The treatment for pain relief is mainly focus on using antinociceptive drugs. However, the current collection isn't enough and many have side effects and adverse reactions that precludes their chronic use. Based on this problem, the article's aims to evaluate a supposed antinociceptive effect of Morinda citrifolia L in rats using hot plate assays (HPA) observing the latency time (LT) in the following groups: control (C); ethanolic pulp extract (EPE) and pulp extract (PE), in natura, both of noni; ascorbic acid (AA); diazepam (D); morphine (M) and association diazepam-morphine (DM). In the post-30 min experiments with EPE and PE, there was a partial increase in TL with EPE equal to that observed after 20 min with PE. In t 30 to 40 min, there was moderate tolerance to the thermal stimulus with PE that declined after 40 min, showing an antinociceptive tendency. The AA group showed a nociceptive effect at 30 and at 40 min it showed a similar effect to the PE at the same time, indicating a moderate antinociceptive action. The results suggest a tendency that both EPE and PE have antinociceptive effects, although not significant, when compared to C, with PE having this effect a little more pronunced.

The model of restraint is used to induce stress. Ascorbic acid is a biomarker stored in the adrenal (AAA) whose depletion measures the stress level. Noni has been subject of research because of the potential benefits, but studies associated with stress are scarce, and the pulp seems to contain high levels of vitamin C (VITC). Rats treated with distilled water (gavage) for 14 days were used as controls (C, n = 8); Stress (S, n = 8), treated with distilled water (gavage, 14 days); Noni + stress group (SN, n = 6), treated pulp of noni (gavage, 14 days);Stress + VITC group (SvitC, n = 7) treated with VITC (gavage, 14 days). SN and SvitC received the same dosage of VITC, which in the SN group was determined by titration of the pulp of noni. The procedure was stressful for pet bottles (500 mL) for 1 h / day / 7 days. The adrenal glands were weighed and extracted with AAA metaphosphoric acid. The filtrate was reacted with 2,6‐dichlorophenol indophenol and absorbance reading taken in spectrophotometer (λ = 520 ηm), inserted in the standard curve of ascorbic acid, standardized weights of the adrenals and body. Approval of CEUA under number 017. Data were analyzed using ANOVA and Tukey results show significant depletion of AAA in group S compared to C (p = 0.053) and in groups SN and SvitC no AAA depletion compared to C. It is concluded that possibly the combating stress action noni is due to the vitamin C content in the pulp of this fruit. Rats Control Group ugAAA/100mgAdrenal/100gBodyWeight Stress Group / ugAAA/100mgAdrenal/100gBodyWeight Stress + Noni Group/ ugAAA/100mgAdrenal/100gBodyWeight Stress + VITC Group/ ugAAA/100mgAdrenal/100gBodyWeight 1 53,39105339 34,27910812 53,05312158 46,95012019 2 44,24261893 32,64925373 63,42821782 74,2464539 3 52,94006428 38,88750622 60,11479988 55,37917922 4 40,29100547 31,49325827 62,61824905 66,76718701 5 54,11566135 34,78447632 33,83190883 48,97720334 6 48,42196282 37,46436955 44,16282642 40,63548658 7 65,90104111 37,20238095 32,77972028 8 52,1609538 39,11960892 imageimage