Highly Oxygenated Triterpenoids from the Marine Red Alga Laurencia mariannensis (Rhodomelaceae)

Abstract

Two new and one known squalenoid-derived triterpenoids, namely, laurenmariannol (1) and (21a)-21-hydroxythyrsiferol (2), and the known thyrsiferol (3) were isolated and identified from the marine red alga Laurencia mariannensis, which was collected off the coast of Hainan and Weizhou Islands of China. The structures of these compounds were established by means of spectroscopic analyses, as well as by comparison with literature data. Compounds 1 and 2 displayed significant cytotoxic activity against P-388 tumor cells with IC 50 values of 0.6 and 6.6 mg/ml, respectively.Introduction. -Marine red algal species of the genus Laurencia, i.e., L. viridis, L. obtusa, L. thyrsifera, L. pinnatifida, and L. venusta were found to be a prolific source of triterpenoids, which are characterized by a high degree of oxygenation and fused cyclicether systems. These triterpenoids exhibited potent cytotoxic effects against some tumor cell lines [1].In our investigations towards the discovery of structurally new and biologically active compounds from Chinese marine red algal species of Rhodomelaceae [2 -11], we examined the chemical constituents of L. mariannensis, which was collected off the coast of Hainan and Weizhou Islands of China. As a result, two new and one known triterpenoids, namely, laurenmariannol (1) and (21a)-21-hydroxythyrsiferol 1 ) (2), and the known thyrsiferol (3) [12 -14], were isolated and characterized. This paper reports the isolation and structure identification of these compounds and the cytotoxic activity of compounds 1 and 2.

Halogenated Organic Molecules of Rhodomelaceae Origin: Chemistry and Biology

“…It should be noted that 21α-hydroxythyrsiferol (367) and laurenmariannol (368) were reported as new compounds from L. mariannensis in 2008. 243 However, the spectroscopic data of these two compounds were very similar to those of aplysiols A and B, which were isolated from the sea hare Aplysia dactylomela in 2007. 244 Sea hare are known to feed upon Laurencia species, and it thus seems likely that the true origin of these compounds is dietary algae.…”

“…230 Of these, thyrsiferyl 23-acetate (349) displayed the most potent activity against P-388 cells, with an ED 50 (367) and laurenmariannol (368) also showed cytotoxicity toward P-388 with IC 50 values of 6.6 and 0.60 μg/mL, respectively. 243 Further examination revealed that thyrsiferyl 23-acetate (349) induced rapid cell death in various leukemic T-and B-cell lines, and that the cell death follows a typical apoptotic process. 501 Thyrsiferol (347) inhibited hypoxia-inducible factor-1 (HIF-1) activation in T47D human breast tumor cells.…”

Sesquiterpenes and Other Metabolites from the Marine Red Alga Laurencia composita (Rhodomelaceae)

“…A detailed NMR comparison with those reported for phytyl acetate revealed that 4 differed from phytyl acetate mainly at C(2) and C(3) [25]. The olefinic 13 (2)) of phytyl acetate [25] was replaced by an epoxy signal at d(H) 2.98 (dd, J ¼ 6.9, 4.3 Hz, HÀC(2)) in 4. So, compound 4 was deduced to be a 2,3-epoxy derivative of phytyl acetate.…”

Laurenidificin, a new brominated C15-acetogenin from the marine red alga Laurencia nidifica

“…Chemical investigation of L. nidifica for secondary metabolites started from 1974 [1] and the majority of these metabolites are halogenated sesquiterpenes and C 15 -acetogenins [2,3], many of which possess antimicrobial and antiviral activities [2,4]. In our continuing investigation on halogenated bioactive natural products from Laurencia species [5][6][7][8][9][10][11][12][13][14], we casually collected the species L. nidifica from Sanya coast of Hainan Province. Chemical examination of this species resulted in the isolation and identification of a new brominated C 15 -acetogenin, namely, laurenidificin (1) (Fig.…”