1) 2, 2', 4, 6-Tetramethoxybiphenyl was obtained from substance B monomethyl ether, C₁9H₂0O₇, by oxidation followed by decarboxylation, (II)→(III)→(IV)→(V), and it was also newly synthesized by the Ullmann reaction. 2) 4-Methoxyisophthalic acid was obtained from substance A (VIII) and B (VI) by oxidation. 3) The structure of sciadopitysin trimethyl ether was established as a new-type bisflavonoid of formula (VII) or (VII'), the former being preferable. 4) Formula (IX) or (X) was deduced as the structure of sciadopitysin.