Thalassia

Zidorn, Christian, 2016, Secondary metabolites of seagrasses (Alismatales and Potamogetonales; Alismatidae): Chemical diversity, bioactivity, and ecological function, Phytochemistry 124, pp. 5-28 : 17-18

3.13. Thalassia (2, Hydrocharitaceae, Caribbean, tropical Indian and Pacific Oceans)

T. hemprichii collected off the coast of China yielded 10, 16, 19, 23, 27, 28, 36, 62, 71, 73, and 74 ( Qi et al., 2012). T. hemprichii collected off the coast of Egypt yielded five phenolics, caffeic acid 28, rosmarinic acid 32 (though the structure in the original publication shows a similar but different compound), and ssavonoids 75–77 ( Hawas, 2014).

T. testudinum was found to contain chrysoeriol 7- O -sulfate 69, using analytical 2D paper chromatography ( Harborne and Williams, 1976). The compound was isolated during the same study from Z. marina . Moreover, these authors reported on the occurrence of one partially characterized chrysoeriol derivative and partially characterized sulfated caffeoyl quinic acid derivatives. T. testudinum collected off the coast of the Bahamas provided the first source of 62 ( Jensen et al., 1998). T. testudinum collected off the coast of the Bahamas yielded three sulfated ssavonoids 51, 62, and 71 ( Rowley et al., 2002). Using RP-HPLC, Steele et al. (2005) identified and quantified vanillin 7, p -hydroxybenzoic acid 10, 3,4-dihydroxybenzoic acid 13, and p -coumaric acid 25 in leaves of T. testudinum collected off the coast of Florida. Compound identifications were based on retention times only and the extraction method with 2% acetic acid in methanol/water 1/1 as extraction solvent was rather harsh; therefore, the detected compounds might also represent other compounds with similar polarity or hydrolysis products of more complex genuine natural products.

Nogueiras et al. (2010) confirmed the presence of 10, 51, 62, and 71 in T. testudinum . Regalado et al. (2011) studied the apolar compounds of a T. testudinum leaf-extract by gas chromatography. A total of 43 compounds (structures not shown) were detected and 1,1-bis-(p -tolyl)-ethane, 4,4’-diisopropylbiphenyl, and an 1,1-bis-(p -tolyl)-ethane isomer were identified as the main compounds. T. testudinum leaves collected off the coast of Cuba yielded eleven phenolics (5, 10, 11, 47, 50–51, 58, 67, and 70–72), including the new natural product ethyl 4-(sulfoxy)-benzoate 11 ( Regalado et al., 2012). However, based on the described isolation procedures, it is likely that the new compound 11 is actually an artefact generated in the course of the extraction (with a 1/1 ethanol/water mixture) and isolation process and not a genuine natural product. Bio-guided fractionation (against Labyrinthula protists) resulted in the identification of vanillin 7, p -hydroxybenzoic acid 10, 3,4- dihydroxybenzoic acid 13, and p -coumaric acid 25 as the active principles in leaves of T. testudinum (Trevathan-Tackett et al., 2015) .