Preliminary Screening of Philippine Seaweeds for In-vitro Antituberculosis Activity and Cytotoxicity

Abstract

In response to the need for novel nontoxic therapeutics to combat tuberculosis (TB), the in-vitro antituberculosis activity and cytotoxicity of 15 Philippine seaweeds were examined. A colorimetric, microplate-based Alamar Blue Assay (MABA) was used to determine the minimum inhibitory concentrations (MICs) of the crude methanol. hexane and dichloromethane (DCM) extracts for Mycobacterium tuberculosis Hi;Ra. Cytotoxicity was evaluated using the Brine Shrimp Assay. Hydroclathratus clathratus, Gracilaria coronopifolia, Halymenia durvillaei and Turbinaria decurrens (MIC < 50 pg/ml), as well as Valonia aegagropila and Padina australis (50 ug/ml < MIC < 500 pg/ml) in hexane were active against M. tuberculosis. DCM extracts of Galaxaura oblongata, Dictyota sp., Titanophora weberae, Valonia aegagropila, Hydroclathratus clathratus, Gracilaria coronopifolia, Halymenia durvillaei, Caulerpa serrulata, Caulerpa racemosa, Padina australis, Turbinaria decurrens and Halimeda macroloba also inhibited the growth of Hj;Ra (MIC < 50 pg/ml). In contrast, hexane extracts of Caulerpa sertularoides, Galaxaura oblongata, Boodlea compositae, Dictyota sp.. Sargassum crassifolium, Titanophora weberae, Caulerpa serrulata, Caulerpa racemosa and Halimeda macroloba, DCM extracts of Caulerpa sertularoides and Boodlea Compositae, and all methanol extracts exhibited poor antituberculosis activity (MIC > 500 pg/ml). Of the 12 seaweeds active against Hj3;Ra, only T. weberae, C. serrulata. C. racemosa and H. macroloba in DCM and G. coronopifolia in hexane were not lethal (LCso > 1000 pg/ml) to Artemia salina. These seaweeds thereby contain potential antituberculosis substances with low cytotoxicity.