Analgesics are a popular folk medicine amongst the tribes of South America and one has been used in such folk medicine for centuries. The plant Piper amalago (Piperaceae) was recently examined for its pharmacological benefits using an extract and a pure sample of its amides to provide releief for various conditions.
Researchers at the Universidade Federal da Grande Dourados in Brazil looked at an ethanolic extract of the plant (EEPA) with regards to its anti-nociceptive, anti-hyperalgesic, anti-arthritic and anti-depressive activities in animal models. The unusual amides isolated from the extract were N-[7-(3′,4′-methylenedioxyphenyl)-2(Z),4(Z)-heptadienoyl] pyrrolidine and N-[7-(3′,4′-methylenedioxyphenyl)-2(E), 4-(E)-heptadienoyl] pyrrolidine.
A mouse model was used to test the efficacy of the Piper extracts. These mice were treated daily with EEPA (100 mg/kg, p.o.) or with the individual amides extracted from the plant. They were assayed for 20 days for knee oedema (micrometer measurement), mechanical hyperalgesia (analgesiometer analysis), heat sensitivity and immobility (forced swim test) in the Complete Freund’s Adjuvant (CFA) model. Cold (acetone test) and mechanical hyperalgesia (electronic von Frey analysis) responses were evaluated for 15 days in rats treated with oral EEPA (100 mg/kg) in the spared nerve injury (SNI) model. A formalin model was used to evaluate mice for carrageenan-induced oedema and mechanical hyperalgesia and for nociception.
It would appear that the extract from P. amalago was effective for inhibiting various pain and arthritis parameters but not against any forms of depressive behaviour nor have any impact on locomotor activity. The active amides were highly effective in combating acute pain. The authors believe the plant might be a new combatant in pain relief.
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