Sodium Nitroprusside Improves the Growth and Behavior of the Stomata of Silybum marianum L. Subjected to Different Degrees of Drought

The use of growth-stimulating signals to increase the tolerance of plants to water deficits can be an important strategy in the production of plants in dry areas. Therefore, a split-plot experiment with three replications was conducted to evaluate the effects of sodium nitroprusside (SNP) application rate as an NO donor (0, 100, and 200 µM) on the growth and yield parameters of Silybum marianum L. (S. marianum) under different irrigation cut-off times (control, irrigation cut-off from stem elongation, and anthesis). The results of this study showed that with increasing drought severity, leaf RWC, proline content and capitula per plant, 1000 grain weight, plant height, branch per plant, capitula diameter, and the biological and grain yield of S. marianum decreased significantly, whereas the number of grains per capitula increased compared with the control. Also, by irrigation cut-off from the stem elongation stage, the density of leaf stomata at the bottom and top epidermis increased by 64% and 39%, respectively, and the length of the stomata at the bottom epidermis of the leaf decreased up to 28%. In contrast, the results of this experiment showed that the exogenous application of nitric oxide reduced the negative effects of irrigation cut-off, such that the application of 100 µM SNP enhanced RWC content (up to 9%), proline concentration (up to 40%), and grain (up to 34%) and biological (up to 44%) yields in plants under drought stress compared with non-application of SNP. The decrease in the number of capitula per plant and capitula diameter was also compensated by foliar application of 100 µM SNP under stress conditions. In addition, exogenous NO changed the behavior of the stomata during the period of dehydration, such that plants treated with SNP showed a decrease in the stomatal density of the leaf and an increase in the length of the stomata at the leaf bottom epidermis. These results indicate that SNP treatment, especially at 100 µM, was helpful in alleviating the deleterious effects of water deficiency and enhancing the tolerance of S. marianum to withholding irrigation times.

Investigation on the Essential Oils of the Achillea Species: From Chemical Analysis to the In Silico Uptake against SARS-CoV-2 Main Protease

In this study, phytochemicals extracted from three different Achillea genera were identified and analyzed to be screened for their interactions with the SARS-CoV-2 main protease. In particular, the antiviral potential of these natural products against the SARS-CoV-2 main protease was investigated, as was their effectiveness against the SARS-CoV-1 main protease as a standard (due to its high similarity with SARS-CoV-2). These enzymes play key roles in the proliferation of viral strains in the human cytological domain. GC-MS analysis was used to identify the essential oils of the Achillea species. Chemi-informatics tools, such as AutoDock 4.2.6, SwissADME, ProTox-II, and LigPlot, were used to investigate the action of the pharmacoactive compounds against the main proteases of SARS-CoV-1 and SARS-CoV-2. Based on the binding energies of kessanyl acetate, chavibetol (m-eugenol), farnesol, and 7-epi-β-eudesmol were localized at the active site of the coronaviruses. Furthermore, these molecules, through hydrogen bonding with the amino acid residues of the active sites of viral proteins, were found to block the progression of SARS-CoV-2. Screening and computer analysis provided us with the opportunity to consider these molecules for further preclinical studies. Furthermore, considering their low toxicity, the data may pave the way for new in vitro and in vivo research on these natural inhibitors of the main SARS-CoV-2 protease.

How do essential oil composition and phenolic acid profile of Heracleum persicum fluctuate at different phenological stages?

Heracleum persicum, commonly named Persian hogweed, is a principal native medicinal plant in Iran. Collecting H. persicum at the most appropriate growing stage is the key factor to achieve the high phytochemical quality to meet consumer's needs. In the present experiment, the aerial parts of this plant were harvested at up to six different developmental stages during the growing season to determine the phytochemical profiles. Our results indicated that the highest essential oil content was obtained in the mid-mature seed stage (3.5%). The most elevated extract content was recorded in the floral budding stage (10.4%). In the vegetative stage, limonene (18.1%), in floral budding stage, caryophyllene (14.1%), anethole (14.6%), and β-bisabolene (12.7%), in the full flowering stage, myristicin (15.0%), and hexyl butyrate (9.1%), in the early development of seeds stage, hexyl butyrate (32.1%), and octyl acetate (11.7%), in the mid-mature seeds stage hexyl butyrate (38.8%), octyl acetate (14.5%), in the late-mature/ripe seeds stage, hexyl butyrate (23.6%), and octyl acetate (10.5%) are recorded as the main components. The highest phenolic acids content was obtained in the floral budding stage (287.40 mg/g dried extract). The analysis of phenolic acids demonstrated cinnamic acid (8.0-225.3 mg/g extract), p-coumaric acid (1.7-39.2 mg/g extract), p-hydroxybenzoic acid (0.8-16.8 mg/g extract), and ferulic acid (2.4-15.8 mg/g extract) as the main phenolic acids. Cinnamic acid was found as the major phenolic compound in the vegetative stage following by floral budding, the full flowering stage, the early development of seeds, and late-mature/ripe seeds stages. P-coumaric acid was the most abundant phenolic compounds in the mid-mature seeds stage. In this regard, the harvest time of H. persicum aerial parts can be selected to achieve the highest secondary metabolites of interest. The results of this study can be used as a guideline for grower to obtain the highest possible amount of desirable metabolites, beneficial in both food and pharmaceutical industries as well as their undeniable economical benefits.