Isolation and purification of potential weed inhibitors from Mimosa pigra L.

The diversity in structure and herbicidal properties detected in natural phytotoxic compounds could bring about advantages for development bio-herbicides. The present study was carried out search for potential weed inhibitors from the parts of Mimosa pigra L. The ethyl acetate (EtOAc) extract of leaf of M. pigra showed inhibitory activity during the time that Echinochloa crus-galli (barnyardgrass) germinates and grows, which is greater than that of other extracts. From this active extract, potent growth inhibitors were isolated and identified by column chromatography (CC), gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (1H and 13C NMR). The six compounds were purified in this study namely: lupeol (C1, 13.2 mg), stigmastane-3,6-dione (C2, 14.7 mg), quercetin (C3, 20.2 mg), chrysoeriol (C4, 28 mg), methyl gallate (C5, 21.5 mg) and daucosterol (C6, 16.0 mg). The C2 (quercetin) compound completely inhibited the emergency, shoot height and root length of E. crus-galli at 1 mg/mL concentration (IC50 shoot height = 0.56 mg/mL). This was also the first study to report the isolation and allelopathic activity of lupeol, chrysoeriol and daucosterol from M. pigra leaf. Findings of this study highlighted that quercetin from M. pigra may become bio-herbicide to control barnyard grass and other grass weeds for the development of safe agriculture.

The insecticidal capacity of ethanol extract from Cascabela peruviana (L.) Lippold against fruit fly.

Cascabela peruviana (L.) Lippold (C. peruviana) has been extensively used for its antifungal and antibacterial properties. However, its role in anti-insect is still under investigation. To investigate the ability of the ethanol extract of C. peruviana against insects, we used the fruit fly (Drosophila melanogaster) as a model to gain more insight into the toxic effects of this extract. We found that the ethanol extract from the stem and leaves of C. peruviana was effective against insects and contained polyphenol and flavonoid compounds. C. peruviana could induce mortality of 2nd-instar larvae and reduce growth and reproduction of fruit flies. Interestingly, the toxicity of C. peruviana extract has been remained to affect the development of the next generation of fruit flies. The locomotor activity and feeding ability of the F1 generation of this insect were significantly reduced by C. peruviana. In addition, flavonoids and polyphenols, as well as saponins and tannins were detected in the ethanol extract of C. peruviana. We assume that the ability of the extract of C. peruviana to control insects may be related to the presence of high levels of these compounds. The findings highlighted that the extract from the leaves of Cascabela peruviana has the potential to be used as an insecticide.

Identification of Pathogens Causing Anthracnose on King Oranges (Citrus nobilis var. Typica Hassk).

<b>Background and Objective:</b> Anthracnose is one of the main causes seriously affecting the fruit yield and quality of king oranges. This study aimed to identify the fungal pathogen <i>Colletotrichum gloeosporioides</i> causing anthracnose on king oranges in Vinh Long. <b>Materials and Methods:</b> Fruits with diseases were collected from the king orange garden located in Vinh Long in September, 2020. Firstly, symptoms of infected fruits were observed and recorded. Next, pathogens were isolated from these fruits and then tested using the Koch procedure. Specifically, the isolated strains of fungi were identified based on their morphological traits and ITS sequences on rRNA amplified by a pair of primers ITS1/ITS4. <b>Results:</b> A pure culture of the identified fungus was later artificially inoculated into healthy fruits for 1 week to confirm its pathogenicity. The fungal spores were cylindrical, rounded or obtuse at 2 ends, 12.8-16.4 mm in length and 3.47-5.27 mm in width. The ITS sequence of <i>Colletotrichum</i> causing anthracnose on king oranges had similar to the following sequences found on the Genbank with percent identities ranging from 97.93-98.29%. In the ITS sequence, the composition of GC was higher than that of AT, with 52.72% against 47.28%, respectively. The results of phylogeny demonstrated that the genetic sequence of the fungus causing anthracnose on king oranges had a close relationship with that of other species of <i>Colletotrichum </i>found on NCBI. <b>Conclusion:</b> The findings show that <i>Colletotrichum gloeosporioides</i>, a type of fungi, was the cause of anthracnose in king orange grown in Vinh Long province.