The present invention relates to the preparation and use of a glycolipid fraction from Oscillatoria Planktothrix sp., for the treatment and/or prevention of bacterial gum diseases primarily caused by: Actinobacillum actinomycetemconcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola and even more preferably by Porphyromonas gingivalis. Said gum diseases, in particular gingivitis and periodontitis (pyorrhea), are primarily caused by a pro-inflammatory response to components of P. gingivalis, leading to destruction of periodontal tissue, and are often accompanied by osteoclastogenesis (increased number of osteoclasts responsible for destruction of bone tissue), and by chronic infection.