In vitro cytotoxic effects of Brazilian plant extracts on squamous cell carcinoma of the oral cavity

The Genus Cynometra: A Review of Ethnomedicine, Chemical, and Biological Data

Cynometra L. is a Fabaceae genus that is widely distributed throughout the tropics, consisting of tropical forest trees with ecological and economic importance since they are used as food and herbal medicines by the populations of their natural habitats. Our goal is to provide a review of the research data concerning the potential of this botanical genus as a source of herbal medicines and secondary metabolites that are useful for human health. To that end, scientific databases, including PubMed, Science Direct, ISI Web of Science, Scopus, and Google Scholar, were searched using the following terms: Cynometra, medicine, chemical, biological activity, toxicity, and “AND” as the Boolean connector. Eleven Cynometra species (9.7%) were reported to be used in traditional medicine to treat different ailments. A total of 185 secondary metabolites of various chemical classes, mainly flavonoids and terpenoids, were identified in eight Cynometra species (7.1%). Vitexin was the only flavonoid identified as bioactive in the sequence of bioguided studies on this botanical genus. Ten species (8.8%) were submitted to in vitro and in vivo biological activity assays. The main evaluated activities were in vitro antioxidant, antimicrobial, cytotoxic, and in vivo anti-inflammatory activities, but no human clinical trials or safety data about this genus were found. Cynometra cauliflora and Cynometra ramiflora were the most studied species. The present work confirms the use of Cynometra species as a source of medicinal plants. However, more experimental studies must be conducted to better understand this botanical genus’s usefulness as a source of raw materials for pharmaceutical use.

Recycled Pequi (Caryocar brasiliense, Camb.) Shell Ethanolic Extract Induces Apoptosis in Canine Osteosarcoma Cells

Abstract Osteosarcoma is a mesenchymal cancer associated with high mortality in dogs and in humans. The biodiversity-rich Cerrado, the predominant biome in the Midwest region of Brazil, is native to locally appreciated fruits such as pequi (Caryocar brasiliense, Camb). Although this plant has been frequently used in folk medicine, the pharmacological properties of pequi fruit shells have not been fully evaluated. Thus, this study aimed to determine the cytotoxic activity of ethanol extract of recycled pequi shells on canine osteosarcoma cells in vitro. Cells were cultured and treated with final extract concentrations of 0, 0.029 µg/µL, 0.29 µg/µL, and 2.91 µg/µL for 24, 48, or 72 hours. Cell viability assay using trypan blue exclusion method and tetrazolium reduction method, cell survival assay, and double labeling with annexin V and propidium iodide were performed in the treated osteosarcoma cells. These allowed the determination of IC50, survival fraction, and type of cell death, respectively. Pequi shell ethanol extract at a concentration of 2.91 µg/µL showed the greatest inhibition of osteosarcoma cell growth in vitro, resulting in a 71.80% decrease in growth compared to the control. The mean IC50 was 155.2 μg/mL at 72 hours. The calculated survival fractions showed that cell growth at 72 hours was 3.33% lower in cells treated with 2.91 µg/µL extract. Results from the double labeling experiment suggest that apoptosis was the predominant type of cell death in cells treated with 2.91 µg/µL extract. These results demonstrate that ethanol extract of recycled pequi shells promotes apoptosis in canine osteosarcoma cells.

Medicinal Plants Towards Modeling Skin Cancer

Skin cancer remains a major cause of mortality worldwide. It can be divided into melanoma and non-melanoma cancer, which comprise mainly squamous cell carcinoma and basal cell carcinoma. Although conventional therapies have ameliorated the management of skin cancer, the search for chemopreventive compounds is still the most effective and safer strategy to treat cancer. Nowadays, chemoprevention is recognized as a novel approach to prevent or inhibit carcinogenesis steps with the use of natural products. Crude extracts of plants and isolated phytocompounds are considered chemopreventive agents since they harbor anti-inflammatory, antioxidant and anti-oncogenic properties against many types of diseases and cancers. In this review, we will discuss the therapeutic effect and preventive potential of selected medicinal plants used as crude extracts or as phytocompounds against melanoma and non-melanoma cutaneous cancers.

Cytotoxic potential of selected medicinal plants in northeast Brazil

BACKGROUND

Great biodiversity is a highlight of Brazilian flora. In contrast, the therapeutic potentialities of most species used in folk medicine remain unknown. Several of these species are commonly used to treat cancer. In this study, we investigated the cytotoxic activity of 18 plants from 16 families that are found in the northeast region of Brazil.

