Subchronic toxicity studies of the antidiabetic herbal preparation ADD-199 in the rat: absence of organ toxicity and modulation of cytochrome P450

Safety Assessment of Vanillic Acid: Subacute Oral Toxicity Studies in Wistar Rats

OBJECTIVES

Vanillic acid (VA) is a flavoring agent, a phenolic acid, and an intermediary by-product formed during transformation of ferulic acid to vanillin. It has been investigated for diverse pharmacological actions and used in Chinese medicine for decades. However, there is no information in the literature about its mechanism of toxicity or safety with long-term use. The present study will not only supply information on its pharmacological profile but also encourage evidence-based pharmacotherapeutic use. Hence, we performed a subacute toxicity study.

MATERIALS AND METHODS

According to the Organisation for Economic Co-operation and Development Test Guideline 407 (2008), 3 groups of rats were formed consisting of 12 rats (6 male and 6 female) in each group. For the subacute toxicity, the dose was chosen after a limit test was conducted. VA (1000 mg/kg/day) was orally administered for 2 weeks to the treatment group, whereas the control group received an equivalent volume of the vehicle. To assess reversibility, VA (1000 mg/kg/day, p.o.) was administered to the satellite group for 2 weeks and animals were observed for an additional 2 weeks after treatment. The adverse signs, variation in body weight, and mortality were evaluated throughout the study period. On days 15 and 29, blood was collected to evaluate essential biochemical and hematological parameters. The animals were subsequently weighed and sacrificed. The weights of internal organs were recorded; gross necroscopy and histopathological studies were performed.

RESULTS

The hematological parameters of the satellite group increased and the serum sodium level decreased after the treatment. Satellite groups showed no other major change in biochemical parameters when compared to the control group. In addition, relative organ weights, gross necropsy examinations and histopathological structure of the internal organs showed no major alterations.

CONCLUSION

VA showed no adverse effect on the process of leukopoiesis, erythropoiesis or on internal organs, as verified by hematological and biochemical evaluations, gross necropsy, and histopathological studies. The decrease in serum sodium is not considered as a major toxic effect.

Nkadimeng S, Lall N, Kabasa JD, J. McGaw L. Ethnobotany, Phytochemistry and Pharmacological Activity of Kigelia africana (Lam.) Benth. (Bignoniaceae)

Kigelia africana has been used in the management of human ailments since time immemorial. Ethnobotanists have documented the traditional uses of K. africana, which include treatment of skin disorders, cancer and gynecological complaints, among others. This has interested scientists, who have examined K. africana plant parts for their bioactivity. This review provides an insightful understanding on the ethnobotany, phytochemistry and pharmacology of K. africana. Web search engines Google and Google Scholar, as well as the databases of PubMed, Scopus, JSTOR, HINARI, SID, AJOL and Springer Link, were exhaustively searched using key words and phrases. Institutional reports and conference papers were also consulted. A total of 125 relevant international literature sources meeting the inclusion criteria were included. Kigelia africana has biologically active phytochemicals, many of which have been isolated. Whilst the fruits are most often cited in pharmacological studies, other plant parts are also used in herbal preparations. Commercially available products have been formulated from K. africana, though many have not been fully standardized. Despite many efforts by researchers to scientifically validate traditional uses of K. africana, many remain merely claims, thus the need to conduct more research, scientifically validate other traditional uses, isolate new bioactive phytochemicals and standardize K. africana products.

Medicinal Plants Used in Traditional Management of Cancer in Uganda: A Review of Ethnobotanical Surveys, Phytochemistry, and Anticancer Studies

