In Vitro and In Silico Studies of the Antimicrobial Activity of Prenylated Phenylpropanoids of Green Propolis and Their Derivatives against Oral Bacteria.

Artepillin C, drupanin, and plicatin B are prenylated phenylpropanoids that naturally occur in Brazilian green propolis. In this study, these compounds and eleven of their derivatives were synthesized and evaluated for their in vitro antimicrobial activity against a representative panel of oral bacteria in terms of their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values. Plicatin B (2) and its hydrogenated derivative 8 (2',3',7,8-tetrahydro-plicatin B) were the most active compounds. Plicatin B (2) displayed strong activity against all the bacteria tested, with an MIC of 31.2 µg/mL against Streptococcus mutans, S. sanguinis, and S. mitis. On the other hand, compound 8 displayed strong activity against S. mutans, S. salivarius, S. sobrinus, Lactobacillus paracasei (MIC = 62.5 µg/mL), and S. mitis (MIC = 31.2 µg/mL), as well as moderate activity against Enterococcus faecalis and S. sanguinis (MIC = 125 µg/mL). Compounds 2 and 8 displayed bactericidal effects (MBC: MIC ≤ 4) against all the tested bacteria. In silico studies showed that the complexes formed by compounds 2 and 8 with the S. mitis, S. sanguinis, and S. mutans targets (3LE0, 4N82, and 3AIC, respectively) had energy score values similar to those of the native S. mitis, S. sanguinis, and S. mutans ligands due to the formation of strong hydrogen bonds. Moreover, all the estimated physicochemical parameters satisfied the drug-likeness criteria without violating the Lipinski, Veber, and Egan rules, so these compounds are not expected to cause problems with oral bioavailability and pharmacokinetics. Compounds 2 and 8 also had suitable ADMET parameters, as the online server pkCSM calculates. These results make compounds 2 and 8 good candidates as antibacterial agents against oral bacteria.

In vitro Evaluation of the Antileishmanial and Antischistosomal Activities of p-Coumaric Acid Prenylated Derivatives.

We have evaluated eight p-coumaric acid prenylated derivatives in vitro for their antileishmanial activity against Leishmania amazonensis promastigotes and their antischistosomal activity against Schistosoma mansoni adult worms. Compound 7 ((E)-3,4-diprenyl-4-isoprenyloxycinnamic alcohol) was the most active against L. amazonensis (IC50=45.92 µM) and S. mansoni (IC50=64.25 µM). Data indicated that the number of prenyl groups, the presence of hydroxyl at C9, and a single bond between C7 and C8 are important structural features for the antileishmanial activity of p-coumaric acid prenylated derivatives.

Antibacterial, Antiparasitic, and Cytotoxic Activities of Chemical Characterized Essential Oil of Chrysopogon zizanioides Roots.

This study aimed to investigate the chemical composition as well as the antibacterial, antiparasitic, and cytotoxic potentialities of the Brazilian Chrysopogon zizanioides root essential oil (CZ-EO) In addition, CZ-EO cytotoxicity to LLCMK2 adherent epithelial cells was assessed. The major compounds identified in CZ-EO were khusimol (30.0 ± 0.3%), ß-eudesmol (10.8 ± 0.3%), α-muurolene (6.0 ± 0.1%), and patchouli alcohol (5.6 ± 0.2%). CZ-EO displayed optimal antibacterial activity against Prevotella nigrescens, Fusobacterium nucleatum, Prevotella melaninogenica, and Aggregatibacter actinomycetemcomitans, with Minimum Inhibitory Concentration (MIC) values between 22 and 62.5 µg/mL and Minimum Bactericidal Concentration (MBC) values between 22 and 400 µg/mL. CZ-EO was highly active against the L. amazonensis promastigote and amastigote forms (IC50 = 7.20 and 16.21 µg/mL, respectively) and the T. cruzi trypomastigote form (IC50 = 11.2 µg/mL). Moreover, CZ-EO showed moderate cytotoxicity to LLCMK2 cells, with CC50 = 565.4 µg/mL. These results revealed an interesting in vitro selectivity of CZ-EO toward the L. amazonensis promastigote and amastigote forms (Selectivity Index, SI = 78.5 and 34.8, respectively) and the T. cruzi trypomastigote form (SI = 50.5) compared to LLCMK2 cells. These results showed the promising potential of CZ-EO for developing new antimicrobial, antileishmanial, and antitrypanosomal drugs.

Hexane extract from Spiranthera odoratissima A. St.-hil. leaves: chemical composition and its bioactive potential against Candida pathogenic species, Leishmania amazonensis and Xylella fastidiosa.

