Taken by Adler to be derived from Theodoret, Commentary on the Psalms PG 80.1193, commenting on LXX Psalm 44:9 (45:8 KJV), where the headword phrase appears (as here) in the nominative. In Theodoret's commentary, however, both the headword phrase and the gloss appear in the accusative, so a parallel or intermediate commentary on the passage may be the Suda's source. This passage is also quoted at kappa 451.
On "extract", generally used in Greek sources to refer to oil of myrrh, cf. sigma 997. In the Psalm, this is listed separately alongside plain myrrh (smu/rna). The original Hebrew is וַאֲהָלוֹת ('ohalot'), which refers to an unknown type of imported spice or perfume (hence "aloes" in KJV and other English translations), but one that is unlikely to be myrrh extract. So perhaps the LXX were applying the term "extract" to something other than oil of myrrh.