Anesthetic activity of plant essential oils on Cyprinus carpio (koi carp)

Efficacy of fennel (Foeniculum vulgare) and anise (Pimpinella anisum) essential oils as anaesthesics in common carp (Cyprinus carpio L. 1758)

In this study, the anaesthetic effects of fennel and anise essential oils were investigated on common carp. Fish (10 ± 0.45 g) were exposed to nine concentrations of essential oils (5, 10, 20, 50, 100, 200, 300, 400 and 500 mg L-1). Additionally, the histopathological effects on the fish tissues including gill, skin and hepatopancreas and physiological effects on some blood parameters (Na+, K+, Ca+2, Cl-, total plasma protein and glucose) of essential oils were investigated in carp. At the end of the experiment, fennel oil showed an anaesthetic effect at a concentration of 500 mg L-1 in carp (anaesthesia induction and recovery times were 308 and 472 s, respectively). Anise essential oil showed deep anaesthesia at a concentration of 100 mg L-1, but anaesthesia induction time was found to be very long (20 min). In addition, anise oil at concentrations above 100 mg L-1 caused 10% mortality in fish. Blood parameters except glucose level in both essential oils were unchanged during deep anaesthesia in carp. However, plasma glucose levels were found lower in fish anaesthetized with anise oil than control and fennel groups (P < 0.05). At the histopathological examination, no pathological findings were observed in any organ of fish in the fennel group. However, severe hyperemia and inflammatory cell infiltrations in gills, erosive lesions in the skin and slight inflammatory reactions in the skin were observed in the anise group. The present study demonstrated that fennel essential oil at 500 mg L-1 concentration can be used as an effective and safe anaesthetic in common carp, but anise essential oil is not suitable.

Synergistic Effect between Eugenol and 1,8-Cineole on Anesthesia in Guppy Fish (Poecilia reticulata)

This study aimed to evaluate the synergistic effect between eugenol and 1,8-cineole on anesthesia in female guppy fish (Poecilia reticulata). Experiment I evaluated the concentrations of 0, 12.5, 25, 50, and 75 mg/L of eugenol and 0, 100, 200, 300, and 400 mg/L of 1,8-cineole for times of induction and recovery from anesthesia. Experiment II divided fish into 16 study groups, combining eugenol and 1,8-cineole in pairs at varying concentrations, based on the dosage of the chemicals in experiment I. The results of the anesthesia showed that eugenol induced fish anesthesia at concentrations of 50 and 70 mg/L, with durations of 256.5 and 171.5 s, respectively. In contrast, 1,8-cineole did not induce fish anesthesia. In combination, using eugenol at 12.5 mg/L along with 1,8-cineole at 400 mg/L resulted in fish anesthesia at a time of 224.5 s. Increasing the eugenol concentration to 25 mg/L, combined with 1,8-cineole at 300 and 400 mg/L, induced fish anesthesia at times of 259.0 and 230.5 s, respectively. For treatments with eugenol at 50 mg/L combined with 1,8-cineole at 100 to 400 mg/L, fish exhibited anesthesia at times of 189.5, 181.5, 166.0, and 157.5 s. In the case of eugenol at 75 mg/L, fish showed anesthesia at times of 175.5, 156.5, 140.5, and 121.5 s, respectively. The testing results revealed that 1,8-cineole as a single treatment could not induce fish anesthesia. However, when supplementing 1,8-cineole in formulations containing eugenol, fish exhibited a significantly faster induction of anesthesia (p < 0.05). Furthermore, all fish that underwent anesthesia were able to fully recover without any mortality. However, the shorter anesthesia duration resulted in a significantly prolonged recovery time. In conclusion, eugenol and 1,8-cineole work better together as anesthetics than when used separately, and demonstrated the safety of using these anesthetic agents on guppy fish.

Anesthesia or seizure-like behavior? The effects of two Amazonian plants, Acmella oleracea and Piper alatabaccum in zebrafish (Danio rerio)

Abstract Currently, available fish anesthetics can produce important side effects, including respiratory arrest and distress. Easy-to-implement alternatives with low toxicity are needed to ensure fish health as well as to help artisanal fisheries and fish sellers in handling and transporting fishes, and native plants seems to be the best alternative. We aimed to implement an anesthetic protocol using crude ethanolic extracts from flowers and leaves of two Amazonian plants, the Acmella oleracea and Piper alatabaccum. We first tested the extracts for anesthesia, using the zebrafish as model. Even though in some treatments the animals apparently entered deep anesthesia, many of them presented aberrant behaviors and even died. Thus, we performed new experiments testing the extracts effects on seizure-like behaviors of the fish. Only the leaf extract of A. oleracea has potential effects for fish anesthesia. Both the flower extract from this plant and the leaf extract from P. alatabaccum induced seizure-like behavior in the animals. In conclusion, besides bringing a possible new anesthetic protocol for fish, our work draws attention for the neurotoxic effects the anesthetic solutions may cause, since several studies defend other Piper species as anesthetic for fish and A. oleracea flowers’ extract was already pointed as fish anesthetic.

Antifungal and mycotoxin detoxification ability of essential oils: A review

With increased popular awareness of food safety and environmental protection, plant essential oil has attracted interest due to the absence of residue, its high efficiency, antioxidant, immune regulation, antibacterial, insecticidal, and other advantages. Their application in degradation and elimination of mycotoxin toxicity has attracted increasing attention. This paper reviews the structure, antibacterial activity, antibacterial mechanism, and toxic effects of essential oils. The inhibitory effects of various essential oils on different mycotoxins were studied. The research progress on the inhibitory effects of plant essential oils on fungi and mycotoxins in recent years was summarized to provide reference for the application of plant essential oils.

Development of Microemulsion Containing Alpinia galanga Oil and Its Major Compounds: Enhancement of Antimicrobial Activities

The aim of the present study was to develop a microemulsion (ME) containing Alpinia galanga oil (AGO), 1,8-cineole (C), or methyl eugenol (M) as an active pharmaceutical ingredient (API) for enhancing their antimicrobial activities. Agar diffusion, broth microdilution, and killing kinetics were used for antimicrobial evaluations. The ME composed of 30% API, 33.4% Tween 80, 16.6% ethanol, and 20% water appeared as translucent systems with droplet size and polydispersity index of 101.1 ± 1.3 nm and 0.3 ± 0.1, 80.9 ± 1.1 nm and 0.4 ± 0.1, and 96.6 ± 2.0 nm and 0.2 ± 0.1 for ME-AGO, ME-C, and ME-M, respectively. These ME formulations showed minimum bacterial concentrations of 3.91–31.25 µg/mL and 50% fungal inhibition concentrations of 1.83 ± 0.27–0.46 ± 0.13 µg/mL, 2–4 times stronger, and faster kinetic killing rate than their respective API alone. Keeping the ME formulations at 4 °C, 25 °C, and 40 °C for 12 weeks did not affect their activities against fungi and Gram-negative bacteria, but the high temperature of 40 °C decreased their activities against Gram-positive bacteria. It is concluded that ME is a promising delivery system for AGO and its major compounds to enhance their water miscibility and antimicrobial activities.