Acaricidal activity of petroleum ether extract of leaves of Tetrastigma leucostaphylum (Dennst.) Alston against Rhipicephalus (Boophilus) annulatus

Molecular characterization of Hyalomma dromedarii and evaluation of acaricidal potential of herbal methanolic extracts against H. dromedarii larvae in comparison to synthetic acaricides

The present study had two aims: molecular characterization of Hyalomma dromedarii infesting one-humped camels of Haryana (North India), and assessment of the acaricidal potential of herbal methanolic extracts against H. dromedarii larvae in comparison to synthetic acaricides. Phylogenetics and population neutrality indices were assessed by targeting partial amplification of mitochondrial 16S rDNA sequences. Larval packet test (LPT) was performed to evaluate the acaricidal efficacy of herbal extracts (Ferula asafoetida and Trachyspermum ammi) and synthetic acaricides (deltamethrin and fipronil). Phylogenetic studies established the collected ticks to be H. dromedarii, exhibiting a homology of 99.8-100%. However, the present study isolates formed a different sub-clade compared to H. dromedarii sequences from Egypt, Senegal, Tunisia and Saudi Arabia. Nucleotide and haplotype diversity values were indicative of demographic expansion and low gene flow. Negative values of Tajima's D (-0.612) and Fu and Li's Fst (-0.479) highlighted deviations from neutrality and emphasized recent population expansion. The median lethal concentration (LC₅₀) values recorded for T. ammi, F. asafoetida and their combination were 3.68, 2.87 and 2.59 mg/mL, respectively, whereas the 90% lethal concentration (LC₉₀) values were 4.09, 3.58 and 3.35 mg/mL, respectively. It was also observed that the H. dromedarii population under study was completely susceptible to both the formulated synthetic acaricides. In conclusion, combination of methanolic extracts of F. asafoetida and T. ammi could provide a potential substitute to toxic synthetic chemical acaricides and might prove a valuable component of integrated tick management strategies.

Chemical Profiling and In Vitro Antiurolithiatic Activity of Pleurolobus gangeticus (L.) J. St.- Hil. ex H. Ohashi & K. Ohashi Along with Its Antioxidant and Antibacterial Properties

Pleurolobus gangeticus (L.) J. St.- Hil. ex H. Ohashi & K. Ohashi (Fabaceae) is an important medicinal plant used to treat various ailments. In this study, we report the antiurolithiatic, antioxidant, and antibacterial potential of chloroform fraction (CF) from P. gangeticus roots. For the chemical profiling, HPTLC, FT-IR, and GC-MS techniques of the CF were carried out, and phytochemical investigation was revealed that stigmasterol (45.06%) is one of the major components present in the fraction. The nucleation and aggregation assays were used to evaluate the in vitro antiurolithiatic activity at various concentration (2-10 mg/mL) of the CF. The results showed that the chloroform fraction had dose-dependent effects on Calcium Oxalate (CaOx) crystal formation. In both the assays, the maximum concentration of 10 mg/mL has shown better results. This concentration resulted significant increase in CaOx crystal nucleation along with the reduction of crystal size and the inhibition of crystal aggregation. Further, the CF showed stronger antioxidant (DPPH, NO, SOD, TRC) potential with an IC₅₀ values of 415.9327, 391.729, 275.971, and 419.14 µg/mL, respectively. The antibacterial evaluation displayed effective results in the Agar well diffusion assay against selective urinary tract infection (UTI) pathogens (Escherichia coli, Klebsiella pneumonia, and Staphylococcus aureus). A maximum zone of inhibition (ZOI) 12.33 ± 1.05 mm for K pneumonia and minimum ZOI of 8.46 ± 0.27 mm for S. aureus were obtained. Further, the ADME-PK property of the stigmasterol was investigated, and it was found to pass the Lipinski and Ghose rules, supporting the drug-likeliness. This is the first record of the antiurolithiatic potential of P. gangeticus along with antioxidant and antibacterial activities. These findings give an insight into the effective drug development and treatment for kidney stones in future.

