Ballast water is essential for maintaining the balance and integrity of a ship. However, exchanging ballast water resulted in discharging water of different origins in vessel recipient ports, and this may have caused ecosystem disturbance or aquatic pollution. The ballast water management (BWM) system is essential for the purification and disinfection of the ballast water that is taken up. Because current BWM systems widely use biocides for the treatment of aquatic organisms, the biocides may result in unintended toxicity of the discharged ballast water. In this study, we suggested thymol and carvacrol as chemical biocides for BWM systems and investigated their effectiveness using Artemia salina and Escherichia coli. Thymol and carvacrol showed biocidal effects in our study. A combination of these substances showed a synergistic increase in the biocidal effects. Moreover, carvacrol naturally degrades after disinfection, which indicates that natural substances may be promising candidates to increase the efficacy and reduce unwanted side effects of the BWM system.

This work describes efforts to encapsulate savory (Satureja hortensis L.) essential oil (EO) with different natural polymers (i.e., Arabic gum/gelatin (AGG), apple pectin (AP), gelatin (G)) and, as a separate set of experiments, with bio cross-linkers (i.e., citric acid and transglutaminase enzyme). The phytotoxic activity of encapsulated savory EO on tomato (Lycopersicon esculentum Mill.) and amaranth weed (Amaranthus retroflexus L.) was investigated. The micro-capsules were evaluated in terms of size, polydispersity, stability, encapsulation efficiency, morphology, and release properties. The Korsmeyer–Peppas model operated when EO was being released from the micro-capsules. Carvacrol (52.5%) and γ-terpinene (30.2%) comprised the main constituents of the savory EO. Based on the results, encapsulating the EO with cross-linked biopolymers increased the stability and herbicidal activity of EO, as compared to simple EO emulsions. Maximum toxicity injuries (MTI) were caused by encapsulations of apple pectin, cross-linked with APe enzyme (15 ml/L) on both plant species. MTI were observed 2 days after using the micro-encapsulated herbicides (MCHs). However, the injury caused by MCHs on tomato was not significant. The lowest values of fresh weight (2.80 g), chlorophyll a (0.194 mg/g Fw), and total chlorophyll content (0.219 mg/g Fw) of amaranth occurred in response to APe (15 ml/L). Moreover, using AP(e) (10 ml/L) caused the lowest values of starch (0.444 mg/g Fw) and flavonoid contents (4.18 mg Cat/g Fw) in amaranth which measured as 59% and 90% reductions, respectively, in comparison with the control. The highest values of MDA (0.0109 nmol/g Fw) and H₂O₂ (0.0432 μmol/g Fw) were observed in amaranth plants treated with AP(e) (10 ml/L). In summary, cross-linked apple pectin can perform well in slow release delivery systems of agrochemicals. It can be recommended for use in the production of commercial, EO-based natural herbicides.

Aging represents the accumulation of progressive changes in a human being over time and can cover physical, psychological, and social changes. It is an oxidative stress-associated process that progresses with age. The antioxidant activity of either eugenol (EU) or carvacrol (CAR) for aging in rats induced by D-gal for 42 days was investigated in the current study using 10 and 20 mg of EU/kg/day/orally, while CAR was supplemented by 40 and 80 mg /kg/day/orally. Biochemical, mRNA expression, and histopathological assessments of brain samples evaluated the oxidative alterations induced by D-gal and the protective role of EU and CAR. Results showed that D-gal was causing oxidative alternation of the brain that was recognized via upregulation of p53 and p21 mRNA expression levels, as aging markers and Bax mRNA expression level, as an apoptotic marker. Also, the results observed alterations in the levels of biochemical markers as creatine phosphokinase (CPK) and triacylglycerol (TAG), besides, enhancement of brain antioxidant capacity. Finally, these results compared with the groups treated with EU and CAR to observe that the EU and CAR potentially attenuate these aging-related oxidative alterations in a dose-dependent manner. Finally, we can conclude that EU and CAR supplementations are considered promising natural protective compounds that could delay aging and maintain health.

