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Rev. bras. farmacogn. vol.21 no.6 Curitiba Nov./Dec. 2011 Epub Aug 12, 2011
Luiz Fernando Verissimo; Andre D. Bacchi; Tiago Zaminelli; Gustavo Henrique O. de Paula; Estefania G. Moreira*
Departamento de Ciências Fisiologicas, Universidade Estadual de Londrina, Brazil
In 2009 the Brazilian Ministry of Health published a document named RENISUS that lists 71 herbs traditionally used in Brazil that could result in phytomedicines to be dispensed by the governmental health care program. This manuscript reviews female reproductive and/or developmental toxicity information of these herbs. More than half (35) of the herbs lack information regarding female reproductive and/or developmental effects. From the fourteen herbs used traditionally to disturb female reproduction, five present experimental data corroborating their actions as abortifacients (Maytenus ilicifolia, Momordica charantia, Plectranthus barbatus, Ruta graveolens) or labour facilitator (Bidens pilosa). For 23 of the herbs evaluated experimentally for any type of female reproductive endpoint, only a single study was retrieved and at least twelve of these studies were conducted with a single dose. This scenario suggests that the scientific power of the published information is very low and that a scientifically-based risk/benefit analysis about the use of these herbs during pregnancy is not possible. Considering the appeal that phytomedicines have for pregnant women, usually aware and afraid of the risks that synthetic drugs may have in their pregnancy and progeny, well designed studies evaluating reproductive and/or developmental toxicity of these herbs urge.
Keywords: developmental toxicity, female reproductive toxicity herbal medicine products phytomedicines
In 2006, the Federal Government from Brazil announced the National Politics of Herbal Products and Phytomedicines that would result in actions to warranty a safe and rational use of herbal products by the Brazilian population (Brasil, 2006). Since then, documents have been published in order to accomplish the program goals. Among these documents is RENISUS, a list of 71 herbal species and/or genus traditionally used in Brazil and that the Ministry of Health considers that could result in phytomedicines to be prescribed and dispensed by the governmental health program (Sistema Único de Saúde-SUS) (Ministério da Saúde, 2009). Many of those herbs lack scientific pharmacological validation for their use as well as toxicological evaluation but the publication of RENISUS should trigger public and private research to fill this lack of data. Supplemental Table 1 presents the species and their taxonomy whereas the common names in English and Portuguese can be found in Supplemental Table 2.
Due to the widespread use of herbal medicinal products (HMP) worldwide, governments from different countries have been regulating their marketing. In Brazil, phytomedicines are regulated as drugs but the pre-marketing studies necessary for registration are different from conventional drugs. For instance, reproductive and carcinogenic studies are not mandatory for registration.
HMP use during pregnancy has been reported at 4-55% (Nordeng & Havnen, 2005; Refuerzo et al., 2005; Tiran, 2003) not considering abortifacient use. Besides abortifacient use, which should not be underestimated especially in countries where abortion is forbidden by law (e.g., Brazil), there are two other situations in which pregnant women might be exposed to HMP: i) substitution of prescribed medications by HMP generally perceived as "natural and safe"; ii) unintended or accidental use since many pregnancies are unplanned and women of childbearing age use HMP for a variety of disorders, such as disphoric premenstrual disorder, depression, anxiety, sleep aid as well as weight loss. Despite the prevalent use of HMP by pregnant women, information regarding their safety on this population is sparse. In most of the international reference monographs for HMP as well as in the physician prescribing information of phytomedicines marketed in Brazil, HMP can be broadly categorized into two groups. In the first group are HMP contra-indicated during pregnancy based on reports of historical use of herbs as abortifacients or uterotonics. In the second group are HMP that have no data regarding safety of use during pregnancy and whose use are not recommended during these periods without medical advice. Advising without any scientific support certainly is not an easy task for physicians and other health professionals.
In this work we reviewed the scientific literature as well as some reference monographs in order to update and summarize the knowledge regarding female reproductive and/or developmental toxicity of 69 out of the 71 herbal species listed in RENISUS. Glycine max (soy) was not included due to the wide knowledge on its properties as well as Copaifera spp. because there are multiple species in Brazil and the species of interest have not been defined in RENISUS. For clarification purposes, in this study, the term "female reproductive toxicity" refers to any effect that would interfere with reproductive ability or capacity whereas the term "developmental toxicity" refers to adverse effects resulting from maternal exposure that can be manifested at any point in the life span of the litter. The readers should be aware that his review is intended to provide a general overview about the existing scientific data (or lack of it). It is beyond the scope to judge the adequacy of the retrieved studies for regulatory purposes. In this way, all the retrieved studies are being reported; independently of study desing weakness, plant material or type of extraction employed.
