Background: Hibiscus sabdariffa (HS) leaves are a vegetable, which is used as a healthy sour soup for protection against chronic diseases in Thai traditional medicine.
Objectives: To investigate antioxidant, anti-inflammatory and cytotoxic activities of Hibiscus sabdariffa leave extracts from different extraction methods.
Material and Method: Fresh and dry Hibiscus sabdariffa leaves were extracted by various methods such as maceration with 95% and 50% ethanol, squeeze, and boiling with water or decoction. All extracts were tested for antioxidant activity by using DPPH radical scavenging assay, anti-inflammatory activity by determination on inhibitory effect of nitric oxide production on RAW264.7 cell. Cytotoxic activity also tested against human prostate cancer cell line (PC-3) by using sulforhodamine B (SRB) assay. Total phenolic content determined by the Folin-Ciocalteu colorimetric method.
Results: The results found that the 95% ethanolic extract of Hibiscus sabdariffa dried leaves (HSDE95) showed the highest antioxidant activity with an EC50 of 34.51+2.62 μg/ml and had the highest phenolic content (57.00+3.73 mg GAE/g). HSDE95 also showed potent cytotoxicity against prostate cancer cell line with an IC50 of 8.58+0.68 μg/ml whereas HSDE95 and all of extracts of Hibiscus sabdariffa leaves had no anti-inflammatory activity.
Conclusion: The obtained results revealed that HSDE95 extract showed potent cytotoxic activity against prostate cancer cells but low antioxidant and anti-inflammatory activities. This extract should be further isolated as active compounds against prostate cancer.

Keywords: Hibiscus sabdariffa leaves, Antioxidant, Anti-inflammatory, Cytotoxicity