The increasing use of complementary and alternative medicine (CAM) has kindled the need for scientific evaluation of the mechanism of action of CAMs. Although, licorice, a common ingredient in many Traditional Chinese medicine (TCM) has attracted great attention for its antitumor and immunomodulatory activities, the mechanism of action of its polysaccharides is still unclear. Here we report the immunomodulatory activity of licorice polysaccharides in vivo. The differential anticancer activities of licorice polysaccharides by tumorigenesis and immunomodulation was evaluated in vivo. Six weeks old, 120 CT-26 tumor bearing BALB/c mice, weighing 20 ± 2 g were used. They were randomly divided into six groups, three groups receiving high molecular weight (fraction A), low molecular weight (fraction B) polysaccharides and crude extract (fraction C); positive, negative and normal groups receiving cytoxin, saline and normal diet respectively. Weight of mice and tumors was determined and tumorigenicity assay calculated to determine the anticancer effects. Immunomodulatory potential was determined by immune organ indices, immune cell population and serum cytokine levels using immune organ weight and index, flow cytometry and cytokine/chemokine bead panel kit respectively. Licorice polysaccharides exhibited immunomodulatory activities in CT 26 tumor bearing BALB/c mice. The polysaccharides significantly suppressed tumor growth and increased immune organ index. Furthermore, the immunomodulatory effect was evident with activation of CD4+ and CD8+ immune cells population. The polysaccharides also affected the production of various cytokines, by increasing IL 2, IL 6, IL 7 levels and a decreasing TNFα levels. In summary, licorice polysaccharide especially of low molecular weight exhibit anticancer and immunomodulatory activities by suppressing tumor growth and improving general health of mice. They also augment the thymus/spleen index and population of T lymphocytes. Furthermore, the polysaccharides enhance the levels of serum antitumor cytokines, IL 2, IL 6 and IL 7 while decreasing pro-tumor cytokine TNFα.

Withania somnifera, Warbugia ugandensis, Prunus africana and Plectrunthus barbatus are used traditionally in Kenya for treatment of microbial infections and cancer. Information on their use is available, but scientific data on their bioactivity, safety and mechanisms of action is still scanty. A study was conducted on the effect of organic extracts of these plants on both bacterial and fungal strains, and their mechanisms of action. Extracts were evaluated through the disc diffusion assay. Bacteria and yeast test strains were cultured on Mueller-Hinton agar and on Sabouraud dextrose agar for the filamentous fungi. A 0.5 McFarland standard suspension was prepared. Sterile paper discs 6 mm in diameter impregnated with 10 µl of the test extract (100 mg/ml) were aseptically placed onto the surface of the inoculated media. Chloramphenicol (30 µg) and fluconazole (25 µg) were used as standards. Discs impregnated with dissolution medium were used as controls. Activity of the extracts was expressed according to zone of inhibition diameter. MIC was determined at 0.78–100 mg/ml. Safety studies were carried using Cell Counting Kit 8 cell proliferation assay protocol. To evaluate extracts mechanisms of action, IEC-6 cells and RT-PCR technique was employed in vitro to evaluate Interleukin 7 cytokine. Investigated plants extracts have both bactericidal and fungicidal activity. W. ugandensis is cytotoxic at IC 50 200 µg/ml). Fractions from W. ugandensis and W. somnifera too demonstrated antimicrobial activity. Mechanisms of action can largely be attributed to cytotoxicity, Gene silencing and immunopotentiation. Use of medicinal plants in traditional medicine has been justified and possible mechanisms of action demonstrated. Studies to isolate and characterize the bioactive constituents continue.

