Evaluation of chemical composition, antioxidant, antibiofilm and antibacterial potency of essential oil extracted from gamma irradiated clove (Eugenia caryophyllata) buds

Larvicidal and adulticidal activity of irradiated Thuja orientalis essential oil by gamma radiation for controlling Culexpipiens

Culex pipiens mosquitoes are the primary vector of the West Nile virus worldwide and have a wide distribution. To avoid the development of resistance in insect pests to conventional synthetic pesticides, there have been many attempts to study botanical pesticides. The increasing resistance of insect pests to synthetic pesticides is a threat to the diversity of ecosystems, which makes the study of botanical pesticides all the more important. The study aimed to determine the efficacy of Thuja orientalis essential oil irradiated with 1, 3 and 5 KGy compared to unirradiated T. orientalis as larvicidal agents against the third instar larvae of C. pipiens using six different concentrations (15, 20, 25, 30, 35 and 40 ppm) and as an adulticidal agent against approximately three-day-old female adults 0.2, 0.4, 0.6, 1 and 2%. The results generally showed that the irradiated essential oil with 5 KGy had the highest efficacy by LC50 (20.16 ppm) followed by essential oil irradiated with 3 and 1 KGy (LC50, 23.16 and 26.00 ppm, respectively) compared to unirradiated ones (LC50, 27.28 ppm) after 24 h from the exposure for the third instar larvae. The knockdown effect for adults increased significantly with higher concentrations of the oil, across different exposure times ranging from 5 to 60 min. The time to knock down 100% of mosquito population to Thuja orientalis essential oils at the highest concentration 2% were 20 min at 0, 1, and 3 KGy and 10 min at 5 KGy. Our results indicate that gamma irradiation of T. orientalis fruit improves the efficacy of their essential oil against Culex pipiens and the irradiated oil could be successfully used for management of these insects. The head capsule, antenna, and the last abdominal segments of the 3rd instar larvae exposed to the essential oil of unirradiated or irradiated Thuja orientalis unripe were examined by the scanning electron microscope (SEM).

Comparison of autoclaving and γ-radiation impact on four spices aroma profiles and microbial load using HS-SPME GC-MS and chemometric tools

Herbal spices are widely consumed as food additives owing to their distinct aroma and taste as well as a myriad of economic and health value. The aroma profile of four major spices including bay leaf, black pepper, capsicum, and fennel was tested using HS-SPME/GC-MS and in response to the most widely used spices´ processing methods including autoclaving and γ-radiation at low and high doses. Additionally, the impact of processing on microbial contamination of spices was tested using total aerobic count. GC-MS analysis led to the identification of 22 volatiles in bay leaf, 34 in black pepper, 23 in capsicum, and 24 in fennel. All the identified volatiles belonged to oxides/phenols/ethers, esters, ketones, alcohols, sesquiterpene and monoterpene hydrocarbons. Oxides/phenol/ethers were detected at high levels in all tested spices at ca. 44, 28.2, 48.8, 61.1%, in bay leaves, black pepper, capsicum, and fennel, respectively of the total blend and signifying their typical use as spices. Total oxides/phenol/ethers showed an increase in bay leaf upon exposure to γ-radiation from 44 to 47.5%, while monoterpene hydrocarbons were enriched in black pepper upon autoclaving from 11.4 in control to reach 65.9 and 82.6% for high dose and low dose of autoclaving, respectively. Cineole was detected in bay leaf at 17.9% and upon exposure to autoclaving at high dose and γ-radiation (both doses) its level increased by 29-31%. Both autoclaving and γ-radiation distinctly affected aroma profiles in examined spices. Further, volatile variations in response to processing were assessed using multivariate data analysis (MVA) revealing distinct separation between autoclaved and γ-radiated samples compared to control. Both autoclaving at 115 °C for 15 min and radiation at 10 kGy eliminated detected bioburden in all tested spices i.e., reduced the microbial counts below the detection limit (< 10 cfu/g).

