A comparative study of triterpenes and sterols content in prunus Africana growing in different geographical zones in Tanzania

Prunus africana (Hook. f) Kalm.), is a medicinal tree found in an African continent. The stem bark of this species is the major source of anti Benign Prostatic Hyperplasia (BPH). This plant has been long used for the treatment of BPH, blood cholesterol, hypertension and blood pressure. The aim of this study was to determine and compare the triterpenes and sterols contents of P. africana collected from different geographical zones of Tanzania. Materials and methods: Extraction of plant materials was achieved through using maceration where by the weighed plant materials were soaked in methanol for 24 hours before being concentrated in vacuo using a rotary evaporator. The phytochemical screening of extracts was done to determine the types of secondary metabolites present in each collection. β - sitosterol (sterol), ursolic acid (triterpenes) and n-docosanol (standard reagents) were used as markers to determine their presence in P. africana leaves and stem barks extracts using a High Performance Thin Layer Chromatography (HPTLC) Camag machine, whereby stock solutions of standard reagents were prepared in sepearte flasks then diluted in different concentrations for calibration purposes to determine the their amounts in leaf and stem bark extracts. Chromatography was performed on Silica gel 60 F254 TLC plates with chloroform: methanol 70:30 (v/v) as mobile phase. Densitometry analysis was done at λ=254 nm after derivatization with vanillin-10% (v/v) sulphuric acid alcohol reagent. Results and discussion: The present experiment demonstrates a simple, rapid, precise and sensitive HPTLC protocol for qualitative and quantitative determination of (sterols) β -sitosterol, triterpenes (ursolic acid) contents in P. africana from different ecological zones. The calibration curves for area versus concentrations were found to be linear in the range of 500 – 7500 ng/spot. Good linearity (R2>0.905) was observed throughout the range of 500 - 7500 ng in 1 ml dichloromethane for β-sitosterol, (R2>0.971) throughout the range of 1000 - 7500 ng in 1ml dichloromethane for standard ursolic acid and (R2>0.986) observed throughout the range of 1000 – 7500 ng in 1 ml chloroform for n-docosanol. Results demonstrated that both in the leaf and stem bark samples β - sitosterol was present at RF 0.67, ursolic acid at RF 0.12 and normal docosanol at RF 0.10. TLC analysis showed positive results for the extracts from Suji T-2, Monduli T-2 and Rombo T-2 which revealed that they are not P. africana, they are Olinia rochetiana from the family Oliniaceae. Conclusion and recommendations: This investigation found that sterols, triterpenes and ferulic esters were in both stem barks and leaves of P. africana. Therefore, for the management of BPH, and for the sake of sustainable utilization of P. africana, leaves should further be investigated as an alternative to stem barks. The research should also be done on other parts of P. africana to observe if they can be used in BPH management. O. rochetiana should also be researched if it can be used in the treatment of BPH