A comparative study in rodents of standardized extracts of Bacopa monniera and Ginkgo biloba Anticholinesterase and cognitive enhancing activities Amitava Das a , Girja Shanker a , Chandishwar Nath a , Raghwendra Pal b , Satyawan Singh b , Hemant K. Singh a, * a Division of Pharmacology, Central Drug Research Institute, P.O. Box 173, Lucknow 226 001, India b Division of Pharmaceutics, Central Drug Research Institute, P.O. Box 173, Lucknow 226 001, India Received 14 August 2001; received in revised form 14 February 2002; accepted 26 June 2002 Abstract Bacopa monniera and Ginkgo biloba are well-known cognitive enhancers in Indian and Chinese traditional medicine systems. Standardized extracts of B. monniera and G. biloba were used to evaluate the antidementic and anticholinesterase activities in adult male Swiss mice. Antidementic activity was tested against scopolamine (3 mg/kg ip)-induced deficits in passive avoidance test. Three different extracts of B. monniera (30 mg/kg) and extract of G. biloba (15, 30 and 60 mg/kg) were administered postoperatively, daily for 7 days and 60 min after the last dose, i.e., on Day 7, first trial was conducted. In passive avoidance test, increased transfer latency time (TLT) and no transfer response (NTR) were taken as criteria for learning. TLT and NTR were significantly increased and decreased in second trial, 24 h after the first trial in control group and scopolamine-dementia group, respectively. The B. monniera- and G. biloba-treated groups produced significant increase in TLT and NTR on second trial (40 –80%) after scopolamine treatment, thus, attenuating its antidementic effect. Both the extracts showed a dose (10 – 1000 mg)-dependent inhibitory effect on acetylcholinesterase (AChE) activity (in vitro), performed spectrophotometri- cally. IC 50 of G. biloba was 268.33 mg, whereas none of the extracts of B. monniera showed more than 50% inhibition. At a dose concentration of 30 and 60 mg/kg, extracts of G. biloba showed a cognitive enhancing property and, at the same time, a significant decrease in AChE-specific activity in both per se and scopolamine-dementia groups. These extracts possess a significant anticholinesterase and antidementic properties, which may be useful in the treatment of dementia. D 2002 Elsevier Science Inc. All rights reserved. Keywords: Bacopa monniera; Ginkgo biloba; Cognition; Dementia; Acetylcholinesterase 1. Introduction Bacopa monniera (Linn) Pennel [Syn: Bacopa monniera Wettst; Gratiola monniera (Linn); Herpestis monniera (Linn) Hb and K; Moniera cuncifolia Michx] (Family: Scrophulariaceae) is a perennial creeper found throughout India in wet, damp and marshy areas (Chopra et al., 1956). An infusion of the plant has been used in Indian folklore as a nerve tonic (Chunekar, 1960). In the ancient Indian system of medicine, viz., Ayurved, B. monniera has been classified under medicinal plants rejuvenating intellect and memory. Therefore, this plant has been investigated in several laboratories in India for its various neuropharmacological effects (Malhotra and Das, 1959; Aithal and Sirsi, 1961; Prakash and Sirsi, 1962). The chemistry of the extracts of plant B. monniera was investigated in detail in our institute. The ethanolic extract was found to be a mixture of triterpenoids saponins des- ignated as bacosides A and B (Chatterjee et al., 1963, 1965). Bacoside A comprised of a mixture of three saponins viz., Bacogenin A 1 ,A 2 and A 3 , with A 3 being the major constituent (Kulshreshtha and Rastogi, 1973, 1974; Chandel et al., 1977). Its traditional memory-enhancing claim was established only when we reported the cognitive enhancing property of the alcoholic extract of B. monniera in several 0091-3057/02/$ – see front matter D 2002 Elsevier Science Inc. All rights reserved. PII:S0091-3057(02)00940-1 * Corresponding author. Tel.: +91-522-212411x4391; fax: +91-522- 223405. E-mail addresses: amitavadascdri@rediffmail.com (A. Das), saritahemant@yahoo.co.in (H.K. Singh). www.elsevier.com/locate/pharmbiochembeh Pharmacology, Biochemistry and Behavior 73 (2002) 893–900