Preventive potentials of piperlongumine and a Piper longum extract against stress responses and pain

Abstract

Aim: To compare stress resistance increasing and analgesic activities of piperlongumine and a methanolic Piper longum fruit extract (PLE).

Methods: Efficacies of a single and repeated daily oral doses (1-256 mg/kg/day) of PLE, piperlongumine, and 50 mg/kg/day doxycycline against foot shock stress triggered alteration in body weights and core temperatures, and of their 11 daily doses on antidepressants like activity in tail suspension test and on pentobarbital induced sedation in male mice were compared. In another experiment, analgesic activities of single and repeated daily 5 mg/kg oral doses of piperlongumine and PLE in mice hot plate test and in acetic acid induced writing tests were compared with those of aspirin and doxycycline.

Results: After their single oral doses no effects of piperlongumine or PLE or doxycycline were observed in the footshock stress induced hyperthermia test or in hot plate test. However, significant effects of piperlongumine and PLE in both the tests were observed after their 5 or more daily doses. Both of them also dose dependently suppressed daily handling and repetitive testing triggered alterations in body weights and core temperatures. Their doxycycline like antidepressant activity in tail suspension test and aspirin like analgesic effects in acetic acid writhing test were observed after their 11 daily 5 mg/kg oral dose.

Conclusion: Piperlongumine is another bioactive secondary metabolite of P. longum and other plants of piper species with stress response suppressing, analgesic, and anti-inflammatory activities. Its bactericidal activities can also contribute to its therapeutically interesting bio-activity profile.

Keywords: Hot plate test; Physiological stress responses; Piper longum; Piperine; Piperlongumine.

Graphical abstract

Fig. 1

(a) Summary of the experimental procedures used in the dose finding experiments and (b) for comparing analgesic and activities of single and repeated doses of test agents.

Fig. 2

Effects of occasional foot shock stress on body weights of male mice once daily treated either with piperlongumine (a) or with Piper longum fruits extract (b) for 11 consecutive days. Abbreviations: PL = Piperlongumine, PLE = Piper longum fruits extract, DOX = Doxycycline, CMC = Carboxymethyl cellulose suspension. Values are mean ± SEM (n = 6). * denotes statistically significant difference (Two way ANOVA followed by Bonferroni post hoc test) relative to the corresponding vehicle treated (0.3% CMC) control group (* = p < 0.05).

Fig. 3

Effects of occasional foot shock stress on basal rectal temperature of male mice once daily treated either with piperlongumine (a) or with Piper longum fruits extract (b) for 11 consecutive days. Values are mean ± SEM (n = 6). * denotes statistically significant difference (Two way ANOVA followed by Bonferroni post hoc test) relative to the corresponding vehicle treated (0.3% CMC) control group (* = p < 0.05).

Fig. 4

(a) Effects of daily oral doses of piperlongumine in mice foot shock stress induced hyperthermia test on the 1st, 5th, 7th and 10th observational days of the dose finding experiment and (b) its log dose response curves drawn from the observe values on different observational days. Values are mean ± SEM (n = 6). * denotes statistically significant difference (Two way ANOVA followed by Bonferroni post hoc test) relative to the vehicle treated (0.3% CMC) control group (* = p < 0.05).

Fig. 5

(a) Effects of daily oral doses of piperlongumine in mice foot shock stress induced hyperthermia test on the 1st, 5th, 7th and 10th observational days of the dose finding experiment and (b) its log dose response curves drawn from the observe values on different observational days. Values are mean ± SEM (n = 6). * denotes statistically significant difference (Two way ANOVA followed by Bonferroni post hoc test) relative to the vehicle treated (0.3% CMC) control group (* = p < 0.05).

Fig. 6

Effects of 11 daily oral doses of (a) of piperlongumine or (b)Piper longum fruits extract on tail suspension test in male mice. Values are mean ± SEM (n = 6). * denotes statically significant difference (one way ANOVA followed by t-test) relative to control group (* = p < 0.05).

Fig. 7

Effects of occasional thermal stress on mean body weights (a) and basal rectal temperatures (b) of male mice treated with piperlongumine (PL), Piper longum fruits extract (PLE), Doxycycline (DOX), Aspirin (ASA), or carboxymethyl cellulose (CON + HPT) for 12 consecutive days and subjected to hot plate tests on days 1st, 5th, 7th, and 10th day of experiment. The carboxymethyl cellulose treated control group (CON-HPT) was not subjected to hot plate test. Values are mean ± SEM (n = 6). * denotes statistically significant difference (Two way ANOVA followed by Bonferroni post hoc test) relative to (CON + HPT) group (* = p < 0.05).

Fig. 8

Mean reaction times of male mice treated with piperlongumine (PL), Piper longum fruits extract (PLE), Doxycycline (DOX), Aspirin (ASA), or carboxymethyl cellulose to control group (CON + HPT) subjected to hot plate test on days 1, 5, 7, and 10. Values are mean ± SEM (n = 6). *denotes statistically significant difference (Two way ANOVA followed by Bonferroni post hoc test) relative to CON + HPT group (*p < 0.05).

Fig. 9

Mean number of writhes induced by intraperitoneal injections of acetic acid in male mice treated with piperlongumine (PL), Piper longum fruits extract (PLE), Doxycycline (DOX), Aspirin (ASA), or carboxymethyl cellulose to two control groups for 10 consecutive days. (CON + HPT) – subjected to hot plate test on days 1, 5, 7, and 10. (CON-HPT) – not subjected to hot plate tests. Values are mean ± SEM (n = 6). *denotes statistically significant difference (One way ANOVA followed by student t-test) relative to CON + HPT group (*p < 0.05). ^¥ denotes statistically significant difference (One way ANOVA followed by student t-test) relative to CON-HPT group (^¥p < 0.05).