Inhibitory effects of sword bean extract on alveolar bone resorption induced in rats by Porphyromonas gingivalis infection.
BACKGROUND
The domesticated legume, Canavalia gladiata (commonly called the sword bean), is known to contain canavanine. The fruit is used in Chinese and Japanese herbal medicine for treating the discharge of pus, but its pharmacological mechanisms are still unclear.


OBJECTIVE
This study examined the effect of sword bean extract (SBE) on (i) oral bacteria and human oral epithelial cells in vitro, and (ii) the initiation and progression of experimental Porphyromonas gingivalis-induced alveolar bone resorption in rats.


METHODS
A high-performance liquid chromatography/ultraviolet method was applied to quantitate canavanine in SBE. By assessing oral bacterial growth, we estimated the minimum inhibitory concentration and minimum bactericidal concentration of SBE, canavanine, chlorhexidine gluconate (CHX) solution. The cytotoxicity of SBE, canavanine, CHX, leupeptin and cystatin for KB cells was determined using a trypan blue assay. The effects of SBE, canavanine, leupeptin and cystatin on Arg-gingipain (Rgp) and Lys-gingipain (Kgp) were evaluated by colorimetric assay using synthetic substrates. To examine its effects on P. gingivalis-associated periodontal tissue breakdown, SBE was orally administered to P. gingivalis-infected rats.


RESULTS
Sword bean extract contained 6.4% canavanine. SBE and canavanine inhibited the growth of P. gingivalis and Fusobacterium nucleatum. The cytotoxicity of SBE, canavanine and cystatin on KB cells was significantly lower than that of CHX. Inhibition of Rgp with SBE was comparable to that with leupeptin, a known Rgp inhibitor, and inhibition of Kgp with SBE was significantly higher than that with leupeptin at 500 μg/mL ( p < 0.05). P. gingivalis-induced alveolar bone resorption was significantly suppressed by administration of SBE, with bone levels remaining comparable to non-infected animals ( p < 0.05).


CONCLUSIONS
The present study suggests that SBE might be effective against P. gingivalis-associated alveolar bone resorption.
Division of Periodontology and Endodontology, Department of Oral Rehabilitation, School of Dentistry, Health Sciences University of Hokkaido, Hokkaido, Japan.
Y
Y
Nakatsuka
T
T
Nagasawa
Y
Y
Yumoto
F
F
Nakazawa
Y
Y
Furuichi
D018829:Adhesins, Bacterial / Q000187:drug effects; D016301:Alveolar Bone Loss / Q000382:microbiology / Q000517:prevention & control*; D000818:Animals; D016866:Bacteroidaceae Infections / Q000382:microbiology*; D032449:Canavalia / Q000737:chemistry; D002172:Canavanine / Q000032:analysis / Q000494:pharmacology / Q000633:toxicity; D002710:Chlorhexidine / Q000031:analogs & derivatives / Q000494:pharmacology / Q000633:toxicity; D002851:Chromatography, High Pressure Liquid; D015891:Cystatins / Q000494:pharmacology / Q000633:toxicity; D003546:Cysteine Endopeptidases / Q000187:drug effects; D018450:Disease Progression; D004847:Epithelial Cells / Q000187:drug effects; D000080867:Gingipain Cysteine Endopeptidases; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D006801:Humans; D007624:KB Cells; D007976:Leupeptins / Q000494:pharmacology / Q000633:toxicity; D008297:Male; D008826:Microbial Sensitivity Tests; D009061:Mouth Mucosa / Q000166:cytology / Q000187:drug effects; D008517:Phytotherapy / Q000379:methods*; D010936:Plant Extracts / Q000032:analysis / Q000627:therapeutic use*; D016966:Porphyromonas gingivalis / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D013047:Specific Pathogen-Free Organisms
D018829:Adhesins, Bacterial; D015891:Cystatins; D000080867:Gingipain Cysteine Endopeptidases; D007976:Leupeptins; D010936:Plant Extracts; D002172:Canavanine; D003546:Cysteine Endopeptidases; C032854:leupeptin; C010882:chlorhexidine gluconate; D002710:Chlorhexidine
Porphyromonas gingivalis; alveolar bone resorption; sword bean