We scanned articles through the website from Biblioteca Virtual em Saúde (Virtual Health Library, http://regional.bvsalud.org/php/index.php) using the Latin name of each herb listed in RENISUS. This website allows the simultaneous search in thirty electronic bibliographic databases including Medline, Lilacs, IBECS, Cochrane, SciELO, PAHO, WHOLIS as well as some databases of dissertations and thesis developed in Brazil. No language restriction was applied. Searching by hand for published data was also conducted through: 1) the reference lists of identified articles; 2) The European Medicines Agency (EMA) website (http://www.europa.ema.eu); 2) ESCOP Monographs (Escop, 2003); 3) The WHO monographs on selected medicinal plants (WHO, 1999; 2002; 2007; 2009). The final internet search of the literature was conducted in January 17th, 2011.
Evaluation of the data retrieved
To filter out toxicological studies, two independent observers (Moreira EG and Bacchi AD) reviewed the titles, abstracts and keywords of every record retrieved after the search by the Latin name of each herb. The toxicological studies that reported data regarding female reproductive and/or developmental endpoints were carefully evaluated and summary tables were constructed for each herb containing plant material, animal, exposure regimen (route, dose, period of treatment) and effects observed.
Herbs lacking female reproductive and/or developmental toxicity studies
In the current review, studies or traditional information regarding female reproductive and/or developmental toxicity could not be retrieved for 35 out of 69 herbs listed in RENISUS. For fifteen out of these 35 herbs, no toxicological information was retrieved (Arrabidaea chica, Costus spp., Eleutherine plicata, Erythrina mulungu, Lamium album, Malva sylvestris, Orbignya speciosa, Petroselinum sativum, Polygonum spp., Portulaca pilosa, Solidago microglossa, Syzygium cumini, Tagetes minuta, Trifolium pretense, Vernonia spp.) whereas for twenty of them at least one study evaluating acute oral toxicity, genetic toxicity and/or suchronic toxicity was available (Alpinia speciosa, Anacardium occidentale, Caesalpinia ferrea, Casearia sylvestris, Chenopodium ambrosioides, Croton spp., Cynara scolymus, Equisetum arvense, Eugenia uniflora, Jatropha gossypiifolia, Kalanchoe pinnata, Lippia sidoides, Mentha piperita, Mentha pulegium, Mikania glomerata, Morus spp., Persea americana, Psidium guajava, Schinus terebinthifolius, Solanum paniculatum).
Despite the lack of toxicological studies for T. pratenses, WHO monograph contra-indicates its use during pregnancy and breastfeeding due to the potential estrogenic effects of the crude extract (WHO, 2009).
Herbs with traditional information or experimental evaluation of female reproductive and/or developmental toxicity
Experimental studies evaluating reproductive and/or developmental toxicity were retrieved for 28 herbs listed in RENISUS and they are summarized in Tables 2-4. Unfortunately we could not have full access to six out of 31 studies (indicated in Tables 2 and 4) and we are reporting information extracted from WHO and EMA monographs, ESCOP, or paper abstracts.
