After TLC of fungal extract the resulted band of taxol has varying colors from TLC to another. The same variation in color was observed for standard too.
Yellow color of the compound is formed due to three reasons, one effect of heat, photoactivation and addition of developer group to the spot. Though it is true it may form complex due to effect of heat and photoradiation.
i mean that under all the constant conditions the color vary from a TLC to another for the same fungal extract and standard. sometimes appears blue-green others violet.