Medicinal plant extracts and nematode control.

Abstract

Several aspects should be taken into consideration in relation to the use of active botanical extracts or compounds in parasite control: extraction, conservation, phytochemical study, determination of lethal concentration in vitro, toxicity to the host, effective dose in vivo, residual period, stability, residues/metabolites generated and costs. The in vitro tests that have been used to screen biological activity were developed to detect parasite resistance to anthelmintics. In this way, the effects of a potent plant extract can be underestimated or dismissed if the selected methods disregard some factors that can influence the results, such as solubility or an indirect effect on the nematode. Despite this, the development of strategies that are less dependent on in vivo testing is important. There is a need for fuller investigations not restricted only to indicating whether or not a phytotherapy was effective against parasites. The divergence between efficacy in vitro and inefficacy in vivo can be attributed to key factors related to bioavailability as well as pharmacology of the botanical substances in the host organism. It is important to focus studies to determinate the most appropriate adjuvants and to develop formulation models that can be adapted according to the nature of the plant extract or bioactive compound isolated, to serve as starting points for the development of semi-synthetic and synthetic substances.

First report of the effect of Ocotea elegans essential oil on Rhipicephalus (Boophilus) microplus

“…O. aciphylla also had efficacy higher than 90% in the LPT at 50 mg/mL (Conceição et al, 2017). These findings may be related to the type of extraction from the plant material, as well as the difference of composition among species, since this can vary widely in the same genus (Chagas, 2015). Therefore, we suggest that other forms of extraction also should be explored for O. elegans, to evaluate its potential against R.…”

“…microplus to the chemical acaricides available in the market are alarming (Higa et al, 2016;Klafke et al, 2017;Raynal et al, 2013). In the search for new drugs, substances of plant origin have demonstrated high efficacy in vitro and can be associated with commercial products to prolong the efficacy by reducing the selective pressure for development of resistant tick strains (Chagas, 2015;Roel, 2001). Active molecules from plant species have interesting characteristics for parasite control in animal production systems, such as reduced environmental impact, reduced residues in food, lower cost and delayed parasite resistance (Mello-Peixoto et al, 2013;Roel, 2001).…”

Efficacy of essential oils from plants cultivated in the Amazonian Biome against gastrointestinal nematodes in sheep

“…M. arvensis presented slight efficacy in vivo and pure menthol none. This can be attributed to key factors related to bioavailability and pharmacology of those compounds in the host organism, destruction of active compounds by gut flora metabolism in rumen and ruminal pH (Chagas 2015;Ferreira et al 2016).…”

Phytotherapeutics: As anticipating substitutes to synthetic drugs in combating antinematicidal-resistant gastrointestinal nematodes of small ruminants

“…Moreover, the plant kingdom is rich with phytomedicines in addition to their relatively low costs, accessibility and acceptability by farmers mainly in developing countries. Routinely, different parts of the plants are being used including the whole plant, leaves, barks, fruit, root, rhizomes, vinegar, aerial parts, cake, bulb, pulp, latex, wood, stigmas, stem, oil, wine, gum, shoots, buds, seeds, flowers, inflorescence…etc (Iwu, 1993;Van Wyk et al, 1997;Akhtar et al, 2000;Hamad et al, 2012;Chagas, 2015 ). It is noteworthy to mention that medicinal botanicals contain various active phytoconstituents such as phenols, flavonoids, tannins, alkaloids (approximately present in 158 botanical families), terpenoids, glycosides, exudates…etc.…”

“…It is noteworthy to mention that medicinal botanicals contain various active phytoconstituents such as phenols, flavonoids, tannins, alkaloids (approximately present in 158 botanical families), terpenoids, glycosides, exudates…etc. (Cowan, 1999;Chagas, 2015). Regarding the current problem which is associated with the development of antinematicidal resistance (AR) among GI nematodes in a wide range of countries, herbal medicines could be the apposite substitute to overcoming this dilemma.…”