(13R,23S)-22,23-Dihydro-5-O-demethyl-23-hydroxyavermectin A(sub 1a) 13-epi-Avm B(sub 2) 135680-93-2 Avermectin A(sub 1a), 22,23-dihydro-5-O-demethyl-23-hydroxy-, (13R,23S)- Avermectin A1a, 5-O-demethyl-22,23-dihydro-23-hydroxy-, (13R,23S)-