Camila G. de Almeida

Comparative Properties of Amazonian Oils Obtained by Different Extraction Methods

Pequi (Caryocar brasiliense Camb.), babaçu (Orbignya phalerata Mart.), buriti (Mauritia flexuosa), and passion fruit (Passiflora edulis) oils were studied to determine their antibacterial, antioxidant and cytotoxic activities, as well as their total phenol and carotenoid contents. The fatty acid contents were determined by GC-MS. The three types of passion fruit oils studied were refined, cold pressed or extracted from seeds in a Soxhlet apparatus. The oils thus obtained showed differences in antioxidant activity and carotenoid content, but were similar in regard to total phenols. Buriti and pequi had the highest carotenoid contents, while refined and cold pressed passion fruit oil displayed the highest antioxidant activity. Pequi oil was the only oil to display antibacterial and cytotoxic activity.

Relationship between structure and antibacterial activity of lipophilic N-acyldiamines

We report in this work the preparation and antibacterial evaluation of a series of N-monoacylated diamines against six Gram-positive and 11 Gram-negative bacteria. The results obtained showed the existence of relationship between lipophilicity and antibacterial activity of the tested compounds. The best results were obtained against Gram-positive bacteria for compounds having a 10-12 carbons alkyl chain. Compound 4e was the most active against Microccus lentus (MIC=2 microg/mL), Staphylococcus aureus ATCC 29213 (MIC=4 microg/mL) and Enterobacter aerogenes CDC 1680 (MIC=8 microg/mL).

Synthesis and Antibacterial Activity of Aromatic and Heteroaromatic Amino Alcohols

Two series of aromatic and heteroaromatic amino alcohols were synthesized from alcohols and aldehydes and evaluated for their antibacterial activities. All the octylated compounds displayed a better activity against the four bacteria tested when evaluated by the agar diffusion method and were selected for the evaluation of minimal inhibitory concentration. The best results were obtained for p‐octyloxybenzyl derivatives against Staphylococcus epidermidis (minimal inhibitory concentrations = 32 μm).

Antileishmanial activity of aldonamides and N-acyl-diamine derivatives.

A number of lipophilic N-acyl-diamines and aldonamides have been synthesized and tested for their in vitro antiproliferative activity against Leishmania amazonensis and L. chagasi. Ribonamides, having one amino group, displayed good to moderate inhibition of parasite growth. The best result was obtained for compounds 10 and 15 with IC50 against L. chagasi below 5 μM.

Raman Spectroscopic Investigation of Carotenoids in Oils from Amazonian Products

ABSTRACT In this work several different natural products from the Amazon forest were analyzed by means of Raman spectroscopy, using the 1064-nm laser line as a way to obtain the spectra. All the oil samples from handmade produced buriti, babaçu, and pequi, as well as the refined andiroba, cold-pressed passion flower, and palm oils, were acquired in the local market in Brazil. Some products present in all the spectra of the ν(C˭C) vibration, observed in the 1525 cm−1 region, the ν(C-C) mode near 1158 cm−1, and the ρ(C-CH3) mode near 1008 cm−1, can be seen; all these bands are assigned generally to the presence of a C9 carotenoid and can be more precisely attributed to the ν1, ν2, and δ modes of β-carotene. Also, the characteristic Raman scattering bands common to all the oils arising from vibrations of the hydrocarbon chains can be observed, namely, aromatic ring C˭C stretching at 1658 cm−1 (ν(C˭C)); CH2 scissoring deformation at 1439 cm−1 (δ(CH2); vibrations of in-phase methylene twisting at 1301 cm−1, and symmetric CH rocking in unconjugated cis-double bonds at 1270 cm−1 (δ(C–H)), as well as C˭O stretching from the ester groups at 1747 cm−1 [ν(C˭O)]. It is noteworthy that most natural oils have a major contribution of components of some of the main fatty acids: palmitic (C16), oleic (C18:1), and linoleic (C18:2), and no carotenoid was detected in the Raman spectra of the white babaçu oil or in the pale yellow andiroba oil. As a major conclusion, direct Raman spectroscopic measurements using a near-infrared wavelength as the excitation source can be used as a primary test to monitor the quality control of natural oils extracted from the Amazon forest, namely, andiroba, burity, babaçu, and pequi oils.

Activity of pyrrolizidine alkaloids against biofilm formation and Trichomonas vaginalis.

Crotalaria genus belongs to the subfamily Papilionoideae comprising about 600 species spread throughout tropical, neotropical and subtropical regions. In this study, seeds of Crolatalaria pallida were used to the isolation of usaramine, a pyrrolizidine alkaloid. Thus, Pseudomonas aeruginosa and Staphylococcus epidermidis were utilized as strains to test some activities of this alkaloid, such as antibiofilm and antibacterial. Meanwhile, monocrotaline obtained from Crotalaria retusa seeds, was used as the starting material for synthesis of necine base derivatives with anti-Trichomonas vaginalis potential. Alkaloids were characterized by 1D and 2D NMR techniques and GC-MS analysis. Usaramine demonstrated a highlighted antibiofilm activity against S. epidermidis by reducing more than 50% of biofilm formation without killing the bacteria, thus it could be assumed as a prototype for the development of new antibiofilm molecules for pharmaceutical and industrial purposes. Monocrotaline activity against T. vaginalis was evaluated and results indicated inhibition of 80% on parasite growth at 1mg/mL, in addition, neither cytotoxicity against vaginal epithelial cells nor hemolytic activity were observed. On the other hand, retronecine showed no anti-T. vaginalis activity while azido-retronecine was more active than monocrotaline killing 85% of the parasites at 1mg/mL. In conclusion, pyrrolizidine alkaloids are suggested as promising prototypes for new drugs especially for topical use.

Synthesis and Antibacterial Activity of Alkylated Diamines and Amphiphilic Amides of Quinic Acid Derivatives

Different series of N‐alkylated diamines and their derivatives condensed to quinic acid were synthesized and tested for antibacterial properties against Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Mycobacterium tuberculosis. The lipophilic chain and carbohydrate moiety modulate the antibacterial activity and the compounds showed a structure–activity relationship. Overall, 11 compounds displayed better activity than chloramphenicol against Gram‐positive and Gram‐negative bacteria. Monoalkylated amines 2a‐h displayed an activity similar to that of ethambutol against Mycobacterium tuberculosis.

Antibacterial Activity of Lipophilic Fluoroquinolone Derivatives

We report in this work the antibacterial evaluation of 12 lipophilic fluoroquinolone derivatives containing diaminoalkyl side chains at C-7 position. The compounds were investigated against 15 bacterial strains including gram-negative and gram-positive species of clinical and microbiological importance. Three compounds (5, 10 and 11) were as active as or more efficient than gatifloxacin against gram-positive bacteria M. lentus. When compared with gatifloxacin compound 10 was 16 times more active. Two compounds (11 and 12) were twice more active than the reference compound against S. aureus.