From the fourteen herbs with traditional use (Table 1), five of them have experimental studies corroborating their actions. Maytenus ilicifolia, Momordica charantia, Plectranthus barbatus and Ruta graveolens are used as emmenagogues and abortifacients and there is at least one experimental study reporting pre-implantation loss in rodents treated with these plants or, in the case of Mormodica charantia, isolated proteins (references listed in Tables 2 and 3). Bidens pilosa, used traditionally to facilitate labour, has shown in vitro uterotonic effect (Table 2). Even though there is one experimental study conducted with Phyllanthus amarus (Rao & Alice, 2001), one with Curcuma longa (Garg, 1974), and one with Achillea millefolium (Boswell-Ruys et al., 2003), the reported endpoints are not directly related to their traditional use. Rao & Alice (2001) designed their study to evaluate estrous ciclicity and not embryo/fetal loss that is the P. amarus traditional use. Curcuma longa, used as contraceptive, did not present antiovulatory effect in rabbits but induced pre and postimplantation loss in rats (Garg, 1974). Achillea millefolium, used as emmenagogue and abortifacient did not induce pre or postimplantation loss in rats but decreased fetal weight (Boswell-Ruys et al., 2003). Noteworthy is the lack of experimental studies with four species that have traditional use for inducing female reproductive effects: Ananas comosus, Foeniculum vulgare, Justicia pectoralis and Uncaria tomentosa. Actually, for Foeniculum vulgare there are some alerts in the literature. WHO monograph (2007) reports that it should not be used in pregnancy due to the potential estrogenic effects of essential oil from the seeds and ESCOP (2003) highlights that for aqueous infusions estrogenicity would not be of concern. However, a study published in 2008 reported the case of four patients with premature thelarche associated with long term use of Foeniculum vulgare tea to eliminate gas pain (Turkyilmaz et al., 2008). In this way, estrogenicity of Foeniculum vulgare is certainly an issue that deserves further investigation.
For 23 out of the 28 herbs that have been evaluated experimentally for any type of female reproductive and/or developmental endpoint only a single study was retrieved (Tables 2 and 4). Broadly, the results could be divided into two major groups: the herbs that have presented reproductive adverse effect and the herbs that have not. The first group (Tables 2 and 3) can be subdivided into herbs that induced maternal toxicity (Baccharis trimera), anti-implantation effect (Artemisia absinthium, Curcuma longa, Maytenus ilicifolia, Mormodica charantia, Plectranthus barbatus, Punica granatum, Ruta graveolens); embryo/fetotoxicity (Achillea millefolium, Curcuma longa, Ruta graveolens, Stryphnodendron adstringens, Tabebuia avellanedae); teratogenicity (Momordica charantia, Tabebuia avellanedae); uterotonic effect (Bidens pilosa, Passiflora incarnata, Harpagophytum procumbens) and altered estrous ciclicity (Phyllanthus amarus). In the second group (i.e., herbs that did not present reproductive adverse effect) are: Aloe vera, Bauhinia forficata, Calendula officinalis, Carapa guianensis, Chamomilla recutita, Cordia verbenacea, Dalbergia subcymosa, Eucalyptus globulus, Ocimum suave (synonym for O. gratissimum), Rhamnus purshiana, Salix alba and Vernonia condensata (Table 4).
It should be noted that the studies being reported for Mormodica charantia, Rhamnus purshiana and Tabebuia avellanedae were conducted with isolated compounds. Even though these studies would not be appropriate to make extrapolations to the traditional human use, they may serve as alerts on potential adverse effects. In fact, WHO monograph on Momordica charantia considered the studies conducted with momorcharins to describe a precautionary alert for teratogenicity (WHO, 2009).
Our review on Zingiber officinale resulted in puzzling data. Due to its use by pregnant women for morning sickness, there are at least two clinical trials that have tested ginger during pregnancy. Reproductive endpoints were assessed and no adverse effect was detected (Fischer-Rasmussen et al., 1991; Portnoi et al., 2003). In experimental studies with rodents, maternal toxicity was not detected either but embryonic loss was observed (Wilkinson, 2000). Certainly human data should overweight rodents' data but there are concerns regarding the full adequacy of clinical trials with HMP since they are conducted with reduced number of individuals and adverse events are evaluated through self-reports. This discussion is beyond the scope of this paper but readers can have a general idea about different points of views regarding the safety of ginger in the literature (for example, Fugh-Berman et al., 2005; Marcus & Snodgrass, 2005).
Finally, for Allium sativum no reproductive and/or developmental study was retrieved but both ESCOP (2003) and WHO monograph (1999) report that there are no objections to use during pregnancy and lactation because neither long term nutritional experience nor any other important circumstances give reason for suspicion.
Discussion and Conclusions
In this work, studies and reference monographs were reviewed looking for information about female reproductive and/or developmental toxicity of herbs listed by the Brazilian government as potential phytomedicines to be prescribed and dispensed by the governamental health care program. Few of these herbs are already registered for marketing in Brazil and most of them are classified as category C for pregnancy risks by the Brazilian sanitary surveillance agency (Anvisa) following the classification previously adopted by the Food and Drug Administration (FDA) (Doering et al., 2002). Category C is assigned to drugs with positive or inadequate animal teratology studies that are lacking well-controlled human studies. In this way, the physician prescribing information of the marketed species attributes to the physician the decision of prescribing them to pregnant women which is certainly not an easy task with the available information. This work aimed to summarize female reproductive and/or developmental toxicity information available for all the herbs listed in RENISUS in order to sense the real scenario regarding this type of information.
