In Vitro Screening for Cytotoxic, Anti-bacterial, Anti-HIV1-RT Activities and Chemical Constituents of Croton fluviatilis, Croton acutifolius, and Croton thorelii

Background: Although the chemical constituents and biological activities of a large number of plants in the Croton genus have been studied, there are still recently discovered plants that need to be investigated. Objective: 1. To investigate the anti-bacterial, anti-HIV1-RT, and cytotoxicity activities of crude extracts of these plants. 2. To investigate the chemical constituents of Croton fluviatilis, Croton acutifolius, and Croton thorelii. Methods: The anti-bacterial, anti-HIV1-RT, and cytotoxicity of the three plants were evaluated by standard techniques. Extraction, separation, and purification of extracts of the three plants were performed. Results: The ethyl acetate extract of C. fluviatilis showed low anti-bacterial activity against E. aerogenes, E. coli 0157: H7, and P. mirabilis, together with the ethyl acetate extract of C. acutifolius displayed low anti-bacterial activity against E. aerogenes, while all the crude extracts of C. thorelii were inactive. The ethyl acetate extracts of C. thorelii and C. fluviatilis showed strong HIV1-RT activities, whereas the ethyl acetate extract of C. acutifolius and the hexane extract of C. fluviatilis displayed moderate HIV1-RT activities. Cytotoxic properties of three Croton plants were specific to KKU-M213, MDA-MB-231, A-549, and MMNK-1. Especially, the ethyl acetate extract of C. acutifolius exhibited strong cytotoxic activities against MDA-MB-231, A-549, and MMNK-1. Furthermore, the ethyl acetate extract of C. thorelii showed high cytotoxic activities against KKU-M213 and MDA-MB-231. Compounds 1 and 4 were found in C. fluviatilis. Compounds 2 and 4 were found in C. acutifolius. Moreover, compound 3 was only found in C. thorelii. Conclusion: The present study revealed that the three Croton species are good sources of flavonoid compounds, and further investigation of the chemical constituents from these plants may prove to be fruitful to discover more active compounds to be tested as potential medicines.