Orthosiphol A

J Nat Prod. 2001 May;64(5):592-596.

Five novel highly oxygenated diterpenes of Orthosiphon stamineus from Myanmar[Pubmed: 11374950]

Five novel highly oxygenated diterpenes, orthosiphols K (1), L (2), M (3), and N (4) and norstaminone A (5), were isolated from the aerial part of Orthosiphon stamineus, together with three known diterpenes, orthosiphols A (6) and B (7) and neoOrthosiphol A (8). Orthosiphol L (2) is an isopimarane-type diterpene with a hydroxyl group at C-12, which supports the biogenesis of staminane-type diterpenes, i.e., migration of a vinylic group from C-13 of isopimarane to C-12. Norstaminone A (5) has a staminane carbon framework and supports the biosynthetic pathway from staminols to norstaminols via staminolactones. All the isolated compounds showed mild to weak antiproliferative activities toward highly liver metastatic colon 26-L5 carcinoma and human HT-1080 fibrosarcoma cell lines.

Nat Prod Commun. 2014 May;9(5):639-641.

Orthosiphol A from the aerial parts of Orthosiphon aristatus is putatively responsible for hypoglycemic effect via alpha-glucosidase inhibition[Pubmed: 25026708]

An infusion of Orthosiphon aristatus has long been used for diabetes therapy; however, the active principles remained unknown. Herein, we report the identification of the putative agents responsible for this antidiabetic activity using an a-glucosidase-guided isolation. Four flavonoids named sinensetin (1), salvigenin (2), tetramethylscutellarein (3) and 3,7,4'-tri-O-methylkaempferol (4), together with a diterpenoid named Orthosiphol A (5), were characterized, based on analysis of their spectroscopic data. Flavonoids 3 and 4 inhibited yeast a-glucosidase with IC,o values of 6.34 and 0.75 mM, respectively, whereas Orthosiphol A (5) selectively inhibited intestinal maltase with an IC5o, value of 6.54 mM. A kinetic investigation of 5 indicated that it retarded maltase function in a noncompetitive manner.

J Nat Prod . 2003 Feb;66(2):255-258.

Nitric oxide inhibitory isopimarane-type diterpenes from Orthosiphon stamineus of Indonesia[Pubmed: 12608860]

A methanolic extract of Orthosiphon stamineus yielded six new highly oxygenated isopimarane-type diterpenes, orthosiphols U-Z (1-6), and 15 previously reported diterpenes. The isolated diterpenes all showed significant dose-dependent inhibitory effects on the nitric oxide (NO) production in lipopolysaccharide (LPS)-activated macrophage-like J774.1 cells. Orthosiphols A (7), B (8), D (9), and X (4) showed more potent inhibitory activities than a positive control, N(G)-monomethyl-l-arginine (l-NMMA), and 1 displayed the strongest activity with an IC(50) value of 6.4 microM.