Natural and Semisynthetic Triterpenes from Combretum leprosum Mart. with Antiplasmodial Activity

Malaria is responsible for thousands of deaths each year. Currently, artemisinin combination therapy (ACT) is used as first-choice medication against the disease. However, the emergence of resistant strains prompts the search for alternative compounds. The present study aimed to investigate the antiplasmodial activities of natural triterpenes (compounds 1 and 2), and semisynthetic derivatives 1a, 1b, 1c, and 1d. Antiplasmodial assays were carried out using the SYBR Green technique, whereas cytotoxicity was evaluated by the MTT (3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide) method. Hemolytic assays were performed on human erythrocytes. An in silico analysis of the compounds against PfENR (Plasmodium falciparum 2-trans-enoyl-reductase) was carried out by molecular docking. Experiments with 1, and its derivatives against P. falciparum showed that 1a was very similar in terms of biological activity to compound 1 (half maximal inhibitory concentration (IC50) ca. 4 μM), whereas 1b, 1c, and 1d had reduced antiplasmodial activities (IC50 between 8-103 μM). The selectivity indexes of 1 and 1d for HepG2, and Vero cells were > 10. Docking results partially agreed with the in vitro experiments, with 1 and 1c having the best and worst affinities with PfENR, respectively. In conclusion, the results showed that 1 and 1d may serve as biotechnological tools in the development of antimalarial drugs.

Caracterização vegetacional do Monumento Natural Vale dos Dinossauros em Sousa, Paraíba, Brasil

O objetivo do presente trabalho foi caracterizar a vegetação arbórea da mata ciliar do trecho do Rio do Peixe, inserido no Monumento Natural do Vale dos Dinossauros (MONA), em Sousa-PB. Foram mensuradas árvores em 20 unidades amostrais quadradas de 400 m², dispostas às margens do Rio do Peixe, de maneira equidistante. Foram mensuradas, com fita métrica, a Circunferência do fuste a 1,30 m do solo e a 0,3 m do solo dos indivíduos arbóreos com circunferência a altura do peito (1,3 m) maior ou igual a 6 cm, além da altura total dos indivíduos, com o auxílio de vara graduada. Avaliou-se a diversidade, equabilidade, florística e as estruturas horizontal e vertical, além da distribuição diamétrica. Foram identificados 919 indivíduos, 16 famílias botânicas, 32 gêneros e 35 espécies. As famílias botânicas mais representativas em número de indivíduos foram a Fabaceae Linl. a Combretaceae R. Br., sendo a Fabaceae a mais representativa em número de espécies. A área apresenta boa diversidade florística, com boa distribuição dos indivíduos nas espécies. A espécie com maior importância e abundância na área foi o Combretum leprosum Mart. (mofumbo), com 32% dos indivíduos amostrados, e 16,69% do valor de importância. As espécies Cenostigma pyramidale (Tul.) Gagnon & G.P.Lewis., Senegalia bahiensis (Tul.) Gagnon & G.P.Lewis e Pseudobombax marginatum (A.St.-Hil., Juss. & Cambess.) A. Robyns, foram menos abundantes com um indivíduo cada, em toda a amostra. A distribuição diamétrica apresentou comportamento característico de populações naturais, em J-invertido. Há forte presença de espécies exóticas na área, porém, na amostra, constatou-se a presença de Prosopis juliflora (Sw) DC., Leucaena leucocephala (Lam.) de Wit., Cryptostegia madagascariensis Bojer. e Malpighia glabra L., espécies que naturalmente não deveriam existir em unidade de conservação.

Allelopathy, toxicity and phytochemical profile of aqueous extracts from Aspidosperma pyrifolium and Combretum leprosum

This study characterizes the allelopathic effect in the germination of Allium cepa seeds, and toxic on the species Artemia salina, of aqueous extracts of leaves of Aspidosperma pyrifolium and Combretum leprosum and the constituent phytochemical compositions. For this, Allium cepa seeds were germinated in systems containing aqueous extracts (200, 400 and 800 mg.L-1) and distilled water, to evaluate aspects of germination, mitotic phases, mitotic index and limit value of cytotoxicity. The toxicity of the aqueous extracts was evaluated in Artemia salina. The extracts were evaluated qualitatively and quantitatively when the substances present to define the phytochemical profile. The aqueous extract of A. pyrifolium negatively affects the germination process in the hypocotyl and seedling growth at 800 mg.L-1. The LC50 found for the aqueous extract of A. pyrifolium was 4986 mg.L-1. The effect of C. leprosum extract on germination resulted in an increase in the dry matter of the root at 400 mg.L-1 and in the density of the dry matter of the root at 800 mg.L-1. In addition, it reduces the seedling matter at 200 mg.L-1, corresponding to the trend observed in the mitotic index, in which this concentration presented a sublethal score for the limit value of cytotoxicity. The maximum concentration evaluated was not sufficient to determine an LC50 in A. salina. The phytochemical profiles of both species demonstrated classes of substances with potential pharmacological application. This information is important because these species are commonly used as food for farm animals and for purposes in folk medicine.

Physiological and biochemical responses of “mofumbo” seeds during storage

“Mofumbo” (Combretum leprosum Mart. (Combretaceae) is a neotropical species of wood, pharmacological, beekeeping and environmental importance. Thus, the objective was to evaluate the biochemical and physiological responses in C. leprosum seeds under different storage environments. The experiment was carried out in a factorial (2 x 7), with two storage conditions (natural and climate-controlled environments) and seven storage periods (0; 60; 120; 180; 240; 300 and 360 days), in four replications per treatment. At the beginning of storage and at 60-day intervals, the seeds were analyzed for water content, physiological potential (germination, germination speed index, root and shoot lengths and seedling dry mass) and biochemical (neutral lipids, lipid peroxidation, total and reducing sugars, total free amino acids, and starch). The results indicated that storing “mofumbo” seeds for 360 days reduced viability, being more pronounced after 180 days, regardless of the storage environment. “Mofumbo” seeds were stored in a natural environment for 180 days, resulting in less lipid degradation. After this period, the reduction was associated with the attack of reducing sugars on amino acids. Thus, it is concluded that “mofumbo” seeds must be stored in a natural environment for up to 180 days.