Alfred Chanda, Angela Gono-Bwalya and Lavina Prashar

Background: Pregnant women in Chongwe, Zambia, traditionally use the root of Azanza garckeana (F.Hffm.) Exell & Hillc (Malvalceae) to induce or accelerate labour. A previous study on the plant showed that the crude root extracts possess uterotonic potential on isolated Wistar rat uterine smooth muscles. In addition, the methanol crude root extract was the most potent extract.

Aim: The study aimed to isolate by Bioactivity-guided fractionation method the compound with the significant uterotonic activity in the root of Azanza garckeana.

Materials and Methods: This was a laboratory-based study designed using the uterus isolated from adult non-gravid female virgin albino Wistar rats estrogenised with 0.2 mg/kg Diethylstilbestrol. The fresh plant materials (leaves and roots) were collected from Chongwe district. The methanol crude extract was prepared by continuous maceration, was concentrated to powder, and reconstituted with water. The crude extract was then partitioned with Hexane, Chloroform, Ethyl acetate, and n-butanol in the increasing order of polarity, respectively. Fractionation of the most active fraction was performed with column chromatography.

The uterine smooth muscle strips isolated from estrogenised adult non-gravid female virgin albino Wistar rats were attached to the signal transducer connected to the power lab (A.D. Instruments, UK) and computer installed with Lab tutor software. Non-cumulative doubling concentrations of fractions and sub-fractions from the Azanza garckeana Methanol crude extract were added one at a time to the De Jalon's physiological solution in the organ bath where the uterine smooth muscle strips were suspended. Each sample was allowed to act for 10 minutes, and the amplitude of contraction was measured. One-way ANOVA, Bonferroni post hoc tests were used to analyze data using STATA version 13. Bar charts and dose-response curves were designed using Graphpad Prism version 5.00 for Windows (San Diego, California U.S.A.).

Results: The final aqueous suspension demonstrated the highest uterotonic potency (EC₅₀ = 2.49 x 10^-3 mg/ml; 95% CI 1.19 x 10^-3 to 5.23 x 10^-3 mg/ml, p=0.0001), while sub-fraction pool number 2 (sub-fractions number 41 to 61) demonstrated the highest uterotonic potency (EC₅₀ at 2.05 x 10^-3 mg/ml; 95% CI 2.09 x 10^-3 to 3.85 x 10^-3 mg/ml, p=0.0001). Sub-fraction pool number 2 demonstrated highest uterotonic activity, and the compound was suggested to be related to the family of glycosides after High Performance Liquid Chromatography (HPLC) and Fourier Transform Infrared Spectroscopy (FTIR) analysis.

Conclusions: The study suggests the presence of a significant uterotonic phytochemical constituent in the methanol root crude extract of Azanza garckeana, which may be related to the family of glycosides. The study has provided scientific evidence suggesting the root of Azanza garckeana, a plant used traditionally for inducing or accelerating labor, possesses uterotonic activity. Further pharmacological and toxicological studies need to be undertaken on the plant.

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