Chemical Composition and Biological Activity of Essential Oil and Extract from the Seeds of Tropaeolum majus L. var. altum

Chemical Profile of Kumquat (Citrus japonica var. margarita) Essential Oil, In Vitro Digestion, and Biological Activity

Kumquat is one of the smallest citrus fruits (from the Rutaceae family), and its essential oil's biological effects have not yet been sufficiently researched, in contrast to the essential oils of its relatives. Therefore, the aim of this large-scale study was to investigate the chemical profile of kumquat essential oils (KEOs) isolated by microwave-assisted distillation (MAD) and Clevenger hydrodistillation using GC-MS analysis. To test the bioaccessibility of their bioactive components, in vitro digestion with commercially available enzymes was performed. The final step of this research was to test their cytotoxic activity against a cervical cancer cell line (HeLa), a human colon cancer cell line (HCT116), a human osteosarcoma cell line (U2OS), and a healthy cell line (RPE1). Two methods were used to test the antioxidant activity: DPPH (2,2-diphenyl-1-picrylhydrazyl) and ORAC (oxygen radical absorbance capacity). The antibacterial activity was tested in relation to the growth and adhesion of Escherichia coli and Staphylococcus aureus on a polystyrene surface. The GC-MS analysis showed that the major compound in both kumquat essential oils was limonene, which was stable before and after in vitro digestion (>90%). The results showed that the cytotoxic activity of the KEOs in all three cancer cell lines tested was IC50 1-2 mg/mL, and in the healthy cell line (RPE1), the IC50 value was above 4 mg/mL. The antibacterial activity of the KEOs obtained after MAD and Clevenger hydrodistillation was 4 mg/mL against E. coli and 1 mg/mL against S. aureus. The KEOs after MAD and Clevenger hydrodistillation reduced the adhesion of E. coli by more than 1 log, while there was no statistically significant effect on the adhesion of S. aureus to the polystyrene surface. Both KEOs exhibited comparable levels of antioxidant activity using both methods tested, with IC50 values of 855.25 ± 26.02 μg/mL (after MAD) and 929.41 ± 101.57 μg/mL (after Clevenger hydrodistillation) for DPPH activity and 4839.09 ± 91.99 μmol TE/g of EO (after MAD) and 4928.78 ± 275.67 μmol TE/g of EO (after Clevenger hydrodistillation) for ORAC. The results obtained show possible future applications in various fields (e.g., in the food, pharmaceutical, cosmetic, and agricultural industries).

Antimalarial Activity of Aqueous Extracts of Nasturtium (Tropaeolum majus L.) and Benzyl Isothiocyanate

Malaria remains an important and challenging infectious disease, and novel antimalarials are required. Benzyl isothiocyanate (BITC), the main breakdown product of benzyl glucosinolate, is present in all parts of Tropaeolum majus L. (T. majus) and has antibacterial and antiparasitic activities. To our knowledge, there is no information on the effects of BITC against malaria. The present study evaluates the antimalarial activity of aqueous extracts of BITC and T. majus seeds, leaves, and stems. We used flow cytometry to calculate the growth inhibition (GI) percentage of the extracts and BITC against unsynchronized cultures of the chloroquine-susceptible Plasmodium falciparum 3D7 - GFP strain. Extracts and/or compounds with at least 70% GI were validated by IC50 estimation against P. falciparum 3D7 - GFP and Dd2 (chloroquine-resistant strain) unsynchronized cultures by flow cytometry, and the resistance index (RI) was determined. T. majus aqueous extracts showed some antimalarial activity that was higher in seeds than in leaves or stems. BITC's GI was comparable to chloroquine's. BITC's IC50 was similar in both strains; thus, a cross-resistance absence with aminoquinolines was found (RI < 1). BITC presented features that could open new avenues for malaria drug discovery.

Co-inoculation of the endophytes Bacillus thuringiensis CAPE95 and Paenibacillus polymyxa CAPE238 promotes Tropaeolum majus L. growth and enhances its root bacterial diversity

