Anticancer and Antifolate Activities of Extracts of Six Saudi Arabian Wild Plants Used in Folk Medicine

Six indigenous folk medicinal plants growing wild in the area of Tabuk, Saudi Arabia which were selected for the study of their phytochemistry as well as their biological activities as antitumor and antifolate agents. Antitumor activities of methanol extracts of the six plants were measured in vitro using three human tumor cell lines （breast, lung and CNS cancers） while antifolate activities were assessed using commercial dihyrofolate reductase obtained from Sigma Co. Among the six plant extracts tested, the most remarkable were those of Caralluma sinaica and Fagonia tenuifolia. Caralluma extract showed strong antitumor activity （low GIso） against the three human tumor cell lines. Fagonia extract, on the other hand, was quite inhibitory to the growth of CNS cancer and breast cancer cell lines but much less so against lung cancer cells. Extracts of both Sonchus oleraceus and Caralluma sinaica were strongly inhibitory to DHFR. These results suggest that the mechanism of anticancer activity of Caralluma plant is through DHFR inhibition but that of Fagonia may follow a different path.

Prevalence of antifolate drug resistance markers in Plasmodium vivax in China

The dihydrofolate reductase(dhfr)and dihydropteroate synthetase(dhps)genes of Plasmodium vivax,as antifolate resistance-associated genes were used for drug resistance surveillance.A total of 375 P.vivax isolates collected from different geographical locations in China in 2009–2019 were used to sequence Pvdhfr and Pvdhps.The majority of the isolates harbored a mutant type allele for Pvdhfr(94.5%)and Pvdhps(68.2%).The most predominant point mutations were S117T/N(77.7%)in Pvdhfr and A383G(66.8%)in Pvdhps.Amino acid changes were identified at nine residues in Pvdhfr.A quadruple-mutant haplotype at 57,58,61,and 117 was the most frequent(57.4%)among 16 distinct Pvdhfr haplotypes.Mutations in Pvdhps were detected at six codons,and the double-mutant A383G/A553G was the most prevalent(39.3%).Pvdhfr exhibited a higher mutation prevalence and greater diversity than Pvdhps in China.Most isolates from Yunnan carried multiple mutant haplotypes,while the majority of samples from temperate regions and Hainan Island harbored the wild type or single mutant type.This study indicated that the antifolate resistance levels of P.vivax parasites were different across China and molecular markers could be used to rapidly monitor drug resistance.Results provided evidence for updating national drug policy and treatment guidelines.

Syntheses and Antiproliferative Evaluation of 6-Thienyl, 6-Polyphenyl Aryl and 6-Naphthyl Derivatives of 2,4-Diaminopyrido [3,2-d] pyramidine as Non-classical Antifolate Targeting DHFR

A series of 6-thienylethenyl, 6-polyphenyl arylethenyl, 6-thienylethyl and 6-polyphenyl arylethyl deriva- tives of 2,4-diaminopyrido[3,2-d]pyrimidine for targeting dihydrofolate reductase（DHFR） was designed and synthe- sized as non-classical antifolates in order to overcome drug resistance. The compounds were evaluated for in vitro antitumor activities, rhDHFR and antimicrobial activities. All the compounds exhibited antitumor activities, with ICs0 values in the range of 0.13--17.8 gmol/L against HL-60, HeLa and A549. Both the types of aryl groups and the orientation of polyphenyl aryl made an impact on the biological activities. 6-Naphthylethyl derivatives 5c and 5d were proved to be the most active Dt-IFR inhibitors, which were more potent than 6-phenylethyl, 6-thienylethyl and 6-biphenylethyl derivatives. Docking studies reveal that flexible saturated carbon-carbon bond of C9--C10 is essential for biological activities in molecular backbone. Antimicrobial test shows that most of the compounds exhibit antibacterial activities.

Analytical methodologies for determination of methotrexate and its metabolites in pharmaceutical,biological and environmental samples

Methotrexate(MTX)is a folate antagonist drug used for several diseases,such as cancers,various malignancies,rheumatoid arthritis(RA)and inflammatory bowel disease.Due to its structural features,including the presence of two carboxylic acid groups and its low native fluorescence,there are some challenges to develop analytical methods for its determination.MTX is metabolized to 7-hydroxymethotrexate(7-OH-MTX),2,4-diamino-N10-methylpteroic acid(DAMPA),and the active MTX polyglutamates(MTXPGs)in the liver,intestine,and red blood cells(RBCs),respectively.Additionally,the drug has a narrow therapeutic range;hence,its therapeutic drug monitoring(TDM)is necessary to regulate the pharmacokinetics of the drug and to decrease the risk of toxicity.Due to environmental toxicity of MTX;its sensitive,fast and low cost determination in workplace environments is of great interest.A large number of methodologies including high performance liquid chromatography equipped with UVevisible,fluorescence,or electrochemical detection,liquid chromatography-mass spectroscopy,capillary electrophoresis,UVevisible spectrophotometry,and electrochemical methods have been developed for the quantitation of MTX and its metabolites in pharmaceutical,biological,and environmental samples.This paper will attempt to review several published methodologies and the instrumental conditions,which have been applied to measure MTX and its metabolites within the last decade.

Assessment of in vitro sensitivity of Plasmodium vivax fresh isolates

Objective:To compare the applicability of the SYBK Grcen-Ⅰ assay with the standard schizont maturalion assay,for determination of sensitivity of Plasmodium vivax(P.vivax) to chloroquine and a new antifolale WR 99210.Methods:The study was conducted at Mae Tao Clinic for migrant workers,Tak Province during April 2009 to July 2010.A total of 64 blood samples(1 mL blood collected into sodium heparinized plastic tube) were collected from patients with monoinfection with P.vivax malaria prior to treatment with standard regimen of a 3-day chloroquine. In vitro sensitivity of P.vivax isolates was evaluated by schizont maturation inhibition and SYBR Green-Ⅰ assays.Results:A total of 30 out of 64 blood samples collected from patients with P.vivax malaria were successfully analyzed using both the microscopic schizont maturation inhibition and SYBR Green-I assays.The failure rates of the schizont maturation inhibition assay(50%) and the SYBR Green-I assay(54%) were similar(P=0.51).The median IC_(10)s,IC_(50)s and IC_(90)s of both chloroquine and WR99210 were not significantly different from the clinical isolates of P.vivax tested.Based on the cut-off of 100 nM,the prevalences of chloroquine resistance determined by schizont maturation inhibition and SYBR Green-I assays were 19 and 11 isolates,respectively.The strength of agreement between the two methods was very poor for both chloroquine and WR992I0.Conclusions:On the basis of this condition and its superior sensitivity,the microscopic method appears better than the SYUK Green-I Green assay for assessing in vitro sensitivity of fresh P.vivax isolates to antimalarial drugs.