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Antibacterial activity of polysaccharide gel extract from fruit rinds of Durio zibethinus Murr. against oral pathogenic bacteria.

AIM
The polysaccharide gel (PG) extract from durian fruit rinds (Durio zibethinus Murr. "Monthong") is a pectic polysaccharide with antibacterial activity. This study aimed to investigate the in vitro antibacterial activity of PG against oral pathogens, Streptococcus mutans (S.mutans) and Aggregatibacter actinomycetemcomitans (A.actinomycetemcomitans).


METHODS
  The inhibitory activity of PG at 50, 100, and 150 mg/mL against S.mutans (American Tissue Culture Collection 25175) and A. actinomycetemcomitans (American Tissue Culture Collection 43718) was determined after 1- and 5-min exposure by broth macrodilution susceptibility test and scanning electron microscopy. Normal saline or culture broth medium and 0.1% chlorhexidine were used as negative and positive controls, respectively.


RESULTS
  For 1-min exposure, 150 mg/mL PG or 0.1% chlorhexidine significantly possessed bactericidal activity against both tested bacteria (P=0.037), while PG at 100 mg/mL possessed significant bactericidal activity against S.mutans (P=0.037) and inhibitory activity against A.actinomycetemcomitans (P=0.05). Blebs, irregular-shaped cells, and disrupted cells were found in bacteria treated with either 0.1% chlorhexidine or 50-150mg/mL PG under scanning electron microscopy.


CONCLUSION
  The bactericidal activity of PG at 150 mg/mL against oral bacteria at 1-min exposure suggests its possibility to be used as a natural antibacterial ingredient in oral hygiene products.