Tropaeolum majus L. is a versatile edible plant that is widely explored due to its medicinal properties and as a key element in intercropping systems. Its growth could be improved by the use of biofertilizers that can enhance nutrient uptake by the plant or provide tolerance to different abiotic and biotic stresses. In a previous study, 101 endophytes isolated from T. majus roots showed more than three plant growth-promoting (PGP) features in vitro, such as phosphate mineralization/solubilization, production of siderophores, antimicrobial substances and indole-related compounds, and presence of the nifH gene. To provide sustainable alternatives for biofertilization, the genomes of two promising endophytes-CAPE95 and CAPE238-were sequenced to uncover metabolic pathways related to biofertilization. Greenhouse experiments were conducted with 216 seeds and 60 seedlings, half co-inoculated with the endophytes (treatment) and half inoculated with 1X PBS (control), and the impact of the co-inoculation on the plant's bacteriome was accessed through 16S rRNA gene metabarcoding. The strains CAPE95 and CAPE238 were taxonomically assigned as Bacillus thuringiensis and Paenibacillus polymyxa, respectively. Metabolic pathways related to the enhancement of nutrient availability (nitrogen fixation, sulfate-sulfur assimilation), biosynthesis of phytohormones (indole-3-acetic acid precursors) and antimicrobial substances (bacilysin, paenibacillin) were found in their genomes. The in vivo experiments showed that treated seeds exhibited faster germination, with a 20.3% higher germination index than the control on the eleventh day of the experiment. Additionally, treated seedlings showed significantly higher plant height and leaf diameters (p < 0.05). The bacterial community of the treated plants was significantly different from that of the control plants (p < 0.001) and showed a higher richness and diversity of species (Chao and Shannon indexes, p < 0.001). A higher relative abundance of potential synergistic PGP bacteria was also shown in the bacteriome of the treated plants, such as Lysinibacillus and Geobacter. For the first time, co-inoculation of B. thuringiensis and P. polymyxa was shown to have great potential for application as a biofertilizer to T. majus plants. The bacterial consortium used here could also be explored in other plant species in the future.

Significant Benefits of Environmentally Friendly Hydrosols from Tropaeolum majus L. Seeds with Multiple Biological Activities

Tropaeolum majus L. is a traditional medicinal plant with a wide range of biological activities due to the degradation products of the glucosinolate glucotropaeolin. Therefore, the goals of this study were to identify volatiles using gas chromatography-mass spectrometry analysis (GC-MS) of the hydrosols (HYs) isolated using microwave-assisted extraction (MAE) and microwave hydrodiffusion and gravity (MHG). Cytotoxic activity was tested against a cervical cancer cell line (HeLa), human colon cancer cell line (HCT116), human osteosarcoma cell line (U2OS), and healthy cell line (RPE1). The effect on wound healing was investigated using human keratinocyte cells (HaCaT), while the antibacterial activity of the HYs was tested against growth and adhesion to a polystyrene surface of Staphylococcus aureus and Escherichia coli. Antiphytoviral activity against tobacco mosaic virus (TMV) was determined. The GC-MS analysis showed that the two main compounds in the HYs of T. majus are benzyl isothiocyanate (BITC) and benzyl cyanide (BCN) using the MAE (62.29% BITC and 15.02% BCN) and MHG (17.89% BITC and 65.33% BCN) extraction techniques. The HYs obtained using MAE showed better cytotoxic activity against the tested cancer cell lines (IC50 value of 472.61-637.07 µg/mL) compared to the HYs obtained using MHG (IC50 value of 719.01-1307.03 μg/mL). Both concentrations (5 and 20 µg/mL) of T. majus HYs using MAE showed a mild but statistically non-significant effect in promoting gap closure compared with untreated cells, whereas the T. majus HY isolated using MHG at a concentration of 15 µg/mL showed a statistically significant negative effect on wound healing. The test showed that the MIC concentration was above 0.5 mg/mL for the HY isolated using MAE, and 2 mg/mL for the HY isolated using MHG. The HY isolated using MHG reduced the adhesion of E. coli at a concentration of 2 mg/mL, while it also reduced the adhesion of S. aureus at a concentration of 1 mg/mL. Both hydrosols showed excellent antiphytoviral activity against TMV, achieving100% inhibition of local lesions on the leaves of infected plants, which is the first time such a result was obtained with a hydrosol treatment. Due to the antiphytoviral activity results, hydrosols of T. majus have a promising future for use in agricultural production.

Synergistic Antibiofilm Action of Cinnamomum verum and Brazilian Green Propolis Hydroethanolic Extracts against Multidrug-Resistant Strains of Acinetobacter baumannii and Pseudomonas aeruginosa and Their Biocompatibility on Human Keratinocytes

The accumulated dental biofilm can be a source of oral bacteria that are aspirated into the lower respiratory tract causing ventilator-associated pneumonia in hospitalized patients. The aim of this study was to evaluate the synergistic antibiofilm action of the produced and phytochemically characterized extracts of Cinnamomum verum and Brazilian green propolis (BGP) hydroethanolic extracts against multidrug-resistant clinical strains of Acinetobacter baumannii and Pseudomonas aeruginosa, in addition to their biocompatibility on human keratinocyte cell lines (HaCaT). For this, High-performance liquid chromatography analysis of the plant extracts was performed; then the minimum inhibitory and minimum bactericidal concentrations of the extracts were determined; and antibiofilm activity was evaluated with MTT assay to prevent biofilm formation and to reduce the mature biofilms. The cytotoxicity of the extracts was verified using the MTT colorimetric test, evaluating the cellular enzymatic activity. The data were analyzed with one-way ANOVA and Tukey's tests as well as Kruskal-Wallis and Dunn's tests, considering a significance level of 5%. It was possible to identify the cinnamic aldehyde in C. verum and p-coumaric, caffeic, and caffeoylquinic acids as well as flavonoids such as kaempferol and kaempferide and Artepillin-C in BGP. The combined extracts were effective in preventing biofilm formation and reducing the mature biofilms of A. baumannii and P. aeruginosa. Moreover, both extracts were biocompatible in different concentrations. Therefore, C. verum and BGP hydroethanolic extracts have bactericidal and antibiofilm action against multidrug resistant strains of A. baumannii and P. aeruginosa. In addition, the combined extracts were capable of expressively inhibiting the formation of A. baumannii and P. aeruginosa biofilms (prophylactic effect) acting similarly to 0.12% chlorhexidine gluconate.