Spiranthera odoratissima A. St.-Hil. (Rutaceae) has been popularly used against abdominal pain and rheumatism. This study aimed at extracting hexane from S. odoratissima (HE-SO) leaves to identify and quantify its volatile compounds by GC-MS and GC-FID and to evaluate its antifungal, antileishmanial and antibacterial activities in vitro. HE-SO exhibited antileishmanial activity against promastigote forms of Leishmania (Leishmania) amazonensis (IC50 = 38.16 µg/mL) and was moderately active against Xylella fastidiosa (MIC = 100 µg/mL). HE-SO also showed remarkable antifungal potential against six strains of Candida species, i. e., C. albicans, C. glabrata, C. parapsilosis, C. krusei, C. tropicalis and C. orthopsilosis. The lowest MIC values were between 31.25 and 250 µg/mL. Spathulenol (20.2%), τ-cadinol (11.7%), α-cadinol (9.4%), caryophyllene oxide (9.2%) and isoaromadendrene epoxide (8.2%) were the major components identified in HE-SO. Therefore, results showed that HE-SO has promising antileishmanial and antifungal actions.

Trypanocidal Activity of Dysphania ambrosioides, Lippia alba, and Tetradenia riparia Essential Oils against Trypanosoma cruzi.

Despite the current treatments against Chagas Disease (CD), this vector-borne parasitic disease remains a serious public health concern. In this study, we have explored the in vitro and/or in vivo trypanocidal and cytotoxic activities of the essential oils (EOs) obtained from Dysphania ambrosioides (L.) Mosyakin & Clemants (Amaranthaceae) (DA-EO), Lippia alba (Mill.) N.E. Brown (Verbenaceae) (LA-EO), and Tetradenia riparia (Hochst.) Codd (Lamiaceae) (TR-EO) grown in Brazil Southeast. DA-EO was the most active against the trypomastigote and amastigote forms in vitro; the IC50 values were 8.7 and 12.2 µg mL-1 , respectively. The EOs displayed moderate toxicity against LLCMK2 cells, but the DA-EO showed high selectivity index (SI) for trypomastigote (SI=33.2) and amastigote (SI=11.7) forms. Treatment with 20 mg/kg DA-EO, LA-EO, or TR-EO for 20 days by intraperitoneal administration reduced parasitemia by 6.36 %, 4.74 %, and 32.68 % on day 7 and by 12.04 %, 27.96 %, and 65.5 % on day 9. These results indicated that DA-EO, LA-EO, and TR-EO have promising trypanocidal potential in vitro, whereas TR-EO has also potential trypanocidal effects in vivo.

In vitro anti-Trypanosoma cruzi activity enhancement of curcumin by its monoketone tetramethoxy analog diveratralacetone.

Chagas disease is a tropical disease caused by the protozoan parasite Trypanosoma cruzi and currently affects millions of people worldwide. Curcumin (CUR), the major constituent of turmeric spice (dry powder of Curcuma longa L. plant rhizomes and roots), exhibits antiparasitic activity against protozoan parasites in vitro. However, because of its chemical instability, poor cellular uptake and limited bioavailability it is not suitable for clinical use. The objective of this study was to synthesize and evaluate in vitro CUR monoketone analog dibenzalacetone (DBA 1) and its non-phenolic, methoxy (2-4) and chloro (5) derivatives for better stability and bioavailability against T. cruzi. Diveratralacetone, the tetramethoxy DBA (DBA 3), was found to be the CUR analog with most enhanced activity against the amastigote forms of four strains of T. cruzi tested (Brazil, CA-I/72, Sylvio X10/4 and Sylvio X10/7) with 50% inhibitory concentration (IC50) < 10 µM (1.51-9.63 µM) and selectivity index (SI) > 10 (C2C12 non-infected mammalian cells). This was supplemented by time-course assessment of its anti-T. cruzi activity. DBA 1 and its dimethoxy (DBA 2) and hexamethoxy (DBA 4) derivatives were substantially less active. The inactivity of dichloro-DBA (DBA 5) was indicative of the important role played by oxygenated groups such as methoxy in the terminal aromatic rings in the DBA molecule, particularly at para position to form reactive oxygen species essential for anti-T. cruzi activity. Although the DBAs and CUR were toxic to infected mammalian cells in vitro, in a mouse model, both DBA 3 and CUR did not exhibit acute toxicity or mortality. These results justify further optimization and in vivo anti-T. cruzi activity evaluation of the inexpensive diveratralacetone for its potential use in treating Chagas disease, a neglected parasitic disease in economically challenged tropical countries.

Biological properties and chemical composition of essential oil from Nectandra megapotamica (Spreng.) Mez. leaves (Lauraceae).

