Neli Kika Honda

A química dos liquens

Lichens are symbiotic associations between fungi and algae and/or cyanobacteria. They produce common intracellular products including proteins, amino acids, polyols, carotenoids, polysaccharides and vitamins. The secondary metabolites found in lichens are phenolics which accumulate either on the cortex or on the cell walls of medullary hyphae and they are mainly acetyl-polimalonyl pathway derivatives. Polysaccharides, proteins and secondary metabolites produced by lichens have attracted the attention of investigators due their biological activities. This revision coments about the biosynthetic origin and structures of the principal classes of compounds produced by these organisms.

Evaluation of anti-Mycobacterium tuberculosis activity of Campomanesia adamantium (Myrtaceae)

The anti-Mycobacterium tuberculosis activity of Campomanesia adamantium fruits extracts were evaluated. Six compounds, identified as flavanones and chalcones were quantified by HPLC-DAD-UV. Promising antitubercular activity was observed with ethyl acetate extract (MIC 62.5 μg/mL) and their fractions (MIC values ranging from 39 to above 250 μg/mL). The better MIC result of 39 μg/mL was associated with two fractions that contain bigger amounts of 5,7-dihydroxy-6, 8-di-C-methylflavanone and 2’,4’-dihydroxy-3’,5’dimethyl-6’-methoxychalcone. These compounds exhibited MICs >250 and 62.5 μg/mL, respectively, while their mixtures showed values ranging from 62.5 to 7.8 μg/mL, demonstrating a synergism between them.

Determination of phenolic compounds and evaluation of antioxidant capacity of Campomanesia adamantium leaves

Five flavanones and three chalcones were isolated from Campomanesia adamantium Berg. (Myrtaceae) leaves. The contents of these compounds were determined by HPLC. The phe- nolic contents were also determined. The monitoring of the antioxidant activity was carried out by inhibition of peroxidation using the linoleic acid system and radical-scavenging (DPPH). The plants were collected from 4 distinct cities of the Mato Grosso do Sul State, Brazil. The different samples exhibited a range of 4.67-232.35 mg/g chalcones and 15.62-50.71 mg/g flavanones and phe- nolic contents of the 7.24-21.19 mg/g gallic acid. All extracts showed high antioxidant activity with a wide range of the radical-scavenging (DPPH) from 52.0 to 92.2 % and inhibition oxidation of linole- ic acid from 14.6 to 94.2%.

Rapid determination of furanocoumarins in creams and pomades using SPE and GC

A solid-phase extraction and chromatography-flame ionization detection (GC-FID) method has been developed for the routine analysis of psoralen, bergapten, isopimpinellin and pimpinellin in creams and pomades employed in Brazil for the treatment of vitiligo. The calibration curve for psoralen was linear in the range 10-100 microg ml(-1), for bergapten 5-90 microg ml(-1), for pimpinellin 10-90 microg ml(-1) and for isopimpinellin 5-100 microg ml(-1). The best recoveries of the furanocoumarins in the creams analysed were 94-97%, whereas in the pomades, recoveries were 94-96%. The R.S.D. of the quantitative-analysis of the furanocoumarins in the products analyses were within 5%.

Gas Chromatography-Mass Spectrometry (GC-MS) and evaluation of antioxidant and antimicrobial activities of essential oil of Campomanesia adamantium (Cambess.) O. Berg (Guavira)

The essential oils from Campomanesia adamantium (Cambess.) O. Berg leaves, collected in the reproductive (flowering and fruit-bearing) and vegetative stages, were characterized by GC-MS (Gas Chromatography-Mass Spectrometry). A total of 95 compounds of the essential oils were identified. In the reproductive stage (flowering) the major constituents were monoterpenes (limonene, α-pinene and β-pinene) while during the vegetative stage the major constituents were the sesquiterpenes (bicyclogermacrene and globulol). The essential oil of the reproductive stage shows high antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans, and all show moderate activity against Escherichia coli. The essential oils were also evaluated for their radical-scavenging activity by DPPH. The chemogeographical variations of the oil composition from the four distinct localities studied all contained α-pinene, β-pinene, limonene, linalool, β-caryophyllene, germacrene D and bicyclogermacrene, however the samples from Jardim city contained neither limonene nor linalool.

