RESUMO

This work aimed to rectify Cunila galioides essential oil and evaluate the raw oil and the fractions' antifungal, allelopathic, and antioxidant activities. The results showed that the raw essential oil and the bottom fraction were primarily composed of linalyl propionate (42.9 wt.% and 60.2 wt.%). The top fraction was composed mainly of limonene (45.7 wt.%). The antioxidant activity changed with the radical and the fraction. The bottom had a weaker antifungal effect than the raw oil and the top. Nevertheless, the essential oil and the fractions had a similar antifungal activity at 0.50 % v/v and higher. Similar behavior was observed for the allelopathic tests. No difference occurred between the raw oil and the fractions, with reduced germination percentages and speed at 0.25 % v/v and complete inhibition at 0.50 % v/v. The oil can be rectified, and the fractions may be used without harming their biological activity.

RESUMO

Coriolopsis rigida was isolated as an endophytic fungus from the medicinal plant Cochlospermum regium, and their production of secondary metabolites has not yet been investigated. Thus, the endophyte was cultivated on rice solid media to evaluate its ability to produce bioactive compounds and then the chloroform extract was obtained. Two phenolic compounds, tyrosol (1) and a new natural product p-hydroxyphenylacetamide (2), were isolated from the extract. The structures of the compounds were elucidated mainly by NMR. The extract showed potent antioxidant activity with an efficient concentration (EC50) value of 0.33 mg mL-1. Additionally, demonstrated allelopathic activity inhibited the seedling growth of Lactuca sativa L. and Raphanus sativus L. by 63% and 55%, respectively.

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The in-vitro antioxidant activity of Rhaponticum acaule essential oil (RaEO) was evaluated using ß-carotene/linoleic acid bleaching, chelating activity, and lipid peroxidation inhibition (TBARS) assays. The antimicrobial activity of RaEO was assessed by disc diffusion and microdilution methods against 8 bacteria and 4 yeast. Finally, the allelopathic activity of RaEO on the seed germination and the shoot and root elongation of lettuce (Lactuca sativa L.) seedlings were investigated. According to our results, the RaEO exhibited significant antioxidant activity, similar to those of standards (BHT and ascorbic acid) with IC50 values of 0.042 and 0.045 mg/mL obtained by ß-carotene bleaching and TBARS assays, respectively. On the other hand, despite its interesting ferrous chelating activity, RaEO possesses moderate IC50 value (0.35 mg/mL) as compared with that of EDTA (0.015 mg/mL). RaEO exhibited a strong antimicrobial activity against all the tested microorganisms, with IZ, MIC and MBC values being in the range of 7.67 ± 0.58 to 13.33 ± 0.58 mm, 1.25 to 5.00 and 5.00 to 10.00 mg/mL, respectively. The results reveled also that RaEO inhibited the shoot and root growth of Lactuca sativa L. seedlings. Our data suggested that the RaEO had pharmaceutical benefits and could be used as a potential natural herbicide resource

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The use of kaurane diterpenes as substrates in fungal biotransformation to achieve bioactive compounds has been widely reported. In this work, the natural product kaurenoic acid, a diterpene widely distributed in the plant Kingdom, was chemically converted into ent-15α-hydroxy-kaur-16-en-19-oic acid (1). Substrate 1 was subjected to biotransformation by the fungus Fusarium proliferatum, furnishing a new derivative, ent-2α,15α-dihydroxy-kaur-16-en-19-oic acid (2). The structure of metabolite 2 was deduced on the basis of spectroscopy and MS data. Derivative 2 showed allelopathic activity on germination and growth of root and stem of lettuce (Lactuca sativa), inhibiting 100% of germination and growth of roots and stem, at higher concentration assayed (10-4 mol/L).

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Despite the increase in recent decades in herbicide research on the potential of native plants, current knowledge is considered to be low. Very few studies have been carried out on the chemical profile or the biological activity of the Brazilian savanna (Cerrado) species. In the study reported here, the allelopathic activity of AcOEt and MeOH extracts of leaves, stems, and roots from Ocotea pulchella Nees was evaluated. The extracts were assayed on etiolated wheat coleoptiles. The AcOEt leaf extract was the most active and this was tested on standard target species (STS). Lycopersicon esculentum and Lactuca sativa were the most sensitive species in this test. A total of eleven compounds have been isolated and characterized. Compounds 1, 2, 4, and 6 have not been identified previously from O. pulchella and ocoteol (9) is reported for the first time in the literature. Eight compounds were tested on wheat coleoptile growth, and spathulenol, benzyl salicylate, and benzyl benzoate showed the highest activities. These compounds showed inhibitory activity on L. esculentum. The values obtained correspond to the activity exhibited by the extract and these compounds may therefore be responsible for the allelopathic activity shown by O. pulchella.

