A large number of marine organisms are known to posses bio-active substances that have tremendous pharmaceutical potential for the future [28
]. However, considerable progress has been made to isolate and characterize the toxic components of marine cnidarians [29
]. Several antimicrobial peptides have been isolated from Cnidaria [13
]. To our knowledge, no antimicrobial activity of P. noctiluca
venom has been reported.
Fortunately, we could obtain adequate P. noctiluca material because of the exceptional abundance of this jellyfish in the coastal water of Tunisia, in these recent years. The extraction of crude venom from nematocysts is essential before any research into crude venom toxicity can be conducted.
In an attempt to obtain crude venom from the nematocysts of P. noctiluca
, we tried some mechanical methods including sonication, which did not destroy P. noctiluca
In the present study, Protein components of P. noctiluca
nematocysts crude venom were determined by using SDS-PAGE on 12% polyacrylamide gel. 15 distinct clear bands were determined with molecular weight of 4; 14; 16 ; 20; 29 ; 33 ; 37 ; 45 ; 55 ; 64 ; 66 ; 70 ; 80 ; 115 and 120 kDa in P. noctiluca
crude venom (Figure
). It has been reported that toxic fractions of P. noctiluca
crude venom has a molecular weight of 54, 92, 130 and 150 kDa [36
Separation of crude crude venom of P. noctiluca
was achieved by a size exclusion chromatography (sephadex G 75). This gel is a dextran capable of separating proteins with molecular weights between 3 and 70 KDa. The volume outside the gel matrix is known as the void volume (Vo). This is the volume required to elute a substance so large that it cannot penetrate the pores at all. Proteins with molecular weights greater than 70 KDa are completely excluded. Two peaks were collected and screened for their analgesic and BuChE inhibitory activities (Figure
Great progress has been made in the last 30 years toward understanding the neural substrates of pain and identifying novel molecular targets for analgesic drug development [37
]. Acetic acid induced writhing method is a sensitive procedure in detecting analgesic effect of medicinal agents [38
]. P. noctiluca
crude venom and its fractions (F1 and F2) showed significant analgesic action compared to the reference drug acetyl salicylate of lysine (ASL). The fraction 2 was found to exhibit higher analgesic activity than fraction 1 against acetic acid induced pain in mice at two dose levels (1 & 2 mg/kg b.w.), these doses were not toxic for mice.
Suganthi et al [17
] reported that intraperitoneally administration of 200 mg/kg of Crambionella stuhalmanni
and Chrysaora quinquecirrha
extracts significantly inhibit acetic acid induced writhing in mice, the inhibition of writhing response and central nervous system depressing activity percentage were 35%, 55% and 90%, 95%.
The present results coincide with those reported by other authors who studied the analgesic property of Conus lentiginosus
and C. mutabilis
, which was 128 times more than that of paracetamol [39
]. Shanmuganandam [40
] reported the effectiveness of Conus figulinus
venom on guinea pig skin as an infiltration anaesthetic agent. Salivary gland secretion of the gastropod Conus sp.
is one of the most important venoms to possess analgesic property [41
It is, therefore, assumed that central mechanisms may be involved in the observed phenomenon since the extract could elicit activities against pain model. Agents that exhibit these activities are believed to act primarily on the central nervous system.
stings produce distinctive psychiatric signs and symptoms [43
]. The brain operation experiments show that this organ can be affected by the venom of Chrysaora quinquecirrha
. The biphasic action, an early disorientation followed by recovery then eventual death may indicate two separate neuro-active principles in the venom [45
Neurotoxins are components of venoms that are specifically directed against the nervous system. The molecular variety of these substances extends from low molecular weight alkaloids to peptides and complex proteins [46
]. In Cnidaria the neurotoxins have been the subject of numerous studies [11
]. Sanchez-Rodriguez et al [48
] isolated a 120-kDa protein from the cubomedusa Carybdea marsupialis
with a strong neurotoxic activity on marine crabs (Ocypode quadrata
The principal role of cholinesterase (ChE) is the termination of nerve impulse transmission at the cholinergic synapses by rapid hydrolysis of acetylcholine (ACh). Inhibition of ChE serves as a strategy for the treatment of Alzheimer’s disease (AD), senile dementia, ataxia, myasthenia gravis and Parkinson’s disease [49
In this study, the crude venom of P. noctiluca
and its fractions (F1and F2) were tested to determine their ability as human BuChE inhibitors. The BuChE inhibition was determined using an adaptation of the method described by Ellman et al [25
]. P. noctiluca
crude venom, F 1 and F 2 exhibited moderate to good anti-BuChE activity. In fact, the best inhibitory activity was determined by the F 2, with an order of inhibition capacity: F2
In spite of the widespread occurrence of AChE in animals only a few AChE inhibitors from natural sources have been isolated. For example, polypeptide fasciculins from mamba venom [50
] and an alkaloids such as physostigmine from ordeal or Calabar bean [51
]. An ethanolic extract from a zoanthid crust coral Parazoanthus axinellae
exhibited anticholinesterase activity [52
The present study indicated that jellyfish P. noctiluca crude venom and its fractions contained peptides with specific cholinesterase inhibitory activities which might be responsible for some of the neurotoxic effects of the venom on animals and humans.