Antimycobacterial Activity of the Red Alga Polysiphonia virgata.

Abstract

The red marine alga (Polysiphonia virgata. C. Agardh; Rhodomelaceae) was investigated for antimycobacterial activity. Bioassay-guided fractionation of the dichloromethane algal extract using direct bioautography resulted in isolation of a mixture of long-chain fatty acids, namely oleic acid, linoleic acid, lauric acid, and myristic acid as the major antimycobacterial compounds. Oleic acid showed the greatest inhibition of the growth of Mycobacterium smegmatis. with a minimum inhibitory quantity (MIQ) of 0.8 μ g; linoleic acid and lauric acid had MIQ values of 1.56 and 3.125 μ g, respectively. Stearic acid, palmitic acid, and myristic acid did not inhibit the growth of M. smegmatis.. Using the Bactec-460 radiometric method, oleic acid showed 100% inhibition of the growth of Mycobacterium tuberculosis. at a minimum inhibitory concentrations (MIC) of 25 μ g/mL; lauric acid, myristic acid, and linoleic acid all showed 100% inhibition at MIC values of 50 μ g/mL. Myristic acid and lauric acid showed 90% and 76% inhibition at 50 μ g/mL. Linoleic acid showed moderate inhibition of the growth of a clinical strain of multidrug-resistant M. tuberculosis. 50 μ g/mL.

Keywords:

• Antimycobacterial
• marine algae
• marine natural products
• Mycobacterium tuberculosis
• Polysiphonia virgata
• seaweeds
• tuberculosis