Both PXA and PXB were discovered in 2001, and their preparation by isolation from Phomopsis fungal cultures was described in the corresponding publication. Briefly, a MeOH extract of a Phomopsis culture is mixed with HO and washed with hexane. The aqueous phase is then dried and the residue is dissolved in EtOAc, washed with HO, concentrated and repeatedly purified by size-exclusion chromatography. The resulting mixture of PXA and PXB is separated by HPLC. A modified method, in which the initial extraction is done with EtOAc instead of MeOH and the drying step is skipped, was described in 2013.