<i>Trigonella foenum graecum</i> (fenugreek) seeds were treated with different dilutions of aqueous leaves extract of <i>Antigonan</i> (i.e., from 10 to 50%) and grown on sterile cotton and Whatman filter paper in a Petri dish. The seedling length, fresh weight and dry weight of plants was taken after 5 to 15 days. It was found that the germination was 62% (85% in distilled water control and the germination process was completed in 2 days) in all dilutions and growth was severely inhibited as compared to distilled water grown control. Growth inhibition was increases with extract concentration. Maximum inhibition was recorded in radicle growth after five days of sowing in treated seedling with 50% aqueous extracts. Qualitative LCMS analysis of methanolic leaf extract of <i>A. leptopus</i> reveals the presence of various phenolic acid derivatives, like ferulic acid derivatives, arachidonic acid, citronellic acid, and coumarins derivatives etc. These phytotoxins not only inhibits the germination but also plant growth and interfere with ion accumulation of the plant. These results indicate that <i>Antigonan</i> plants have strong negative allopathic interactions with <i>Trigonella</i>. <i>Antigonan</i> may be harmful for our crop as well as native plants. However, the plant has certain medicinal properties like anti-cancerous properties, anti-diabetic properties that can be utilized for human welfare.