Although the green synthesis of nanometals is eco-friendly, the toxicity or safety of these biosynthesized nanoparticles in living organisms is not fully studied. This study aimed to evaluate the potential protective role of encapsulated thyme oil (ETO) against zinc oxide nanoparticles (ZnO-NPs). ETO was prepared using a mixture of whey protein isolate, maltodextrin, and gum Arabic, and ZnO-NPs were synthesized using parsley extract. Six groups of male Sprague-Dawley rats were treated orally for 21 days which included the control group, ZnO-NP-treated group (25 mg/kg body weight (b.w.)), ETO-treated groups at low or high dose (50, 100 mg/kg b.w.), and the groups that received ZnO-NPs plus ETO at the two tested doses. Blood and tissue samples were collected for different assays. The results showed that carvacrol and thymol were the major components in ETO among 13 compounds isolated by GC-MS. ZnO-NPs were nearly spherical and ETOs were round in shape with an average size of 38 and 311.8 nm, respectively. Administration of ZnO-NPs induced oxidative stress, DNA damage, biochemical, ctyogentical, and histological changes in rats. ETO at the tested doses alleviated these disturbances and showed protective effects against the hazards of ZnO-NPs. It could be concluded that encapsulation of thyme oil using whey protein isolate, maltodextrin, and gum Arabic improved the antioxidant properties of ETO, probably possess synergistic effects, and can be used as a promising tool in pharmaceutical and food applications.

Plutella xylostella L. is a cosmopolitan pest of wild and cultivated crucifer vegetables worldwide. It has developed resistance to almost all commercial chemicals, making them one of the most problematic field pests in China. The natural plant extracts and essential oils (EOs) could be a safe alternative for agricultural pests. The development and production of EOs decrease the negative effects of synthetic chemicals. In the present study, the fumigation activity of 8 pure monoterpenes against P. xylostella was evaluated. Results from fumigation tests revealed that 8 tested compounds exhibited various degrees of toxicity against adults of the diamondback moth. Cuminaldehyde was the most toxic compound based on the 12-h LC₅₀ (0.17 mg/L) and 24-h LC₅₀ (0.12 mg/L) values, respectively. Also for larvae and eggs, cuminaldehyde was the most toxic compound. The 12-h LC₅₀ value for cuminaldehyde to 1st, 2nd, and 3rd instar larvae was 0.10 mg/L, 0.12 mg/L, and 0.55 mg/L, respectively. The 24-h LC₅₀ value for the different instar larvae was 0.07 mg/L, 0.09 mg/L, and 0.35 mg/L, respectively. The 24-h LC₅₀ value for eggs (endpoint hatching rate) was 1.95 mg/L for cuminaldehyde, followed by carvacrol and eugenol (2.05 mg/L and 2.31 mg/L, respectively). Cuminaldehyde was very friendly to the larvae and adults of Harmonia axyridis and did not cause any mortality. Our results indicated that cuminaldehyde had potential insecticidal activity against P. xylostella and could be utilized in the novel biological pesticide development.

This study evaluated the larvicidal activity, and ovicidal activity of Origanum vulgare EO and its major components against the cotton bollworm, Helicoverpa armigera. The chemical composition of the O. vulgare EO was analyzed by gas chromatography-mass spectroscopy. GC-MS analysis revealed that the O. vulgare EO was composed of ten compounds. The major constituents were carvacrol (78.35%), followed by p-cymene (6.85%) and γ-terpinene (3.70%). In larvicidal activity assay, the O. vulgare EO achieved a LC₅₀ value of 265.51 μg/ml. The three major constituents from the O. vulgare EO were tested individually for toxicity against larvae of H. armigera. Carvacrol, p-cymene, and γ-terpinene appeared to be most effective against H. armigera, with LC₅₀ values of 51.53, 121.32, and 150.15 μg/ml, respectively. Moreover, EC₅₀ values of carvacrol, p-cymene, and γ-terpinene against H. armigera eggs were 33.48, 47.85, and 56.54 μg/ml, respectively. Overall, this study showed that O. vulgare EO and its major constituents have the potential to develop as new eco-friendly insecticides against H. armigera.

The antifungal activity of seven essential oils (eucalyptus, clove, mint, oregano, savory, tea tree, and thyme) was studied on Venturia inaequalis, the fungus responsible for apple scab. The composition of the essential oils was checked by gas chromatography-mass spectrometry. Each essential oil had its main compound. Liquid tests were performed to calculate the IC₅₀ of essential oils as well as their majority compounds. The tests were made on two strains with different sensitivities to tebuconazole: S755, the sensitive strain, and rs552, the strain with reduced sensitivity. Copper sulfate was selected as the reference mineral fungicidal substance. IC₅₀ with confidence intervals were calculated after three independent experiments. The results showed that all essential oils and all major compounds had in vitro antifungal activities. Moreover, it was highlighted that the effectiveness of four essential oils (clove, eucalyptus, mint, and savory) was higher than copper sulfate on both strains. For each strain, the best activity was obtained using clove and eucalyptus essential oils. For clove, the IC₅₀ obtained on the sensitive strain (5.2 mg/L [4.0–6.7 mg/L]) was statistically lower than the IC₅₀ of reduced sensitivity strain (14 mg/L [11.1–17.5 mg/L]). In contrast, for eucalyptus essential oil, the IC₅₀ were not different with respectively 9.4–13.0 and 12.2–17.9 mg/L for S755 and rs552 strains. For mint, origano, savory, tea tree, and thyme, IC₅₀ were always the best on rs552 strain. The majority compounds were not necessarily more efficient than their corresponding oils; only eugenol (for clove) and carvacrol (for oregano and savory) seemed to be more effective on S755 strain. On the other hand, rs552 strain seemed to be more sensitive to essential oils than S755 strain. In overall, it was shown that essential oils have different antifungal activities but do not have the same antifungal activities depending on the fungus strain used.

