Cecropia pachystachya: a species with expressive in vivo topical anti-inflammatory and in vitro antioxidant effects

Abstract

Cecropia pachystachya is a species traditionally used in Brazil to treat inflammation. This work aims to evaluate the topical anti-inflammatory and antioxidant activities of the methanolic extract of C. pachystachya (CPM) and to perform its chemical fingerprint by HPLC-DAD. The topical anti-inflammatory activity was evaluated using the mouse models of acute ear inflammation induced by croton oil, arachidonic acid, capsaicin, EPP, phenol, and chronic inflammation induced by multiple application of croton oil. The in vitro antioxidant effect of CPM was investigated using DPPH, reducing power, β -carotene bleaching, and TBARS assays. HPLC analysis was performed to quantify the antioxidant phenolics orientin, isoorientin, and chlorogenic acid previously identified in CPM. CPM exhibited significant anti-inflammatory effect in the acute models, in some cases comparable to the reference drugs. Histopathological analysis showed a moderate chronic skin anti-inflammatory effect with decrease in vasodilation, edema, cell infiltration, and epidermal hyperproliferation. It also showed strong in vitro antioxidant activity. The contents of orientin, isoorientin, and chlorogenic acid were 66.5 ± 1.8, 118.8 ± 0.7, and 5.4 ± 0.2 µg/mg extract, respectively. The topical anti-inflammatory activity of CPM could be based on its antioxidant properties, although other effects are probably involved, including COX inhibition and other mechanisms.

Figure 1

HPLC fingerprint chromatogram of the methanol extract of C. pachystachya leaves (CPM). The peaks were indicating as follows: (1) chlorogenic acid; (2) isoorientin; (3) orientin. Peaks 4, 5, and 6 are of nonidentified flavonoids. DAD 330 nm was used.

Figure 2

Effect of CPM single application croton oil-induced mouse ear edema. Dexamethasone was used as positive control. Statistical analysis: one-way ANOVA followed by Newman-Keuls test (n = 6–8). *P < 0.05, **P < 0.01,  and ***P < 0.001 compared to negative control group.

Figure 3

Effect of CPM on croton oil multiple application-induced mouse ear edema showing the time-response curve of effect during 9 days. Dark points under times indicate when the croton oil application occurred. The thickness of the ear was measured daily, using a digital micrometer. At the time 120 h (fifth day of the experiment) the ear of the animals received vehicle acetone (negative control), dexamethasone (positive control), or CPM 0.5 mg/ear, twice a day (arrows indicate the days of treatment which treatment). Statistical analysis: two-way ANOVA followed by Bonferroni test (n = 6–8). ***P < 0.001 compared to negative control group.

Figure 4

Effect of CPM single application arachidonic acid- (AA-) induced mouse ear edema. Indomethacin was used as positive control. Statistical analysis: one-way ANOVA followed by Newman-Keuls test (n = 6–8). ***P < 0.001; **P < 0.01 compared to negative control group.

Figure 5

Effect of CPM single application capsaicin-induced mouse ear edema (n = 6–8). Statistical analysis: one-way ANOVA followed by Newman-Keuls test.

Figure 6

Effect of CPM single application EPP-induced mouse ear edema. Dexamethasone was used as positive control. Statistical analysis: one-way ANOVA followed by Newman-Keuls test (n = 6–8). **P < 0.01; *P < 0.05 compared to negative control group.

Figure 7

Effect of CPM single application phenol-induced mouse ear edema. Dexamethasone was used as positive control. Statistical analysis: one-way ANOVA followed by Newman-Keuls test (n = 6–8). *P < 0.05, **P < 0.01, and ***P < 0.001 compared to negative control group.

Figure 8

Photomicrograph of transverse sections of mice ears sensitized with topical application of Croton oil 5% (v/v) in acetone (b–f) or vehicle acetone (a, noninflamed), stained with hematoxylin-eosin and examined under light microscopy (magnification: 10x, 40x). Treatments: acetone (b), dexamethasone 0.1 mg/ear (c), EMCP 1.0 mg/ear (d) 0.5 mg/ear (e), and 0.1 mg/ear (f). The numbers 1 and 2 indicate epidermis and dermis, respectively. Arrows indicate leukocyte infiltrate in the dermis. The shown sections are representative of four animals per group.

Figure 9

Photomicrograph of transverse sections of mice ears sensitized with multiple topical application of Croton oil 5% (v/v) in acetone (b–d) or vehicle acetone (a, noninflamed), stained with hematoxylin-eosin and examined under light microscopy (magnification: 10x, 40x). Treatments: acetone (b), dexamethasone 0.1 mg/ear (c), and EMCP 0.5 mg/ear (d). The numbers 1 and 2 indicate epidermis and dermis, respectively. Arrows indicate leukocyte infiltrate in the dermis. The shown sections are representative of four animals per group.