Earlier work described the purification, chemical structure, and biological activity of CAY-1, a fungicidal, gitgeninbased, steroidal saponin present in the fruit of cayenne pepper and paprika, members of the Capsicum plant family (De Lucca et al. 2001; Yajima et al. 2000). CAY-1 is lethal to fungi: at concentrations between 3 and 20 [micro]mol x [.-1] it produces a 90% lethal dose (L) or greater to the germinating conidia of Aspergillus flavus, A. niger, A. parasiticus, and A. fumigatus. Minimal inhibition concentration (MIC) assays show that CAY-1 inhibits the growth of Candida albicans, C. glabrata, C. tropicalis, and C. parapsilosis at 4-31 [micro]g x [.-1], but Renault et al. (2003) showed that at 100 [micro]g x [.-1] it was not toxic to 55 mammalian cell lines. Purification of CAY-1 requires the use of high pressure liquid chromatography--mass spectrometry (HPLC-MS). During this step, CAY-1 is separated from two compounds having molecular masses that are 162 (compound 1, molecular mass 1081 Da) and 324 (compound 2, molecular mass 919 Da) mass units smaller than that of CAY-1 (molecular mass 1243 Da).
Early sensory tests led to claims that rebaudioside A was 150 to 320 times sweeter than sucrose, stevioside was 10 to 270 times sweeter, rebaudioside C 40 to 60 times sweeter, and dulcoside A 30 times sweeter.  However, a more recent evaluation found rebaudoside A to be about 240 times sweeter, and stevioside about 140 times.  Rebaudioside A also had the least bitterness and aftertaste.  The relative sweetness seems to vary with concentration: a mix of steviol glycosides in the natural proportions was found to be 150 times sweeter than sucrose when matching a 3% sucrose solution, but only 100 times sweeter when matching a 10% sucrose solution.