patented as a herbicide (Inderjit and Bhowmik, 2002). In
addition to its herbicidal activity, alpha-terthienyl was
also toxic to non-target species. Toxicity to non-target
species is one of the main reasons which limit the use of
natural compounds as herbicides. Duke et al. (2000)
discussed some shortcomings of employing natural
products as herbicides. These are: (i) many natural
compounds are extremely expensive to synthesize, e.g. in
spite of the excellent herbicidal activity of tentoxin, it is
too expensive to manufacture, (ii) natural products have
generally short environmental half-lives, and (iii) some
natural compounds have potential mammalian toxicity
and are carcinogenic; for example, AAL-toxin and
fumonisin are toxic to mammalian cells. Some natural
products may have other problems, like allergy.
Sorgoleone, for example, is reported to cause dermatitis