A Study on the Phytotoxic Potential of the Seasoning Herb Marjoram (Origanum majorana L.) Leaves

Extensive analysis of the cultivated medicinal herbal drug Origanum dictamnus L. and antimicrobial activity of its constituents

Phytochemical investigations of the methanol extract from Origanum dictamnus L. (Lamiaceae) resulted in the isolation of forty compounds belonging to the classes of terpenes, resorcinol derivatives, flavonoids, depsides, neolignans and jasmonates. Chromatographic isolations were targeted by using two analytical platforms, NMR and HPLC-PDA-MS. In parallel, HPLC-PDA-MS of individual fractions enabled the unambiguous identification of additionally eight components. In total 48 constituents were isolated/identified. Among the isolated constituents are four undescribed compounds, one resorcinol derivative, one monoterpene, one diterpene and one acylated flavonoid glycoside. The structures of the isolated compounds were elucidated on the basis of spectroscopic analyses, including 1D and 2D NMR, and HPLC-ESI-MS and HRMS experiments. Representative compounds were tested for their antimicrobial activity against Staphylococcus aureus and Pseudomonas aeruginosa. I4-II7-dicarvacrol was the most potent constituent.

Modulation of Immunity, Antioxidant Status, Performance, Blood Hematology, and Intestinal Histomorphometry in Response to Dietary Inclusion of Origanum majorana in Domestic Pigeons’ Diet

This experiment was conducted to evaluate the effect of adding Origanum majorana (OM) powder to domestic pigeon diets on growth performance, feeding and drinking behaviour, blood hematology, blood biochemical parameters, blood inflammatory and oxidative markers, carcass characteristics, the weights of lymphoid organs, and and intestinal cecal, and bursa of Fabricius histology. A random distribution of fifty-four unsexed pigeon squabs (30 days old, average body weight; 321 g ± 7.5) into three groups was done. The first group was fed the grower basal diet without adding OM powder, while OM powder was added at levels of 0.5 and 1% to the basal diets of the second and third groups, respectively. The changes in growth performance parameters and feeding and drinking behavior under OM powder’s effect were insignificant. However, the lymphoid organs (spleen and thymus) significantly increased in weight (p < 0.05) in the OM-fed groups. Moreover, blood examination showed positive responses to OM powder in terms of blood cell counts (RBCs andWBCs), and the values of hemoglobin, hematocrit, mean corpuscular volume, lymphocyte numbers, levels of globulin, and glutathione peroxidase enzyme were significantly increased. The numbers of heterophils, the ratio of heterophil to lymphocyte, malondialdehyde levels were reduced (p < 0.05). Histomorphometry examination revealed increases in intestinal villi height, cecal thickness, and bursal follicle area and number. These results indicated that adding OM powder to the pigeon diet may improve their immunity, increase their antioxidant status, and correct some hematological disorders.

Phytofabrication of Silver Nanoparticles and Their Potent Antifungal Activity against Phytopathogenic Fungi

Fungal plant pathogens cause huge losses in agricultural production by decreasing crop yield and quality. To reduce crop loss from fungal damage, various synthetic fungicides are applied indiscriminately in agricultural practice. The majority of synthetic fungicides are non-biodegradable, and several critical human health risks are associated with them. Green synthesis nanotechnology offers an effectual, cost-effective, ecofriendly, and innocuous method for the synthesis of green nanofungicides, an excellent replacement for synthetic chemical fungicides. Origanum majorana is an aromatic herb with immense pharmacological and medicinal properties. In this context, the present study used the leaves of O. majorana to synthesize silver nanoparticles. The biosynthesized particles showed an absorption peak at 441 nm with ultraviolet-visible spectrophotometry (UV-Vis). The spectra obtained from Fourier transform infrared spectroscopy (FT-IR) of O. majorana extract and AgNPs showed a myriad of functional groups corresponding to vital biomolecules that act as capping and reducing agents. The synthesized silver nanoparticles were spheroidal, and their size measured between 8 nm and 42 nm, as depicted by transmission electron microscopy (TEM). The energy-dispersive X-ray spectrum (EDX) showed a silver peak at 3 keV. The phytofabricated silver NPs demonstrated robust inhibitory activity on the mycelial growth of A. alternata f sp. lycopersici (87%), followed by Pestalotiopsis mangiferae (85%), Macrophomina phaseolina (78%), and Colletotrichum musae (75%). The minimum inhibitory concentration value for A. alternata. f sp. lycopersici and Pestalotiopsis mangiferae was 2 μg/mL, while the minimum fungicidal concentrations were 4 and 8 μg/mL, respectively. Additionally, the fabricated AgNPs induced severe damaging and destructive effects to the morphology of hyphae and conidia, as witnessed by scanning electron microscopy studies.

