The role of seasonality on the inhibitory effect of Brazilian green propolis on the oxidative metabolism of neutrophils

The reactive oxygen species (ROS) produced by neutrophils are involved in the pathogenesis of several diseases, for which the intake of antioxidants could benefit patients either as a prophylactic or therapeutic treatment. Propolis is among the known antioxidants, and its chemical composition may vary under the influence of seasonality, which may interfere in its biological properties. This work evaluates the role of seasonality on the production of some important compounds of propolis samples produced monthly from November 2001 through October 2002 as well as the effect of these samples on the oxidative metabolism of stimulated neutrophils, by using both luminol and lucigenin to produce chemiluminescence (CLlum and CLluc, respectively). The cytotoxicity of the most active extracts to neutrophils was also investigated. The inhibitory effect of the propolis samples varied significantly during the studied period for both assays (3.4 ± 1.1 to 16.0 ± 1.1 μg/mL for CLlum and 6.2 ± 2.0 to 30.0 ± 5.0 μg/mL for CLluc), which was also observed in the quantitative profile of the main analyzed compounds (aromadendrin-4′-methyl ether, artepillin C, and baccharin). This effect started to become more prominent during the fall and, among all the studied extracts, the one obtained in May displayed the highest inhibitory effect on CL production (3.4 ± 1.1 μg/mL for CLlum and 6.2 ± 2.0 μg/mL for CLluc). The HPLC qualitative profiles of the extracts of propolis samples were quite similar, but there was a huge variation in terms of quantitative profile. It seems that aromadendrin-4′-methyl ether and baccharin play an essential role in the antioxidant activity, while artepillin C is not very important for this effect. The extracts presenting the highest antioxidant activity were produced in May, June, and August, and they did not display cytotoxicity at 25 μg/mL; quercetin, used as control, was not toxic to neutrophils at 8.5 μg/mL.     

The antifungal constituents from the seeds of Itoa orientalis

Three new phenolic constituents, itolide A (1), itolide B (2), itoside P (3), and 1D-3-deoxy-3-hydroxymethyl-myo-inositol (4), which is described herein for the first time as a natural product, were isolated along with four other known compounds (5 to 8) from the methanol extract of the seeds of Itoa orientalis Hemsl by the activity-guided fractionation. Their structures were determined by spectroscopic means. Compounds 1 to 8 exhibited antifungal activities against Sclerotium rolfsii with IC₅₀ values ranging from 60.12 to 240.00 μM and against Rhizoctonia solani with IC₅₀ values ranging from 45.34 to 233.14 μM, respectively, and compounds 1, 2, 5 exhibited cytotoxic activity against Tn5B1-4 insect cell line with EC₅₀ values of 203.68, 93.41 and 40.37 μM, respectively.     

Proton translocating ATPase mediated fungicidal activity of eugenol and thymol

Eugenol (1) and thymol (2) exhibit excellent fungicidal activity against pathogenic yeasts, including isolates resistant to azoles. The rapid irreversible action of compound-1 and compound 2 on fungal cells suggested a membrane-located target for their action. We investigated their effect on H⁺-ATPase mediated H⁺-pumping by various Candida species. Both compounds inhibit H⁺-ATPase activity at their respective MIC values — 500 and 100 μg/ml. Glucose stimulated H⁺-extrusion was also inhibited significantly by compound 1 and compound 2. Inhibition of H⁺-ATPase leads to intracellular acidification and cell death. Inhibition of cell growth and H⁺-efflux by test compounds suggests that their antifungal properties are related to their inhibitory effects on H⁺-ATPase.     

Sesquiterpenoids and norterpenoids from Vitex negundo

Chemical investigation on the seeds of Vitex negundo has afforded a new furan-containing sesquiterpenoid, negunfurol (1), a new norlabdane-type diterpenoid, negundoal (2), and two new norursane-type triterpenoids, negundonorins A (3) and B (4), together with two know compounds, 3-formyl-4,5-dimethyl-8-oxo-5H-6,7-dihydronaphtho[2,3-b]furan (5) and 3-epi-corosolic acid (6). Their structures and configurations were elucidated by detailed spectroscopic analyses on the basis of NMR, IR, and MS data. Compound 3 was strongly cytotoxic against ZR-75-30 cell line with IC₅₀ value of 0.56 ± 0.19 μg/mL, whereas compound 1 was most active against HL-60 cell line with IC₅₀ value of 0.94 ± 0.26 μg/mL.     

