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The present investigation entitled “Ethnopharmacology and technology
standardisation for quality retention of anti-diabetic phyto resources” was carried out in
the Department of Plantation Crops and Spices, College of Agriculture, Vellayani
during the period 2019-2021 to identify the potential anti-diabetic medicinal plants used
by Kuruma tribes in Wayanad district and standardise the drying and extraction
techniques for retention of anti-diabetic activity. Analysis of phytochemical
composition as well as pharmacological activity of crude drugs was also envisaged in
the study.
An ethnobotanical and ethnopharmacological survey conducted in Kuruma
tribes of seven different tribal settlements from Sulthan Bathery taluk of Wayanad
district viz; Choyimoola, Kayappura, Kottanod, Mathamangalam, Oorankunnu,
Pilakkavu and Valluvadi recorded 31 different phytoresources and its 47 indigenous
anti-diabetic remedies. Among them the most effective and frequently used antidiabetic phytoresources are Butea monosperma (Lam.) Taub. Leaves, Cassia fistula L.
flowers, Coscinium fenestratum (Goetgh.) Coleb. stem, Desmodium gangeticum
(L.)DC. stem, Pterocarpus marsupium Roxb. bark, Saraca asoka Roxb. Willd. Flowers,
Simarouba glauca DC. leaves, Syzygium cumini L. Skeels. seeds, Terminalia arjuna
(Roxb.) Wight & Arn. Bark and Tinospora cordifolia (Willd.) Miers. stem.
Macerated acetone extracts of T. arjuna (Roxb.) Wight &Arn. bark (71.36%),
P. marsupium Roxb. bark (70.66%), S. cumini L. Skeels. seeds (56.9%), S. asoka Roxb.
Willd. flowers (50.36%), D. gangeticum (L.)DC. stem (36.53%) through conventional
drying method (sun drying) showed superior in vitro anti-diabetic activity (alpha
amylase enzyme inhibition) hence selected for further drying protocol development
study.
The crude drugs were subjected to five different drying methods viz., shade
drying, sun drying, drying in cabinet drier at 50ºC, 60ºC and 70ºC and two extraction
techniques viz., soxhlet extraction and maceration. The prepared crude drug acetone
extracts were analysed for physical and phytochemical quality parameters.
Acetone extracts of all crude drugs contain alkaloids, cardiac glycosides,
flavonoids, phenols and saponins. Phytosterols was absent. T. arjuna bark acetone
extract prepared through drying the crude drug in cabinet drier at 60°C (17.00 h) and
extracted through soxhlet extraction (24.20 h) recorded higher quantity of total
alkaloids, cardiac glycosides, total flavonoids, total phenols and total saponins, 70.02
μg AE mg-1
, 11.05 μg DE mg-1
, 52.67 μg QE mg-1
, 310.36 μg GAE mg-1
and 77.72 μg
DE mg-1
. P. marsupium Roxb. bark acetone extract prepared through drying the crude
drug in cabinet drier at 70°C (21.00h) and extracted through soxhlet extraction (22.30h)
recorded significantly higher quantity of cardiac glycosides and total phenols, 11.54 μg
DE mg-1
190.29μg GAE mg-1
. S. cumini seed acetone extract prepared through drying
the crude drug in cabinet drier at 50°C (15.00 h) and extracted through maceration
extraction (47.78 h) recorded higher quantity of total alkaloids, cardiac glycosides and
total phenols, 77.75 μg AE mg-1
, 11.49 μg DE mg-1
, and 142.82 μg GAE mg-1
. S. asoca
Roxb. Willd. flowers acetone extract prepared through drying the crude drug under
shade (102.10h) and extracted through maceration extraction (47.60h) recorded higher
quantity of total alkaloids, cardiac glycosides and total phenols, 65.95 μg AE mg-1
,
11.03 μg DE mg-1
, and 145.62 μg GAE mg-1
. D. gangeticum (L.)DC. stem acetone
extract prepared through drying the crude drug in cabinet drier at 60°C (12.05h) and
extracted through maceration extraction (20.36 h) recorded significantly higher quantity
of cardiac glycosides, total flavonoids and total saponins, 11.67 μg DE mg-1
, 53.53 μg
QE mg-1
and 39.06 μg DE mg-1
. The crude drug extracts prepared through standardised
protocol were subjected to in vitro pharmacological studies.
T. arjuna (Roxb.) Wight & Arn. bark acetone extract prepared by drying the
crude drug in cabinet drier at 60°C and extracted through soxhlet extraction recorded
significantly highest in vitro anti-oxidant activity (72.62% DPPH radical scavenging
activity) as well as in vitro anti-diabetic activity (73.21% alpha amylase enzyme
inhibition).
This study revealed that acetone extracts of crude drugs prepared using
standardised protocols could retain 1.85% (Terminalia arjuna (Roxb.) Wight &Arn.
bark), 1.83% (Pterocarpus marsupium Roxb. bark), 2.40% (Syzygium cumini L. Skeels.
seed), 2.61% (Saraca asoka Roxb. Willd. flowers) and 2.22% (Desmodium gangeticum
(L.)DC. stem) more in vitro anti-diabetic activity than the conventionally dried ones.