Coupling SFE to uterotonic bioassay: an on-line approach to analysing medicinal plants

Review: Southern African medicinal plants used as blood purifiers

ETHNOPHARMALOGICAL RELEVANCE

Blood purification practices, also referred to as blood cleansing or detoxification, is an ancient concept which is widespread amongst African traditional medicine, but for which no modern scientific basis exists. There prevails considerable ambiguity in defining what a blood purifier is.

AIM OF THE STUDY

The purpose of this review is to firstly define what a blood purifier is in the context of African traditional medicine and compare to other cultural and westernized interpretations. Thereafter, this study identifies traditionally used medicinal plants used as blood purifiers in southern Africa and correlates these species to scientific studies, which may support evidence for these "blood purifying plant species".

MATERIALS AND METHODS

Ethnobotanical books and review articles were used to identify medicinal plants used for blood purification. Databases such as Scopus, ScienceDirect, PubMed and Google Scholar were used to source scientific articles. An evaluation was made to try correlate traditional use to scientific value of the plant species.

RESULTS

One hundred and fifty nine plant species have been documented as traditional remedies for blood purification. Most of the plant species have some pharmacological activity, however, very little link to the traditional use for blood purification. There has been some justification of the link between blood purification and the use as an antimicrobial and this has been explored in many of the plant species identified as blood purifiers. Other pharmacological studies specifically pertaining to the blood require further attention.

CONCLUSION

Irrespective of the ambiguity of interpretation, medicinal plants used to "cleanse the blood", play an important holistic role in traditional medicine and this review with recommendations for further study provides some value of exploring this theme in the future.

Pharmacophore-driven identification of PPARγ agonists from natural sources

In a search for more effective and safe anti-diabetic compounds, we developed a pharmacophore model based on partial agonists of PPARγ. The model was used for the virtual screening of the Chinese Natural Product Database (CNPD), a library of plant-derived natural products primarily used in folk medicine. From the resulting hits, we selected methyl oleanonate, a compound found, among others, in Pistacia lentiscus var. Chia oleoresin (Chios mastic gum). The acid of methyl oleanonate, oleanonic acid, was identified as a PPARγ agonist through bioassay-guided chromatographic fractionations of Chios mastic gum fractions, whereas some other sub-fractions exhibited also biological activity towards PPARγ. The results from the present work are two-fold: on the one hand we demonstrate that the pharmacophore model we developed is able to select novel ligand scaffolds that act as PPARγ agonists; while at the same time it manifests that natural products are highly relevant for use in virtual screening-based drug discovery.

The uterotonic activity of compounds isolated from the supercritical fluid extract of Ekebergia capensis

The wood of Ekebergia capensis Sparrm. is used by the local Zulu community in KwaZulu-Natal Province, South Africa to facilitate childbirth. In this investigation, the uterotonic properties of extracts from this tree were evaluated using both pregnant and non-pregnant guinea pig uterine smooth muscle in vitro. The extracts were prepared using water modified supercritical carbon dioxide at 400 atm and 80 degrees C. As samples of these extracts displayed positive results when screened for uterotonic activity, gravity column chromatography followed by NMR spectroscopy was performed in an attempt to isolate and elucidate the structures of the compounds that were present in the extract. The extract yielded five known compounds of which only two, viz. oleanonic acid and 3-epioleanolic acid, displayed uterotonic activity. Receptor binding assays were subsequently performed with 3-epioleanolic acid to ascertain its mode of action. Bradykinin (30 ng/100 microl) and acetylcholine (1 microg/100 microl) were used as the B2 and cholinergic receptor agonists respectively with icatibant (HOE 140) (30 ng/100 microl) and atropine (60 micro/100 microl) as their corresponding antagonists. 3-epioleanolic acid was observed to mediate its effect through the cholinergic receptor. The results of this study show that two compounds from the extract of this tree possess varying degrees of agonist activity on uterine smooth muscle with minor changes in the molecular structure affecting its intrinsic activity on uterine muscle.