A new abietane diterpene from Glyptostrobus pensilis

A new abietane diterpene, glypensin A (1) and four known compounds, 12-acetoxy-ent-labda-8(17), 13E-dien-15-oic acid (2), quercetin 3-O-α-L-arabinofuranoside (3), quercetin 3-O-β-D-galactopyranoside (4), β-sitosterol (5) were isolated from the branches and leaves of Glyptostrobus pensilis (Staut.) Koch. Their structures were determined by MS, 1D- and 2D-NMR means. Compound 1 showed cytotoxicity on human chronic myeloid leukemia cell line K562 (IC₅₀ = 21.2 μM).     

Antibacterial dihydrobenzopyran and xanthone derivatives from Garcinia cowa stem barks

Two new compounds, garciniacowol (1) and garciniacowone (2) along with 15 known compounds were isolated from the stem barks of Garcinia cowa. Their structures were determined by intensive spectroscopic methods. The structure of 1 was a symmetrical dimeric dihydrobenzopyran derivative, whereas the framework of 2 was a triprenyl caged-xanthone precursor. The antibacterial activities against Escherichia coli TISTR 780, Salmonella typhimurium TISTR 292, Staphylococcus aureus TISTR 1466, and methicillin-resistant S. aureus (MRSA) SK1 of the isolated compounds were also evaluated. Compounds 2 and 9 exhibited good antibacterial activity against MRSA SK1 with the same minimum inhibitory concentration (MIC) value of 2 μg/mL. Moreover, compound 2 also showed good antibacterial activity against S. aureus with an MIC value of 2 μg/mL.     

Trichalasins C and D from the plant endophytic fungus Trichoderma gamsii

Two new cytochalasans, trichalasins C (1) and D (2) together with known cytochalasans aspochalasins D (3), M (4) and P (5) were isolated from one endophytic fungus Trichoderma gamsii inhabiting in traditional medicinal plant Panax notoginseng (BurK.) F.H.Chen. The structures for the new compounds 1 and 2 were determined by NMR and HRESIMS, and their relative configurations were established by analysis of coupling constants and NOESY correlations. Compound 3 displaying inhibitory activity with EC₅₀ value 5.72 μM, whereas the EC₅₀ values for compounds 1, 2 and 4, 5 are more than 40 μM.     

Cytotoxic prenylated flavonoids from Morus alba

A phytochemical fractionation of the methanol extract of the Morus alba leaves led to the isolation of eleven flavonoids (1–11). The structure of the new 3′-geranyl-3-prenyl-2′,4′,5,7-tetrahydroxyflavone (1) was elucidated by means of spectroscopic methods. The cytotoxicity of the isolated compounds against human cervical carcinoma HeLa, human breast carcinoma MCF-7, and human hepatocarcinoma Hep3B cells was evaluated. Of note, morusin (9) was the most potent with an IC₅₀ value of 0.64 μM against HeLa cells.     

New diterpenoids and cytotoxic and anti-inflammatory diterpenoids from Amentotaxus formosana

Two new abietane diterpenoids, ramentoxide (1) and ramentoxidone (2) and a new icetexane diterpenoid, amentonone (3) were isolated from the barks of Amentotaxus formosana. The structures of 1-3 were determined by spectroscopic methods. Known compounds brevitaxin (4), and (+)-ferruginol (5) and ent-kaur-16-en-15-one (6) isolated from this plant revealed potent cytotoxic activity against human breast adenocarcinoma cells, MCF-7 cells with an IC₅₀ value of 0.08 ± 0.05 μg/mL, and significant anti-inflammatory activities, respectively.     

Antiparasitic antioxidant phenylpropanoids and iridoid glycosides from Tecoma mollis

A radical scavenging guided phytochemical study on the stem bark of Tecoma mollis afforded seven active phenylpropanoid glycosides (1–7), including a new one (4), and one iridoid (8). The structures of the isolated compounds were elucidated on the basis of spectroscopic evidences and correlated with known compounds. Compounds (1–7) displayed promising antioxidant activity (DPPH assay) in relation to ascorbic acid (positive control). The antimicrobial activity for compounds (1–8) was evaluated against five bacterial and five fungal strains. The isolated compounds exhibited nonselective weak to moderate antimicrobial activity. The highest antileishmanial activity against Leishmania donovani was observed for compound (7) with an IC₅₀ value of 6.71 μg/ml, using pentamidine and amphotericin B as drug controls. Compound (5) exhibited moderate antimalarial activity (45% inhibition) against chloroquine sensitive (D6) clones of Plasmodium falciparum.     

