11'-α-Tocomonoenol is the major α-tocomonoenol isomer in cyanobacteria and microalgae from Costa Rica

•Tocomonoenols (T1) have structural similarity to tocopherols (Vitamin E).•Microalgae tocomonoenol content up to 17 % in terms of total tocochromanol content.•Plant-associated 11′-αT1 is major α-tocomonoenol in microalgae and cyanobacteria.•Marine associated 12′-αT1 is negligeable form in microalgae and cyanobacteria.•Biosynthesis of 11′-αT1 may not be restricted to land plants.