Structural and Stereochemical Studies of Laurokamurols A-C, Uncommon Bis-sesquiterpenoids from the Chinese Red Alga Laurencia okamurai Yamada

Three novel heterodimeric laurane-type sesquiterpenoids, laurokamurols A-C (1-3), along with eight known related monomeric ones (4-11) were isolated from the East China Sea red alga Laurencia okamurai Yamada. The absolute configurations of the new bis-sesquitepenoids, especially their axial chirality, were determined by extensive spectroscopic analyses and TDDFT-ECD method. All of the new compounds showed promising PTP1B inhibitory activities with IC50 values comparable to the positive control, indicating them as potential food additives or pharmaceutical drug leads toward obesity or diabetes.