Beneficial effect of standardized extracts of Amorphophallus paeoniifolius tuber and its active constituents on experimental constipation in rats

Abstract

The tubers of Amorphophallus paeoniifolius (Elephant foot yam), principally consumed as crop food and vegetables, are used in ethno-medicinal practices in mitigation of constipation and piles. Hence, present study evaluated the effect of tubers of A. paeoniifolius and its active constituents glucomannan and betulinic acid on experimentally-induced constipation. The tuber and its extracts were standardized as per Ayurvedic Pharmacopoeia of India and physicochemical constants were found within the pharmacopoeial limit. HPTLC fingerprint profile of extracts has been developed using suitable mobile phase. Methanolic extract was subjected to column chromatography. The isolated phytoconstituents were characterized by FT-IR, NMR and MS and identified as betulinic acid and β-sitosterol. Functional constipation was induced in rats by oral administration of loperamide (3 mg/kg) for first 3 consecutive days. The rats were orally treated with methanolic and aqueous tuber extracts in the doses of 125, 250 and 500 mg/kg, glucomannan (300 mg/kg) and betulinic acid (1.5 mg/kg) for 7 days. The parameters viz. number of stools, wet weight of stools and moisture content of stools and intestinal transit were studied. Treatment with tuber extracts, glucomannan and betulinic acid showed significant (p < 0.05) increase in fecal parameters and intestinal transit in constipated rats. The effects were comparable to standard laxative drug, sodium picosulfate (5 mg/kg, orally). The results indicated that tuber extracts and its active constituents showed laxative effect and relieved constipation. It is concluded that tuber of A. paeoniifolius exhibited beneficial effect in functional constipation possibly through its laxative action. The study validates its ethno-medicinal use in correction of constipation. The principal constituents, betulinic acid and glucomannan in tuber extracts might have played important role in relieving the constipation.

Keywords: Betulinic acid; Constipation; Food science; Glucomannan; HPTLC; Loperamide; Pharmaceutical science; Rats.

Figure 1

HPTLC chromatogram of Amorphophallus paeoniifolius tuber. (A) At UV 254 nm (B) At UV 366 nm (C) After derivatization. Track 1 (10 μg) and 2 (20 μg) of methanolic extract; Track 3 (10 μg) and 4 (10 μg) of aqueous extract. (For full non adjustable images, please refer Fig. S1 in supplementary material).

Figure 2

HPTLC densitogram of Amorphophallus paeoniifolius tuber. (A) Methanol extract (B) Aqueous extract (For full non adjustable images, please refer Fig. S2 and S3 in supplementary material).

Figure 3

Mass spectrum of isolated compound 1. Mass spectrum of compound 1 showed m/z- 397.4948, m+ = 497.5575, (448.5262, 414.5113, 413.4786, 383.4654).

Figure 4

Mass spectrum of isolated compound 2. Mass spectrum of compound 2 showed m/z–439.4729, m+ = 474.5029, (441.4919, 411.4768, 3983.4573, 425.4936).

Figure 5

¹H NMR spectrum of isolated compound 1.

Figure 6

¹H NMR spectrum of isolated compound 2.

Figure 7

¹³C NMR spectrum of isolated compound 1.

Figure 8

¹³C NMR spectrum of isolated compound 2.

Figure 9

Effect on fecal parameters (A) Number of stool (B) Weight of wet stools (C) Moisture content. Results are expressed as mean ± SEM (N = 6) ∗p < 0.001 compared to NC; $p < 0.05, @p < 0.01, #p < 0.001 compared to CVC. [NC-Normal control, CVC-Constipated vehicle control, SPS- sodium picosulfate, Methanolic (APME) and aqueous (APAE) extract of Amorphophallus paeoniifolius]. Doses are expressed as mg/kg.

Figure 10

Effect on intestinal transit. Results are expressed as mean ± SEM (N = 6) ∗p < 0.001 compared to NC; $p < 0.05, @p < 0.01, #p < 0.001 compared to constipated vehicle control (CVC). [NC-Normal control, CVC-Constipated vehicle control, SPS- sodium picosulfate, Methanolic (APME) and aqueous (APAE) extract of Amorphophallus paeoniifolius]. Doses are expressed as mg/kg.