If you Google, "Terra Sigillata," you'll get a number of hits for various clay pottery recipes. Very complicated stuff, requiring the use of a deflocculant to separate out large clay particles from the small ones. Terra sig, as it is known among pottery hipsters, is then used to coat finished pieces to produce a very smooth, high luster and waterproof finish.
What does this have to do with pharmacology and natural products?
Terra Sigillata literally means "sealed earth." In the common potter's vernacular, "seal" probably relates to the waterproof character of the product. But, in ancient pharmacy history, Terra Sigillata refers to the first trademarked drug product, a small clay tablet or planchet bearing an official mark of authenticity. In this case, the "seal" was a mark for trade and marketing purposes.
Yes, pre-Christian cultures ingested dirt (but only special dirt) as medicine. (Admonishment from my soil scientist colleagues: I meant to say, "soil" - sorry.). Terra Sigillata was a rather fatty clay first harvested around 500 B.C. from a particular hill on the Mediterranean island of Lemnos, now part of Greece. Dug on a special day annually in the presence of governmental and religious dignitaries, the clay was rolled to a defined thickness and pressed with an official seal by priestesses and dried in the sun. Kind of reminds me of my favorite beer, Samichlaus, brewed once a year on Dec 6.
Known as geophagy today, the practice is not as odd as it sounds. Today, we now know that clays contain kaolin (an active antidiarrheal component of Kaopectate), minerals like iron oxides and others like calcium carbonate and magnesium hydroxide that may have served as nutrients or antiacids. Moreover, various ethnomedical cultures have encouraged clay consumption by pregnant women, both to ease nausea and to adsorb dietary alkaloids and steroids present in the plant diet from harming the developing fetus.
Having lived in the southern US for over a quarter of my life, I'm also aware the red clay of the southeastern region is highly regarded for settling the stomach. According to John and Dale Reed in "1001 Things Everyone Should Know About the South," the practice of geophagy seems to have originated in Africa and was widespread in the 19th century South among the poor of both races. The Reeds claim that the taking of the clay is the source of "sandlappers," a nickname for South Carolinians. Heck, I've even heard Michael Stipe of R.E.M. (and Athens, GA) remark that red clay is in his blood, although I suspect his claim may be more figurative.
I learned of all this great history when I began leafing through a classic 1965 pharmacy history book, "Great Moments in Pharmacy History." (Washington State University's College of Pharmacy received permission to post the images online; here is the painting and brief description of Terra Sigillata.) The drug company then known as Parke, Davis & Company, commissioned Robert A Thom, a Birmingham, Michigan artist, to prepare paintings of historical scenes to accompany historical text collected by Prof George A Bender from pharmacy sources worldwide. It's a great book that can be found through e-tailers focusing on out-of-print texts. If you went to pharmacy school anytime since the mid-1960s, you know what I'm talking about because Thom's unmistakable portraits can be found in labs and offices in most US colleges of pharmacy.
The idea of Terra Sigillata stuck with me. When thinking of a name for this blog, I didn't want to restrict it to plants or fungi or soil microorganisms because creatures big and small, terrestrial and oceanic, have been used as sources for medicinal agents. I had certainly known that my predecessors had been culturing soil for novel medicinal-producing organisms since Selman Waksman first discovered streptomycin. But I frankly hadn't realized that the Earth itself had been used as a medicine.
Hence, Terra Sigillata is a metaphor for the fact that the Earth itself has provided medicines to various cultures for centuries.
The trademarking aspect of Terra Sigillata also holds significance for thinking about how important drug branding has become in our current culture, both for the buyer and the seller. Whether declared by a priestess, a charlatan, a shaman, a late-night infomercialist, or a drug regulatory agency, branding carries with it some implicit guarantee of quality or assurance of purity of authenticity.