- Streblus asper Lour. (Shakhotaka): A Review of its Chemical, Pharmacological and Ethnomedicinal Properties
Several workers have reported the different biological activities of S. asper in various in vitro and in vivo test models. Different parts of this plant have been found to exhibit cardiotonic, antifilarial, anticancer, antimicrobial, anti-allergic and antimalarial activities. These have been described in greater detail in the following.
The effect of aqueous and alcoholic extract of S. asper was also studied on the spontaneous movements of the whole worm and nerve-muscle preparation of Setaria cervi, the bovine filarial parasite, and on the survival of microfilariae in vitro. Aqueous as well as alcoholic extract caused inhibition of spontaneous motility of the whole worm and the nerve-muscle preparation of S. cervi characterized by decreased tone, amplitude and rate of contractions. The concentration required to inhibit the movements of the nerve-muscle preparation was l/25 for aqueous and l/160 for alcoholic extract suggesting a cuticular permeability barrrier. The stimulatory response of acetylcholine was blocked by alcoholic and not by aqueous extract of S. asper. Both alcoholic as well as aqueous extracts caused death of microfilariae in vitro, LC50 and LC90 being 90 and 33.5 ng ml−1, respectively (33). The in vitro effects of asperoside and strebloside on S. cervi females were also studied. Both asperoside and strebloside caused death of the worms within 2–3 h at concentrations of 10 g ml−1 (1.7 pmol) and were found to inhibit motility and glucose uptake of the parasites at lower concentrations (0.1 g ml−1; 0.17 pmol). These glycosides also inhibited the incorporation of [U-14] C-glucose into macromolecules of S. cervi females. Parasites preincubated with either asperoside and strebloside had lowered profiles of glucokinase (EC 126.96.36.199), malate dehydrogenase (EC 188.8.131.52) and succinate dehydrogenase (EC 184.108.40.206) activities, suggesting that the lethal effects of the glycosides were owing to effects on glucose metabolism (34). It was found that asperoside and strebloside interfere with the glutathione metabolism of the adult S. cervi, which cause disturbance in various vital activities of the parasites that ultimately results in the death of the parasites (35).
A preliminary study of S. asper (shakhotak) as an antilymphoedematous agent was carried out by Baranwal et al. (36).
The volatile oil from fresh leaves of S. asper showed significant anticancer activity (ED50 ≪ 30 µg ml−1) from cytotoxicity primary screening tests with P388 (mouse lymphocytic leukemia) cells but no significant antioxidant activity (IC50 values ≫ 100 µg ml−1) in a DPPH radical scavenging assay (28).
In vitro study was carried out to determine the effects of a sublethal concentration of S. asper leaf ethanolic extract on adherence of C. albicans to human buccal epithelial cells (HBEC). The findings indicated that the sublethal concentration of this extract may modulate candidal colonization of the oral mucosa thereby suppressing the invasive potential of the pathogen (40). An in vivo one group time series design and single blind study was carried out to determine the antimicrobial effectiveness of a mouthrinse containing S. asper leaf extract on S. mutans and total salivary bacteria following single 60 s rinse. The results concluded that the mouthrinse containing S. asper leaf extract can reduce S. mutans without changing an oral ecology (41). Streblus asper extract solution at 0.5% concentration (w/v) was investigated for inhibitory effect on adherence of S. mutans on glass surfaces. However, it did not show significant inhibitory effect on bacterial adherence to glass surfaces (42). A single blind and crossover design study was also carried out to study the effect of the mouthrinse containing S. asper leaf extract on gingivitis and plaque formation (43). The results revealed that when used in mouthrinse the S. asper leaf extract significantly effected only the gingival health. It reduced the gingival index but no significant effect was seen on plaque growth.
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