Comparative Phytochemical Profiling of Psophocarpus tetragonolobus (L.) D.C. Seed Extracts for Effective Storage of Cowpea Seeds

Winged bean [Psophocarpus tetragonolobus (L.) D.C.], is unique legume which has numerous phytochemical with distinct properties. So, this research work was performed to explore and quantify the bioactive compound from different extracts of winged bean seeds through GC-MS and to assess the bio-efficacy on cowpea seed to protect them against deterioration and bruchid.

The bioactive compounds of winged bean seed extracts (from different solvents, viz., water, ethanol and hexane) were analysed by GC-MS and the bio-efficacy of identified superlative extract on maintaining the quality of cowpea seed var. VBN 3 was done using accelerated ageing method.

The GC-MS results showed the attendance of 30 different compounds in different extracts of the winged bean seeds. Of the different compounds eluted from extract, the ethanolic seed extract revealed the existence of distinct phytocompounds such as d-mannitol,1,4-anhydro-(1.59%), diethyl phthalate (27.21%), n-hexadecanoic acid (4.54%), 9,12-octadecadienoic acid (Z,Z)- (9.71%), oleic acid (14.16%), octadecanoic acid (4.89%), 9,12,15-octadecatrienoic acid and 2-phenyl-1,3-dioxan-5-yl ester (1.05%) which possess significant antioxidant and insecticidal properties. Among the different concentration of ethanolic extract, cowpea seeds treated with 2.5% of ethanolic seed extract of winged bean showed the highest germination (94%) and vigour index I (4436) compared to other treatments while the control recorded lowest germination (88%) and vigour index (3572) at initial day. As ageing progresses, seed germination percent and vigour index of 2.5% ethanolic extract treated seeds dropped to 63% and 1845 while, it is 42% and 953 in case of untreated seeds. The bio-efficacy study of ethanolic extract against bruchid revealed the LD90 value (2.5%) of winged bean seed extract. This study clearly shows that ethanolic extract of winged bean seeds have many bioactive compounds with distinct properties that maintain the seed quality under storage.