Simple and rapid determination of psoralens in topic solutions using liquid chromatography.

A method for sample preparation and high-performance liquid chromatography detection and quantification has been developed for the routine analysis of psoralen and bergapten, photosensitizing compounds, in topic solutions employed in Brazil for treatment of vitiligo and psoriasis. The linearity, accuracy, the inter- and intra-day precision of the procedure were evaluated. The calibration curve for psoralen and bergapten were linear in the range 1.0-20.0 microg ml(-1). The best recoveries of the psoralens in the topic solutions analysed were 96.3-98.2%. The percentage coefficient of variation of the quantitative analysis of the psoralens in the product analyses was within 5%.

Antimicrobial Activity of the Extracts and Fractions of Hexanic Fruits of Campomanesia Species (Myrtaceae)

The antimicrobial activity of the hexanic extracts and fractions of fruits of Campomanesia pubescens pubescens (D.C) O. Berg and Campomanesia adamantium (Cambess.) O. Berg were assayed against six microorganisms. The hexanic extracts of C. pubescens and C. adamantium fruits were also investigated in their composition by gas chromatography-mass spectrometry and high-performance liquid chromatography with diode array detection. The results of this study showed the presence of 34 volatile compounds and flavonoids in the hexanic extract of C. pubescens and 33 volatile compounds and flavonoids in the hexanic extract of C. adamantium.

Qualitative determination of indole alkaloids, triterpenoids and steroids of Tabernaemontana hilariana

Abstract This paper reports the separation and identification of indole alkaloids, steroids and triterpenoids from the ethanolic extracts of Tabernaemontana hilariana (Apocynaceae). The alkaloidal fractions from the ethanolic extracts obtained (root barks, green fruits, ripe fruits and seeds) were fractionated and analysed by thin-layer chromatography, capillary gas chromatography–flame ionization detection (cGC–FID) as well as by high-resolution gas chromatography–mass spectrometry (HRGC–MS). 3-Hydroxycoronaridine, ibogamine, coronaridine pseudoindoxyl, coronaridine, catharanthine, voacangine hydroxyindolenine, voacangine pseudoindoxyl, tabernanthine, tetraphyllicine, 3-hydroxyvoacangine, voacangine, isovoacangine and 3-oxocoronaridine were identified. The insoluble fraction of ethanolic extracts obtained from the root barks and green fruits were analysed and ten aliphatic constituents were also identified by cGC–FID and HRGC–MS.

Influência da variação sazonal nos teores de flavonóides e atividade antioxidante das folhas de Campomanesia adamantium (Cambess.) O. Berg, Myrtaceae

Campomanesia adamantium (Cambess.) O. Berg, Myrtaceae, is a native species. The extracts of ethyl acetate and hexane showed little variation in their chemical composition at different seasons of the year associated with the development of the plant, while the ethanol extract showed significant change in relationship to chemical composition. All ethanol extracts showed high antioxidant activity against DPPH method and from moderate to high antioxidant activity for β-carotene/linoleic acid.

Antibacterial activity of orsellinates

In order to obtain new compounds with antibacterial activity, the derivatives 2,4-dihydroxy-6-methylbenzoic acid (orsellinic acid) and 2,4-dihydroxy-6-methylbenzoates (orsellinates) were obtained through alcoholyses of lecanoric acid. All these substances were tested against Gram-positive and Gram-negative bacteria by a microdilution method. Staphylococcus aureus, Xanthomonas campestris var. vesicatoria and Ralstonia solanacearum were most sensitive to n-propyl 2,4-dihydroxy-6-methylbenzoate, n-pentyl 2,4-dihydroxy-6-methylbenzoate and n-hexyl 2,4-dihydroxy-6-methylbenzoate with MIC (Minimal Inhibitory Concentration) values ranging from 62.5 to 7.8 µg×mL1. These results showed that homologation in carbon chain may lead to compounds with more pronunced activities.