Three Diterpenoids (Excoecarins V1—V3) and a Flavanone Glycoside from the Fresh Stem of Excoecaria agallocha.

Abstract

Excoecaria agallocha LINN. (family Euphorbiaceae) is distributed on seashores and edge-mangroves throughout tropical Africa, Asia, and northwest Australia. 1) The Excoecaria genus is well known to contain skin irritants, called irritant Excoecaria factors. In traditional Thai medicine, the bark and wood of the plant is used to treat flatulence. 2,3) In Sri Lanka, the smoke of the burning wood is used in the treatment of leprosy, and the root, when pounded with ginger, as an embrocation for swollen hands and feet. 4) The milky latex exuded from the bark of E. agallocha may cause blindness or blistering of the skin. 2,3) This latex has been used as a poison for fish by adding it to water and to poison arrowheads. The piscicidal constituent excoecariatoxin characterizing the daphnane diterpene ester and some related compounds have been obtained from the twigs, bark, and latex of Excoecaria agallocha in Japan and Thailand, respectively. 2,3,5) Daphnane-and tigliane-type diterpene esters are known to be skin irri-tants and tumor promoters. 2,3) Previously we reported the isolation and structural elucida-tion of many diterpenoids from the resinous wood of this plant, 6) as well as their inhibitory effect on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells. 7) In our search for bioactive compounds from plants of the Euphor-biaceae, we isolated three new diterpenoids, excoecarins V1-V3 (1-3) and a new flavanone glycoside (7) with five known compounds, ent-atisane-16a-ol (4) 8-11) and ent-2,3-secobeyer-15-ene-2,3-dioic acid (5), 12) ent-15,18-dihydroxy-labda-8(17),13E-diene (6), 13) methyl 3,4,5-trihydroxybezoate (8), 14) and 3,4,5-trimethoxyphenol 1-O-b-D-(6-galloyl)-glu-copyranoside (9) 15) from the fresh stem of E. agallocha collected in Okinawa. In this paper, we describe the stereochem-istry of the new diterpenoids (1-3) and flavanone glycoside (7). Excoecarin V1 (1) was obtained as colorless prisms, mp 177-179 °C and [a] D 19.3°. The molecular formula of 1 was determined by high-resolution (HR)-EI-MS to be C 20 H 30 O 4 on the basis of the molecular ion peaks observed at m/z 334 [M]. The IR spectrum of 1 showed hydroxyl (3410, 3300 cm 1), ether (1188, 916 cm 1), and disubstituted olefinyl (1600, 746 cm 1) groups. The 1 H-NMR spectrum of 1 in DMSO-d 6 (Table 1) showed the presence of two methyl signals at d 0.90 and 0.97, disubstituted olefin at d 5.45 (d, J5.5 Hz) and 5.68 (d, J5.5 Hz), and three hydroxyl groups at d 4.41 (dd, J4.0, 6.0 Hz), 4.42 (d, J6.5 Hz), and 4.95 (s). The coupling patterns of a methine group at d 3.81 (ddd, J2.5, 6.5, 9.7 Hz) and methylene protons [d 3.16 (dd, J4.0, 10.5 Hz), 3.25 (dd, J6.0, 10.5 Hz)] on the carbons bearing the oxygen functions were changed to a double dou-blet and doublet in CDCl 3 , respectively. However, the coupling patterns of the methylene protons at d 3.61 (d, J8.5 Hz) and 3.67 (dd, J2.6, 8.5 Hz), which coupled with one of the methylene protons at d 1.54 (ddd, J2.6, 9.7, 13.5 Hz), did not change in...

Bioactivity of Excoecaria agallocha

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Potential Anti-Diabetic Mangroves in Kerala, India: A Review

“…Phytochemical screening shows the presence phorbol ester, flavanone, glycoside, various di-and triterpenoids, 15 dichloromethane, lignin, pentosan, α cellulose saponin, tannins, phenols, volatile oils. 16,17,18 Pharmacological investigation of the various extracts of the plant shows antibacterial, antioxidant, anti-diabetic, antibacterial, antinociceptive effects .it is also reported it has some impact on the treatment of mosquito borne diseases and pandemic diseases.…”

Subcritical water extraction of bioactive components from algae

“…They are formed from the oligomeric structures of phloroglucinol (1,3,5trihydroxybenzene) (Parys et al, 2007). Also, some flavanone glycosides have been found even in fresh water algae (Konishi et al, 2003).…”