Leandro Rocha

HLB value, an important parameter for the development of essential oil phytopharmaceuticals

Essential oils are used primarily as natural preservatives, flavourants and fragrances in cosmetic products. Several pharmacopeias possess monographs of plants which are good sources of essential oils, such as Brazilian Pharmacopeia, including Illicium verum Hook. f., Schisandraceae and Rosmarinus offi cinalis. Since determination of Hydrophile-Lipophile Balance (HLB) value of essential oils appears as a critical step for development of emulsions and other semi-solid formulations, evaluation of required HLB values for I. verum and R. offi cinalis essential oils is the aim of this study. They were obtained by hydrodistillation and several emulsions were prepared by changing emulsifiers. The couple sorbitan oleate/polysorbate 20 provided best emulsions and was used at different ratios, at a total blend concentration of 5% w/w. The lowest mean droplet diameters for R. offi cinalis and I. verum emulsions were obtained at HLB 16.5 (97.12 nm) and 16.7 (246.6 nm), respectively. Moreover, emulsions with R. offi cinalis were finer and presented some bluish reflection, characteristic of nanoemulsions. The lowest turbidity value for R. offi cinalis emulsion was also obtained at HLB 16.5 (0.33). Thus, the present study describes for the first time HLB values for R. offi cinalis (16.5) and I. verum (16.7) essential oils, contributing to their physicochemical characterization and technology development of phytopharmaceuticals.

Chemical composition and antibacterial activity of Brazilian propolis essential oil

The present study aimed at investigating the chemical composition of essential oil extracted from Brazilian propolis and the susceptibility of Staphylococcus aureus, Staphylococcus epidermides, Streptococcus pyogenes and Escherichia coli to this substance. The essential oil was obtained by steam distillation of propolis and examined by gas chromatography/mass spectrometry (GC/MS). In addition, the agar diffusion method using filter paper disks was employed. Antibacterial activity was measured as equivalent diameters of inhibition zones (in millimeters) after incubation at 37o C for 24 hours. From the 26 identified constituents, β-caryophyllene (12.7%), acetophenone (12.3%) and β-farnesene (9.2%) were found to be major components. New components, namely linalool, methyl hydrocinnamate, ethyl hydrocinnamate, α-ylangene, γ-elemene and valencene, are reported for the first time to be present in propolis essential oil. This oil also exhibited antibacterial activity.

Atividade antibacteriana de floroglucinóis e do extrato hexânico de Hypericum brasiliense Choysi

Three phloroglucinols were obtained from Hypericum brasiliense: japonicine A (1), isouliginosin B (2) and uliginosin B (3). Bioautography and disk diffusion methods were used to determine antibacterial activity of the hexanic extract. Strains of the Coagulase Negative Staphylococcus and American Methicillin Resistant Staphylococcus aureus clones showed a growth inhibition zone ranging from 10 to 12 mm and 7 to 15 mm, respectively. Minimal inhibitory concentration (MIC) values were used to measure antistaphylococcal activity for all phloroglucinols. Isouliginosin B and uliginosin B presented MIC values of 1.5 and 3.0 µg/mL, respectively, while japonicine A displayed MIC value of 50.0 µg/mL.

Effects of the essential oil obtained from Pilocarpus spicatus Saint-Hilaire (Rutaceae) on the development of Rhodnius prolixus nymphae

Bioassays against fifth-instar nymphae of Rhodnius prolixus were conducted with essential oil of Pilocarpus spicatus extracted by hydrodistillation. The main results may be summarized as follows: (i) high levels of toxicity and paralysis together with discrete moulting inhibition were caused by topical application of either 0.5 µL or 1.0 µL per insect of the crude essential oil; (ii) partial fagoinhibition, high moulting inhibition, prolonged intermoulting period and high number of paralyzed insects, but no toxicity were observed after oral treatment using either 5 µL or 10 µL of Pilocarpus spilcatus essential oil per mL of ingested blood meal. The importance of these results in relation to the relevant biological events in R. prolixus is herein discussed.

Avaliação da atividade IMAO e antibacteriana de extratos de Mikania glomerata Sprengel

Antibacterial and IMAO inhibition activities of different polarities extracts of Mikania glomerata were evaluated. The antibacterial activity was assayed against a multiresistant strain of Staphyllococus aureus PI57. The IMAO activity was measured with a suspension of mitochondrion. In the hexanic extract of Mikania glomerata substances with antibacterial activity were detected. Hexanic and CH2Cl2 extracts showed MAO-B inhibition activity while MAO-A inhibition activity was not detected. The methanolic extract showed non-selective inhibition activity of MAO-A and MAO-B.