The burden of neoplastic diseases is a significant global health challenge accounting for thousands of deaths. In Uganda, about 32,617 cancer cases were reported in 2018, accompanied by 21,829 deaths. In a view to identify some potential anticancer plant candidates for possible drug development, the current study was designed to compile the inventory of plants with reported anticancer activity used in rural Uganda and the evidences supporting their use in cancer therapy. An electronic survey in multidisciplinary databases revealed that 29 plant species belonging to 28 genera distributed among 24 families have been reported to be used in the management of cancer in Uganda. Anticancer plants were majorly from the families Bignoniaceae (7%), Caricaceae (7%), Fabaceae (7%), Moraceae (7%), and Rutaceae (7%). Most species occur in the wild (52%), though some are cultivated (48%). The growth habit of the plants is as trees (55%) or herbs (45%). Anticancer extracts are usually prepared from leaves (29%), bark (24%), roots (21%), and fruits (13%) through decoctions (53%), as food spices (23%) or pounded to produce ointments that are applied topically (10%). Prunus africana (Hook.f.) Kalkman, Opuntia species, Albizia coriaria (Welw. ex Oliver), Daucus carota L., Cyperus alatus (Nees) F. Muell., Markhamia lutea (Benth.) K. Schum., and Oxalis corniculata L. were the most frequently encountered species. As per global reports, Allium sativum L., Annona muricata L., Carica papaya L., Moringa oleifera Lam., Opuntia species, Prunus africana (Hook.f.) Kalkman, and Catharanthus roseus (L.) G. Don. are the most studied species, with the latter having vincristine and vinblastine anticancer drugs developed from it. Prostate, cervical, breast, and skin cancers are the top traditionally treated malignancies. There is a need to isolate and evaluate the anticancer potential of the bioactive compounds in the unstudied claimed plants, such as Cyperus alatus (Nees) F. Muell., Ficus dawei Hutch., Ficus natalensis Hochst., and Lovoa trichilioides Harms, and elucidate their mechanism of anticancer activity.

Safety evaluation of syringic acid: subacute oral toxicity studies in Wistar rats

Syringic acid (SA) is a phenolic acid and have been investigated for diverse pharmacological activities, but the safety and/or mechanism of toxicity is still lacking in the literature. Subacute toxicity studies will add value to its pharmacological profile and support its exploration as a future medicine. According to OECD TG 407 (OECD, 2008), rats were divided into 3 groups (n = 12). The dose of SA was decided by limit test. Treatment and satellite groups received SA (1000 mg/kg/day, p.o for 14 days), whereas an equal volume of vehicle was given to control groups. In order to access reversibility, satellite groups were kept for another 14 days post-treatment. The toxic signs, mortality and body weight changes were recorded. On day 15 and 29 the rats were anesthetized to collect blood for estimation of hematological and biochemical parameters and then sacrificed to collect internal body organ for weighing and histopathological studies. SA has no major adverse effect on the body weight, food intake, erythropoiesis, leucopoiesis and on internal body organs which was confirmed by evaluating various biochemical and hematological parameters, relative body organ weight and histopathological studies. Therefore, SA could be considered safe over limited period of time and this study may help researchers in establishing the doses for the longer-term subchronic studies. Further, subchronic and chronic toxicity studies are required to evaluate safety on long term use.

Potential therapeutic applications of the genus Annona: Local and traditional uses and pharmacology

ETHNO-PHARMACOLOGICAL RELEVANCE

Annona species (Annonaceae) have long been used as traditional herbal medicines by native peoples in tropical areas. In different countries they are used against a large variety of illnesses, such as parasitic and infectious diseases, cancer, diabetes, peptic ulcers, and mental disorders.

AIM OF THE STUDY

This review aims to achieve a comprehensive understanding of the research conducted so far on the local and traditional uses, pharmacological activities, mechanism of actions of active compounds, toxicity, and possible interactions with other drugs of the Annona species. Through analysis of these findings, evidences supporting their applications in ethno-medicines are described. We discuss the possible research opportunities and stand out the weak points in our knowledge that deserves further investigation.

MATERIAL AND METHODS

Information on ethno-medicinal uses and pharmacological activities of the Annona genus was collected. The main scientific biomedical literature databases (Cochrane, PubMed, Scopus, Lilacs, SeCiMed, Elsevier, SpringerLink, Google Scholar, SciFinder) were consulted. The search covered all the literature available until September 2017. National and regional databases of Herbal Medicine and Complementary and Alternative Medicine were also revised in order to explore further data. For a better understanding of the therapeutic importance of these species, we have classified the pharmacological activities within each group of disorders. The International Classification of Diseases (ICD), used from WHO Member States, was chosen as the reference classification.

RESULTS

From among the 27 species revised, four species are highlighted for their important pharmacological activities in most of the groups of illnesses: A. muricata, A. squamosa, A. senegalensis, and A. cherimola. Many investigations have been performed with extracts from the leaves, bark, fruit and seeds and have shown a wide range of pharmacological activities, such as antiprotozoal, antitumoural, antidiabetic, hepato-protective, anti-inflammatory and anxiolytic activities. The chemistry on the annonaceous acetogenins (ACGs) has been extensively investigated due to their potent antitumoural activity. Many of the assays were carried out with the isolated acetogenins in different lines of tumour culture cells and were found effective at very low doses even in multidrug-resistant tumours, and hence constitute promising compounds in the treatment of different types of cancers. No studies were found with extracts rich in acetogenins in the clinical field.

