Bioactivity and molecular docking studies of selected plant compounds.

BACKGROUND: The shortcomings of synthetic pesticides are becoming increasingly evident. In the pursuit of looking for alternative, environmentally friendly pesticides, the potential use of two naturally occurring sesquiterpenes, α-bisabolol and bisabolol oxide A, as bactericides or acaricides, was investigated against three gram-positive and three gram-negative bacteria, and the eggs and larvae of the cattle tick Hyalomma scupense, respectively. The primary targeted site of synthetic insecticides is acetylcholinesterase (AChE), so the inhibitory activity of both sesquiterpenes was evaluated. Then, molecular docking and molecular mechanics generalized Born surface area (MM-GBSA) studies were performed to gain insight into their binding mode in the AChE active site. RESULTS: Bisabolol oxide A showed good activity against Staphylococcus aureus, Escherichia coli, and Salmonella enteritidis with inhibition zones ranging from 16 to 34 mm and minimal inhibitory concentration (CIM) of 3.125 mg mL-1. Ovicidal and larvicidal assays revealed promising activity of α-bisabolol and bisabolol oxide A against H. scupense, with bisabolol oxide A being more effective against larval ticks with lethal concentration (LC50) value of 0.78%. Both compounds also displayed potent anti-AChE activity with inhibition concentration (IC50) values of 37.09 and 28.14 µg mL-1, respectively. Furthermore, α-bisabolol and bisabolol oxide A exhibited good and comparable docking scores (-7.289 and -7.139 Kcal mol-1, respectively) and were found to accommodate in the active-site gorge of AChE via hydrogen bonding and hydrophobic interactions. CONCLUSION: Bisabolol oxide A and, to a lesser degree, α-bisabolol are active against bacteria and ectoparasites and may represent an economical and sustainable alternative to toxic synthetic pesticides to control pathogens. © 2024 Society of Chemical Industry.

Laboratory assessment of the acaricidal, repellent and anti-cholinesterase effects of Melaleuca alternifolia and Chamaemelum nobile essential oils against Hyalomma scupense ticks.

In cattle, Hyalomma scupense serves as an important vector of several pathogens resulting in diseases, subsequently affecting the agricultural field as well as the economy. Resistance to chemical acaricides has become widespread affirming the need for new drugs to tick control. The goal of this study was to investigate the acaricidal, repellent activities as well as the putative mode of action of two essential oils (EOs) from Melaleuca alternifolia (Tea tree) and Chamaemelum nobile (Roman chamomile) on Hyalomma scupense. The chemical composition of EOs was also evaluated. Different concentrations of EOs were tested in vitro for their acaricidal property on adults and larvae of H. scupense using adult immersion test (AIT) and larval packet test (LPT). Additionally, using Ellman's spectrophotometric method, the anticholinesterase (AChE) inhibition activity of M. alternifolia and C. nobile EOs was assessed in order to understand their putative mode of action. The main compounds of C. nobile were α-Bisabolene (22.20%) and (E)-ß-Famesene (20.41%). The major components in the analyzed M. alternifolia were Terpinen-4-ol (36.32%) and γ-Terpinene (13.69%). Adulticidal and larvicidal assays demonstrated a promising efficacy of the essential oils against tick H. scupense. The lethal concentration (LC50) values obtained for M. alternifolia and C. nobile oils were 0.84 and 0.96 mg/mL in the AIT and 0.37 and 0.48 mg/mL in the LPT, respectively. Regarding repellent activity, M. alternifolia achieved 100% repellency at the concentration of 1 mg/mL while C. nobile showed 95.98% repellency activity at concentration of 4 mg/mL. Also, M. alternifolia and C. nobile EOs displayed potent AChE inhibition with IC50 value of 91.27 and 100.12 µg/mL, respectively. In the present study, M. alternifolia and, to a lesser degree, C. nobile EOs were found to be effective in vitro acaricides, repellents and acetylcholinesterase inhibitor against H. scupense ticks. These plants may represent an economical and sustainable alternative to toxic synthetic acaricides in the management of ectoparasites of veterinary importance.

Pistacia lentiscus essential oil and its pure active components as acaricides to control Dermanyssus gallinae (Acari: Mesostigmata).

