Search for solar axions emitted in the M1-transition of 7Li*with Borexino CTF

Results of background measurements with a prototype of the Borexino detector were used to search for 478 keV solar axions emitted in the M1-transitions of Li-7*. The Compton conversion of axion to a photon A + e -> e + gamma, axioelectric effect A + e + Z -> e + Z, decay of axion in two photons A -> 2 gamma and Primakoff conversion on nuclei A + Z -> gamma + Z are considered. The upper limit on constants of interaction of axion with electrons, photons and nucleons - g(Ae)g(AN) <= (1.0-2.4) x 10(-10) at m(A) <= 450 keV and g(A gamma)g(AN) <= 5 x 10(-9) GeV-1 at m(A) <= 450 keV are obtained (90%c.l.). For heavy axions with mass at 100 < m(A)< 400 keV the limits g(Ae) < (0.7 - 2.0) x 10(-8) and g(A gamma) < 10(-9) - 10(-8) are obtained in assumption that g(AN) depends on m(A) as for KSVZ axion model. These limits are stronger than obtained in previous laboratory-based experiments using nuclear reactor and artificial radioactive sources.