tests of chondriol (4) and cycloeudesmol (3) ... described previously (3-5, 8, 9). .... Int. Seaweed Symp. Pergamon Press, New York. 3. Fenical, W., and J. J. Sims.
ANTIMICPROBIAL AGENTS AND CHEMOTHERAPY, Mar. 1975, p. 320-321 Copyright 0 1975 American Society for Microbiology
Vol. 7. No. 3
Printed in U.S.A.
Antimicrobial Agents from Marine Algae JAMES J. SIMS, MARK S. DONNELL, JOHN V. LEARY,* AND GEORGE H. LACY Department of Plant Pathology, University of California, Riverside, California 92502
Received for publication 16 December 1974
The antimicrobial activity of five compounds extracted from marine algae was tested against Staphylococcus aureus, Salmonella choleraesuis, Mycobacterium smegmatis, Candida albicans, and Escherichia coli. Three of the compounds, cycloeudesmol, laurinterol, and debromolaurinterol, exhibited activity at concentrations approaching that of streptomycin. None of the compounds inhibited all of the organisms tested. There appeared to be selectivity for gram-positive microbes. this period was interpreted as inhibition. Control plates of tryptic soy agar not containing the algal compounds were streaked with each of the test organisms and scored along with the test plates. In all cases, visible growth was observed after 48 h.
There have been a number of reports of antibiotic activity from marine algae (1, 2, 7, 10). For the most part, these reports represented preliminary studies of crude extracts and little follow-up work has been done to isolate the substance(s) responsible for the activity. We have been examining the secondary metabolites from a number of such algae and have found compounds with potent antimicrobial activity. Described here are the results of preliminary tests of chondriol (4) and cycloeudesmol (3) from Chondria oppositiclada, pre-pacifenol (9) from Laurencia filiformis, and laurinterol and debromolaurinterol from Laurencia pacifica (5, 8).
RESULTS AND DISCUSSION Each of the five compounds was tested at varying concentrations to determine that concentration at which growth was completely inhibited when assayed 48 h after inoculation (Table 1). In each test, streptomycin sulfate was included for comparison. The most active compound of the five tested was laurinterol, which gave complete inhibition of S. aureus and M. smegmatis at concentrations comparable to those of streptomycin. The five compounds tested exhibited an interesting selectivity since primary activity was against gram-positive organisms. Only one compound, cycloeudesmol, significantly inhibited a gram-negative bacterium. The greater activity of debromolaurinterol compared with laurinterol against C. albicans ATCC 10321 is noteworthy since the bromine
MATERIALS AND METHODS Compounds. Five natural products from marine algae were tested; the structures are given in Fig. 1. The methods for extraction, purification, and structural determination of these compounds have been described previously (3-5, 8, 9). The desired amounts of the compounds were dissolved in 1:1 dimethyl sulfoxide and ethanol added to 10 ml of melted agar to give a constant concentration of 0.04 ml of solvent per ml of agar. Control plates contained the same concentration of solvent. Organisms. The American Type Culture Collection names and numbers of the organisms used in these studies are as follows: Staphylococcus aureus, 6538 and 12600; Salmonella choleraesuis, 13312; Mycobacterium smegmatis, 14468; Candida albicans, 10231; and Escherichia coli, 11775. A second isolate of C. albicans, CA-5, was obtained from Frank E. Swatek at California State University, Long Beach. Screening methods. The procedure was adapted from that of Mitscher et al. (6) as follows. Compounds to be tested were mixed well with 10 ml of sterile liquid tryptic soy agar and poured into petri plates. The test organisms were streaked on the surface of the agar. These organisms had been grown previously for 48 h in tryptic soy broth at 36 C. The plates were then incubated at 36 C for 48 h, and lack of growth after
CI
HO0
OH
BrII 2
OH
O
Oi R= Br 5 R= H
Br
CI
FIG. 1. Structures of five algal natural products. (1) Chondriol; (2) cycloeudesmol; (3) pre-pacifenol; (4) laurinterol; (5) debromolaurinterol. 320
ANTIMICROBIAL AGENTS FROM MARINE ALGAE
VOL. 7, 1975
321
TABLE 1. Antimicrobial activity of the algal natural products Concn (Ag/ml) for complete inhibition after 48 h Compound
6538
Chondriol
Pre-pacifenol Laurinterol .1-5 10-30 Debromolaurinterol Cycloeudesmol Streptomycin sulfate
M. smegmatis
10-100 10-100 1-5
> 1,000 > 1,000 > 1,000
10-30
> 1,000
10-100 10-100 1-5 10-50
10-50 1-10
50-100 10-20
10-50 < 10
12600
atom was not required for antibiosis. However, when retested with CA-5, it was found that both compounds were equally active. The differential susceptibility of ATCC 10321 may have been a character of that isolate. The study of natural products, especially from terrestrial plants, has long been the source of pharmaceuticals. The studies reported here extend earlier studies to compounds for which the structures are known. 1. 2. 3.
4.
C. albicans
Salmonella cholraeuis choleraesuts
Staphylococcus aureus
LITERATURE CITED Baslow, M. H. 1969. Marine pharmacology. The Williams & Wilkins Co., Baltimore. Chisters, C. G. C., and J. A. Stott. 1956. The production of antibiotic substances by seaweeds, p. 49. In Proc. 2nd Int. Seaweed Symp. Pergamon Press, New York. Fenical, W., and J. J. Sims. 1974. Cycloeudesmol, an antibiotic cyclopropane containing sesquiterpene from the marine alga, Chondria oppositiclada Dawson. Tetrahedron Lett. p. 1137-1140. Fenical, W., J. Sims. and P. Radlick. 1973. Chondriol, a
5.
6.
7. 8.
9.
10.
10231
CA-5
> 1,000 > 1,000
10-100 10-50 10-50 < 100
E. coli
10-30 10-30
> 1,000 > 1,000 > 1,000
> 1,000 > 1,000 < 10
halogenated acetylene from the marine alga Chondria oppositiclada. Tetrahedron Lett. p. 313-316. Irie, T., M. Suzuki. E. Kurosawa, and T. Masamune. 1966. Laurinterol and debromolaurinterol, constituents from Laurencia intermedia. Tetrahedron Lett. p. 1837-1840. Mitscher, L. A., R. Leu, M. S. Bathala. W. Wu, and J. L. Beal. 1972. Antimicrobial agents from higher plants. I. Introduction, rational, and methodology. Lloydia 35: 157-166. Pratt, R., R. H. Mautner, S. M. Gardner, Y. Sha, and J. Dufrendy. 1951. Report on antibiotic activity of seaweed extracts. J. Am. Pharm. Assoc. 40:575-579. Sims, J. J., W. Fenical, R. M. Wing, and P. Radlick. 1971. Marine natural products. I. Pacifenol, a rare sesquiterpene containing bromine and chlorine from the red alga, Laurencia pacifica. J. Am. Chem. Soc. 93:3774-3775. Sims, J. J., W. Fenical, R. M. Wing, and P. Radlick. 1973. Marine natural products. IV. Prepacifenol, a halogenated epoxy sesquiterpene and precursor to pacifenol from the red alga, Laurencia filiformis. J. Am. Chem. Soc. 95:972. Welch, A. M. 1962. Preliminary survey of fungistatic properties of marine algae. J. Bacteriol. 83:97-99.