The goal of this work was to assess the in vitro acaricidal effects of Pistacia lentiscus essential oil and its pure active components against red poultry mites Dermanyssus gallinae as an alternative to chemical acaricide (formamidines). Essential oil was obtained using hydrodistillation and then analyzed using GC-MS. The following major components were identified: α-pinene (20.58 %), D-Limonene (18.16 %), ß-Myrcène (15.06 %), 4-Terpineol (7.68 %), caryophyllene (5.45 %) and γ-terpinene (5.21 %). The toxicity of essential oil and its six monoterpenes were tested at concentrations ranging from 0.43 to 3.50 mg/cm2, using contact and spraying bioassays. Toxicity was expressed as a lethal concentration (LC50 or LC90). The experiment results revealed that activity was method and concentration dependent, and the spraying method was more effective than the contact bioassay for acaricidal activity. In this bioassay, the highest mortality was observed with 4-Terpineol. The LC50 was estimated to be 0.184 mg/cm2 for this substance, followed by α-pinene, the LC50 of which was estimated to be 0.203 mg/cm2. Caryophyllene and γ-terpinene were found less effective in controlling D. gallinae. P. lentiscus oil and its major compounds were also evaluated for anti-acetylcholinesterase (AChE) effects; 4-Terpineol was found to be the most effective AChE inhibitor with IC50 values reaching 18.73 ± 2.83 µg/mL. This framework pointed out the importance of the traditional use of P. lentiscus as an ecofriendly alternative against ectoparasite of veterinary importance; D. gallinae. In vivo trials should also be conducted to assure the safe use of essential oils or individual compounds and to achieve efficient acaricidal property.

Toxicity, repellency, and anti-cholinesterase activities of bioactive molecules from clove buds Syzygium aromaticum L. as an ecological alternative in the search for control Hyalomma scupense (Acari: Ixodidae).

Introduction: The goal of the current study is to evaluate the acaricidal and repellent properties of the ethanolic extract, essential oil, and primary component eugenol from Syzygium aromaticum against Hyalomma scupense cattle ticks. Their potential mechanisms of action were also examined, using an in vitro assay. Methods: Clove essential oil was extracted using hydrodistillation technique. Gas chromatography-mass spectrometry (GC-MS) was performed to identify the chemical composition of clove. To evaluate the adulticidal, ovicidal, larvicidal and repellent proprieties of clove essential oil, eugenol and ethanolic extract on H. scupense, in vitro assays were performed using the adult immersion test (AIT), the ovicidal test, the larval packet test (LPT), the filter paper test and anti-acetylcholinesterase (AChE) activity. Results: After treatment, eugenol, the primary phytoconstituent of clove oil, which accounts for 97.66% of the whole oil, had 99.22% acaricide activity and inhibited egg hatching at a concentration of 10 mg/mL. Eugenol and clove essential oil showed potent adulticidal effect at high concentrations (10 mg/mL), achieving 100 and 93.76% mortality, respectively. The ethanolic extract exhibited moderate activity. At high concentration, the larvicidal activity of S. aromaticum oil, eugenol, and ethanolic extract were 100, 100, and 77.18%, respectively. In filter paper experiments, when tested at the concentration 5 mg/mL; eugenol showed the longest repellent effect up to 6 h. We also found that eugenol was the most active AChE inhibitor (IC50 = 0.178 mg/mL). Nevertheless, additional investigations are required to confirm the accurate mechanism and the relevance of clove in practical application. Conclusion: Overall, our research indicated that, because its effectiveness as acaricide, S. aromaticum essential oil and its phytoconstituent eugenol may offer an alternative source for the control of H. scupense cattle ticks.

Enhanced textile dye removal from wastewater using natural biosorbent and Shewanella algae B29: Application of Box Behnken design and genomic approach.

In this study, Box-Behnken design combining seven factors at three levels were used to optimize the elimination of CI Reactive Red 66 in artificial seawater, by the combination of eco-friendly bio-sorbents and acclimated halotolerant microbial strain. Results showed that macro-algae and cuttlebone (2 %) were the best natural bio-sorbent. Additionally, the selected halotolerant strain able to rapidly remove dye was identified as Shewanella algae B29. The optimization process revealed that decolourization of CI Reactive Red 66 yields reached 91.04 % under the following variable values: dyes concentration (100 mg/l), salinity (30 g/l), peptone (2 %), pH (5), algae C (3 %), cuttlebone (1.5 %) and agitation (150 rpm). The whole genome analysis of S. algae B29 demonstrated the presence of several genes coding for valuable enzymes involved in textile dyes biotransformation, adaptation to stress as well as biofilm formation implying its potential use in biological textile wastewater treatment.

Acaricidal and anthelmintic efficacy of Ocimum basilicum essential oil and its major constituents estragole and linalool, with insights on acetylcholinesterase inhibition.

