On the basis of NMR and HRESI-MS analysis, the molecular formulas
were determined as C29H30O8 for A4 and C30H32O8 for A5.
No resemblance was noted when the structures of compounds A4
and A5 were compared with those reported in the literature such
as databases www.sciencefinder.com and www.chemspider.com,
and also antibiotics described in dictionary of antibiotics and
related substances, in dictionary of natural products
, and in the review of bioactive microbial
metabolites .