PMC full text:
Published online 2011 Jan 10. doi: 10.3945/an.110.000117
Table 1.
The comparative mechanisms of action and behavioral effects of alkaloid secondary metabolites in insects and humans/mammals
| Phytochemical (group) | Insect models | Human/mammal models | |||
| Mechanism | Genus, family, or plant | Effect on behavior | Mechanism | Effect on behavior | |
| Atropine (tropane alkaloid) | Family: Solanaceae | Muscarinic ACh receptor antagonist (80) | Impaired memory retrieval (one trial olfactory conditioning) (81) | Muscarinic ACh receptor antagonist (82) | Impairs memory in primates and humans (83) |
| Plant: e.g. Atropa belladonna (deadly nightshade) | |||||
| Caffeine (purine alkaloid) | Plants: e.g. Coffea arabica, Camellia sinensis (tea), Paulinia cupana (guarana), Ilex paraguariensis (Maté), Theobroma cacao (Cocoa) | Adenosinergic (63) and dopaminergic (84) receptor interactions, specifically involving DA D1 receptor signaling (63) | Increased arousal and decreased sleep (46, 61), decreased tonic immobility (62) | competitive antagonist of inhibitory adenosine A1 and A2 receptors → increased dopaminergic and glutamatergic activity (64) | Increased alertness and improved attention in humans (69) |
| Cocaine (tropane alkaloid) | Plant: Erythroxylum coca (Coca) | DA synthesis and binding – plus interaction with tyramine (85) | Increased drosophila grooming (86) and dancing in bees (87) at low doses. Increased and erratic acivity, paralysis and death with increasing dose. | Increased extracellular DA by blockade of DA transporter (88) | Increased alertness, euphoria, motor activity in humans (89) |
| Ephedrine (alkaloid) | Family: Ephedraceae | Increased dopaminergic signaling (90) via DA D1 receptors (63) | Increased arousal/decreased sleep (63, 90) | Interact with adrenergic receptors (91) increase DA efflux and inhibit monoamine oxidase (88) | Increased alertness, arousal, motor activity, concentration, well-being in humans (89) |
| Plant: e.g. Ephedra sinica | |||||
| Synthesized as Methamphetamine | |||||
| Morphine (isoquinoline alkaloid) | Plant: Papaver somniferum | Opioid receptor binding (92) | Decreased protective reaction to noxious stimuli (92) and increased feeding behavior (93) | Opioid receptor binding (94) | Euphoria, analgesia, sedation in humans (89) |
| Nicotine (pyridine alkaloid) | Plant: Nicotiana tabacum (tobbaco) | Agonist nicotinic ACh receptor binding (95) | hyperactivity at low doses - hypokinesis and akinesis at higher doses (96) | Agonist nicotinic ACh receptor binding → ACh, glutamate, 5-HT and DA activity (75) | Stimulant effects and improved attention and memory (78) |
| Physostigmine (indole alkaloid) | Plant: Physostigma venenosum (Calabar bean) | Cholinesterase inhibitor and direct agonistic nicotinic ACh receptor binding (97) | Allosteric nicotinic ACh receptor agonist, but at higher doses blocks open channels (98) | Improves memory in aged primates and humans (83) | |
| Pilocarpine (imidazole alkaloid) | Genus: Pilocarpus | Muscarinic ACh receptor agonist (80) | Improved memory (nestmate recognition) (36) | Muscarinic ACh receptor agonist (82) | Improved cognitive function inc memory in old rats (99) and young primates (but high level of side effects) (100) |
| Scopolamine (tropane alkaloid) | Family: Solanaceae | Muscarinic ACh receptor antagonist (80) | Memory decrements (one trial olfactory conditioning) (80) decrements in memory (nestmate recognition) (36) | Muscarinic ACh receptor antagonist (101) | Human cognitive and memory decrements (101) |
| Plant: e.g. Atropa belladonna (deadly nightshade) | |||||