Phototoxic and modulatory effects of natural products from the skin of Rhinella jimi (Stevaux, 2002)

The skin of amphibians possesses a large diversity of biologically active compounds that are associated with the natural defenses of these animals against pathogens. Five different extracts and fractions were obtained from the skin of Rhinella jimi: methanol extract (ME), methanol fractions (MF), chloroform extract of methanol extract (CF), aqueous alkaloid fraction (AAF) and aqueous non-alkaloid fraction (ANAF). All fractions were evaluated with respect to their antibiotic modifying activity in standard bacterial strains and multiresistant clinical isolates. Antagonism was detected with kanamycin and gentamicin when combined with substances obtained from the skin of R. jimi. Phototoxic activity was observed in the methanol and chlorophorm fractions, as well as the aqueous non-alkaloid fraction. The antagonistic action was apparently associated with the protection afforded by the bacterial populations that inhabit the skin of this amphibian, preventing colonization by pathogenic fungi. The phototoxic activity demonstrated by natural products from the skin of R. jimi showed an interruption of the bacterial growth after UV exposure. This could indicate an antibacterial effect activated by the UV light, opening a path for carrying the attack by pathogenic fungi, causing the disease related with the amphibian decline.

Potentiation of aminoglycoside antibiotic activity using the body fat from the snake Boa constrictor

Boa constrictor is widely used in traditional communities in many different folk remedies and products derived from it are sold in public markets throughout northeastern Brazil and as its body fat has many different therapeutic indications as a folk remedy. The present work evaluates the antibacterial activity of the body fat from the snake Boa constrictor when employed either alone or in combination with antibiotics and discusses the ecological implications of the use of this traditional remedy. Oil (OBC) was extracted from body fat located in the ventral region of B. constrictor using hexane as a solvent. The antibacterial activity of OBC was tested against standard as well as multi-resistant lines, either alone and in combination with antibiotics. OBC did not demonstrate any relevant antibacterial activity against standard or multidrug-resistant bacterial strains. OBC showed synergistic activity when combined with the aminoglycoside antibiotics. Our results indicate that the body fat of Boa constrictor does not possess bactericidal activity, from the clinical point of view, but when combined with an antibiotic, the fat demonstrated a significant synergistic activity.

Térmitas construtores de ninhos conspícuos em duas áreas de Mata Atlântica com diferentes níveis de perturbação antrópica / Termites that build conspicuous nests in two areas of Atlantic Forest under different levels of anthropogenic disturbance

Os efeitos do corte seletivo da vegetação sobre a assembléia de térmitas construtores de ninhos conspícuos foram avaliados em duas áreas de Mata Atlântica semidecídua, localizadas na Reserva Biológica Guaribas, Nordeste do Brasil. Essas áreas sofreram cortes seletivos, sendo uma até o ano de 1985 (A17) e a outra até 1972 (A30). O estudo foi realizado em 2002, sendo demarcada uma parcela de 1 ha em cada área. Nas parcelas, os ninhos foram mapeados e as espécies construtoras foram categorizadas em grupos alimentares. A estrutura da assembléia apresentou diferença entre as áreas. A maior diversidade e riqueza de espécies construtoras foram registradas na A30. As espécies humívoras foram as mais sensíveis ao corte seletivo. A abundância dos ninhos das espécies humívoras foi significativamente maior na A30, enquanto os ninhos dos xilófagos foram significativamente mais abundantes na A17. A razão entre os ninhos das espécies humívoras e xilófagas foi de 1:3 na A30 e de 1:12 na A17. Os ninhos mais volumosos foram encontrados na A30, enquanto que na A17 a abundância de ninhos inativos foi significativamente maior. O tempo de recuperação do hábitat após o corte seletivo influenciou a estrutura da assembléia de térmitas construtores de ninhos conspícuos de forma semelhante aos padrões encontrados em outros estudos desenvolvidos em florestas tropicais envolvendo todas as espécies de térmitas.

The effects of selective logging on termite assemblages that build conspicuous nests were studied in two areas of semideciduous Atlantic Forest, located in the Reserva Biológica Guaribas, Northeastern Brazil. The two study areas went through selective logging until 1985 (A17) and 1972 (A30). In 2002, termite nests were studied in two plots of 1 ha (100 x 100 m), being one plot in each area. The nests were placed in each plot and the species were categorized in feeding groups. The structure of the study assemblages was different between the two areas. Diversity and richness of builder species were greater in the A30 area. Species that consume humus were more sensitive to selective logging. Nest abundance of humus feeding species was significantly higher in the A30 area, whereas nests of wood feeding species were significantly more abundant in the area A17. Nest ratio between humus and wood feeding species was 1:3 in the A30 area and 1:12 in the A17 area. Nests with greater volume were observed in the area A30, whereas abundance of inactive nests was significantly higher in A17. The time for habitat resilience after the selective logging influenced patterns of assemblage structure of termites in similar ways as described in other studies in tropical forests.