Essential Oil Coating: Mediterranean Culinary Plants as Grain Protectants against Larvae and Adults of Tribolium castaneum and Trogoderma granarium

Simple Summary

The protection of stored agricultural products has been established as a global priority serving both food safety and security. Toxicity and residual issues of synthetic insecticides shifted the research focus towards natural pest control agents. In this context, six edible plants were selected for the conduction of a novel bioprospecting effort aiming to identify potential control agents against the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) and the khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae). The proposed bioprospecting effort aims to identify the chemodiversity of essential oils (EOs) and exploit the potential of EO-based microemulsion (ME) coating as alternative tools for the management of the tested stored-product insects and the concomitant postharvest losses. Elevated toxicity was recorded against T. castaneum larvae and T. granarium adults. The fact that these EO-based MEs originate from culinary plants renders them safe for human consumption. The present study pioneers the utilization of EO-based MEs as grain protectants in the form of grain coating.

Abstract

Postharvest agricultural losses constitute a major food security risk. In contrast, postharvest protection is strongly linked with food safety. The present study aims to develop novel postharvest protection tools through a bioprospecting protocol utilizing edible essential oils (EOs) as grain coatings. For this purpose, six Mediterranean culinary plants were selected for evaluation. The EOs of juniper, Juniperus phoenicea L. (Pinales: Cupressaceae), marjoram, Origanum majorana L. (Lamiales: Lamiaceae), oregano, Origanum vulgare ssp. hirtum (Link) A.Terracc. (Lamiales: Lamiaceae), bay laurel, Laurus nobilis L. (Laurales: Lauraceae) and tarhan, Echinophora tenuifolia ssp. sibthorpiana (Guss.) Tutin (Apiales: Apiaceae) were retrieved through steam distillation, while lemon, Citrus limon (L.) Osbeck (Sapindales: Rutaceae) EO was retrieved through cold press extraction. All EOs were formulated to microemulsions (MEs) and applied uniformly as a coating on wheat against larvae and adults of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) and Trogoderma granarium Everts (Coleoptera: Dermestidae). All EO-based MEs have been evaluated for the first time as grain coatings. They caused moderate to high mortality to T. castaneum larvae (67.8–93.3% 14 days post-exposure) and T. granarium adults (70.0–87.8% after 7 days of exposure). Citrus limon, O. majorana and E. tenuifolia ssp. sibthorpiana EO-based MEs were the most efficient against T. castaneum larvae, by exhibiting 93.3%, 91.1% and 90.0% mortality 14 days post-exposure, respectively. Origanum majorana, L. nobilis and J. phoenicea EO-based MEs were the most efficient against T. granarium adults, exhibiting 87.8%, 84.4% and 83.3% mortality after 7 days of exposure, respectively. These results indicate that EO-based ME coating is a potent tool against the tested postharvest pests.

Origanum majorana L.: A Nutritional Supplement With Immunomodulatory Effects

Origanum majorana L. is an aromatic herb that has been grown in several Mediterranean countries since ancient times, but became popular during the Middle Ages as a medicinal plant and seasoning ingredient. O. majorana has many pharmacological effects, but its immunoreactive components and mechanisms are still unclear. In this study, four compounds were isolated and identified from O. majorana by a spectral analysis, including ¹H and ¹³C-NMR. They were 1H-indole-2-carboxylic acid (1), (+)-laricresol (2), (+)-isolaricresol (3), and procumboside B (4, pB), which were isolated for the first time in O. majorana. The immunomodulatory effects of the four compounds were screened, and pB had good immunomodulatory activity on RAW 264.7 cells. The immunomodulatory mechanism of pB was proved, in which pB could increase the secretion of nitric oxide (NO), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and reactive oxygen species (ROS) and simultaneously upregulate the expression of CD80 and CD86 on the cell surface. These results suggested that the mechanism of pB may be related to the activation of nuclear factor-kappaB (NF-κB) and mitogen-activated protein kinases (MAPKs)-signaling pathways. O. majorana is rich in nutrients and is commonly used in diets, so it can be used as a nutritional supplement with immunomodulatory effects.

Bioactive Diterpenes from the Brazilian Native Plant (Moquiniastrum pulchrum) and Their Application in Weed Control

Even today, weeds continue to be a considerable problem for agriculture. The application of synthetic herbicides produces serious environmental consequences, and crops suffer loss of their activity due to the appearance of new resistant weed biotypes. Our aim is to develop new effective natural herbicides that improve the problem of resistance and do not harm the environment. This work is focused on a bioassay-guided isolation and the characterization of natural products present in Moquiniastrum pulchrum leaves with phytotoxic activity and its preliminary application in weeds. Moquiniastrum pulchrum was selected for two reasons: it is an abundant species in the Cerrado region (the second most important ecosystem in Brazil, after the Amazon)—the explanation behind its being a dominant species is a major focus of interest—and it has traditional employment in folk medicine. Six major compounds were isolated in this plant: one flavone and five diterpenes, two of which are described for the first time in the literature. Four of the six compounds exhibited phytotoxic activity in the bioassays performed. The results confirmed the phytotoxic potential of this plant, which had not been investigated until now.