Peltate Glandular Trichomes of Colquhounia coccinea var. mollis Harbor a New Class of Defensive Sesterterpenoids

A new class of unique sesterterpenoids, colquhounoids A-C (1-3), were identified from the peltate glandular trichomes of Colquhounia coccinea var. mollis (Lamiaceae) through precise laser-microdissection coupled with UPLC/MS/MS and spectroscopic analyses and X-ray diffraction. Very interestingly, their structural features and defensive function are closely related to leucosceptroid-class sesterterpenoids harbored by the glandular trichomes of another Lamiaceae taxon, Leucosceptrum canum, even though this is morphologically distinct and taxonomically distant.