Modulation of the PGE2-Mediated Pathway in the Eclosion Blocking Effect of Flumethrin and Terpenoid Subfraction Isolated from Artemesia nilagirica in Rhipicephalus annulatus

Prostaglandins are a group of important cell-signaling molecules involved in the regulation of ovarian maturation, oocyte development, egg laying and associated behaviors in invertebrates. However, the presence of prostaglandin E₂ (PGE₂), the key enzymes for PGE₂ biosynthesis and its interference by drugs were not investigated previously in the ovary of ticks. The present study was undertaken to assess the modulation of the PGE₂-mediated pathway in the eclosion blocking effect of flumethrin and terpenoid subfraction isolated from Artemisia nilagirica in Rhipicephalus annulatus ticks. The acaricidal activities and chemical profiling of the terpenoid subfraction were performed. The localization of the cyclooxygenase1 (COX1) and prostaglandin E synthase (PGES) enzymes and the quantification of PGE₂ in the ovaries of the ticks treated with methanol (control), flumethrin and terpenoid subfraction were also undertaken. In addition, the vitellogenin concentration in hemolymph was also assayed. Both flumethrin and the terpenoid subfraction of A. nilagirica elicited a concentration-dependent inhibition of fecundity and blocking of hatching of the eggs. The COX1 could not be detected in the ovaries of treated and control ticks, while there was no significant difference observed in the concentration of vitellogenin (Vg) in them. The presence of PGES in the oocytes of control ticks was confirmed while the immunoreactivities against PGES were absent in the vitellogenic oocytes of ticks treated with flumethrin and terpenoid subfraction. The levels of PGE₂ were below the detection limit in the ovaries of the flumethrin-treated ticks, while it was significantly lower in the ovaries of the terpenoid subfraction-treated ticks. Hence, the prostaglandin E synthase and PGE₂ were identified as very important mediators for the signaling pathway for ovarian maturation and oviposition in ticks. In addition, the key enzyme for prostaglandin biosynthesis, PGES and the receptors for PGE₂ can be exploited as potential drug targets for tick control. The detection of PGES by immunohistochemistry and quantification of PGE₂ by LC-MSMS can be employed as valuable tools for screening newer compounds for their eclosion blocking acaricidal effects.

Acaricidal Activity of Artemisia nilagirica Leaves Against Rhipicephalus (Boophilus) annulatus Ticks

Since time immemorial, human beings have used various parts of plants in either prevention or treatment of ailments. Plants are rich sources of secondary metabolites such as alkaloids, steroids, terpenoids, flavonoids, and phenolic compounds with a high structural diversity. Many plants/herbs with specific biological activities such as antitumor, antioxidant, anti-inflammatory, antifungal, sedative, and acaricidal activity have been reported. Artemisia nilagirica (C. B. Clarke) Pamp. (Compositae) is a plant traditionally used for insect control in the southern part of India. Previous studies have demonstrated the activity of Artemisia species against pests. The present study thus evaluates the acaricidal activity of crude ethanolic extract of A. nilagirica leaves and its fractions against Rhipicephalus (Boophilus) annulatus. Ticks are ectoparasites that transmit several protozoal, viral, and rickettsial diseases. In south India, R. (B.) annulatus is the commonly observed tick species. Control of these acarine parasites that adversely affect milk and meat production is a tough task. Chemical acaricides such as organophosphates, synthetic pyrethroids, amitraz, and ivermectin are commonly used in tick control. The high cost, environmental hazards, and development of acaricidal resistance are some of the drawbacks of these chemical acaricides. Plant-based formulations are one of the promising approaches for the control of ectoparasites. Previously, extracts from various medicinal/aromatic plants were reported for acaricidal activity from our laboratory, such as Tetrastigma leucostaphylum (Dennst.) Alston, Chassalia curviflora (Wall.) Thwaites, Jatropha curcas L., and Ageratum conyzoides Hieron. Biochemical quantification, fluorescence analysis, and primary phytochemical analysis are already reported for the ethanolic extract and its fractions of areal parts of A. nilagirica. Phytochemical characterization of ethanolic extract of A. nilagirica from Kerala, India was shown to have the presence of terpenoids, flavonoids, steroids, saponins, fixed oils and fats, tannins, and glycosides.

