There is a minor error with the drawn structure.
The second ring from the top should be an aminocyclitol instead of a sugar. Specifically, the oxygen atom on the six-membered ring has to replaced by a carbon.
Please check the following links:
1) National Intitutes of Health link at:neomycin applications
2) Scripps Research Institute neomycin modification
3) Pfizer Center Source PfizerCS documentation