The present study evaluated the acaricidal and anthelmintic action of Ocimum basilicum essential oil and its main components against ticks and helminth parasites as well as to relate these activities to acetylcholinesterase inhibition. The in vitro acaricidal activity against Hyalomma scupense was evaluated by Adult Immersion Test (AIT) and Larval Packet Test (LPT), while the in vivo nematocidal potential was assessed in laboratory mice infected with Heligmosomoides polygyrus using fecal egg count reduction (FECR) and total worm count reduction (TWCR). Chemical analyzes were performed by gas chromatography coupled to mass spectrometry (GC-MS). Estragole (80.87%) and linalool (16.12%) were the major compounds detected in O. basilicum essential oil. In the AIT assay for H. scupense tick, LC50 of estragole, O. basilicum oil and linalool were 0.73, 0.81 and 0.97 mg/mL, respectively. In LPT, estragole, linalool and essential oil showed LC50 of 0.22, 1.11 and 1.19 mg/mL, respectively. Against He. polygyrus, the highest activity was observed with estragole administered at 100 mg/kg body weight (bwt), which resulted in a FECR of 90.86% and a TWCR of 82.91%. The O. basilicum essential oil, estragole and linalool inhibited the enzyme acetylcholinesterase (AChE) extracted from both parasites species. Estragole was found the most active AChE inhibitor with IC50 of 0.176 mg/mL for H. scupense and IC50 of 0.138 mg/mL for He. polygyrus larvae. The results of the present study pointed out the importance of the traditional use of O. basilicum as an eco-friendly alternative against endo and ectoparasites. In vivo trials should also be conducted to confirm the above-mentioned activities and to assure the safe use of natural plants.

Efficacy of synergistic activity of seed oils from Carthamus tinctorius (Safflower) and Nasturtium officinale (Watercress) on the lethality of the cattle tick Hyalomma scupense (Acari: Ixodidae).

Background: Ticks and tick-borne diseases are a severe economic and public-health problem for cattle producers. The emergence of acaricide resistance to synthetic chemical treatments has prompted interest in developing alternative tick control methods. Aim: The main objective of the current research was to identify the chemical structure of Carthamus tinctorius and Nasturtium officinale seed oils and to assess their anti-tick properties against Hyalomma scupense ticks both alone and in combination (1:1). Methods: Analytical methods were used to analyze the chemical components. For in vitro assays, adults of H. scupense were immersed in C. tinctorius and N. officinale seed oils at 100, 125, 200, and 300 mg/ml concentrations; for 5 minutes. Larvae of H. scupense were dipped in 25, 50, 100, 125, 200, and 300 mg/ml doses of seed oils; the mortality percentage was determined after 24 hours. Results: The seed oil safflower was mainly composed of linoleic acid (84.48%), followed by palmitic acid (6.54%) and stearic acid (3.77%). Meanwhile, watercress seed oil was mainly composed of linolenic acid (50.78%), gondoic acid (13.57%), linoleic acid (10.58%), palmitic acid (8.02%), and erucidic acid (6.62%). The Adults Immersion Test showed the sensitivity of ticks to C. tinctorius and N. officinale seed oil: C. tinctorius seed oil caused (95%) mortality of H. scupense at 300 mg/ml, while N. officinale seed oil induced (88.68%) mortality at the same concentration. At a 200 mg/ml concentration, C. tinctorius and N. officinale oil combined caused 100% mortality. Tested oils showed larvicidal efficacy. LC50 values for C. tinctorius and N. officinale seed oils were 84.16 and 61.78 mg/ml, respectively, in 24 hours. LC50 value of oils association (50% C. tinctorius: 50% N. officinale) was 47.96 mg/ml.The mixture of seed oils from two plants tested against H. scupense larvae and adult females at a 1:1 ratio showed synergistic interaction. Conclusion: Seed oils tested alone, and the mixture could be used as an alternative solution in the fight against ticks.

Phytochemistry, anti-tick, repellency and anti-cholinesterase activities of Cupressus sempervirens L. and Mentha pulegium L. combinations against Hyalomma scupense (Acari: Ixodidae).