The development of natural plant extracts and essential oils will help to decrease the negative effects of synthetic chemicals. In the present study, the antifungal activity of individual and combined monoterpenes against Rhizopus stolonifer and Absidia coerulea was evaluated. The results from antifungal tests showed that eugenol, carvacrol, and isoeugenol, among all the tested compounds, exhibited strong antifungal activity against the two tested fungi. Furthermore, carvacrol exhibited the most toxic effects against R. stolonifer and A. coerulea, and the IC₅₀ values of carvacrol for the two fungi were 44.94 μg/ml and 50.83 μg/ml, respectively. The compounds (±)-menthol, b-citronellol, geraniol, 3,7-dimethyl-1-octanol, citral, and cuminaldehyde had only strong antifungal activity against R. stolonifer. In addition, the value of the synergistic co-efficient (SR) of a combination of isoeugenol and eugenol (1:1) showed an additive effect against R. stolonifer. The combination of isoeugenol and cuminaldehyde (1:1) showed an antagonistic effect against A. coerulea. Our results indicated that carvacrol and isoeugenol had potential antifungal effects against the two tested fungi and could be utilized in novel biological fungicide development.

The development of natural plant extracts and essential oils will assist to decrease the negative effects of synthetic chemicals. Many plant extracts and essential oils contain monoterpenes, sesquiterpenes, and aliphatic compounds. In the present study, the fumigation activity of 42 pure monoterpenes against housefly, Musca domestica, was evaluated. Results from fumigation tests revealed that ρ-cymene, terpinolene, (±)-menthol, thymol, carvacrol, (−)-carvone, (+)-camphor, (+)-pulegone, (−)-menthone, citral, (±)-citronellal, cuminaldehyde, and citronellyl acetate exhibited strong fumigation activity against M. domestica. Specifically, the compounds of (+)-pulegone, cuminaldehyde, citral, and ρ-cymene had a highest toxicity toward M. domestica with LC₅₀ values of 0.26, 0.60, 0.64, and 0.77 μl/L, respectively. The present results indicated that (+)-pulegone, cuminaldehyde, citral, and ρ-cymene are promising toxicants against M. domestica and could be useful in the search for new natural insecticides.

The recent outbreaks of dengue, chikungunya, and Zika virus highlighted the pivotal importance of mosquito vector control in tropical and subtropical areas worldwide. However, mosquito control is facing hot challenges, mainly due to the rapid development of pesticide resistance in Culicidae and the limited success of biocontrol programs on Aedes mosquitoes. In this framework, screening botanicals for their mosquitocidal potential may offer effective and eco-friendly tools in the fight against mosquitoes. In the present study, the essential oil (EO) obtained from the medicinal plant Origanum scabrum was analyzed by GC-MS and evaluated for its mosquitocidal and repellent activities towards Anopheles stephensi, Aedes aegypti, Culex quinquefasciatus, and Culex tritaeniorhynchus. GC-MS analysis showed a total of 28 compounds, representing 97.1 % of the EO. The major constituents were carvacrol (48.2 %) and thymol (16.6 %). The EO was toxic effect to the A. stephensi, A. aegypti, C. quinquefasciatus, and C. tritaeniorhynchus larvae, with LC₅₀ of 61.65, 67.13, 72.45, and 78.87 μg/ml, respectively. Complete ovicidal activity was observed at 160, 200, 240, and 280 μg/ml, respectively. Against adult mosquitoes, LD₅₀ were 122.38, 134.39, 144.53, and 158.87 μg/ml, respectively. In repellency assays, the EOs tested at 1.0, 2.5, and 5.0 mg/cm² concentration of O. scabrum gave 100 % protection from mosquito bites up to 210, 180, 150, and 120 min, respectively. From an eco-toxicological point of view, the EO was tested on three non-target mosquito predators, Gambusia affinis, Diplonychus indicus, and Anisops bouvieri, with LC₅₀ ranging from 4162 to 12,425 μg/ml. Overall, the EO from O. scabrum may be considered as a low-cost and eco-friendly source of phytochemicals to develop novel repellents against Culicidae.