Effect of the plant matrix on the uptake of luteolin derivatives-containing Artemisia afra aqueous-extract in Caco-2 cells.

AIM OF THE STUDY: Luteolin is a major flavonoid constituent and a primary candidate that might contribute to the claimed in vivo protective effects of Artemisia afra (Jacq. Ex. Willd). However, an exhaustive search yielded no literature evidence on the absorption, metabolism and fate of this flavonoid from the traditional plant preparation. The purpose of this study was to investigate the effect of the plant matrix on the uptake of luteolin derivatives from Artemisia afra aqueous extract in human intestinal epithelial Caco-2 cells. MATERIALS AND METHODS: Cell monolayers were incubated with 5, 10 and 20 microg/ml doses of luteolin aglycone, luteolin-7-0-glucoside, un-hydrolyzed or acid-hydrolyzed Artemisia afra extracts, and samples of 150 microl each were collected from both apical and basolateral sides of cells at 30, 60 and 120 min for HPLC and LC-MS analyses. RESULTS: After 1-h exposure, the uptake of luteolin aglycone and luteolin-7-0-glucoside from the un-hydrolyzed and acid-hydrolyzed extracts was significantly faster and quantitatively higher (i.e. >77% vs. <25% of the initial doses over the first 30 min, p<0.05) than that from non-plant solutions. Apical to basolateral permeability coefficients for luteolin and its-7-0-glucoside in the extracts were 1.6- to 2-fold higher than that for the non-plant solutions. Glucuronidation was an important pathway of metabolism for luteolin in both non-plant and plant extract forms. CONCLUSIONS: Luteolin in Artemisia afra aqueous extract, regardless of its form (i.e. whether aglycone and 7-0-glucoside), is taken up better and more efficiently metabolized than the aglycone and 7-0-glucoside forms administered as pure solutions in Caco-2 cells. Flavonoid actives from Artemisia afra plant extracts and especially traditionally prepared dosage forms may thus have better bioavailability, and consequently greater in vivo potency, than that predicted from studies done using the pure solutions.

Acute and sub-chronic oral toxicity profiles of the aqueous extract of Polygala fruticosa in female mice and rats.

Polygala fruticosa (P.J. Bergius) is one of the most popular medicinal plants in South Africa but to date there is no documented evidence corroborating its safety. This study thus aimed to determine the toxicity profile of the aqueous extract of Polygala fruticosa by determining its effects after acute and sub-chronic oral administration in female mice and rats, respectively. In adult mice, single oral administrations of the aqueous extract of Polygala fruticosa (2-20 g/kg body weight) induced an increase in the incidence of general behavioural adverse effects. The mortality rate also increases with increasing dosage (LD(50)=10.8 g/kg). In rats, daily single oral doses of Polygala fruticosa aqueous extract (0.1 and 1g/kg) were well tolerated behaviourally after 31 days of dosing (LD(50) much higher than 1g/kg) and induced no significant changes in body and organs weights. However, haematological and biochemical parameters showed a significant decrease in platelet count and significant increases in ALT, AST and creatinine levels suggesting disturbances of haemopoiesis, liver and kidney functions. Overall, the findings of this study indicate that Polygala fruticosa is non-toxic and has, at low dose, a low toxicity potential in acute and chronic oral administrations, respectively. However, at high chronic oral doses, Polygala fruticosa has significant anti-haemopoietic, hepatotoxic and nephrotoxic activities.

Efficacy of Artemisia afra phytotherapy in experimental tuberculosis.

Artemisia afra [Jacq] (Asteraceae) phytotherapy is widely used for its medicinal properties in traditional practices. In this study we investigated whether extracts of A. afra are capable of controlling mycobacterial replication. For Mycobacterium aurum cultured in the presence of aqueous-, methanol- and dichloromethane (DCM) extracts of A. afra we found that bacterial replication was inhibited by the dichloromethane extract only. Activity of the DCM extract was confirmed in dose-dependent studies against both M. aurum and M. tuberculosis with an IC(50) =270 microg/ml and IC(50) = 290microg/ml, respectively. Fractionation of the DCM extract and evaluation of its efficacy in vitro found that most of the antimycobacterial activity was associated with isolate fraction C8 that contained several sesquiterpene lactones, the most prominent of which are Artemin and Arsubin. Evaluation of the bactericidal efficacy in vitro showed that isolate fraction C8 reduced replication of M. aurum and M. tuberculosis in a dose-dependent manner with IC(50) =1.9 microg/ml and IC(50) = 2.0 microg/ml, respectively, and an MIC = 10 microg/ml. Further, isolate fraction C8 and the DCM extract was administered to M. tuberculosis-infected mice at a tolerated dose of 1000 microg/kg for up to 26 weeks and mycobacterial burdens compared to untreated-, INH/RIF treated- and aqueous-extract-treated animals to assess its bactericidal activity in vivo. Bacterial replication remained unaffected during treatment with either isolate fraction C8 or the DCM extract resulting in pulmonary and splenic bacilli burdens comparable to that of untreated mice. In contrast, INH/RIF treatment cleared M. tuberculosis infection after only 8 weeks to undetectable levels. Interestingly, treatment of M. tuberculosis-infected mice with aqueous extract of A. afra regulated pulmonary inflammation during early infection notwithstanding its inability to inhibit mycobacterial growth. This study clearly demonstrates that A. afra contains in vitro anti-mycobacterial activity, modulates pulmonary inflammation in early mycobacterial infection, and that the mouse experimental tuberculosis model may serve as a useful assay for evaluating the utility of phytotherapy.