Phytochemical Screening, In vitro Antifungal and Antioxidant Activity of Essential Oil from roots of Rheum webbianum Royle from Himalayan Region

Abstract

Aim: The aim of our study is to evaluate the phytogenic chemical compounds and assess their antifungal and antioxidant activity of essential oil of Rheum webbianum Royle growing in greater Himalayan region. Materials and Methods: In the present study, the phytochemical constituents of essential oil were isolated by steam distillation and screened by gas chromatography (GC) and GC-mass spectrometry analysis in relation with their Kovats indices from R. webbianum is rich in oxygenated monoterpenoids and sesquiterpenoids. The essential oil was further evaluated for their antifungal activity by well diffusion method and antioxidant activity by 1, 1-diphenyl-2-picrylhydrazyl scavenging (DPPH) scavenging assay at various concentrations. Results: The major chemical constituent’s were undecanone (19.72%), maaliol (13.03%), 4-vinyl guaiacol (10.40%), 2E-undecanal (7.81%), valerianol (6.87%), viridiflorol (4.7%), eucalyptol (2.87%), and eugenol (2.98%) as the major constituents. The oil from the aerial parts of R. webbianum has shown moderate antifungal and activity with 100% mycelia growth inhibition against Alternaria alternata at concentration of 2400 μg/ml and Bipolaris maydis and Rhizoctonia solani at concentration of 2800 μg/ml. However, Fusarium oxysporum was found less susceptible for this oil. The IC50 showed a range from 873.4 μg/ml to 1502.3 μg/ml as compared with standard fungicides with IC50 values ranging from 37.8 μg/ml to 88.6 μg/ml. The free radical scavenging activity of R. webbianum oil employed by in vitro assay methods like DPPH at concentration of 600 μg/ml was 83%, respectively. Conclusion: Our study showed that maaliol followed by ρ-vinylguaiacol as the major components in this oil which was absent in previous findings. The essential oil had potent antifungal and antioxidant activity, respectively.