A new coumestan with immunosuppressive activities from Flemingia philippinensis

A new coumestan, 1,3,9-trihydroxy-8-methoxycoumestan, named flemicoumestan A 1 together with nine isoflavone-related compounds were isolated from the ethyl acetate extract of the roots of Flemingia philippinensis. Their structures were elucidated and confirmed by spectroscopic methods and literature data. Compounds 3 and 4 showed strong lymphocyte proliferation inhibitory activity with an IC₅₀ value of 1.04-2.76 μM, and the low cytotoxicity with the CC₅₀ value of 71.01 and 56.36 μM, respectively.     

A new dimeric resveratrol from the roots of Shorea roxburghii

A new resveratrol dimer, roxburghiol A (1) together with eleven known compounds were isolated from the roots of Shorea roxburghii. Their structures were identified on the basis of spectroscopic evidence and physicochemical properties. All isolated compounds were evaluated for their cytotoxicity (KB and HeLa cells). Compounds 8 and 9 showed potent cytotoxicity against both KB and HeLa cell lines with IC₅₀ values of 6.5, 8.5 and 8.7, 10.1 μg/mL, respectively.     

Cyclic bisdesmosides from Actinostemma lobatum MAXIM (Cucurbitaceae) and their in vitro cytotoxicity

Two new cyclic bisdesmosides elucidated as lobatoside L (1) and lobatoside M (2) and four known cyclic bisdesmosides (3-6) were isolated from Actinostemma lobatum MAXIM (Cucurbitaceae). Their structures were determined on the basis of spectroscopic analyses including IR, HR-FAB-MS, TOCSY, 1D- and 2D-NMR experiments and chemical reactions. The inhibitory effects of the six compounds on human cancer cell growth (including esophageal squamous carcinoma cell line ECA109, lung cancer cell line A549 and gastric cancer cell line MGC-803) were determined using the MTT assay. The results revealed that the six compounds exhibited cytotoxicity against all the cell lines tested, and compounds 1, 3 and 5 showed significant activities in a dose dependent manner against all the cell lines, especially for compound 1 and 5, the IC₅₀ values for ECA-109 cells were 8.25 μM and 3.71 μM. The results demonstrated that compounds 1 and 5's activities are 2- and 4-fold that of cisplatin.     

Tabebuialdehydes A–C,cyclopentene dialdehyde derivatives from the roots of Tabebuia rosea

Two new cyclopentene dialdehydes, tabebuialdehydes A and B (1 and 2) and a new dihydrocyclopenta[c]furan monoaldehyde, tabebuialdehyde C (3), along with ten known compounds were isolated from the roots of Tabebuia rosea. The structures of all isolated compounds were elucidated through their physical properties and by the use of spectroscopic methods, as well as comparisons with previous literature data. Moreover, all isolated compounds were evaluated for their cytotoxicity (KB and HeLa cell lines). Compounds 6, 7 and 9 showed significant cytotoxicity against both KB and HeLa cells with IC₅₀ values of 1.35 and 1.15, 0.53 and 0.77, 1.79 and 0.73 μg/mL, respectively.     

Anti-inflammatory, antioxidant and antifungal furanosesquiterpenoids isolated from Commiphora erythraea (Ehrenb.) Engl. resin

The topical anti-inflammatory, free radical scavenging and antifungal activities of essential oils and extracts of Commiphora erythraea (Ehrenb.) Engl. resin were investigated. The hexane extract significantly inhibited oedema when applied topically in Croton oil-induced ear oedema assay in mice. The same extract showed antioxidant activity in DPPH radical scavenging assay. A bioguided separation of the hexane extract led to the isolation of furanosesquiterpenoids 1 and 2 that showed a weak antifungal activity, while compounds 3-5 resulted to be antioxidant (EC₅₀ 4.28, 2.56 and 1.08 mg/mL, respectively) and anti-inflammatory (30, 26 and 32% oedema reduction, respectively).     

Kujigamberol, a new dinorlabdane diterpenoid isolated from 85million years old Kuji amber using a biotechnological assay

A new compound, 15,20-dinor-5,7,9-labdatriene-18-ol (1), named kujigamberol, was isolated from amber, fossilized tree resin from the Kuji area in Japan, has been dated as being 85 million years old (late Cretaceous). Kujigamberol was identified using the hypersensitive mutant yeast (zds1? erg3? pdr1? pdr3?) with respect to Ca²⁺-signal transduction. The structure was elucidated on the basis of spectroscopic analysis including 1D NMR, 2D NMR and HR-EI-MS. It was different from known diterpenoids with a similar activity isolated from Baltic amber (agathic acid 15-monomethyl ester (2), dehydroabietic acid (3) and pimaric acid (4)). Kujigamberol showed glycogen synthase kinase-3β (GSK-3β) inhibition activity involving the growth restored activity against the mutant yeast and was cytotoxic to HL60 cells (IC₅₀ = 19.6 μM).     

