Chromatographic exploration of methanol extract derived from Saussurea lappa roots yielded four sesquiterpene lactones, santamarin (1), dehydrocostuslactone (2), costunolide (3) and zaluzanin C (4) along with the well-known triterpene, beta-sitosterol (5). Chemical structures were determined based on extensive 1D/2D NMR analyses. In antiviral assay, compounds 1-5 showed antiviral activity ranging from 2.18 +/- 3.1 to 53.7 +/- 10.05 and from 15.39 +/- 4.83 to 92.91 +/- 2.47 when tested against hepatitis A virus (HAV) and Herpes simplex virus type 1 (HSV-1), respectively. Molecular docking simulation studies against (HSV-1) DNA polymerase and (HAV) 3 C proteinase enzymes showed similar binding interactions as for acyclovir. Compounds (1 and 3-5) showed moderate to potent antibacterial activity against Bacillus subtilis ATCC 6633 (MIC values between 7.9 and 31.25 mu g/ml) whereas, dehydrocostuslactone (2) and costunolide (3) exhibited comparable antibacterial activities against Pseudomonas aeruginosa ATCC 90274 (MIC values=125 mu g/ml) compared to gentamicin as a positive control. In cytotoxicity assay against human colorectal carcinoma (HCT-116) and human epithelioid cervical carcinoma (HeLa), compounds 1 and 4 exhibited weak to moderate activities. Compound 1 showed IC50 values of 46.05 mu g/ml (185.44 mu M) and 59.38 mu g/ml (239.1153 mu M) whereas compound 4 showed IC50 values of 36.08 mu g/ml (146.48 mu M) and 46.59 mu g/ml (189.175 mu M), respectively.
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