The mono-benzo-derivatives are coumarone, benzothiophene and indole; the dibenzo-derivatives are diphenylene oxide, dibenzothiophene or diphenylene sulphide, and carbazole.
In 1820 was published his treatise on the gospel of St John, entitled Probabilia de Evangelii et Epistolarum Joannis Apostoli indole et origine, which attracted much attention.
Joannis Apostoli indole et origine (1820), the first systematic assault on the traditional attribution, remains unrefuted in its main contention.
The most noteworthy of which being ibogaine, an indole alkaloid derived from an African plant source.
Many derivatives of indole are known.