Evaluation of Various Solvent Extracts of Tetrastigma leucostaphylum (Dennst.) Alston Leaves, a Bangladeshi Traditional Medicine Used for the Treatment of Diarrhea

Tetrastigma leucostaphylum (TL) is an important ethnic medicine of Bangladesh used to treat diarrhea and dysentery. Hence, current study has been designed to characterize the antidiarrheal (in vivo) and cytotoxic (in vitro) effects of T. leucostaphylum. A crude extract was prepared with methanol (MTL) and further partitioned into n-hexane (NTL), dichloromethane (DTL), and n-butanol (BTL) fractions. Antidiarrheal activity was investigated using castor oil induced diarrhea, enteropooling, and gastrointestinal transit models, while cytotoxicity was evaluated using the brine shrimp lethality bioassay. In antidiarrheal experiments, all doses (100, 200, and 400 mg/kg) of the DTL extract significantly reduced diarrheal stool frequency, volume and weight of intestinal contents, and gastrointestinal motility in mice. Similarly, in the cytotoxicity assay, all extracts exhibited activity, with the DTL extract the most potent (LC50 67.23 μg/mL). GC-MS analysis of the DTL extract identified 10 compounds, which showed good binding affinity toward M3 muscarinic acetylcholine, 5-HT3, Gut inhibitory phosphodiesterase, DNA polymerase III subunit alpha, and UDP-N-acetylglucosamine-1 carboxyvinyltransferase enzyme targets upon molecular docking analysis. Although ADME/T analyses predicted the drug-likeness and likely safety upon consumption of these bioactive compounds, significant toxicity concerns are evident due to the presence of the known phytotoxin, 2,4-di-tert-butylphenol. In summary, T. leucostaphylum showed promising activity, helping to rationalize the ethnomedicinal use and importance of this plant, its safety profile following both acute and chronic exposure warrants further investigation.

In vitro evaluation of acaricidal activity of novel green silver nanoparticles against deltamethrin resistance Rhipicephalus (Boophilus) microplus

An investigation was undertaken to study, for the first time, in vitro acaricidal activity of green silver nanoparticles on deltamethrin resistance Rhipicephalus (Boophilus) microplus. The compounds tested were neem coated silver nanoparticles (N-Ag NPs), deltamethrin neem coated silver nanoparticles (DN-Ag NPs), 2, 3 dehydrosalannol (2,3 DHS), 2, 3 DHS coated silver nanoparticles (2, 3-DHS-Ag NPs), Quercetin dihydrate (QDH) and QDH coated silver nanoparticles (QDH-Ag NPs). Also included in this study, for the purpose of comparison, were neem leaf extract (NLE), silver nitrate (AgNO₃) and deltamethrin (D). Acaricidal activity on larvae and adults of R. (B.) microplus was tested by larval packet test (LPT) and adult immersion test (AIT) respectively. In the LPT, 100% mortality was obtained at concentrations (ppm) of 360, 6000, 260, 200, 50, 300, 85, 600 and 200 for the compounds, D, NLE, Ag NO₃, N-Ag NPs, DN-Ag NPs, 2, 3 DHS, 2, 3 DHS-Ag NPs, QDH, QDH-Ag NPs respectively. In AIT, the proportions of mortality and oviposition inhibition were proportionate but the reproductive index was inversely proportional to the concentration of the compounds used. The effect of DN-Ag NPs on mortality was the highest (93.33%) at 50ppm concentration. The mean reproductive index (0.01) and oviposition inhibition (99.16%) values were statistically significant when compared to control group. DN-Ag NPs showed significantly (P<0.05) lower LC₅₀ (3.87ppm; 21.95ppm) and LC₉₉ (53.05ppm; 90.06ppm) values against both the larvae and adults of R. (B.) microplus. The oviposition inhibiting ability of various compounds was determined to assess the reproductive performance of adult female ticks. The DN-Ag NPs had potent oviposition inhibitory activity with significantly lower IC₅₀ and IC₉₉ values compared to the rest of the treatments at 0.034 and 51.07ppm respectively. These results showed that the DN-Ag NPs had significant acaricidal activity against R. (B.) microplus.