Effect of gamma radiation on the protective efficacy of Thuja orientalis essential oil on stored cowpea against Callosobruchus maculatus and Callosobruchus chinensis

PURPOSE

Cowpea is an essential pulse food in several regions throughout the world. Essential oil isolated from Thuja orientalis unripe fruits exposed to gamma radiation at dose levels of 0, 1, 3 and 5 kGy was evaluated as cowpea seed protectant against Callosobruchus maculatus and Callosobruchus chinensis.

MATERIALS AND METHODS

Cowpea seeds were treated with three rates of the oils from non-irradiated and irradiated fruits, 0.5, 1.5 and 3.0 g kg-1. Mortality of C. maculatus and C. chinensis adults after 3 and 7 days, progeny reduction and weight loss of cowpea seeds after 45 days were recorded for all treatments.

RESULTS

The pronounced mortality of C. maculatus adults was achieved at the highest rate 3.0 g kg-1 of the irradiated oil with 5 kGy (98.3%). While in the case C. chinensis, all tested application rates induced marked adult mortality and a complete mortality (100%) resulted at two application rates (0.5 and 1.5 g kg-1) of irradiated oil with 5 kGy and 3.0 g kg-1 after 7 days. Strong progeny suppression of C. maculatus and C. chinensis was resulted at the highest rate of 3.0 g kg-1 of irradiated oil with 5 kGy (11.3 ± 0.3) and (8.5 ± 3.8) after 45 days of treatment, respectively. High protection of cowpea seeds with weight loss 0.5 and 1.4% for C. maculatus and C. chinensis was achieved at 3.0 g kg-1 of irradiated oil dose of 5 kGy, respectively after 45 days.

CONCLUSIONS

Our results indicate that gamma irradiation of T. orientalis fruits improve the protective activity of their essential oil against C. maculatus and C. chinensis on stored cowpea seeds and the irradiated oil could be successfully used for management of these bruchid insects.

Mode of Antifungal Action of Daito-Gettou (Alpinia zerumbet var. exelsa) Essential Oil against Aspergillus brasiliensis

Plant-derived essential oils (EOs) are used in medicines, disinfectants, and aromatherapy products. Information on the antifungal activity of EO of Alpinia zerumbet var. exelsa (known as Daito-gettou) found in Kitadaito Island, Okinawa, is limited. Therefore, we aimed to evaluate the antifungal activity of EOs obtained via steam distillation of leaves of Daito-gettou, which is a hybrid of A. zerumbet and A. uraiensis. Daito-gettou EO showed antifungal activity (minimum inhibitory concentration = 0.4%) against Aspergillus brasiliensis NBRC 9455, which was comparable to that of A. zerumbet found in the Okinawa main island. Gas chromatography/mass spectrometry revealed that the main components of Daito-gettou EOs are γ-terpinene, terpinen-4-ol, 1,8-cineole, 3-carene, and p-cymene. Terpinen-4-ol content (MIC = 0.075%) was 17.24%, suggesting that the antifungal activity of Daito-gettou EO was mainly attributable to this component. Daito-gettou EO and terpinen-4-ol inhibited mycelial growth. Moreover, calorimetric observations of fungal growth in the presence of Daito-gettou EO showed a characteristic pattern with no change in the initial growth rate and only a delay in growth. As this pattern is similar to that of amphotericin B, it implies that the action mode of Daito-gettou EO and terpinen-4-ol may be fungicidal. Further studies on the molecular mechanisms of action are needed for validation.

Promising antimicrobial and antibiofilm activities of Orobanche aegyptiaca extract-mediated bimetallic silver-selenium nanoparticles synthesis: Effect of UV-exposure, bacterial membrane leakage reaction mechanism, and kinetic study

