Inhibition of Nematocyst Discharge from Pelagia noctiluca (Cnidaria: Scyphozoa)—Prevention Measures against Jellyfish Stings

Abstract

Pelagia noctiluca stings are common in Mediterranean coastal areas and, although the venom is non-lethal, they are painful. Due to its high toxicity and abundance, P. noctiluca is considered a target species for the focus of research on active ingredients to reduce the symptoms of its sting. To determine the effect of 31 substances and formulations on nematocyst discharge, we performed three tests: (1) screening of per se discharge activator solutions, (2) inhibitory test with nematocyst chemical stimulation (5% acetic acid) and (3) inhibitory test quantifying the hemolytic area. Ammonia, barium chloride, bleach, scented ammonia, carbonated cola, lemon juice, sodium chloride and papain triggered nematocyst discharge. All of them were ruled out as potential inhibitors. Butylene glycol showed a reduction in nematocyst discharge, while the formulations of 10% lidocaine in ethanol, 1.5% hydroxyacetophenone in distilled water + butylene glycol, and 3% Symsitive® in butylene glycol inhibited nematocyst discharge. These last results were subsequently correlated with a significant decrease in hemolytic area in the venom assays versus seawater, a neutral solution. The presented data represent a first step in research to develop preventive products for jellyfish stings while at the same time attempting to clarify some uncertainties about the role of various topical solutions in P. noctiluca first-aid protocols.

Effect of Rinse Solutions on Rhizostoma pulmo (Cnidaria: Scyphozoa) Stings and the Ineffective Role of Vinegar in Scyphozoan Jellyfish Species

“…In the present research, scented ammonia was also considered an activator solution for R. pulmo (Figure 1D and Table 1), in agreement with the findings of Birsa et al (2010) [25] for C. quinquercirrha. In contrast, unfired nematocysts were observed after the application of urine (Figure 1G), as reported in previous research [25,35]. Our results are in contrast to those of Doyle et al (2017) [21] in C. capillata; therefore, in order to clarify the role of urine, further research with other scyphozoan species is needed.…”

“…In the present study, in addition to R. pulmo, the nematocysts of Aurelia sp., Cassiopea sp., and R. luteum were also activated after the application of vinegar (Figure 2D-F and Table 2). In previous studies, vinegar or acetic acid promoted discharge in scyphomedusae such as Chrysaora quinquecirrha [25], Cyanea capillata [24,34], Nemopilema nomurai [22], and P. noctiluca [23,35]. Overall, the scientific evidence contraindicates rinsing the sting area with vinegar, acetic acid, or commercial products based on these compounds for the Scyphozoa class.…”

“…Rinsing with deionized, distilled, or freshwater has been contraindicated due to the induction of discharge by osmotic pressure [38]. Nevertheless, methods that have directly evaluated the effect on cnidocyst discharge (e.g., Tentacle Solution Assay [33]) have shown no solid evidence to support this contraindication [8,22,25,33,35,39]. Pyo et al (2016) [22] did not observe discharge after the application of distilled water in both the cubozoan Carybdea mora and the scyphozoan N. nomurai.…”

Jellyfish Stings: A Review of Skin Symptoms, Pathophysiology, and Management

“…Some propose the application of sand or clothing to envelop the tentacles, followed by gentle wiping; however, this may induce pressure alterations that trigger tubule discharge [ 17 ]. Ballesteros et al identified ammonia, barium chloride, bleach, scented ammonia, carbonated cola, lemon juice, sodium chloride, and papain as substances capable of inducing nematocyst discharge, which should be avoided [ 47 ]. Rinsing with fresh water should also be avoided due to its lower osmotic pressure [ 16 , 48 ].…”

A Study of Nematocyst Discharge of Physalia physalis and Venom Composition

“…A variety of chemosensory, mechanosensory and endogenous pathways regulate the depolarization of the nematocyst membrane, culminating in the discharge of the sting [8]. Different works shown that specific compounds and ions can evoke depolarizing events and induce the discharge of nematocysts [9][10][11][12][13]. Regarding P. physalis, some works have been conducted to study the discharge [14], but this organism remains poorly understood.…”