“…Gliotoxin with a unique disulfide bridge is a representative fungal toxin that has been obtained from Trichoderma viride for the first time (Brian, 1944), and later this compound along with its analogues have also been found in some marine-derived fungi (Chen et al, 2015;Luo et al, 2017;Sun et al, 2012;Wang et al, 2012). In continuation of our efforts to search for the chemical diversity of marine algicolous Trichoderma species (Liang et al, 2016;Miao et al, 2012), an epiphytic strain (Y13-3) of T. virens obtained from the marine red alga Gracilaria vermiculophylla was examined. As a result, two naturally occurring gliotoxin derivatives, dehydroxymethylbis(dethio)bis(methylthio)gliotoxin (1) and (3S,6R)-6-(para-hydroxybenzyl)-1,4-dimethyl-3,6-bis(methylthio)piperazine-2,5-dione (2), together with three known analogues, (3R,6R)-6-(para-hydroxybenzyl)-1,4-dimethyl-3,6-bis(methylthio)piperazine-2,5dione (3) (Hanson and O'Leary, 1981), bis(dethio)bis(methylthio)gliotoxin (4) (Lee et al, 2001;Sun et al, 2012), and bis(dethio)bis(methylthio)-12,13-didehydrogliotoxin (5) (Forseth et al, 2011;Sun et al, 2012), were isolated and identified from the culture (Fig.…”