A Crystalline Antibacterial Substance from the Lichen Ramalina reticulata

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Abstract
On cold extraction with acetone or acetone-alcohol, the lichen R. reticulata, known as California Spanish moss, yields a yellow crystalline antibacterial substance, in the amt. of approx. 8 g. per 10 lbs. of lichen. The substance melts at 191-192[degree]C, has a mol. wt. of 312, an empirical formula of C16H14O6, contains one COOH group and no CH3O groups, and inhibits the growth of streptococci and pneumo-cocci but not of staphylococci or Gram-negative bacilli at a conc. of 50 y per ml. Human strains of tubercle bacilli (with one exception) are also inhibited at this or lower conc. but bovine and avian strains are more resistant. Guinea pigs can tolerate daily injns. of the purified substance in oil, of 10-20 mg. for 3 weeks without toxic symptoms. When given in the above dosages intraperit. to guinea pigs infected with human tubercle bacilli, the progress of the disease was retarded, as shown by wt. studies and necropsy findings.