Do you know what purpuroxanthin means? If you've read the title, you probably know it has something to do with colors--namely the complementary colors purple and yellow. Purpuroxanthin is a reddish yellow crystalline compound obtained from the reduction of purpurin, which is another chemical compound. Xanthos is the Greek word for yellow, which has a clear connection to the word--a reddish yellow crystalline compound. The connection to purpura, the Latin word for purple, however, is a bit more vague. Purpurin itself is not a purple compound--according to Merriam-Webster, it's actually orange or red. It's somewhat unclear as to why purpurin was named for the color purple, but it was, and purpura came to be a significant part of purpuroxanthin.
This post, of course, wouldn't be complete without mentioning a second important root used for the color yellow. The Greek word chrysos is technically the word for gold, but it is often used for the color yellow as well. Picture, for example, a chrysanthemum--although they're not always yellow, they frequently are, and they were named for this characteristic. Most frequently, though, it is used to mean gold, which is reflected in the word "chrysalis"--chrysalides were originally named for the chrysalis of the common crow butterfly, which is known for its brilliant gold-colored chrysalis.
Let me know what colors and roots you'd like to see me discuss next!