[Investigation of the In Vitro and In Vivo Antimalarial Activity of Styrax liquidus Extracts]

Malaria is one of the most common and fatal parasitic diseases worldwide and the increasing rate of drug resistance has made the development of new treatment alternatives an urgent necessity. The aim of this study was to evaluate the in vitro and in vivo antimalarial activities of Styrax liquidus extracts. Styrax liquidus samples were macerated to obtain extracts in ethanol, 60% ethanol, methanol, chloroform, n-butanol, hexane, dichloromethane and water. The cytotoxicity profiles of the obtained extracts were evaluated using the MTT assay on the L929 cell line. In vitro antimalarial activity was tested using the ring-stage survival assay with the Plasmodium falciparum 3D7A strain. The antimalarial activity of the extracts was evaluated and those to be used in the in vivo stage were selected based on these results. For in vivo antimalarial activity assessment, Plasmodium berghei-infected Balb/c mice were used and the experimental animals were divided into methanol extract, water extract, chloroquine (positive control) and placebo groups. The predetermined doses were administered to the experimental groups via oral gavage in accordance with Peters' four-day suppression test protocol. The treatment schedule was administered at zero, 24, 48 and 72 hours post-infection and the animals' clinical course and parasitemia levels were regularly monitored using Giemsa-stained thin smears. The chemical profiles, component identification and the characterization of the extracts were evaluated using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) analyses. In the ring-stage survival test, the methanol and water extracts of Styrax liquidus completely inhibited P.falciparum at a concentration of 58 µg/mL. In the in vivo model, parasitemia appeared on day five in the placebo group and all animals died by day 11. In the water extract group, parasitemia was detected on day 17, and the animals died on days 24-25. In contrast, no parasitemia was observed in the methanol extract group during the 25- day follow-up period and survival was similar to that of the chloroquine group. The mean survival time was calculated as 25 days for the methanol and chloroquine groups, 24 days for the water extract group and 10 days for the placebo group. According to GC-MS and LC-MS analyses, cinnamic acid derivatives, phenolic compounds and fatty acid esters were identified as the main constituents of the methanol and water extracts. In conclusion, Styrax liquidus, particularly its methanol extract, appears to have a promising antimalarial potential. The findings indicate that further comprehensive studies are needed to evaluate this natural product as a potential alternative therapeutic agent.