Otimização do processo de extração de própolis através da verificação da atividade antimicrobiana

Bee glue (propolis) possesses antimicrobial, antiinflammatory, anaesthetic and immunostimulating activities. Propolis composition is extraordinary variable; samples from different geographic origin may posses entirely different chemical composition. In different propolis samples, various substance combinations are responsible for the antibacterial activity of the bee glue. The aim of the study was to evaluate the best ethanolic extract concentration using Staphylococcus aureus multiresistant. Ethanol extracts from different concentration (10 to 90%) were applied on paper disks, dried, and put on the surface of nutrient agar plates with the overlay containing S. aureus. The plates were then incubated and evaluated the next day for the presence of inhibition zones. The best result was verified among 60 to 90% of ethanolic extract of propolis. This paper suggests the use of the alcool 70% as the ideal for the extration of propolis.

Mikania glomerata Spreng: desenvolvimento de um produto fitoterápico

Although the pharmacological activity of Mikania glomerata Spreng. has been well known for a long time, there are a few studies concerning the elaboration of phytopharmaceutical products that assure an uniform preparation, effective doses and stability. In this work, tests with the objective of the optimization of the extraction process were performed; treatment of the plant drug for preparation of tinctures; determination of the adequate form of storage and the optimization of the preparation of the pharmaceutical form (syrup).

Development of an insecticidal nanoemulsion with Manilkara subsericea (Sapotaceae) extract

BackgroundPlants have been recognized as a good source of insecticidal agents, since they are able to produce their own defensives to insect attack. Moreover, there is a growing concern worldwide to develop pesticides with low impact to environment and non-target organisms. Hexane-soluble fraction from ethanolic crude extract from fruits of Manilkara subsericea and its triterpenes were considered active against a cotton pest (Dysdercus peruvianus). Several natural products with insecticidal activity have poor water solubility, including triterpenes, and nanotechnology has emerged as a good alternative to solve this main problem. On this context, the aim of the present study was to develop an insecticidal nanoemulsion containing apolar fraction from fruits of Manilkara subsericea.ResultsIt was obtained a formulation constituted by 5% of oil (octyldodecyl myristate), 5% of surfactants (sorbitan monooleate/polysorbate 80), 5% of apolar fraction from M. subsericea and 85% of water. Analysis of mean droplet diameter (155.2 ± 3.8 nm) confirmed this formulation as a nanoemulsion. It was able to induce mortality in D. peruvianus. It was observed no effect against acetylcholinesterase or mortality in mice induced by the formulation, suggesting the safety of this nanoemulsion for non-target organisms.ConclusionsThe present study suggests that the obtained O/A nanoemulsion may be useful to enhance water solubility of poor water soluble natural products with insecticidal activity, including the hexane-soluble fraction from ethanolic crude extract from fruits of Manilkara subsericea.

Triterpene Esters and Biological Activities from Edible Fruits of Manilkara subsericea (Mart.) Dubard, Sapotaceae

Manilkara subsericea (Mart.) Dubard (Sapotaceae) is popularly known in Brazil as “guracica.” Studies with Manilkara spp indicated the presence of triterpenes, saponins, and flavonoids. Several activities have been attributed to Manilkara spp such as antimicrobial, antiparasitic and antitumoral, which indicates the great biological potential of this genus. In all, 87.19% of the hexanic extract from fruits relative composition were evaluated, in which 72.81% were beta- and alpha-amyrin esters, suggesting that they may be chemical markers for M. subsericea. Hexadecanoic acid, hexadecanoic acid ethyl ester, (E)-9-octadecenoic acid ethyl ester, and octadecanoic acid ethyl ester were also identified. Ethanolic crude extracts from leaves, stems, and hexanic extract from fruits exhibited antimicrobial activity against Staphylococcus aureus ATCC25923. These extracts had high IC50 values against Vero cells, demonstrating weak cytotoxicity. This is the first time, to our knowledge, that beta- and alpha-amyrin caproates and caprylates are described for Manilkara subsericea.

Antiherpetic activity of a flavonoid fraction from Ocotea notata leaves

This study describes the isolation of a flavonoid fraction from leaves of Ocotea notata (Nees & Mart.) Mez, Lauraceae, the identification of six major compounds (an A-type proanthocyanidin trimer [3], isoquercitrin [4], reynoutrin [5], miquelianin [6], quercitrin [7], afzelin [8]) and four minor compounds (catechin [1], epicatechin [2], quercetin [9], kaempferol [10]) present in the fraction and its activity against the Herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2). The 50% effective concentrations values (EC50) calculated from the dose-response curve and the selectivity indices (SI) against the virus were: EC50 35.8 µg/mL and SI 5.5 to HSV-1 and EC50 23.5 µg/mL and SI 8.5 to HSV-2. The flavonoid fraction was more active against HSV-2 than HSV-1. The mechanisms of antiviral action of the flavonoid fraction against the virus were also evaluated. The percentage inhibition (PI) obtained for HSV-2 was higher than 90% in the following assays: virucidal, pre-treatment of cells, treatment of cells after viral adsorption and treatment of cells after viral penetration. For HSV-1, the flavonoid fraction had no effect in pre-treatment of cells and showed 60% of inhibition in virucidal assay.