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eCAM Advance Access published online on December 26, 2007
eCAM, doi:10.1093/ecam/nem172
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© 2007 The Author(s).
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Comfrey (Symphytum Officinale. L.) and Experimental Hepatic Carcinogenesis: A Short-term Carcinogenesis Model Study

Maria Fernanda Pereira Lavieri Gomes1, Cristina de Oliveira Massoco2, José Guilherme Xavier3 and Leoni Villano Bonamin1,3

1Laboratory of Veterinary Pathology, Faculty of Veterinary Medicine, University of Santo Amaro, 2Oncocell biotecnologia LTDA and 3Laboratory of Pathology, Health Sciences Institute, University Paulista, São Paulo, Brazil

Comfrey or Symphytum officinale (L.) (Boraginaceae) is a very popular plant used for therapeutic purposes. Since the 1980s, its effects have been studied in long-term carcinogenesis studies, in which Comfrey extract is administered at high doses during several months and the neoplastic hepatic lesions are evaluated. However, the literature on this topic is very poor considering the studies performed under short-term carcinogenesis protocols, such as the ‘resistant hepatocyte model’ (RHM). In these studies, it is possible to observe easily the phenomena related to the early phases of tumor development, since pre-neoplastic lesions (PNLs) rise in about 1–2 months of chemical induction. Herein, the effects of chronic oral treatment of rats with 10% Comfrey ethanolic extract were evaluated in a RHM. Wistar rats were sequentially treated with N-nitrosodiethylamine (ip) and 2-acetilaminofluorene (po), and submitted to hepatectomy to induce carcinogenesis promotion. Macroscopic/microscopic quantitative analysis of PNL was performed. Non-parametric statistical tests (Mann–Whitney and {chi}2) were used, and the level of significance was set at P ≤ 0.05. Comfrey treatment reduced the number of pre-neoplastic macroscopic lesions up to 1 mm (P ≤ 0.05), the percentage of oval cells (P = 0.0001) and mitotic figures (P = 0.007), as well as the number of Proliferating Cell Nuclear Antigen (PCNA) positive cells (P = 0.0001) and acidophilic pre-neoplastic nodules (P = 0.05). On the other hand, the percentage of cells presenting megalocytosis (P = 0.0001) and vacuolar degeneration (P = 0.0001) was increased. Scores of fibrosis, glycogen stores and the number of nucleolus organizing regions were not altered. The study indicated that oral treatment of rats with 10% Comfrey alcoholic extract reduced cell proliferation in this model.

Keywords: Comfrey – hepatocarcinogenesis – phytotherapy – Symphytum sp

For reprints and all correspondence: Prof. Leoni Villano Bonamin, University Paulista, Setor de Pós Graduação, Rua Doutor Bacelar, 1212. 4th andar. CEP 04026-002, São Paulo, Brazil. Tel: 5511-55819291; Fax: 5511-55819291; E-mail: leonibonamin{at}gmail.com

Received June 10, 2005; accepted September 25, 2007


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