Banca de DEFESA: PALOMA MATHIAS DO NASCIMENTO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : PALOMA MATHIAS DO NASCIMENTO
DATE: 26/02/2026
TIME: 13:30
LOCAL: https://meet.google.com/anc-omvz-nhp
TITLE:

Influence of phytochemicals on the life cycle of Caenorhabditis elegans and Haemonchus contortus: a strategy in the search for new anthelmintic agents

KEY WORDS:

anthelmintics; essential oils; synergy; nematodes

PAGES: 111
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUMMARY:

The increasing resistance of helminths to conventional anthelmintics represents a critical challenge for animal health and the sustainability of livestock production. This thesis aimed to evaluate the potential of essential oils (EOs) from Origanum vulgare (oregano) and Cinnamomum cassia (cinnamon), as well as their main components, carvacrol and cinnamaldehyde, as alternative helminth control agents. Caenorhabditis elegans was used as an experimental model for initial screening, assessing the activity of EOs and isolated compounds at different parasite life stages. Specific objectives included: (i) determining lethal (adulticidal) and inhibitory (ovicidal) activities; (ii) evaluating efficacy against strains resistant to major classes of anthelmintics; (iii) investigating synergy between carvacrol and cinnamaldehyde; (iv) developing stable formulations; and (v) comparing effects in Haemonchus contortus, an important gastrointestinal nematode of ruminants. Results demonstrated significant anthelmintic activity for both EOs. Oregano EO exhibited high adulticidal potency against the wild-type C. elegans strain (LC₅₀ = 1.03 µg.mL⁻¹), superior to isolated carvacrol (LC₅₀ = 6.81 µg.mL⁻¹), suggesting synergy among the oil constituents. For eggs, carvacrol was the primary active ovicidal component. Cinnamon EO showed adulticidal activity similar to isolated cinnamaldehyde (LC₅₀ ≈ µg.mL⁻¹), but cinnamaldehyde displayed potent ovicidal activity (LC₅₀ = 3.08 µg.mL⁻¹). Both EOs induced severe morphological alterations in nematodes. In resistant C. elegans strains, oregano EO efficacy was reduced, while cinnamon EO remained active, indicating distinct mechanisms and potential to overcome resistance. Synergy analysis revealed predominantly additive or moderate effects in adults and additive to slightly antagonistic effects in eggs, without strong overall synergy. Bead-type formulations, developed by ionic gelation with calcium sulfate, showed good incorporation and stability of active compounds. Tests in Haemonchus contortus confirmed EO activity, highlighting the ovicidal effect of cinnamon EO. In conclusion, oregano and cinnamon EOs, as well as carvacrol and cinnamaldehyde, demonstrated complementary and promising profiles as candidates for new anthelmintic agents. Oregano EO is more potent in adults, potentially due to internal synergy, whereas cinnamaldehyde exhibits strong ovicidal activity, including against resistant strains. These findings provide a basis for in vivo studies, formulation optimization, 9 and the development of combinatorial strategies with conventional anthelmintics.

COMMITTEE MEMBERS:
Presidente - 1173660 - FABIO BARBOUR SCOTT
Interna - 3161989 - GABRIELA FERREIRA DE OLIVEIRA
Externo ao Programa - 1705075 - DOUGLAS SIQUEIRA DE ALMEIDA CHAVES - UFRRJExterna ao Programa - ***.185.477-** - VIVIANE DE SOUZA MAGALHAES - UFRRJ
Externa ao Programa - 1256224 - BIANCA FERNANDES GLAUSER - UFRRJExterno à Instituição - FERNANDO DE ALMEIDA BORGES - UFMS
Externa à Instituição - JULIANA CAMACHO PEREIRA - UFRJ
Externo à Instituição - CAIO MOTA MACHADO