Nectandra megapotamica is a tree species that naturally occurs in the Atlantic Forest, Brazil. This paper aims to investigate the chemical composition and in vitro antibacterial, antileishmanial and antiproliferative activities of essential oil from N. megapotamica leaves (NM-EO). It displayed high antibacterial activity against Streptococcus mutans, S. sobrinus, Prevotella nigrescens and Bacteroides fragilis. NM-EO also exhibited high antileishmanial activity against promastigote forms of Leishmania amazonensis. Its antiproliferative activity was evaluated against the following cells: GM07429A (normal cell), MCF-7 (human breast adenocarcinoma), HeLa (human cervical adenocarcinoma) and M059J (human glioblastoma). Its major components, which were determined by GC-FID and GC-MS, were α-bisabolol (13.7%), bicyclogermacrene (10.9%), (E,E)-farnesene (10.6%), Z-caryophyllene (9.5%) and (E)-ß-farnesene (7.0%). These results suggest that N. megapotamica, a Brazilian plant, shows initial evidence of a new and alternative source of substances of medicinal interest.

Electrospray ionization tandem mass spectrometry of monoketone curcuminoids.

RATIONALE: Although monoketone curcuminoids (MKCs) have been largely investigated due to their biological activities, data on the gas-phase fragmentation reactions of protonated MKCs under collision-induced dissociation (CID) conditions are still scarce. Here, we combined electrospray ionization tandem mass spectrometry (ESI-MS/MS) data, multiple-stage mass spectrometry (MSn ), deuterium exchange experiments, accurate-mass data, and thermochemical data estimated by computational chemistry to elucidate and to rationalize the fragmentation pathways of eleven synthetic MKCs. METHODS: The MKCs were synthesized by Claisen-Schmidt condensation under basic (1-9) or acidic (10-11) conditions. ESI-CID-MS/MS analyses and deuterium-exchange experiments were carried out on a triple quadrupole mass spectrometer. MSn analyses on an ion trap mass spectrometer helped to elucidate the fragmentation pathways. Accurate-mass data and thermochemical data, obtained at the B3LYP/6-31+G(d,p) level of theory, were used to support the ion structures. RESULTS: The most intense product ions were the benzyl ions ([C7 H2 R1 R2 R3 R4 R5 ]+ ) and the acylium ions ([M + H - C8 H3 R1 R2 R3 R4 R5 ]+ ), which originated directly from the precursor ion as a result of two competitive hydrogen rearrangements. Product ions [M + H - H2 O]+ and [M + H - C6 HR1 R2 R3 R4 R5 ]+ , which are formed after Nazarov cyclization, were also common to all the analyzed compounds. In addition, •Br and •Cl eliminations were diagnostic for the presence of these halogen atoms at the aromatic ring, whereas •CH3 eliminations were useful to identify the methyl and methoxy groups attached to this same ring. Nazarov cyclization in the gas phase occurred for all the investigated MKCs and did not depend on the presence of the hydroxyl group at the aromatic ring. However, the presence and the position of a hydroxyl group at the aromatic rings played a key role in the Nazarov cyclization mechanism. CONCLUSIONS: Our results reinforce some aspects of the fragmentation pathways previously published for 1,5-bis-(2-methoxyphenyl)-1,4-pentadien-3-one and 1,5-bis-(2-hydroxyphenyl)-1,4-pentadien-3-one. The alternative fragmentation mechanism proposed herein can explain the fragmentation of a wider diversity of monoketone curcuminoids.

Geraniol and linalool anticandidal activity, genotoxic potential and embryotoxic effect on zebrafish.

AIM: Geraniol and linalool are major constituents of the essential oils of medicinal plants. MATERIALS & METHODS: Antifungal activity of geraniol and linalool were evaluated against five Candida species. The genotoxicity of these compounds was evaluated by the cytokinesis-block micronucleus test, and the embryotoxic assays use zebrafish model. RESULTS: Geraniol and linalool inhibited Candida growth, but geraniol was more effective. The geraniol at concentration of 800 µg/ml and the linalool at concentration of 125 µg/ml significantly increased chromosome damage. Geraniol was more toxic to zebrafish embryo than linalool: LC50 values were 31.3 and 193.3 µg/ml, respectively. CONCLUSION: Geraniol and linalool have anticandidal activity, but they also exert genotoxic and embryotoxic effects at the highest tested concentrations.

Antimicrobial Activity of Monoketone Curcuminoids Against Cariogenic Bacteria.

We evaluated the antimicrobial activity of 25 monoketone curcuminoids (MKCs) against a representative panel of cariogenic bacteria in terms of their minimum inhibitory concentration (MIC) values. Curcumin A (10) displayed promising activity against Streptococcus mutans (MIC = 50 µg/ml) and Streptococcus mitis (MIC = 50 µg/ml) as well as moderate activity against S. sanguinis (MIC = 100 µg/ml), Lactobacillus casei (MIC = 100 µg/ml), and Streptococcus salivarius (MIC = 200 µg/ml). Results indicated higher activity of compound 10 than that of its bis-ß-diketone analog. Additionally, compounds 3a (1,5-bis(4-methylphenyl)pentan-3-one) and 7b (1,5-bis(4-bromophenyl)pentan-3-ol) were moderately active against S. mitis (MIC = 100 µg/ml) and S. salivarus (MIC = 200 µg/ml).