Two pairs of new dimeric diketopiperazine alkaloids, (+/-)-dibrevianamides Q1 and Q2 ((+/-)-1 and (+/-)-2), together with seven previously reported analogues ((+/-)-3, 4-6, and (+/-)-7) were obtained from a marine-derived fungus Aspergillus sp. The structures of (+/-)-1 and (+/-)-2 were clarified using comprehensive spectroscopic analyses, the calculated ECD, and DP4 + probability methods. Speculated from the biogenesis, (+/-)-dibrevianamides Q1 and Q2 ((+/-)-1 and (+/-)-2) might be the key precursor of [2 + 2] diketopiperazine dimers ((+/-)-3). Compounds (+)-1 and (-)-2 displayed anti-H1N1 virus activity with IC50 values of 12.6 and 19.5 mu M. Compound (+)-1 showed significant activity against Mycobacterium tuberculosis (MIC, 10.2 mu g/mL).Key pointsTwo pairs of new dimeric diketopiperazine alkaloids were obtained from the marine-derived fungus Aspergillus sp.The structures of the new compounds were clarified using comprehensive spectroscopic analyses, the calculated ECD, and DP4 + probability methods.(+/-)-Dibrevianamides Q1 and Q2 were speculated to be the key precursor of [2 + 2] diketopiperazine dimers (+/-)-asperginulin A.