In the present review, no information on reproductive and/or developmental effects have been retrieved for more than half of the herbs listed in RENISUS, i.e., for 35 out of 69. Per se this result would already be disappointing but to make things worse, for the herbs with published studies, only for five more than one study was available and for at least twelve studies were conducted with single doses. Moreover, the majority of the studies were conducted with lower number of animals in each experimental group than the recommended by international guidelines such as OECD (Organization for Economics Cooperation and Development) and ICH (International Conference on Harmonisation of Technical Requirements for Registraion of Pharmaceuticals for Human Use). With this scenario, a deep analysis of study design and quality is certainly not necessary to assume that the scientific power of the published information is very low and that a scientifically-based risk/benefit analysis about the use of these herbs during pregnancy is not possible at this time. Based on the precautionary principle, these herbs should be avoided during pregnancy due to the lack of data. However, considering the appeal that "the natural and safe" HMP have for special population including pregnant women, studies evaluating reproductive and/or developmental toxicity urge in order to refine the risk evaluation and communication. Prioritization of species to be evaluated could take into account information on genetic toxicity as well as endocrine and pro-apoptosis actions, which are known to be involved in the disruption of pregnancy course and/or embryo/fetal development. Studies evaluating these endpoints are more usual in the literature. It seems reasonable to suggest that herbs with central nervous system action should also be prioritized due to their ability to cross barriers (blood-brain and blood-placental) and reach the embryo or fetus. Additionaly, developmental neurotoxicity endpoints should also be included when evaluating herbs that target the nervous system. The developing central nervous system is especially susceptible to toxic insults and it is known that functional changes can be induced at a lower exposure level than those resulting in structural teratogenicity (for one example, Francis et al., 1990).
After reviewing the literature, it seems that the only species that we could deposit more weight on the available information are Maytenus ilicifolia, Momordica charantia, Plectranthus barbatus, Ruta graveolens and Bidens pilosa. These species have reported traditional use as emmenagogues and abortifacients (Maytenus ilicifolia, Momordica charantia, Plectranthus barbatus, Ruta graveolens) or labour facilitator (Bidens pilosa) supported by experimental evidences of these actions. However, it should be noted that the weight of the experimental evidences is weak due to experimental design issues or lack of studies replication.
Two observations are noteworthy. The first one was the high number of experimental studies performed without taking into account any guideline for toxicological evaluation, such as those published by ICH or OECD. As a result, not only there is lack of harmonization among studies as well as there are some basic biases regarding experimental design (number of replicates, experimental unit, route of exposure and period of treatment) that could have been avoided if a guideline had been followed. It was surprising to realize that most of the LD50 studies retrieved (references not included in this review) employed an unnecessary high number of animals, a situation that could be avoided if OECD guidelines (OECD, 2001a, 2001b, 2001c) had been followed. These guidelines are a scientific advance for LD50 estimation but it seems that few researchers from the HMP area are employing them. The second observation to be pointed out is the lack of information regarding extract standardization. It is common sense the variation in active principles that different extracts may have and efforts should be taken to present at least a qualitative chromatogram of the extract for which toxicological results are being reported.
In summary, the present review summarizes the available information regarding female reproductive and/or developmental toxicity of the herbs listed in RENISUS and indicates the paucity of studies in this area. Considering the appeal that phytomedicines have for pregnant women, usually aware and afraid of the risks that synthetic drugs may have in their pregnancy and progeny, well designed studies evaluating female reproductive and/or developmental toxicity of these herbs urge if they may become phytomedicines.
The authors thank Fundação Araucária and CNPq for the Scientific Initiation fellowship provided to LFV and TZ, respectively, as well as CAPES for the Master fellowship provided to ADB.
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* Correspondence: Estefania G. Moreira, Depto de Ciências Fisiológicas, CCB, Universidade Estadual de Londrina, Campus Universitário, 86051-980 Londrina-PR, Brazil. E-mail: firstname.lastname@example.org. Tel. +55 43 3371 4307, Fax: +55 43 3371 4254