In this research, Orobanche aegyptiaca extract was utilized as an eco-friendly, and cost-effective green route for the construction of bimetallic silver-selenium nanoparticles (Ag-Se NPs). Bimetallic Ag-Se NPs were characterized by XRD, EDX, FTIR, HR-TEM, DLS, SEM/mapping and EDX studies. Antimicrobial, and antibiofilm potentials were tested against some selected pathogenic bacteria and unicellular fungi by ZOI, MIC, effect of UV exposure, and inhibition %. Reaction mechanism was assessed through membrane leakage assay and SEM imaging. HRTEM analysis confirmed the spherical nature and was ranged from 18.1 nm to 72.0 nm, and the avarage particle size is determined to be 30.58 nm. SEM imaging prove that bimetallic Ag-Se NPs presents as a bright particles, and both Ag and Se were distributed equally across O. aegyptiaca extract and Guar gum stabilizers. ZOI results showed that, bimetallic Ag-Se NPs have antimicrobial activity against S. aureus (20.0 nm), E. coli (18.5 nm), P. aeruginosa (12.6 nm), and C. albicans (18.2 nm). In addition, bimetallic Ag-Se NPs were able to inhibit the biofilm formation for S. aureus by 79.48%, for E. coli by 78.79%, for P. aeruginosa by 77.50%, and for C. albicans by 73.73%. Bimetallic Ag-Se NPs are an excellent disinfectant once it had excited by UV light. It was observed that the quantity of cellular protein discharged from S. aureus is directly proportional to the concentration of bimetallic Ag-Se NPs and found to be 244.21 μg/mL after the treatment with 1 mg/mL, which proves the antibacterial characteristics, and explains the creation of holes in the cell membrane of S. aureus producing in the oozing out of the proteins from the S. aureus cytoplasm. Based on the promising properties, they showed superior antimicrobial potential at low concentration (to avoid toxicity) and continued-phase durability, they may use in pharmaceutical and biomedical applications.

Phytochemical constitutes and biological activities of essential oil extracted from irradiated caraway seeds (Carum carvi L.)

PURPOSE

Essential oils (EOs) obtained from spices, herbs, and medicinal plants are well known in traditional medicine and are an area of interest due to their various biological activities. Therefore, the present study investigates the chemical composition, phytochemical properties, as well as the biological activity of EOs, recovered from un-irradiated and irradiated (2.5, 5, and 10 kGy) caraway seeds.

MATERIALS AND METHODS

Carum carvi L. seeds were irradiated with gamma irradiation at dose levels 2.5, 5, and 10 kGy, then EOs were recovered from all the samples. The chemical composition, phenols, and flavonoids content were evaluated. As well, antimicrobial and antitumor activities against the two cell lines [colorectal adenocarcinoma (Caco-2) and liver cancer (HepG-2)] were investigated.

RESULTS

The results indicated the percentage of oil increased by radiation, especially a dose of 10 kGy, which gave the highest percentage (3.50%) compared to the control. Also, the Gas Chromatography/Mass Spectrometry (GC-MS) analysis revealed the presence of 26 compounds in the essential oil extracts. The main constituent of caraway seeds EOs was Carvone followed by Limonene. According to the results, there was an increase in the content of phenols and flavonoids by using gamma rays compared with control, the maximum increase was observed at dose level 10 kGy (13.70 and 7.38 mg/g oil, respectively) followed by 5 kGy (11.20 and 5.86 mg/g oil, respectively). The antioxidant properties of the caraway essential oils were increased by increasing the irradiation dose level (2.5-10 kGy) analyzed by DPPH radical and metal chelating activity. Caraway essential oils have an antimicrobial action against Gram-positive and Gram-negative bacteria as well as fungi. The antimicrobial activity was increased as the irradiation dose was raised and the10 kGy dose was more effective in suppressing the growth of bacteria and fungi. Additionally, the caraway essential oils have anticancer activity against the two cell lines studied; colorectal adenocarcinoma (Caco-2) and liver cancer cell line (HepG-2) as reduced the cell viability and density.

CONCLUSION

The 10 kGy dose was more effective for oil yield, phenols, flavonoids, and antioxidant activity as well as antibacterial and antifungal activities. Furthermore, the caraway essential oils indicated anticancer activity against the two cell lines studied; colorectal adenocarcinoma (Caco-2) and liver cancer cell line (HepG-2) as reduced the cell viability and density. So caraway could be considered an important herb with multiple therapeutic uses.