In vitro effects of caffeic acid, nortriptyline, precocene I and quercetin against Rhipicephalus annulatus (Acari: Ixodidae)

In the present study, the acaricidal effects of caffeic acid, nortriptyline, precocene I and quercetin against Rhipicephalus annulatus (syn. Boophilus annulatus) Say (Acari: Ixodidae) were evaluated. Adult immersion technique (24 ticks immersed for 2 min in one dilution of the compound) was used for the assessment of the effects of caffeic acid (0.39-100 mg/mL), nortriptyline (0.625-50 mg/L), precocene I (0.004488-5 mg/mL) and quercetin (6.25-100 mg/mL) against R. annulatus. Adult tick mortality, reproductive index, inhibition of fecundity and hatching were calculated. Caffeic acid, nortriptyline, precocene I and quercetin revealed very low adult mortality and inhibition of fecundity, even at the highest concentration tested. Quercetin (>50 mg/mL) caused blocking of hatching of eggs.

Tick repellents and acaricides of botanical origin: a green roadmap to control tick-borne diseases?

Arthropods are dangerous vectors of agents of deadly diseases, which may hit as epidemics or pandemics in the increasing world population of humans and animals. Among them, ticks transmit more pathogen species than any other group of blood-feeding arthropods worldwide. Thus, the effective and eco-friendly control of tick vectors in a constantly changing environment is a crucial challenge. A number of novel routes have been attempted to prevent and control tick-borne diseases, including the development of (i) vaccines against viruses vectored by ticks; (ii) pheromone-based control tools, with special reference to the "lure and kill" techniques; (iii) biological control programmes relying on ticks' natural enemies and pathogens; and (iv) the integrated pest management practices aimed at reducing tick interactions with livestock. However, the extensive employment of acaricides and tick repellents still remains the two most effective and ready-to-use strategies. Unfortunately, the first one is limited by the rapid development of resistance in ticks, as well as by serious environmental concerns. On the other hand, the exploitation of plants as sources of effective tick repellents is often promising. Here, we reviewed current knowledge concerning the effectiveness of plant extracts as acaricides or repellents against tick vectors of public health importance, with special reference to Ixodes ricinus, Ixodes persulcatus, Amblyomma cajennense, Haemaphysalis bispinosa, Haemaphysalis longicornis, Hyalomma anatolicum, Hyalomma marginatum rufipes, Rhipicephalus appendiculatus, Rhipicephalus (Boophilus) microplus, Rhipicephalus pulchellus, Rhipicephalus sanguineus and Rhipicephalus turanicus. Eighty-three plant species from 35 botanical families were selected. The most frequent botanical families exploited as sources of acaricides and repellents against ticks were Asteraceae (15 % of the selected studies), Fabaceae (9 %), Lamiaceae (10 %), Meliaceae (5 %), Solanaceae (6 %) and Verbenaceae (5 %). Regression equation analyses showed that the literature grew by approximately 20 % per year (period: 2005-2015). Lastly, in the final section, insights for future research are discussed. We focused on some caveats for future data collection and analysis. Current critical points mainly deal with (a) not uniform methods used, which prevent proper comparison of the results; (b) inaccurate tested concentrations, frequently 100 % concentration corresponded to the gross extract, where the exact amounts of extracted substances are unknown; and (c) not homogeneous size of tested tick instars and species. Overall, the knowledge summarized in this review may be helpful for comparative screening among extensive numbers of plant-borne preparations, in order to develop newer and safer tick control tools.