Antiproliferative steroidal glycosides from Digitalis ciliata

Two new compounds, a furostanol glycoside (1) and a pregnane glycoside (4), along with eight known compounds, belonging to the classes of spirostane (2,3), pregnane (5–7) and cardenolide (8–10) glycosides, were isolated from the seeds of Digitalis ciliata. Their structures were elucidated by 1D and 2D-NMR experiments as well as ESI-MS analysis. For the first time pregnane glycosides of the diginigenin series have been isolated from D. ciliata. The cytotoxic effects of compounds 1–10 on cell viability of several cancer cell lines, namely human breast cancer (MCF-7), human glioblastoma (T98G), human lung adenocarcinoma (A549), human colon carcinoma (HT-29), and human prostate cancer (PC-3) cell lines were evaluated. Compounds 1, 4, 7 and 8 showed antiproliferative effects against MCF-7, HT-29 and A549 cancer cells with IC₅₀ values ranging from 8.3 to 20 μM. The effects of compounds 1–10 on cell proliferation were evaluated on these three cancer cell lines by cell cycle analysis of DNA content using flow cytometry. Compounds 7, 8 and 10 induced significant changes in G₂/M cell cycle phase of all analyzed cells. The obtained results indicate that compounds 7, 8 and 10 are cytostatic compounds effective in reducing cell proliferation by inducing accumulation of the cells in the G₂/M phase of the cell cycle.     

Polyketides with antimicrobial activity from the solid culture of an endolichenic fungus Ulocladium sp

Two new polyketides, 7-hydroxy-3, 5-dimethyl-isochromen-1-one (1) and 6-hydroxy-8-methoxy-3a-methyl-3a,9b-dihydro-3H-furo[3,2-c]isochromene-2,5-dione (2), along with eleven known compounds, 5′-methoxy-6-methyl-biphenyl-3,4,3′-triol (3), 7-hydroxy-3-(2-hydroxy-propyl)-5-methyl-isochromen-1-one (4), rubralactone (5), isoaltenuene (6), altenuene (7), dihydroaltenuenes A (8), altenusin (9), alterlactone (10), 6-O-methylnorlichexanthone (11), norlichexanthone (12), and griseoxanthone C (13) were isolated from the culture of the endolichenic fungus Ulocladium sp. Compound 2 was obtained as a racemate with an unprecedented chemical skeleton. The NMR data assignments for 3 and 4 were achieved for the first time. Compounds 1-13 were screened for their antimicrobial and radical scavenging activities. Compound 1 showed some antifungal activity against Candida albicans SC 5314 with IC₅₀ of 97.93 ± 1.12 μM. Compounds 11-13 showed strong activity against Bacillus subtilis with IC₅₀ in the range of 1-5 μM. Compound 12 significantly inhibited the growth of methicillin-resistant Staphylococcus aureus with IC₅₀ of 20.95 ± 1.56 μM. Compounds 9 and 10 showed strong radical scavenging activity in comparison with vitamin C. The plausible biosynthetic pathways for compounds 1, 2, and 4-8 were discussed.     

Prenylated phloroglucinol derivatives from Hypericum sampsonii

Six new acylphloroglucinol derivatives, sampsonols A-F (1–6), were isolated from the petroleum ether extract of the aerial parts of Hypericum sampsonii. The structures and relative configurations of sampsonols A-F were elucidated by extensive spectroscopic analyses. All these compounds were tested for their in vitro cytotoxic and anti-inflammatory activities. Sampsonols A and B (1 and 2) showed significant cytotoxicity against four human tumor cell lines with IC₅₀ values in the range of 13–28 μM, whereas sampsonols C and F (3 and 6) showed potent inhibitory activities against LPS-induced NO production in RAW 264.7 macrophages with IC₅₀ values of 27.3 and 29.3 μM, respectively.     

Neuroprotective activity of galloylated cyanogenic glucosides and hydrolysable tannins isolated from leaves of Phyllagathis rotundifolia

The galloylated cyanogenic glucosides based on prunasin (1-7), gallotannins (8-14), ellagitannins (15-17), ellagic acid derivatives (18, 19) and gallic acid (20) isolated from the leaves of Phyllagathis rotundifolia (Melastomataceae) were investigated for their neuroprotective activity against hydrogen peroxide (H₂O₂)-induced oxidative damage in NG108-15 hybridoma cell line. Among these compounds, the gallotannins and ellagitannins exhibited remarkable neuroprotective activities against oxidative damage in vitro as compared to galloylated cyanogenic glucosides and ellagic acid derivatives in a dose-dependent manner. They could be explored further as potential natural neuroprotectors in various remedies of neurodegenerative diseases.