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1.  Antagonistic effect of alkaloids and saponins on bioactivity in the quinine tree (Rauvolfia caffra sond.): further evidence to support biotechnology in traditional medicinal plants 
Background
The Quinine tree (Rauvolfia caffra) is used as a medicinal plant among traditional communities in many countries to manage tumors and other diseases associated with oxidative stress. To validate indigenous knowledge and possibly position this herb for technology uptake and utilization, we established the level of antioxidant activity in R. caffra, and probed for the presence of associated phytochemicals.
Methods
Antioxidant activity was determined on 1,1-diphenyl-2-picrylhydrazyl (DPPH) while major phytochemicals were identified by multiple tests on methanol fractions.
Results
R. caffra showed promise as a cure, with antioxidant activity comparable to the commercially used drug quercetin (R. caffra = 79.7% ±1.9; quercetin = 82.6% ± 2.0). However, we found two phytochemicals with possible antagonistic effect: co-occurrence of alkaloids and saponins significantly reduced antioxidant activity (alkaloids only = 63%; alkaloids plus saponins = 15%; steroids, terpenoids and cardiac glycosides = 82%), thus alkaloids and saponins should be exclusive to each other in drug formulations.
Conclusions
Antagonistic relationship among phytochemicals would affect the efficacy of crude extracts as used in traditional medicine. Unlike in herbal medicine, use of modern biotechnology in extraction, purification and design of optimal combinations will ensure efficient drug formulations with optimum bioactivity and minimum toxicity. Metabolic pathway engineering under a controlled environment may optimize availability of desired compounds.
doi:10.1186/1472-6882-13-285
PMCID: PMC3816308  PMID: 24160735
Rauvolfia caffra; Antioxidant; Alkaloid; Quinine tree
2.  C868T Single Nucleotide Polymorphism and HIV Type 1 Disease Progression Among Postpartum Women in Kenya 
Abstract
The C868T single nucleotide polymorphism in the CD4 receptor encodes an amino acid substitution of tryptophan for arginine in the third domain. Previous studies suggest that C868T increases the risk of HIV-1 acquisition; however, the influence of this single nucleotide polymorphism (SNP) on disease progression has not been established. The presence of the C868T polymorphism was not statistically significantly associated with HIV-1 disease progression outcomes in a cohort of postpartum Kenyan women.
doi:10.1089/aid.2011.0095
PMCID: PMC3358105  PMID: 21902583
3.  Human Leukocyte Antigen (HLA) B*18 and Protection against Mother-to-Child HIV Type 1 Transmission 
Human leukocyte antigen (HLA) molecules regulate the cellular immune system and may be determinants of infant susceptibility to human immunodeficiency virus type 1 (HIV-1) infection. Molecular HLA typing for class I alleles was performed on infants followed in a Kenyan perinatal cohort. Early HIV-1 infection status was defined as infection occurring at birth or month 1, while late infection via breast milk was defined as first detection of HIV-1 after 1 month of age. Likelihood ratio tests based on a proportional hazards model adjusting for maternal CD4 T cell count and HIV-1 viral load at 32 weeks of gestation were used to test associations between infant allelic variation and incident HIV-1 infection. Among 433 infants, 76 (18%) were HIV-1 infected during 12 months of follow-up. HLA B*18 was associated with a significantly lower risk of early HIV-1 transmission [relative risk (RR) = 0.26; 95% confidence interval (CI) 0.04–0.82], and none of the 24 breastfeeding infants expressing HLA B*18 who were uninfected at month 1 acquired HIV-1 late via breast milk. We observed a trend toward increased early HIV-1 acquisition for infants presenting HLA A*29 (RR = 2.0; 95% CI 1.0–3.8) and increased late HIV-1 acquisition via breast milk for both Cw*07 and Cw*08 (RR = 4.0; 95% CI 1.0–17.8 and RR = 7.2; 95% CI 1.2–37.3, respectively). HLA B*18 may protect breast-feeding infants against both early and late HIV-1 acquisition, a finding that could have implications for the design and monitoring of HIV-1 vaccines targeting cellular immune responses against HIV-1.
doi:10.1089/0889222041524616
PMCID: PMC3380108  PMID: 15307911
4.  CD8+ lymphocytes respond to different HIV epitopes in seronegative and infected subjects 
Journal of Clinical Investigation  2001;107(10):1303-1310.
HIV-1–specific cytotoxic T-lymphocyte (CTL) responses have been detected at a low frequency in many HIV-1–exposed, persistently seronegative (HEPS) subjects. However, it is unclear how CTLs could protect against HIV acquisition in HEPS subjects, when high levels of circulating CTL fail to prevent disease progression in most seropositive subjects. To address this issue we studied CD8+ lymphocyte responses to a panel of HIV-1 CTL epitopes in 91 HEPS and 87 HIV-1–infected Nairobi sex workers. HIV-specific responses in seropositive women focused strongly on epitopes rarely or never recognized in HEPS subjects, who targeted epitopes that were subdominant or unrecognized in infected women. These differences in epitope specificity were restricted by only those HLA class I alleles that are associated with a reduced risk of HIV-1 infection in this cohort. Late seroconversion in HEPS donors was associated with a switch in epitope specificity and/or immunodominance to those epitopes preferentially recognized by HIV-1–infected women. The likelihood of detecting HIV-1–specific responses in HEPS women increased with the duration of viral exposure, suggesting that HIV-1–specific CD8+ responses are acquired over time. The association between differential recognition of distinct CTL epitopes and protection from HIV-1 infection may have significant implications for vaccine design.
PMCID: PMC209302  PMID: 11375420

Results 1-4 (4)