A study of the phytotoxic effects of the aerial parts of Senecio westermanii Dusén (Asteraceae) on Lactuca sativa L. and Allium cepa L. seeds

The objective of this study was to evaluate the effects of the ethanolic crude extracts and fractions of the species Senecio westermanii Dusén on Lactuca sativa L. (lettuce) and Allium cepa L. (onion) seeds. We assessed the germination, growth, root respiration and photosynthesis of the target species in Petri dishes (9.0 cm diameter) containing filter paper n°6. The study was conducted using 50 seeds per plate and held in 4 replicates per concentration of each sample. In the germination there was an inhibitory effect of fractions hexane (FH) and chloroform (FCl) at concentrations of 500 and 1000 µg/mL. There was a reduction in the radicle growth of lettuce by 14 to 24% and a reduction of hypocotilum by 14 to 28%. As for the radicle of the onion was up 74% reduction to the FCl and the coleoptile was 24 and 45% reduction for FH and FCl, respectively. Inhibitory effects in the root respiration of lettuce were detected in all the samples analyzed, with results ranging from 16 to 83%. For the seeds of A. cepa, there was an encouragement for the FCl and ethyl acetate fractions (FAE), with results ranging from 94 to 142% and 76 to 150%, respectively. With regard to the photosynthesis of L. sativa, there was no significant difference between the control, and as for the A. cepa, there was a strain in inhibition concentrations of 250 and 500 µg/mL, which ranged from 27 to 68%. The samples of S. westermanii caused changes in the target species and thus can be used as a natural herbicide.

Avaliação da atividade antioxidante e antimicrobiana do extrato etanólico bruto e frações orgânicas obtidas a partir da casca do caule da espécie Guettarda uruguensis Cham, & Scthdl, (Rubiaceae) / Assessment of the antioxidant and antimicrobial activity of the crude ethanolic extract and organic fractions obtained from the stem bark of the specie Guettarda uruguensis Cham. & Scthdl. (Rubiaceae)

Este trabalho teve como objetivo avaliar o potencial antioxidante e antimicrobiano do extrato bruto e frações obtidas das cascas do caule da espécie Guettarda uruguensis, Os ensaios antioxidantes indicaram alto potencial antioxidante, No ensaio de redução de fosfomolibdênio, a fração acetato de etila apresentou atividade antioxidante de 41,67% em relação ao padrão de ácido ascórbico e superou em 35,21% a atividade do padrão rutina, No ensaio de redução do DPPH (2,2-diphenyl-1-picrylhydrazyl), a fração acetato de etila apresentou um IC50 de 10,91 µg mL-1, valor próximo ao do ácido ascórbico (IC50 = 4,78 µg mL-1) e da rutina (IC50 = 6,62 µg mL-1), Pelo ensaio de TBA (acido tiobabitúrico) o extrato bruto (IA = 71,48%) e a fração hexano (IA = 47,85%) apresentaram índices superiores ao controle de BHT (butil hidroxi tolueno) (IA = 42,66), Através do ensaio de microdiluição em placas, foi observado que o extrato bruto e frações apresentaram atividade antimicrobiana, O estudo fitoquímico qualitativo revelou a presença de alcaloides, cumarinas, esteroides e/ou triterpenos, heterosídeos saponínicos, taninos e aminogrupos...

This main purpose of this study was to evaluate the antimicrobial and antioxidant effects of the crude extract and fractions obtained from the stem bark of the plant species. The antioxidant assays indicated high antioxidant capacity. In the reduction assay of the phosphomolybdenum, the ethyl acetate fraction showed antioxidant activity of 41.67% compared to standard ascorbic acid and exceeded in 35.21% the activity of the standard rutin. In the reduction assay of the DPPH (2,2-diphenyl-1-picrylhydrazyl), the ethyl acetate fraction showed an IC50 of 10.91 µg mL-1, equivalent to the ascorbic acid (IC50 = 4.78 µg mL-1) and rutin (IC50 = 6.62 µg mL-1). By the TBA (thiobarbituric acid) assay the crude extract (IA = 71.48%) and hexane fraction (IA = 47.85%) had an index higher than the control of BHT (butyl hydroxy toluene) (IA = 42.675). Through of assay of microdilution on plates was verified that the crude extract and fractions showed antimicrobial activity. The qualitative phytochemical study revealed the presence of alkaloids, coumarins, steroids and/or triterpenoids, saponin glycosides, tannins and amino groups...