Dear Sir. Concerning your issue for the general procedure for iridoid extraction . I think the following link may help you in your analysis.

http://link.springer.com/article/10.1023/A%3A1016072216772#page-1

Thanks

Polar solvents are generally advised to extract iridoids. 85% methanolic extracts are usually used to extract phytoecdysteroids and those extracts also contain iridoids. For isolation point of view, 50-50 aqueous: methanol seems better for iridoids.