Background: Medicinal plants have been used in the treatment of various ailments in most developing countries. Oral infections are the most prevalent diseases in man. The Rhus family has been found to have antimicrobial, antimalarial, and anti-inflammatory properties. Few studies have been done onRhus vulgarisMeikle. A study was conducted to determine the effect ofRhus vulgarisMeikle stem bark extracts against selected oral pathogenic microorganisms and the safety of the extracts in vitro and in vivo.Methods: Methanol:dichloromethane (1:1), methanol and aqueous extracts were tested for bacteriostatic and bactericidal effects against Methicillin ResistantStaphylococcus aureus(MRSA),Staphylococcus aureus, Streptococcus mutansandCandida albicans. Cytotoxicity of the active extracts was determined using Vero E6 cell lines while safety was evaluated in mice and rats. Phytochemical screening was performed on the methanol extracts. One-way ANOVA and Tukey’s multiple comparisons tests were performed using IBM SPSS statistics 20.0 for antimicrobial assay and acute toxicity testing. One-way ANOVA and Dunnett’s multiple comparison tests were conducted using GraphPad Prism 8.0 for cytotoxicity assay.Results: Methanol extract ofRhus vulgarisshowed significant antimicrobial activity against MRSA (12.00 ± 0.00 mm;p-value of < 0.005; Minimum Inhibitory Concentration of 0.391 mg/ml; Minimum Bactericidal Concentration of 1.563 mg/ml). The extract were not cytotoxic at 100 μg/ml which was the highest tested concentration. In acute dermal irritation testing, the methanol extract resulted in mild irritation with erythema and flaking that cleared within 8 days. There were no observable adverse effects from oral administration of the extracts (acute oral toxicity testing) at concentrations of 50 mg/kg, 300 mg/kg and 2000 mg/kg. Tannins, saponins, flavonoids, terpenoids, glycosides, alkaloids and phenols were detected in the methanol extract.Conclusions: Antimicrobial activity ofR. vulgarisextracts supports its traditional use as a toothbrush. Cytotoxicity demonstrated by the extracts as well as the mild skin irritation warrants further study beforeR. vulgariscan be recommended for the development of effective and safe mouthwashes.

Globally, approximately 13% of all deaths annually are attributed to cancer. Surgery, radiation and chemotherapy are the current treatment techniques for cancer, however these methods are expensive, have high failure rates and have been associated with detrimental side effects. Plant derived products could be good candidates in alleviating challenges being experienced with these current methods. This study aimed at evaluating the phytochemistry, antiproliferation potential, and probable mechanism of action of Albizia gummifera , Rhamnus staddo and Senna didymobotrya plant extracts. Phytochemical screening was done as per standard procedures. The common 3– (4, 5-dimethylthiazol-2-yl) -2, 5-diphenyltetrazolium (MTT) dye was used in the determination of the antiproliferative activity of the extracts. Extracts induction of VEGF (angiogenesis) and p53 (apoptosis) genes’ expression was evaluated using Real Time Polymerase Chain Reaction. Phytochemical screening revealed presence of alkaloids, tannins, glycosides, flavonoids, terpenes, phenolics and saponins in the plants extracts. A. gummifera’s stem bark methanol: dichloromethane extract had the highest activity against the cancerous cell lines tested: HCC1395 (IC ₅₀ 6.07±0.04μg/ml), DU145 (IC ₅₀ 3.34±0.05μg/ml), CT26 (IC ₅₀ 5.78±0.08μg/ml) and Hep2 (IC ₅₀ 7.02±0.01μg/ml). R. staddo root bark methanol: dichloromethane extract had an IC ₅₀ value of 15.71±0.04μg/ml on HCC, 9.81±0.09μg/ml on Hep2 and 11.14±0.39μg/ml on CT26. S. didymobotrya root bark methanol: dichloromethane extract inhibited HCC with an IC ₅₀ of 65.06±0.07μg/ml, CT26 with an IC ₅₀ of 15.71±0.04μg/ml and Hep2 with an IC ₅₀ of 62.10±0.11μg/ml. From the results obtained, the plants exhibited selective toxicity to cancer cells while sparing the normal cells (SI ≥ 3). A. gummifera and S. didymobotrya and R. staddo plant extracts upregulated p53 and down-regulated VEGF genes. In conclusion, this study confirms that these plant extracts could be potential candidates for development of drugs for the management of breast, prostrate, colorectal and throat cancer.