PhD Thesis
Synadenium glaucescens is a traditional medicinal plant used in Tanzania for
management of various infections and diseases affecting animals including human. The diseases treated include HIV, TB and East Coast fever among others. Despite the
recorded traditional utilization, limited scientific information exists regarding its
biological and phytochemical importance. This current study, therefore aimed at
investigating its toxicological, pharmacological and phytochemical properties.
Toxicological studies involved the assessment of dermal toxicities using guidelines
stipulated in the Organization for Economic Cooperation and Development (OECD).
Acaricidal activity was evaluated using Larval and Adult immersion tests as described by
Drummond. In pharmacological assays, an in vitro HIV-1 reverse transcriptase (RT) was
used for screening of anti-HIV activity using a Roche HIV kit while chromatographic and
spectroscopic techniques were used in phytochemical studies.
Irritation indices from dermal toxicity studies ranged between 3.2 and 0.05. According to
Draize, these indices range are considered as mild to moderate irritancy since none of
them could reach Primary Irritation Index (PII) of 5 or above which is classified as
irritant. On the other hand, acute dermal toxicity tests showed no overt signs of toxicity.
Similarly the extracts did not produce any sensitization reaction. Acaricidal studies
showed low larvicidal (corrected mortality 37.5%) and adulticidal (corrected mortality
33.33%, LC50 666.91) activities respectively for methanol and ethanol extracts from
leaves. Other extracts of this plant were inactive in these tests.
Anti HIV tests indicated aqueous root and leaves together with dichloromethane extracts
from roots to have high activities with IC50 values of 3.96 µg/mL, 6.04 µg/mL and 11.43 µg/mL respectively. Ethyl acetate and methanol extracts showed low effectiveness in the
inhibition of HIV-1 RT as indicated by their very high values of IC50 relative to positive
control. From the phytochemical studies, four compounds namely euphol and
erythrinacinate C from the root barks and ß-sitosterol and octacosanol from the leaves
were isolated. All compounds have been reported from other plant species but are isolated
from this plant species for the first time.
The findings showed that dried extracts are dermally safe while possessing potential anti HIV activities. The extracts also shows to possess diversity of compounds that could be
responsible for anti HIV activities. Further investigations are however, recommended for
this plant species especially on anti HIV activities and phytochemistry for discovery of
drug leads.
AFFNET, COSTECH and NRF