Page 143 - journal-7-2-S-Full

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PP-25

Bioactive Polysaccharides from Selected Thai Mucilaginous Plants

1 1,2
Chanida Palanuvej , Nijsiri Ruangrungsi
1
College of Public Health Sciences, Chulalongkorn University, Bangkok 10330, Thailand
2
Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand

Rationale: Plant mucilages have been used in traditional or folk medicines for treatment of many dis-
eases. The mucilages are heterogeneous polysaccharides which exhibit hydrocolloid property. The utilizations
of nutritional hydrocolloids are increasing due to their functional properties e.g. water binding, viscosity and
gelation, as well as to their bio-active roles in prevention and / or treatment of certain diseases.
Objective: To investigate the biological activities of selected mucilage polysaccharides.
Methodology: Seven mucilaginous plants were studied as follow: seeds of Ocimum canum Sims. (Labiatae),
seeds of Plantago ovata Forssk. (Plantaginaceae), seeds of Trigonella foenum-graecum Linn. (Papilionaceae),
leaves of Litsea glutinosa (Lour.) C.B. Robinson (Lauraceae), fruits of Hibiscus esculentus Linn. (Malvaceae),
aerial parts of Basella alba Linn. (Basellaceae) and fruits of Scaphium scaphigerum G. Don. (Sterculiaceae). The
mucilages were extracted with warm water and lyophilized to dryness. Glucomannan was used as reference
hydrocolloid polysaccharide. The biological activities were studied in vitro prior to animal models. The activity
for entrapping glucose was studied by dialysis. The releasing glucose was assayed by glucose oxidase method.
Alpha-glucosidase inhibitory activity which delayed carbohydrate digestion was spectrophotometrically as-
sayed using p-nitrophenyl-α-D-glucopyranoside as a substrate. The effect on cholesterol solubility was per-
formed using bile salt micelle model (sodium taurodeoxycholate). The soluble cholesterol was determined by
enzymatic colorimetric assay. The potential antioxidant activity was tested on the basis of the scavenging
activity of the stable diphenylpicrylhydrazyl (DPPH) free radical.
Results: All mucilage showed concentration response on glucose entrapment activity. Percentage of
glucose released from 2 % mucilage suspension were 61.6, 70.8, 71.7, 80.6, 83.4, 85.8 and 92.8 % for O. canum,
P. ovata, T. foenum-graecum, L. glutinosa, H. esculentus, B. alba and S. scaphigerum respectively. Glucomannan
powder showed 65.4 % of glucose releasing at the same concentration. For enzyme alpha-glucosidase inhibition
assay, 5 mg/ml of S. scaphigerum was shown as the best inhibitor with 82.6 % inhibition whilst deoxynojirimycin
(standard inhibitor), L. glutinosa, H. esculentus, O. canum, T. foenum-graecum, P. ovata, B. alba and glucomannan
were shown as 47.6, 41.0, 37.6, 32.8, 30.6, 27.0, 25.0 and 19.7 % inhibition respectively. At 25 mM of sodium
taurodeoxycholate, the soluble cholesterol concentration was 1.56 ± 0.04 mM. With hydrocolloid polysaccharides
in the system, the soluble cholesterol concentration ranged from 1.53 to 1.18 mM. O. canum, T. foenum-
graecum and glucomannan showed inhibition on cholesterol solubility (24.3, 21.3 and 16.0 % inhibition respec-
tively). L. glutinosa, S. scaphigerum, B. alba, H. esculentus and P. ovata had marginal effect on cholesterol
solubility (8.0, 6.4, 4.3, 4.2 and 1.8 % inhibition respectively). The IC values in DPPH scavenger were 0.49, 0.61,
50
0.70, 1.52, 2.00 and 4.15 mg / ml for L. glutinosa, S. scaphigerum, H. esculentus, T. foenum-graecum, B. alba and
glucomannan respectively. O. canum and P. ovata showed the least potential of DPPH scavenger (IC > 10 mg
50
/ ml).
Conclusion: The results revealed some biological activities among selected plant mucilaginous polysac-
charides. The outcome is the scientific evidence of the potential to develop nutritional hydrocolloids from plant
mucilages.