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Two subspecies of Physostegia virginiana from seven different origins were investigated for iridoid glycosides. The plant material included the authentic sources of ‘deoxyloganic acid’, isolated in 1970 by one of the authors. This substance has now been identified as a 2.6:1 mixture of 7-deoxy-8-epiloganic acid and 10-deoxygeniposidic acid. Additionally, we isolated 14 known compounds and three new iridoids: stegioside I from P. virginiana ssp. virginiana (origin Freiburg) and stegiosides II and III from P. virginiana ssp. paemorsa (origin Chicago). The distribution of 16 out of 20 iridoids, previously reported or now isolated from P. virginiana , was determined in all populations. The iridoid patterns were significantly different between the two subspecies. The differences within ssp. virginiana were substantially smaller. The structure of ‘avicennioside’, previously isolated from Avicennia officinalis , is revised to linarioside. Ningpogenin, previously isolated from Scrophularia ningpoensis , is identical to a compound obtained by partial synthesis from aucubin.

Mangrove plant leaves of Avicennia officinalis , Acanthus illicifolius and Bruguiera gymnorhiza , grown under tidal water stress, were found to biosynthesize higher proportions of hydrocarbons, wax esters, sterol esters, triglycerides, sterols and low- M , terpenes, compared to the plants grown normally. Hydrocarbons and n -alcohols of wax esters, with longer chain lengths were found in higher proportions in the plants grown normally. Higher proportions of unsaturated n -alcohols of wax esters were present in the leaves of periodically submerged plants. Proportions of unsaturated fatty acids of wax esters, sterol esters and triglycerides were also higher in the submerged plants. Sitosterol, stigmasterol and campesterol of the sterol esters, were higher in submerged plants, whereas 28-isofucosterol was higher in normal plants. Of the free sterols, sitosterol was higher in submerged plants, whereas stigmast-7-en-3β-ol and campesterol were higher in normal plants and 28-isofucosterol was found only in submerged plants. Pentacyclic triterpenoids were found only in normal plants, whereas, the submerged plants contained low- M , terpenes in higher proportions.

The new iridoids avicennioside and 7-cinnamoyl-8-epiloganic acid, as well as the known compounds geniposidic acid and 2′-cinnamoyl-mussaenosidic acid, have been isolated from the leaves of Avicennia officinalis . In the plant the acids are accumulated as salts. The taxonomic significance of these findings is discussed.

Seven species of fresh mangrove leaves were found to contain saturated normal and branched chain hydrocarbons, mostly between C 16 and C 36 with both odd and even carbon numbers. Significant quantitative variations were found between species. Wax esters were found to contain fatty acids with chain lengths between C 12 and C 22 . Palmitic (16:0) and stearic (18:0) acids were the major component saturated fatty acids, whereas, oleic (18:1) and linolenic (18:3) acids were the major unsaturate α-acids. Chain lengths of the alcohols of wax esters were between C 14 and C 36 . Significant quantitative and minor qualitative differences were noted in the alcohol composition of wax esters. Hydrocarbon and wax ester compositions were characterised by the presence of low M , components in high proportions.