naphthoquinones and Streptococcal-Infections

Streptococcus agalactiae, also known as Group B Streptococcus (GBS), can infect humans, terrestrial animals and fish. The emergence of bacterial resistance of S. agalactiae to antibiotics leads to an urgent need of exploration of new antimicrobial agents. In the study, the antibacterial activity of natural component plumbagin (PLB) against S. agalactiae was investigated in vitro and in vivo. The results showed that the minimal inhibitory concentration (MIC) of PLB against S. agalactiae was 8 mg/L. The growth curve assay revealed that PLB could inhibit the growth of S. agalactiae. In addition, the time-killing curve showed that S. agalactiae was killed almost completely by 2-fold MIC of PLB within 12 h. Transmission electron microscopy results showed obvious severe morphological destruction and abnormal cells of S. agalactiae after treated with PLB. The pathogenicity of S. agalactiae to zebrafish was significantly decreased after preincubation with PLB for 2 h in vitro, further indicating the bactericidal activity of PLB. Interestingly, PLB could kill S. agalactiae without inducing resistance development. Furthermore, pretreatment and post-treatment assays suggested that PLB also exhibited the antibacterial activity against S. agalactiae infection in vivo by effectively reducing the bacterial load and improving the survival rate of S. agalactiae-infected zebrafish. In summary, PLB had potent antibacterial activity against S. agalactiae in vitro and in vivo, and it could be an excellent antimicrobial candidate to prevent and control S. agalactiae infection.

Topics: Animals; Anti-Bacterial Agents; Fish Diseases; Naphthoquinones; Streptococcal Infections; Streptococcus agalactiae; Zebrafish

New semi-naphthaquinone antibiotics A80915A, B, C, and D were isolated from the fermented broth of Streptomyces aculeolatus A80915 (NRRL 18422). Factors A and C, present in both the broth filtrate and mycelial methanol extract, and factors B and D, found predominantly in the broth filtrate, were recovered by extraction with ethyl acetate. Purification of the individual factors was accomplished by preparative reverse phase high performance liquid chromatograph on C18 bonded silica supports. Factors A through D show antimicrobial activity against Gram-positive aerobic and anaerobic organisms in vitro. Mechanism of action studies demonstrated nearly complete inhibition of macromolecular biosynthesis (protein, RNA, DNA, and cell wall) by A80915 factors A through D. A less highly cyclized semi-naphthaquinone, A80915 factor G, was isolated from the broth of the strain fermented in an alternate medium.

Topics: Animals; Anti-Bacterial Agents; Bacteria; Bacterial Proteins; Chromatography, High Pressure Liquid; DNA, Bacterial; Fermentation; Mice; Microscopy, Electron, Scanning; Molecular Structure; Naphthoquinones; RNA, Bacterial; Soil Microbiology; Staphylococcal Infections; Streptococcal Infections; Streptomyces

Hereditary polymorphic light eruption (HPLE) occurs in Indians of North and South America. Affected persons are sensitive to long ultraviolet radiation and therefore receive no substantial benefit from conventional sunscreens. We have treated 46 patients with HPLE at the Red Lake Reservation, Minn, with topically administered dihydroxyacetone and lawsone, orally given beta carotene, or both. Oral beta carotene afforded adequate photoprotection to 33 patients, and four additional patients were protected with the combined use of oral and topical agents. Epidemiologic studies support our proposals that HPLE is a causative factor in streptococcal pyoderma in the American Indian and may be associated with epidemics of streptococcal glomerulonephritis.

Topics: Adolescent; Adult; Aged; Carotenoids; Child; Child, Preschool; Coloring Agents; Dihydroxyacetone; Female; Glomerulonephritis; Humans; Indians, North American; Indians, South American; Male; Middle Aged; Naphthoquinones; Photosensitivity Disorders; Pyoderma; Streptococcal Infections