▁ ▁Mechan ism ▁of ▁action ▁ ▁The ▁principal ▁mechanism ▁of ▁action ▁of ▁the ▁tax ane ▁class ▁of ▁dru gs ▁is ▁the ▁dis ruption ▁of ▁micro t ub ule ▁function . ▁ ▁Micro t ub ules ▁are ▁essential ▁to ▁cell ▁division , ▁and ▁tax anes ▁stabil ize ▁G DP - bound ▁tub ul in ▁in ▁the ▁micro t ub ule , ▁thereby ▁in hib iting ▁the ▁process ▁of ▁cell ▁division ▁as ▁dep ol ym er ization ▁is ▁prevent ed . ▁ ▁Thus , ▁in ▁ess ence , ▁tax anes ▁are ▁mit otic ▁in hib itors . ▁ ▁In ▁contrast ▁to ▁the ▁tax anes , ▁the ▁vin ca ▁al kal oid s ▁prevent ▁mit otic ▁sp ind le ▁formation ▁through ▁in hib ition ▁of ▁tub ul in ▁polym er ization . ▁Both ▁tax anes ▁and ▁vin ca ▁al kal oid s ▁are , ▁therefore , ▁named ▁sp ind le ▁po isons ▁or ▁mit osis ▁po isons , ▁but ▁they ▁act ▁in ▁different ▁ways . ▁Tax anes ▁are ▁also ▁thought ▁to ▁be ▁rad ios ens it izing . ▁ ▁Sub st ances ▁▁ ▁Hong d ous h ans ▁A - C ▁are ▁o xygen ated ▁tax ane ▁d iter pen es , ▁isolated ▁from ▁the ▁wood ▁of ▁Tax us ▁wall ich iana . ▁Hong d ous han ▁A ▁( C 2 9 H 4 4 O 7 ), ▁h ong d ous han ▁B ▁( C 2 7 H 4 0 O 7 ), ▁and ▁h ong d ous han ▁C ▁( C 2 7 H