Isolation of Volatile Compounds by Microwave-Assisted Extraction from Six Veronica Species and Testing of Their Antiproliferative and Apoptotic Activities

This study was conducted to determine the differences in the chemical composition of the essential oils and hydrosols of six different Veronica species (V. agrestis, V. anagalloides, V. austriaca ssp. jacquinii, V. beccabunga, Veronica cymbalaria, and V. officinalis) and to test their antiproliferative and apoptotic activities, according to the authors' knowledge, because of insufficient research and lack of information. Also, the goal was to determine which obtained samples were better in achieving antiproliferative and apoptotic activities and due to which volatile components. Therefore, essential oils (EOs) and hydrosols (HYs) were isolated from the above-mentioned Veronica species by microwave-assisted extraction (MAE). Phytochemical identification of the free volatile compounds was performed using a GC equipped with a flame ionization detector and a mass spectrometer. Their antiproliferative and apoptotic activities against two human cancer cell lines, breast cancer cell line MDA-MB-231 and bladder cancer cell line T24, were determined. The main compounds identified in the studied Veronica EOs and HYs were terpinen-4-ol (0.34-6.49%), linalool (0.34-6.61%), (E)-caryophyllene (0.97-7.55%), allo-aromadendrene (0.18-2.21%), caryophyllene oxide (1.42-23.83%), benzene acetaldehyde (0.26-13.34%), and β-ionone (1.08-16.53%). In general, HYs of the tested Veronica species showed higher antiproliferative activity (IC50 13.41-42.05%) compared to EOs (IC50 158.1-970.4 µg/mL) on MDA-MB-231 and T24 cancer cell lines after 48 and 72 h. V. agrestis EO showed the best apoptotic effect among the EOs on the MDA-MB-231 cancer cell line (10.47 ± 0.53% and 9.06 ± 0.74% of early/late apoptosis, compared with control 3.61 ± 0.62% and 0.80 ± 0.17% of early/late apoptosis, respectively) and among the HYs V. cymbalaria showed 9.95 ± 1.05% and 3.06 ± 0.28% of early/late apoptosis and V. anagalloides 8.29 ± 1.09% and 1.95 ± 0.36% of early/late apoptosis compared with control (for EO was 7.45 ± 1.01% and 0.54 ± 0.25%, and for HY was 4.91 ± 1.97% and 0.70 ± 0.09% of early/late apoptosis, respectively) on the T24 cancer cell line. Future research will include other Croatian species of the genus Veronica to gain a more complete insight into the biological activity of the volatile products of this genus for potential discovery of drugs based on natural plant extracts.

Glucosinolates and Cytotoxic Activity of Collard Volatiles Obtained Using Microwave-Assisted Extraction

Glucosinolates (GSLs) in Brassica oleracea L. convar. acephala var. viridis (collard) flower, leaf, stem, and root were analyzed qualitatively and quantitatively via their desulfo-counterparts using UHPLC-DAD-MS/MS. Twelve GSLs were identified, including Met-derived GSLs (sinigrin, glucoibervirin, glucoerucin, glucoiberin, glucoraphanin, progoitrin), Trp-derived GSLs (4-hydroxyglucobrassicin, glucobrassicin, 4-methoxyglucobrassicin, and neoglucobrassicin), and Phe-derived GSLs (glucotropaeolin and gluconasturtiin). Total GSL content was highest in the root, having 63.40 μmol/g dried weight (DW), with gluconasturtiin (34.02 μmol/g DW) as the major GSL, followed by sinigrin and glucoibervirin (12.43 and 7.65 μmol/g DW, respectively). Total GSL contents in the flower, leaf, and stem were lower than in root, having 6.27, 2.64, and 1.84 μmol/g DW, respectively, with Trp and/or Met-derived GSLs as the predominant ones. GSL breakdown products were obtained via microwave hydrodiffusion and gravity (MHG) and volatile breakdown products were analyzed using GC-MS techniques. Volatile isolates were tested for their cytotoxic activity using MTT assay. MHG volatile extract from the root demonstrated the best cytotoxic activity against human bladder cancer cell line T24 and breast cancer cell line MDA-MB-231 during an incubation time of 72 h (IC₅₀ 21.58, and 11.62 μg/mL, respectively). The activity of the root extract can be attributed to its major volatile, 2-phenylethyl isothiocyanate (gluconasturtiin breakdown product).