Acute Toxicity and Anxiolytic Activity Screening of Hydroalcoholic Leaf Extracts of Bryophyllum pinnatum, Terminalia catappa and Tapinanthus dodoneifolius Growing on Terminalia catappa Tree in MIce

Abstract

Aims: Hydroalcoholic T. dodoneifolius, B.pinnatum and T. catappa leaf extracts were investigated for their acute toxicity and anxiolytic activities. Study Design: Acute toxicity (LD50) was determined using the limit dose acute and Anxiolytic activities were assessed by open-field field behavioural testing in mice. Place and Duration of Study: The study took place in the Neurobehavioural room of Department of Pharmacology & Therapeutics, Faculty of Pharmacy, Ahmadu Bello University, Zaria in late December 2022. Methodology: Groups of mice (n=6; equal sexes) were each exposed to the open-field paradigm (OFT) following 1 hour of single oral administration of distilled water, extracts (125, 250, and 500 mg/kg) and diazepam (0. 5 mg/kg) using the behavioural indices of mean centre zone time (M%CZT), centre zone re-entry (MCZR) and defeaction/urination frequency (MD/UF). Results: Acute toxicity testing shows that the three extracts are safe with LD50 of 5g/kg. Behavioural results indicate, compared to the distilled water treatment (M%CZT, 6.39±1.53; MCZR, 4.67±1.15, & MU/UF, 4.83±0.75), single acute T. dodoneifolius (M%CZT, 7.50±1.73, 13.72±2.43, & 20.94±3.91*; MCZR, 7.33±0.88, 9.50±0.76, & 11.50±1.6*; MD/UF, 4.17±0.48, 3.17±0.54, & 1.83±0.60*), and B.pinnatum (M%CZT, 9.72±1.91, 9.78±1.32, & 19.67±2.01*; MCZR, 6.00±1.15, 10.50±0.76, & 12.50±1.72*; MD/UF, 3.17±0.79, 2.33±0.42, & 1.33±0.49*) extract treatments demonstrated consistent dose-dependency in their anxiolytic activity across the three parameters with T. catappa extract (M%CZT, 6.95±1.27, 12.17±2.01, & 16.84±1.49*; MCZR, 8.17±1.60, 10.17±1.67, & 10.83±1.96; MD/UF, 2.83±0.60, 2.00±0.73, & 3.67±0.42) exhibiting dose-pendent anxiolytic effect only on the M%CZT. However, at the highest dose level of 500 mg/kg, all plant extract treatments caused anxiolytic effects that are comparable with those of 0.5 mg/kg diazepam treatments (M%CZT, 22.61±1.31*; MCZR, 12.17±1.66*; & MD/UF, 2.62±0.21*). Conclusion: These findings justify the traditional use of these medicinal plant extracts in the remediation of nervous and related disorders.

Evaluation of the Neurobehavioural Toxicity Potential of Aqueous Ethanol Extracts of Leaf/Seed of Datura metel, Mucuna pruriens, and Tapinanthus globiferus Growing on Azadirachta indica Host Tree in Mice

“…These findings may the first indicating that MPS extracts may not have cns depressant effect even though several studies have shown its extracts to possess anxiolytic activity [61,62]. This study may be the second report on extracts of Tapinanthus globiferus (TG) not exhibiting negative locomotory effect [13] in mice despite their reported anxiolytic activity [9,10]. The fact that extracts of these medicinal plants have been reported to exert significant anxiolytic activity with no significant sedative effect that may impact locomotion may suggest that the anxiolytic pharmacophores in these plants may be acting on a neural pathway quite distinct from the benzodiazepine GABAergic mechanism(s).…”

“…Previously, crude aqueous methanol and fractionated leaf extracts of Tapinanthus globiferus on Azadirachta indica host tree have demonstrated anxiolytic activity comparable to that of diazepam [9][10]. Although the benzodiazepines, the prototype of which is diazepam, are regarded as gold standard in anxiolytic efficacy, their clinical usefulness is limited by such neurobehavioural adverse effects comprising cognitive, locomotor, sedative, hypnotic and abuse liabilities [11,12].…”

“…It is thus necessary to evaluate potential anxiolytic agents for their liability for these toxicities. Scientific literature on neurobehavioural toxicities associated with Tapinanthus globiferus extracts is however sparse, apart from the report of Umarudeen and Magaji et al [9] on its aqueous methanol leaf extract [13]. Thus, there is a need for further scrutiny of this aspect of the medicinal plant.…”