METHODS

The following species were studied: Byrsonima sericea DC. (Malpighiaceae), Cupania impressinervia Acev. Rodr. var. (revoluta) Radlk (Sapindaceae), Duranta repens Linn. (Verbenaceae), Helicostylis tomentosa (Poepp. & Endl) Rusby (Moraceae), Himatanthus bracteatus (A.DC.) Woodson (Apocynaceae), Ipomoea purga (Wender.) Hayne (Convolvulaceae), Ixora coccinea Linn. (Rubiaceae), Mabea piriri Aubl. (Euphorbiaceae), Miconia minutiflora (Melastomataceae), Momordica charantia L. (Cucurbitaceae), Ocotea glomerata (Nees) Mez (Lauraceae), Ocotea longifolia Kunth (Oreodaphne opifera Mart. Nees) (Lauraceae), Pavonia fruticosa (Mill.) Fawc. & Rendle (Malvaceae), Psychotria capitata Ruiz & Pav. (Rubiaceae), Schefflera morototoni (Aubl.) Maguire, Steyerm. & Frodin (Araliaceae), Solanum paludosum Moric. (Solanaceae), Xylopia frutescens Aubl. (Annonaceae) and Zanthoxylum rhoifolium Lam. (Rutaceae). Their dried leaves, stems, flowers or fruits were submitted to different solvent extractions, resulting in 55 extracts. After incubating for 72 h, the cytotoxicity of each extract was tested against tumor cell lines using the alamar blue assay.

RESULTS

The B. sericea, D. repens, H. bracteatus, I. purga, I. coccinea, M. piriri, O. longifolia and P. capitata extracts demonstrated the most potent cytotoxic activity. The chloroform soluble fractions of D. repens flowers and the hexane extract of I. coccinea flowers led to the isolation of quercetin and a mixture of α- and β-amyrin, respectively, and quercetin showed moderate cytotoxic activity.

CONCLUSION

The B. sericea, D. repens, H. bracteatus, I. purga, I. coccinea, M. piriri, O. longifolia and P. capitata plants were identified as having potent cytotoxic effects. Further investigations are required to determine the mechanisms of cytotoxicity exhibited and their in vivo activities. This work reinforces the need to understand the therapeutics potentialities of Brazilian medicinal plants.

Anti-Streptococcal activity of Brazilian Amazon Rain Forest plant extracts presents potential for preventive strategies against dental caries

Caries is a global public health problem, whose control requires the introduction of low-cost treatments, such as strong prevention strategies, minimally invasive techniques and chemical prevention agents. Nature plays an important role as a source of new antibacterial substances that can be used in the prevention of caries, and Brazil is the richest country in terms of biodiversity.

First chemical evaluation and toxicity of Casinga-cheirosa to Balb-c male mice

Laetia suaveolens, known as “casinga-cheirosa”, crude extract EB719 has previously shown cytotoxic activity against prostate cancer and squamous cell carcinoma. For the first time, seven molecules were isolated from its apolar—α-tocopherol (1) and sitosterol (2)—and polar—3-O-caffeoylquinic acid (3), 4-O-caffeoylquinic acid (4), 5-O-feruloylquinic acid (5), hyperoside (6), and isoquercitrin (7)—fractions. Acute toxicity was determined in a two-stage experiment: (1) a reduced number of Balb-c male mice received 5000 mg/kg of EB719 to allow evaluation of general activity and other 27 parameters, plus death, up to the establishment of non-lethal dose (NLD), as well as lethal dose 50% (LD₅₀); (2) NLD was administered and diazepam introduced as reference drug. EB719 showed LD₅₀ = 178.0 mg/kg, and NLD 156.3 mg/kg. In stage one EB719 did not influence general activity, but provoked impairment in grasp reflexes, tail squeeze and breathing; piloerection and cyanosis were increased. In stage two, alterations occurred in auricular reflex, piloerection and breathing after diazepam administration, but not in response to EB719. Intestinal hemorrhage caused by local bleeding was observed after necropsy, and may be the main cause of animals’ death other than a systemic effect of the extract. Although the isolated compounds are biologically and pharmacologically active in both men and animal systems, it is premature to relate their occurrence in EB719 to the observed intestine hemorrhage in mice.

Novel cytotoxic phenanthrenequinone from Odontioda Marie Noel 'Velano'

A new phenanthrenequinone, 5-hydroxy-2,3-dimethoxy-1,4-phenanthrenequinone (1), was isolated along with a known 9,10-dihydrophenanthrenequinone, ephemeranthoquinone B (2) from an MeOH extract of Odontioda Marie Noel 'Velano' through bioassay-guided fractionation. Their structures were elucidated by spectroscopic analysis, and the compounds were tested for in vitro cytotoxic activity. The compounds showed slightly higher cytotoxicity in human oral squamous cell carcinoma and leukemic cell lines as compared with human oral normal cells. The results suggest that apoptosis may not be involved in the cytotoxicity induction.