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A bio-guided optimization of the extraction of bioactive components from Annona glabra leaves has been developed using the etiolated wheat coleoptile bioassay as the control method. The optimization of an ultrasound-assisted extraction of bioactive compounds using allelopathy results as target values has been carried out for the first time. A two-level fractional factorial experimental design was applied to optimize the ultrasound-assisted extraction. The solvent was the extraction variable that had the most marked effect on the resulting bioactivity of the extracts in the etiolated wheat coleoptile bioassay. Extraction time, extraction temperature and the size of the ultrasonic probe also influenced the bioactivity of the extracts. A larger scale extraction was carried out in the next step in the allelopathic study, i.e., the isolation of compounds from the bioactive extract and chemical characterization by spectroscopic techniques, including NMR. Eight compounds were isolated and identified from the active extracts, namely two steroids (ß-sistosterol and stigmasterol), five diterpenes with the kaurane skeleton (ent-kaur-16-en-19-oic acid, ent-19-methoxy-19-oxokauran-17-oic acid, annoglabasin B, ent-17-hydroxykaur-15-en-19-oic acid and ent-15ß,16ß-epoxy-17-hydroxy-kauran-19-oic acid) and the acetogenin asimicin. The most active compound was annoglabasin B, which showed inhibition with values of -95% at 10(-3) M, -87% at 5×10(-4) M and greater than -70% at 10(-4) M in the etiolated wheat coleoptile bioassay.

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Objetivou-se com este trabalho avaliar a atividade alelopática, antioxidante e o conteúdo de fenóis e flavonóides totais no extrato metanólico de quatro plantas medicinais: Hibiscus sabdariffa, Ocimum gratissimum, Palicourea crocea e Trichilia silvatica. Para isso, folhas, flores e caules de Trichilia silvatica, folhas de Palicourea crocea, cálice e folhas de Hibiscus sabdariffa e folhas de Ocimum gratissimum foram utilizados. A avaliação da atividade alelopática foi realizada pelo ensaio de germinação e crescimento inicial de sementes de alface (Lactuca sativa), com três repetições de 50 sementes em delineamento inteiramente casualizado. A atividade antioxidante foi determinada pelo método fotocolorimétrico in vitro do radical livre estável 2,2-difenil-1-picril-hidrazila (DPPH). O crescimento das plântulas de alface foi mais sensível à ação dos aleloquímicos presentes nos extratos metanólicos do que a germinação das sementes, e evidenciaram o efeito inibitório dos extratos metanólicos do cálice e folhas de H. sabdariffa e das folhas de O. gratissimum e P. crocea. Os extratos metanólicos obtidos das folhas, flores e casca de T. silvatica apresentaram maior capacidade de sequestrar radicais livres com valores de IC50 de 62,36; 19,4 18,38 µg mL-1, no ensaio com DPPH e maior teor de compostos fenólicos 520,80; 545,27 e 546,56 mg de ácido gálico g de amostra-1, respectivamente, avaliado pelo ensaio de Folin-Ciocalteau.

The aim of this work was to evaluate allelopathic and antioxidant activity and total flavonoids and phenols content in methanolic extract of four medicinal plants: Hibiscus sabdariffa, Ocimum gratissimum, Palicourea crocea and Trichilia silvatica. Leaves (TSFo), flowers (TSFl) and stems (TSCa) of T. silvatica; leaves (PCFo) of P. crocea; chalice (HSCa) and leaves (HSFo) of H. sabdariffa and leaves of O. gratissimum (OGFo) were used in experiment. The evaluation of allelopathic activity was carried out by test of seed germination and initial growth of lettuce seedlings (Lactuca sativa), with three replications of 50 seeds in completely randomized design. The antioxidant activity was determined by method photo colorimetric in vitro of stable free radical 2.2-diphenyl-1-picrylhydrazyl (DPPH). The growth of lettuce seedlings was more sensitive to the action of allelochemicals in methanolic extracts than seeds germination, and showed the inhibitory effect of methanolic extracts from leaves and chalice of H. sabdariffa and leaves of O. gratissimum and P. crocea. Methanolic extracts obtained from the leaves (TSFo), flowers (TSFl) and bark (TSCa) of T. silvatica showed higher ability to scavenging free radical with IC50 values of 62.36; 19.4 18.38 µg mL-1, in assay with DPPH and highest content of phenolics, 520.80; 545.27 546.56 mg gallic acid per g of sample, respectively, evaluated by the Folin-Ciocalteau assay.

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