Anti-plaque activity of Piper betle leaf extracts

Leaves of Piper betle L. (Piperaceae) have been shown to possess antimicrobial, gastroprotective, wound healing, hepatoprotective and antioxidant properties [1]. The antimicrobial activity of betel leaves relevant in oral care lead to the investigation of its anti-plaque activity. Five varieties of Piper betle leaves (Banarasi, Calcutta, Desi, Maghai and Puna) were subjected to successive extractions at room temperature with various solvents (hexane, diethyl ether, ethyl acetate, ethanol, hydro-ethanol and water). Two varieties (Banarasi and Calcutta) were selected on the basis of their in vitro activities. Of the extracts, hexane extract was found to be active. Banarasi and Calcutta leaves were also subjected to super critical extraction and steam distillation. TLC was carried on hexane extracts of all varieties, super critical extracts and steam distillation of Banarasi and Calcutta. A solvent system was developed and plates were derivatized with Vanillin sulphuric acid. Since eugenol is present in all varieties this compound was used as marker compound. Anti-plaque activity was evaluated using a microbial assay (Agar Streak Plate method). Leaf extracts were tested for antimicrobial activity against Streptococcus mutans, Streptococcus sobrinus, and Actinomyces viscosus (early colonizers of dental plaque) [2]. Antimicrobial activity of Piper betle leaf extracts are summarized in the table below.

Table 1: Antimicrobial activity of Piper betle – Direct extracts

		Observed MIC (µg/ml)
Extract	Diluent	S. mutans	S. sanguis	A. viscosus
Hexane (Banarasi)	Ethyl acetate	50	75	50
Hexane (Banarasi)	Methanol + Tween-20	>125	>125	>125
Hexane (Calcutta)	Ethyl acetate	100	500	500
Hexane (Maghai)	Ethyl Acetate	50	300	>600
Hexane (Pune)	Ethyl acetate	200	>500	>500
Hexane (Desi)	Ethyl Acetate	200	>500	>500
Di ethyl ether (Calcutta)	Ethyl acetate	100	400	>500
Di ethyl ether (Pune)	Ethyl acetate	250	500	1000
Ethanol (Maghai)	DMSO	>1000	>1000	>1000

Antimicrobial activity was observed for the hexane extract of Piper betle leaves (Banarasi) and could be attributed to the presence of allypyrocatechol [3] obtained in the chromatographic data of these extracts.

References: 1. Arambewala L.S.R et al. (2005), Journal of Ethnopharmacology, 102:239–245.

2. Svensäter G et al. Caries Research, 2003; 37,395.

3. Ramji N. et al. (2002) Journal of Ethnopharmacology, 83: 149–152.