Chemical constituents of Cycas aenigma.

Chemical investigation of Cycas aenigma, a plant endemic to the Philippines, led to the isolation of a rare neolignan, 2-[2-hydroxy-5-(3-hydroxypropyl)-3-methoxyphenyl]-1-(4-hydroxy-3-methoxyphenyl)propane-1,3-diol (1), pinoresinol (2), and fatty alcohols (3) from the leaflets; and triglycerols (4), and a mixture of β-sitosterol (5a) and stigmasterol (5b) from the petiole and rachis. The structure of 1 was elucidated by extensive 1D and 2D NMR spectroscopy, while those of 2-5b were identified by comparison of their 1H and/or 13C NMR data with literature data.

Chemical Constituents of Cycas sancti-lasallei.

Chemical investigation of the dichloromethane extracts of Cycas sancti-lasallei, a plant endemic to the Philippines, led to the isolation of squalene (1), β-sitosterol (2a), stigmasterol (2b), and triglycerides (3) from the sarcotesta; 2a, 2b, 3,and phytyl fatty acid esters (4) from the endotesta; 2a, 2b, 3,and β-sitosteryl fatty acid esters (5) from the sclerotesta; and 3 and 5 from the bark. The structures of 1-5 were identified by comparison of their 1H NMR and/or 13C NMR data with those reported in the literature.

Notes on insect diversity of Indian Cycas species.

The question of an analogue evolution of plant - insect interaction in gymnosperms has remained unanswered until recently, in spite of indications of insect pollination in the extant cycad genera. Earlier observations on insect pollination have now been verified by convincing experiments with several cycads in which anemophilous pollination was excluded. Insects have long been known to visit cycad cones and now it is established that in rest of the cycad species where both male and female reproductive organs are organized in compact cones, these insects help in the pollination. But Cycas is the only genus where female megasporophylls do not form a cone and its pollination mechanism has not been fully comprehended. The present investigation was carried out in the natural habitats of Cycasspecies from the Western Ghats, India. Five coleopteran insects were found abundantly in the male cones of Cycas and our observations on the role of these insects led us to believe that Cycas among cycads which appear to be true remnants of pteridospermous line have somehow has also maintained mutualism with the primitive plant chewing insects like coleopterans couldbe the results of an ancient co-evolution.