CONCLUSIONS

The experimental results from the pharmacological research enable the validation of their traditional uses in several of the groups of diseases in the countries of origin and reveal these plants to be a valuable source for therapeutic molecules. However, more toxicity assays and clinical trials would be necessary to establish optimal and safe doses of consumption on the application of these medicinal plants.

Acute and Subchronic Toxicity Studies of Aqueous Extract of Desmodium adscendens (Sw) DC

Extracts of Desmodium adscendens (Sw) DC are used for the treatment of various diseases but limited toxicological evaluations have been done on the medicinal plant. This study investigates toxicity effects of the leave extract of D adscendens, and the possibility of drug-drug interaction of the plant extract when co-administered with other drugs. Oral administrations of leaf extract of D adscendens to white Wistar rats in an acute toxicity studies allowed the estimation of an LD₅₀ (median lethal dose) value of 1122 mg/kg body weight. In a subchronic toxicity studies, the plant extract caused a decrease in zoxazolamine paralysis time and prevented thiopentone from causing sleep in test animals compared to controls. Overall, the results are consistent with the plant extract being safe at the doses administered in humans. However, the induction of the CYP enzymes is an indication of a possible drug interaction when the plant extract is co-administered with other drugs.

An ethnobotanical study of plants used to treat liver diseases in the Maritime region of Togo

ETHNOPHARMACOLOGICAL RELEVANCE

In Togo, many persons still rely on plants for healing, however very little is known about the medicinal practices of the indigenous people. The present study aimed to document the medicinal plant utilization for the management of liver diseases in the Maritime region of the country.

METHODOLOGY

This was an ethnobotanical survey conducted in the Maritime region of Togo from June to August 2015. The data were gathered from 104 traditional healers (TH) by direct interviews using a semi-structured questionnaire. The calculated use values (UV) were used to analyze the importance of the cited plants.

RESULTS

A total of 99 plant species belonging to 88 genera and 49 families were cited by the TH as curing the hepatic diseases. The most represented families were Caesalpiniaceae with 8 species, followed by Euphorbiaceae with 7 species, Apocynaceae and Asteraceae with 6 species each. The highest UV were recorded with Gomphrena celosioides (0.13), Xylopia ethiopica (0.12), Senna occidentalis (0.12), Bridelia ferruginea (0.12), Cymbopogon citratus (0.12), Kigellia Africana (0.09), Cassia sieberiana (0.08) and Sanseviera liberica (0.08), showing their importance in the management of liver dysfunction in the surveyed region. The main used parts were the leaves, followed by the roots, the whole plant, the rhizome and the bark, accounting for more than 10% each. The herbal medicines were mostly prepared in the form of decoction and administrated by oral route.

CONCLUSION

This study showed that Maritime region of Togo has an important plant biodiversity that is exploited by the indigenous TH. However, some plants cited by the TH have not been studied for their possible hepatoprotective effects. These plants are therefore a starting point for biological screenings.

The use of plants in the traditional management of diabetes in Nigeria: pharmacological and toxicological considerations

ETHNOPHARMACOLOGICAL RELEVANCE

The prevalence of diabetes is on a steady increase worldwide and it is now identified as one of the main threats to human health in the 21st century. In Nigeria, the use of herbal medicine alone or alongside prescription drugs for its management is quite common. We hereby carry out a review of medicinal plants traditionally used for diabetes management in Nigeria. Based on the available evidence on the species׳ pharmacology and safety, we highlight ways in which their therapeutic potential can be properly harnessed for possible integration into the country׳s healthcare system.

MATERIALS AND METHODS

Ethnobotanical information was obtained from a literature search of electronic databases such as Google Scholar, Pubmed and Scopus up to 2013 for publications on medicinal plants used in diabetes management, in which the place of use and/or sample collection was identified as Nigeria. 'Diabetes' and 'Nigeria' were used as keywords for the primary searches; and then 'Plant name - accepted or synonyms', 'Constituents', 'Drug interaction' and/or 'Toxicity' for the secondary searches.

RESULTS

The hypoglycemic effect of over a hundred out of the 115 plants reviewed in this paper is backed by preclinical experimental evidence, either in vivo or in vitro. One-third of the plants have been studied for their mechanism of action, while isolation of the bioactive constituent(s) has been accomplished for twenty three plants. Some plants showed specific organ toxicity, mostly nephrotoxic or hepatotoxic, with direct effects on the levels of some liver function enzymes. Twenty eight plants have been identified as in vitro modulators of P-glycoprotein and/or one or more of the cytochrome P450 enzymes, while eleven plants altered the levels of phase 2 metabolic enzymes, chiefly glutathione, with the potential to alter the pharmacokinetics of co-administered drugs.

