Mixture/Compound?

[sadol76]

Hello everyone,
If a substance (chemical) B is a derivative of chemical A, and both are combined together through a combination of fermentation and chemical synthesis to form a product; will that resultant product be considered a MIXTURE or a COMPOUND?
This is a case of MILBEMYCINE OXIME.
Chemical structure:
5-demethoxy-28-deoxy-6, 28-epoxy-5-hydroxyimino-25-ethyl/methyl-milbemycin B.

5-didehydromilbemycins in the ratio of approximately 80% A4 (C32H45NO7, MW 555.71) and 20% A3 (C31H43NO7, MW 541.68)