| dc.description.abstract | Withania somnifera (L.) Dunal know as Ashwagandha belong to Solanaceae family. It is an
annual herb growing in dry and arid soil as a wild plant. It is extensively used in most of the
Indian herbal pharmaceuticals and nutraceuticals. It is widely cultivated in India and throughout
the Middle East and is also found in eastern Africa. In Kenya, it grows wildly and is widely
spread especially in drier areas.
The plant is well described in Ayurveda, the ancient Indian system of plant medicine for
immunomodulation and anti-aging effect. The plant root is used as an anti-inflammatory, antitumor,
anti-aging, anti-Alzheimer‟s disease, anti-stress, anti-oxidant, for mind or memory
boosting, immunostimulant, as an aphrodisiac and for rejuvenation, as neuroleptic, for reducing
blood sugar and cholesterol levels and as a diuretic.
Most of the beneficial ph
In this study, the plant was collected from different areas in Kenya where it is known to grow
naturally. The powdered dry root, stem and leave materials of the plant were subjected to solvent
extraction using composition of methanol-water (60:40).
Quantitative determination of withaferin-A in the samples was carried out using RP-HPLC
performed isocratically with acetonitrile/ water (75:25) as the mobile phase. The column
temperature was kept at 27 oC, flow rate and sample volume were set to 1.0 ml/min and 20 µl,
respectively. All separations were monitored at 225 nm. Stability studies and efficiency of
extraction of withaferin-A were also carried out.
Results and Discussion
The analysis of Withania somnifera root, stem and leaf confirmed the presence of withaferin-A
in all parts of the plant but with significant differences in content. Withaferin-A content was
highest in the leaves, with an average of 0.95 %w/w; the highest percentage recorded in a single
leaf sample being 1.69 % w/w. This compound was lowest in stems, with an average of 0.29
%w/w, the highest content recorded in a single stem sample being 0.49 % w/w. The average
withaferin-A content in the roots was 0.51 %w/w, with the highest content recorded in a single
root sample being 0.77 %w/w. Two imported market products RT8 and RTA9 formulated from
Withania somnifera root were analyzed. The percentage contents of withaferin-A in RTA8 and
RTA9 were 0.16 % w/w in each. The Kenyan Withania somnifera plant collected from Limuru
in Kiambu county showed the highest percentage withaferin-A content in the roots and stems,
contents being 0.77 %w/w and 0.49 %w/w respectively, while the withaferin-A content in the
leaves of the same plant collected in Limuru was the second highest (1.64 %w/w). Leaf samples
collected from Narok town and environs in Narok county contained the highest withaferin-A
content (1.69 %w/w).
Conclusion and Recommendation
From the results of this research, the Kenyan Withania somnifera root appears had higher content
of the pharmacologically active compound withaferin-A than the imported root formulations of
the plant. The Kenyan plant also has more withaferin-A in the leaves than other parts.
Kenyan Withania somnifera could be endangered due to over use of the roots, whilst herbal
pharmaceutical products derived from Withania somnifera leaves and stems products could offer
useful alternatives to the Withania somnifera root products. Thus, Withania somnifera leaves and
stems products merit further investigation.
Further studies should also be carried out to determine the effects of agro-ecological and pest
infestation on the active compounds in Withania somnifera. | en_US |
| dc.description.department | a
Department of Psychiatry, University of Nairobi, ; bDepartment of Mental Health, School of Medicine,
Moi University, Eldoret, Kenya | |