Chemical Composition, Antioxidant, Anti-Diabetic, Anti-Acetylcholinesterase, Anti-Inflammatory, and Antimicrobial Properties of Arbutus unedo L. and Laurus nobilis L. Essential Oils

The objectives of this work were to determine the phytochemical composition and antioxidant, anti-diabetic, antibacterial, anti-inflammatory, and anti-acetylcholinesterase properties of Arbutus unedo L. and Laurus nobilis L. EOs. The antioxidant effects were estimated using four complementary methods. In addition, the anti-diabetic activity was assessed by targeting three carbohydrate-hydrolyzing enzymes, namely α-amylase, α-glucosidase, and lipase. The anti-inflammatory and anti-acetylcholinesterase effects were evaluated by testing the inhibitory potential of both plants on lipo-oxygenase and acetylcholinesterase (AChE), respectively. The antimicrobial activity of these oils was evaluated using disc-diffusion, minimum inhibitory concentration (MIC), and minimum lethal concentration (MLC) tests. The chemical composition of L. nobilis essential oil (EO) was dominated by eucalyptol (36.40%), followed by α-terpineole (13.05%), α-terpinyl acetate (10.61%), linalool (10.34%), and northujane (5.74%). The main volatile compounds of A. unedo EOs were decenal (13.47%), α-terpineol (7.8%), and palmitic acid (6.00%). L. nobilis and A. unedo EOs inhibited α-amylase with IC₅₀ values of 42.51 ± 0.012 and 102 ± 0.06 µg/mL, respectively. Moreover, both oils inhibited the activity of α-glucosidase (IC₅₀ = 1.347 ± 0.021 µg/mL and IC₅₀ = 76 ± 0.021 µg/mL) and lipase (IC₅₀ = 21.23 ± 0.021 µg/mL and IC₅₀ = 97.018 ± 0.012 µg/mL, respectively). In addition, L. nobilis EO showed an anti-AChE activity (IC₅₀ = 89.44 ± 0.07 µg/mL) higher than that of A. unedo EO (IC₅₀ = 378.57 ± 0.05 µg/mL). Regarding anti-inflammatory activity, in vitro assays showed that L. nobilis significantly inhibits (IC₅₀ = 48.31 ± 0.07 μg/mL) 5-lipoxygenase compared to A. unedo (IC₅₀ = 86.14 ± 0.05 μg/mL). This was confirmed in vivo via a notable inhibition of inflammation recorded after 6 h of treatment in both plants at a dose of 50 mg/kg. The microbiological results revealed that EOs from both plants inhibited the growth of all tested organisms except P. aeruginosa, with the highest antimicrobial effect for L. nobilis. The results of these tests showed that these two plants possess remarkable biological and pharmacological properties, explaining their medicinal effects and suggesting them as promising sources of natural drugs.

Gamma-Rays Induced Synthesis of Ag-Decorated ZnCo2O4–MoS2 Heterostructure as Novel Photocatalyst and Effective Antimicrobial Agent for Wastewater Treatment Application

The development of novel semiconductors-based-photocatalysts is a promising strategy for addressing environmental pollution. In the present study, gamma irradiation was utilized to induce the synthesis of the exceptionally efficient Ag-decorated ZnCo2O4–MoS2 heterostructure. XRD and EDX analyses were verified the successful synthesis of Ag-decorated ZnCo2O4–MoS2 heterostructure. Also, SEM and HR-TEM images were illustrated the heterostructure nature of the synthesized photocatalyst in the nanoscale regime. The obtained optical bandgap values verified that photocatalyst possesses a narrow semiconductor bandgap. Further, the Ag-decorated ZnCo2O4–MoS2 heterostructure exhibited superior photodegradation potential towards MB (95.4% removal of the MB). The antimicrobial potency of the synthesized samples had been investigated through ZOI, MIC, growth curve assay, and the effect of UV illumination. Also, the antibiofilm behaviour has been studied. The antibacterial reaction mechanism had been estimated by membrane leakage assay and SEM imaging. The tested samples displayed a positive potency to a broad spectrum of bacteria like Proteus mirabilis, Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. In particular, Ag–MoS2–ZnCo2O4 nanocomposite possessed the highest impact, followed by the spinal ZnCo2O4 NPs towards all the tested pathogenic microbes. In this assessment, the Ag-decorated ZnCo2O4–MoS2 heterostructure has been shown to be a promising candidate for wastewater treatment application.