The adulticidal, larvicidal, and repellent effects of Cupressus sempervirens, Mentha pulegium, and their combination (C. sempervirens and M. pulegium) against Hyalomma scupense were investigated, as well as their putative mode of action. The evaluation on H. scupense was performed with the adult immersion test at concentrations ranging from 2.5-20 mg/mL and the larval packet test from 0.625 to 20 mg/mlL. The same concentrations were used for combined oils. Essential oils were obtained using hydrodistillation and then analyzed using GC-MS. The following major components were identified: α-pinene (56.89 %) and δ-3-Carene (15.61 %) for C. sempervirens, while pulegone (70.50 %) and cis-Menthone (18.26 %) for M. pulegium. At 20 mg/mL concentration, C. sempervirens had (94.40 %) acaricide action and inhibited the egg from hatching, however at 10 mg/mL, it had 100 % larvicidal activity. Adulticidal and larvicidal activities of M. pulegium oil reached to 87.19 % and 81.02 % respectively, at 20 mg/mL concentration. The highest acaricidal property against H. scupense was exhibited by combination oils with minimum LC50 values of 1.76 mg/mL on adultes and 0.60 mg/mL on larvae. The repellent activities were 100, 95.80 and 100 %, at the 20 mg/mL concentration used in 6 h, for C. sempervirens, M. pulegium and mixture oil respectively. Our findings revealed that the mixture of C. sempervirens and M. pulegium, at the ratio 1:1 (v: v) of each oil, showed high synergistic effect (SF > 1) and the use of combination oil (C. sempervirens 50 %: M. pulegium 50 %) is more toxic against H.scupense. Furthermore, the volatile oils examined revealed significant inhibition of H.scupense acetylcholinesterase activity AChE. Based on the findings of the present framework, these essential oils have the potential to be applied as substitute for synthetic acaricides in the management of H.scupense bovine ticks.

In vitro acaricidal activity of essential oil and crude extracts of Laurus nobilis, (Lauraceae) grown in Tunisia, against arthropod ectoparasites of livestock and poultry: Hyalomma scupense and Dermanyssus gallinae.

The current study assayed the toxicity of Laurus nobilis essential oil and crude extracts obtained using solvents of increasing polarity (cyclohexane, acetone and ethanol), on two ectoparasites of veterinary importance, i.e., Hyalomma scupense and Dermanyssus gallinae. The major components detected in bay laurel essential oil were dominated by 1.8-cineole (46.56 %), α-terpinenyl acetate (13.99 %), sabinene (7.69), α-pinene (5.75), linalool (5.50), methyleugenol (5.36 %) and ß-pinene (3.97). The highest total phenolic and flavonoids contents were present in the ethalonic extract of L. nobilis leaves at an amount of 152.88 mg gallic acid equivalents per gram of dry weight (GAE/g DW) and 21.77 mg quercetin equivalent per gram of dry weight (QE/g DW), respectively. In vitro acaricidal effects of essensial oil and crude extract of L. nobilis against H. scupense were ascertained by adult immersion test of engorged females (AIT) and larval packet test (LPT) compared with a reference drug amitraz. The essential oil exhibited strong acaricidal activity against tick engorged female and inhibition of hatching eggs. After 24 h of exposure, at the highest tested concentration (100 mg/mL) essential oil induced 90.67 % mortality of H. scupense larvae (LC50 = 10.69 mg/mL). Otherwise, essential oil exhibited high acaricidal activity compared to extracts, and among the extract, the ethanolic extract revealed the highest acaricidal efficacy (81.27 % female mortality). Results from mite contact toxicity showed that essential oil and extracts from L. nobilis were toxic to D. gallinae. Bay essential oil was both more toxic to mites, and faster in exerting this toxicity than other tested crude extracts. L. nobilis essential oil concentration leaded to enhance mortality of D. gallinae reaching the highest (100 %) mortality at 12 h with a concentration of 320 mg/mL. While, ethanolic extract acheived this rate after 24 h of exposure at same concentration. Cyclohexanic extract showed weak acaricidal activity.

Pistacia lentiscus oil attenuates memory dysfunction and decreases levels of biomarkers of oxidative stress induced by lipopolysaccharide in rats.

Pistacia lentiscus L. is a well-known medicinal plant that has been used for its antioxidant, anti-inflammatory, neuroprotective, and hepatoprotective effects. However, the neuroprotective effect of Pistacia lentiscus oil (PLo) of has not been reported. The present study was designed to examine the neuroprotective and hepatoprotective effects of PLo aigainst lipopolysaccharide (LPS)-induced memory impairment and oxidative damage in rats. Twenty-four adult male Wistar rats were equally divided into three groups. The first group was kept as a control. In the second group, LPS was given at the single dose of 1 mg/kg intraperitoneally (i.p.). In the third group, PLo (3.3 mL/kg; per orally (p.o.)) was administered daily for 15 days, and challenged with LPS (1 mg/kg; i.p. injection two h before behavioral test). Thereafter, memory was assessed using spatial object recognition test. Cholinesterase activity and oxidative stress response were estimated in brain tissues and liver. PLo attenuated LPS-induced memory impairment in spatial object recognition test (p < 0.05). LPS treatment caused significant oxidative damage via induction of lipid peroxidation and reductions antioxidant defense system potency in the brain tissue and liver. Moreover, LPS increased brain activity of acetylcholinesterase and butyrylcholinesterase activity in the liver. The present results suggest that the beneficial effects of PLo on memory impairment of LPS-treated rats may be due to its protective effects against oxidative stress damage presumably via its antioxidant property.