Bioefficacy potential of different genotypes of walnut Juglans regia L.

The purpose of investigation was to assess the phytochemical and nutraceutical of walnut in leaf extracts through diverse quantitative and qualitative phytochemical tests followed by array of assays. The screening of 50 elite walnut genotypes which exhibited wide range of discrepancy in terms of phytochemicals as well as their anti-oxidant potential was done. Walnut genotypes displayed maximum divergence in quercetin content (2.86–5.78 mg/100 g) as represented by cluster analysis. The phenolic rich genotypes exhibiting total phenols (37.61–46.47 mg/g GAE) having higher DPPH potential (IP of 32.82–73.50) where as genotypes that accumulate flavonoids/flavanols (5.52–28.48 mg/g QE and 4.11–21.76 mg/g QE showed immense FRAP activity (418.92–1067.94 µM Fe2+/g FW). There was positive correlation between the phenolics content and anti-oxidant potential. The results showed oil content of 50.1–85.08% and kernel percentage 25.21–81.92% of all walnut genotypes. To evaluate the anti-proliferative potential of walnut genotypes, Trypan blue exclusion test, MTT assay and Griess assay was used. Each assay was repeated with different positive controls against a panel of human cancer cell lines viz THP-1, U2OS, IMR-32 and HBL-100 and then compared with the walnut extracts for their efficiency in anti-proliferative activity. The SPS 1 walnut extract at concentration of 500 µg/ml exhibited 10% cell viability and with 1000 µg/ml walnut extract there was consequent decline towards (6.25%) viability. The results indicated that walnut leaf constitutes an excellent source of effective natural antioxidants and chemo-preventive agents that can act as anti cancer agents.