CONCLUSION

This review, therefore, provides a useful resource to enable a thorough assessment of the profile of plants used in diabetes management so as to ensure a more rational use. By anticipating potential toxicities or possible herb-drug interactions, significant risks which would otherwise represent a burden on the country׳s healthcare system can be avoided.

Plants traditionally used individually and in combination to treat sexually transmitted infections in northern Maputaland, South Africa: antimicrobial activity and cytotoxicity

ETHNOPHARMACOLOGICAL RELEVANCE

Although medicinal plants are used extensively to treat sexually transmitted infections (STIs) in rural northern Maputaland, KwaZulu-Natal, the efficacy and safety of these plants have not previously been evaluated.

AIM OF STUDY

A study was designed to investigate the in vitro antimicrobial activity and cytotoxicity profiles of a selection (individual plants and selected combinations) of traditionally used plants in this study area.

MATERIALS AND METHODS

Aqueous and organic (dichloromethane: methanol, 1:1) extracts were prepared. Antimicrobial activity was assessed using the minimum inhibitory concentration (MIC) assay against the STI associated pathogens; Candida albicans ATCC 10231, Ureaplasma urealyticum clinical strain, Oligella ureolytica ATCC 43534, Trichomonas vaginalis clinical strain, Gardnerella vaginalis ATCC 14018 and Neisseria gonorrhoeae ATCC 19424. For the combination study, interactions were assessed using the fractional inhibitory concentration (ΣFIC). The plant species were assessed for safety using the 3-[4,5-dimethyl-2-thiazol-yl]-2,5-diphenyl-2H-tetrazolium bromide (MTT) cellular viability assay on the human embryonic kidney epithelial (Graham, HEK-293) cell line.

RESULTS

For the antimicrobial studies, U. urealyticum was the most sensitive of the six test organisms, with the aqueous extract of Ranunculus multifidus (0.02mg/ml) and the organic extract of Peltophorum africanum (0.04mg/ml) being the most antimicrobially active plant species studied. Sclerocarya birrea was found to have the broadest spectrum of activity (mean MIC of 0.89mg/ml). The only plant species to exhibit some degree of cytotoxicity against the kidney epithelial cell line was Kigelia africana (100µg/ml), with 22% and 16% cell death for the aqueous and organic extracts, respectively. Of the 13 combinations studied, several synergistic combinations were evident, the most prominent being the combination of Albizia adianthifolia and Trichilia dregeana (aqueous extract) with an ΣFIC value of 0.15 against O. ureolytica. Synergistic interactions were observed regardless of the ratio of the aqueous mixtures of the two plants. Syzygium cordatum and S. birrea (aqueous extract) was also a combination of interest, demonstrating synergistic (ΣFIC=0.42) interactions against O. ureolytica. This combination, however, also displayed some cytotoxicity towards the human epithelial cell line.

CONCLUSION

This study demonstrated that anecdotal evidence of plant use does not always correlate with in vitro activity. Furthermore, the toxicological profiling is of utmost importance as if not combined in its correct ratio can lead to potential adverse effects.

Detoxification rates of wild herbivorous woodrats (Neotoma)

The detoxification systems of mammalian herbivores are thought to have evolved in response to the ingestion of plant secondary compounds. Specialist herbivores consume high quantities of secondary compounds and are predicted to have faster rates of Phase 1 detoxification compared to generalist herbivores. We tested this hypothesis by comparing the performances of a specialist (Neotoma fuscipes) and generalist (Neotoma lepida) herbivore using hypnotic state assays. Herbivores foraging in nature were live trapped and injected with hexobarbital (100 mg/kg). We measured the length of time in the hypnotic state as the time in which the animal was unable to right itself twice in 30 s. The specialist metabolized hexobarbital 1.7 times faster than the generalist (F(1, 19) = 9.31, P = 0.007) as revealed by its significantly shorter time spent in the hypnotic state (56+/-9 min vs. 87+/-8 min, respectively). The results are consistent with the hypothesis that specialists have faster rates of Phase 1 detoxification. This is the first evaluation of the detoxification capability of mammalian herbivores foraging under natural conditions. Hypnotic state assays have broad potential applications to the study of vertebrate-plant interactions.