ABSTRACT
In the search for new environmental friendly antifouling (AF) agents, four coumarins were isolated from the herbal plant Cnidium monnieri, known as osthole (1), imperatorin (2), isopimpinellin (3) and auraptenol (4). Furthermore, five coumarin derivatives, namely 8-epoxypentylcoumarin (5), meranzin hydrate (6), 2'-deoxymetranzin hydrate (7), 8-methylbutenalcoumarin (8), and micromarin-F (9) were synthesized from osthole. Compounds 1, 2, 4, 7 showed high inhibitory activities against larval settlement of Balanus albicostatus with EC(50) values of 4.64, 3.39, 3.38, 4.67 µg mL-1. Compound 8 could significantly inhibit larval settlement of Bugula neritina with an EC(50) value of 3.87 µg mL-1. The impact of functional groups on anti-larval settlement activities suggested that the groups on C-5' and C-2'/C-3' of isoamylene chian could affect the AF activities.
Subject(s)
Bryozoa/drug effects , Cnidium/chemistry , Coumarins/pharmacology , Thoracica/drug effects , Animals , Bryozoa/growth & development , Coumarins/chemical synthesis , Coumarins/chemistry , Dose-Response Relationship, Drug , Furocoumarins/chemistry , Furocoumarins/pharmacology , Larva/drug effects , Larva/growth & development , Lethal Dose 50 , Models, Chemical , Molecular Structure , Plant Extracts/chemistry , Plant Extracts/pharmacology , Thoracica/growth & developmentABSTRACT
One new dimeric diterpenoid, 8(14)-enyl-pimar-2'(3')-en-4'(18')-en-15'(16')-endolabr- 16,15,2',3'-oxoan-16-one (1) and five known terpenoids: Tagalsin C (2), Tagalsin I (3), lup-20(29)-ene-3ß,28-diol (4), 3-oxolup-20(29)-en-28-oic acid (5) and 28-hydroxylup- 20(29)-en-3-one (6) were isolated from the roots of the mangrove plant Ceriops tagal. Their structures and relative stereochemistry were elucidated by means of extensive NMR, IR and MS analysis. The antifouling activity against larval settlement of the barnacle Balanus albicostatus were evaluated using capsaicin as a positive control. All these terpenoids exhibited antifouling activity against cyprid larvae of the barnacle without significant toxicity. The structure-activity relationship results demonstrated that the order of antifouling activity was diterpenoid (Compound 2) > triterpenoid (Compounds 4, 5 and 6) > dimeric diterpenoid (Compounds 1 and 3). The functional groups on the C-28 position of lupane triterpenoid significantly affect the antifouling activity. The diterpenoid dimmer with two identical diterpenoid subunits might display more potent antifouling activity than one with two different diterpenoid subunits. The stability test showed that Compounds 2, 4, 5 and 6 remained stable over 2-month exposure under filtered seawater.
Subject(s)
Rhizophoraceae/chemistry , Terpenes/chemistry , Animals , Larva/drug effects , Magnetic Resonance Spectroscopy , Molecular Conformation , Plant Roots/chemistry , Plant Roots/metabolism , Rhizophoraceae/metabolism , Structure-Activity Relationship , Terpenes/isolation & purification , Terpenes/pharmacology , Thoracica/drug effects , Thoracica/growth & developmentABSTRACT
A new atisane-type diterpene, ent-16alpha-hydroxy-atisane-3,4-lactone (4) and three known diterpenes, ent-16alpha-hydroxy-atisane-3-one (1), ent-atisane-3beta,16alpha-diol (2), ent-3,4-seco-16alpha-hydroxyatis- 4(19)-en -3-oic acid (3) were isolated from the bark of the mangrove plant Excoecaria agallocha. Their structures and relative stereochemistry were elucidated by means of extensive NMR and MS analysis. Compound 3 exhibited significant anti-microfouling activity against the adherence of Pseudomonas pseudoalcaligenes, with an EC(50) value of 0.54+/-0.01 ppm.
Subject(s)
Diterpenes/isolation & purification , Euphorbiaceae/chemistry , Plant Bark/chemistry , Animals , Biofilms , Diterpenes/chemistry , Humans , Mass Spectrometry/methods , Models, Molecular , Nuclear Magnetic Resonance, BiomolecularABSTRACT
The new diterpene methoxy-ent-8(14)-pimarenely-15-one (1) and three known metabolites: ent-8(14)-pimarene-15R,16-diol (2), stigmasterol (3) and beta-sitosterol (4), were isolated from the roots of the mangrove plant Ceriops tagal. Their structures and relative stereochemistry were elucidated by means of extensive NMR, IR and MS analysis. Compounds 1, 2, 3 and 4 exhibited significant antifouling activities against cyprid larvae of the barnacle Balanus albicostatus Pilsbry, with EC(50) values of 0.32 +/- 0.01, 0.04 +/- 0.00,4.05 +/- 0.15 and 18.47 +/- 0.40 microg/cm(2), respectively, whereas their toxicities towards cyprids were very low, with LC(50 )values all above 10 microg/cm(2).
