopyranoside of ß-sitosterol (6). The structure of the new compound was characterised by analyses of NMR (1D and 2D) and MS data, and chemical conversion. Tephrokaempferoside (1) had weak antibacterial activity against Klebsiella pneumoniae with an MIC value of 150 µg/mL.

Antibacterial activities of chemical constituents from the aerial parts of Hedyotis pilulifera.

CONTEXT: Hedyotis pilulifera (Pit.) T.N. Ninh (Rubiaceae) has been used in Vietnamese ethnomedicine; the methanol extract exhibited antibacterial activity in our preliminary screening. OBJECTIVES: In this study, compounds from H. pilulifera were isolated and their antibacterial activity in vitro was evaluated. MATERIALS AND METHODS: The aerial parts of H. pilulifera (1.4 kg) were extracted with MeOH, suspended in water and ethyl acetate extract was chromatographed on a silica gel column. The structures of isolated compounds were elucidated by the combination analyses of spectroscopy including 1D-, 2D-NMR, HRMS and in comparison with the reported NMR data in the literature. All isolated compounds were evaluated for inhibitory effect using the microdilution method toward Staphylococcus aureus, Bacillus subtilis and Mycobacterium smegmatis, and MIC values were determined. RESULTS: Twenty compounds were isolated, including five triterpenoids, two steroids, two aromatic compounds, three fatty acids, one quinone derivative, one lignan glycoside, one ceramide and five glycolipids. Among these, oleanolic acid showed significant antibacterial activity against M. smegmatis with the MIC value of 2.5 µg/mL. Remarkably, rotungenic acid showed strong activity against S. aureus, B. subtilis, M. smegmatis with MIC values of 2.5, 2.5 and 1.25 µg/mL, respectively. Rotundic acid exhibited significant antibacterial activity against B. subtilis with the MIC value of 5 µg/mL. To the best of our knowledge, the antibacterial activity of rotungenic acid, stigmast-4-ene-3,6-dione and (2S,3S,4R,2'R)-2-(2'-hydroxytetracosanoylamino) octadecane-1,3,4-triol was reported for the first time. CONCLUSIONS: Oleanolic acid, rotungenic acid, and rotundic acid were considered to be useful for developing new antimicrobial therapeutic agents for human.

Two new cyclopentenones and a new furanone from Baeckea frutescens and their cytotoxicities.

Two new cyclopentenones, frutescencenones A (1) and B (2), and a new furanone derivative, frutescencenone C (3), together with two known cyclopentenones (4 and 5), were isolated from the leaves of Baeckea frutescens. Their structures were deduced by comprehensive spectroscopic analyses, including 1D and 2D NMR, and HREIMS data. Frutescencenone A (1) showed moderate growth inhibitory activity against human lung A549, pancreatic PSN-1, and breast MDA-MB-231 cancer cell lines, with IC50 values of 36.3µM, 38.2µM, and 29.3µM, respectively. In contrast, frutescencenone C (3) showed selective cytotoxic activity against PSN-1, with an IC50 value of 20.1µM.

A New Iridoid from the Aerial Parts of Hedyotis pilulifera.

A new iridoid, 10-acetylborreriagenin (1), and five known iridoid glycosides (2-6), were isolated from the aerial parts of Hedyotis pilulifera. Their structures were elucidated by spectral analyses, including 1D- and 2D-NMR, and HR-ESI-MS, and comparisons with the NMR data reported in the literature. The isolated compounds 1-6 were tested against six bacterial species. Among them, 10-acetylborreriagenin (1) showed antibacterial activity against Staphylococcus aureus, with an MIC value of 100 µg/mL.

Isopimarane diterpenoids from Kaempferia pulchra rhizomes collected in Myanmar and their Vpr inhibitory activity.

Viral protein R (Vpr), an accessory gene of HIV-1, plays important roles in viral pathogenesis. Screening of Myanmar medicinal plants that are popular as primary treatments for HIV/AIDS and for HIV-related problems revealed the potent anti-Vpr activity of the CHCl3-soluble extract of Kaempferia pulchra rhizomes, in comparison with that of the positive control, damnacanthal. Fractionation of the active CHCl3-soluble extract led to the identification of 30 isopimarane diterpenoids, including kaempulchraols A-W (1-23). All isolates were assayed for anti-Vpr activity against TREx-HeLa-Vpr cells, in which Vpr expression is tightly regulated by tetracycline. Kaempulchraols B (2), D (4), G (7), Q (17), T (20), U (21), and W (23) exhibited potent anti-Vpr activity, at concentrations ranging from 1.56 to 6.25µM. The structure-activity relationships of the active kaempulchraols suggested that the presence of a hydroxy group at C-14 in an isopimara-8(9),15-diene skeleton and the presence of an acetoxy group at C-1 or C-7 in an isopimara-8(14),15-diene skeleton are the critical factors for the inhibitory effects against TREx-HeLa-Vpr cells.

New cytotoxic phloroglucinols, baeckenones D-F, from the leaves of Indonesian Baeckea frutescens.

Three new phloroglucinols, baeckenones D-F (1-3), were obtained from the leaves of Indonesian Baeckea frutescens, along with the known unusual endoperoxide, phloroglucinol (4). The structures of the isolated compounds were elucidated by 1D and 2D NMR and HREIMS spectra. Furthermore, the stereochemistry of baeckenone D (1) was established by an X-ray diffraction analysis. Among the isolated compounds 1-4, baeckenone F (3) showed moderate cytotoxic activities against human pancreatic (PSN-1), lung (A549), and breast (MDA-MB-231) cancer cell lines, with IC50 values of 33.3 µM, 34 µM, and 39.3 µM, respectively.