Antimicrobial and antioxidant properties of different solvent extracts of five cultivars of Zingiber officinale were investigated. Out of the test organisms, Staphylococcus aureus was found most susceptible to chloroform extract of majhauley cultivar (26±0.1mm), while there was no activity recorded against Escherichia coli. The highest total phenol and flavonoid contents were recorded in the chloroform extract of charinangrey and majhauley cultivars. The mean differences in the total phenolic content among five ginger cultivars were statistically significant (P< 0.0001), whereas the flavonoid contents were statistically non significant (P> 0.05). The relationships between total phenol content and antimicrobial activity showed significant positive relationships for Pseudomonas aeruginosa (R2=-1.02, P<0.001), Klebsiella pneumonia (R2=-2.99, P<0.001) Staphylococcus aureus (R2=-0.53, P<0.001) and Bacillus subtilis (R2=-0.58, P<0.001). Similarly, the total flavonoid content also showed significant positive relationships with the antimicrobial activity in Pseudomonas aeruginosa (R2=-0.43, P<0.001), Klebsiella pneumonia (R2=-3.48, P<0.001), Staphylococcus aureus (R2=-0.75, P<0.001) and Bacillus subtilis (R2=-0.71, P<0.001). Of the total 25 extracts, the highest DPPH scavenging activity was recorded in acetone extract of majhauley cultivar (94.18%), the highest reductive capability in chloroform extract of charinangrey (OD 700 nm = 1.177) and highest H2O2 scavenging activity in methanol extract of bhaisay (70.99 %). All the extracts of Zingiber officinale showed strong antioxidant and antibacterial activity, which clearly suggests that ginger of Sikkim Himalaya can be used as natural antioxidant agents. Received 30 March, 2015;Accepted 21 March, 2016

Keywords: Zingiber officinale, DPPH, phenolics, antimicrobial, antioxidant, Sikkim Himalaya