A UPLC-DAD-Based Bio-Screening Assay for the Evaluation of the Angiotensin Converting Enzyme Inhibitory Potential of Plant Extracts and Compounds: Pyrroquinazoline Alkaloids from Adhatoda vasica as a Case Study.

Angiotensin converting enzyme (ACE) plays a crucial role in regulating blood pressure in the human body. Identification of potential ACE inhibitors from medicinal plants supported the idea of repurposing these medicinal plants against hypertension. A method based on ultra-performance liquid chromatography (UPLC) coupled with a diode array detector (DAD) was used for the rapid screening of plant extracts and purified compounds to determine their ACE inhibitory activity. Hippuryl-histidiyl-leucine (HHL) was used as a substrate, which is converted into hippuric acid (HA) by the action of ACE. A calibration curve of the substrate HHL was developed with the linear regression 0.999. The limits of detection and quantification of this method were found to be 0.134 and 0.4061 mM, respectively. Different parameters of ACE inhibitory assay were optimized, including concentration, incubation time and temperature. The ACE inhibition potential of Adhatoda vasica (methanolic-aqueous extract) and its isolated pyrroquinazoline alkaloids, vasicinol (1), vasicine (2) and vasicinone (3) was evaluated. Compounds 1-3 were characterized by various spectroscopic techniques. The IC50 values of vasicinol (1), vasicine (2) and vasicinone (3) were found to be 6.45, 2.60 and 13.49 mM, respectively. Molecular docking studies of compounds 1-3 were also performed. Among these compounds, vasicinol (1) binds as effectively as captopril, a standard drug of ACE inhibition.

Flavonol Glycosides: In Vitro Inhibition of DPPIV, Aldose Reductase and Combating Oxidative Stress are Potential Mechanisms for Mediating the Antidiabetic Activity of Cleome droserifolia.

Diabetes is a major health problem that is associated with high risk of various complications. Medicinal plants hold great promise against diabetes. The traditional use of Cleome droserifolia as an antidiabetic agent was correlated to its flavonol glycosides content. In the current study, five major flavonol glycosides appeared on the RP-HPLC chromatogram of the aqueous extract namely; quercetin-3-O-ß-d-glucosyl-7-O-α-rhamnoside (1), isorhamnetin-7-O-ß-neohesperidoside (2), isorhamnetin-3-O-ß-d-glucoside (3) kaempferol-4'-methoxy-3,7-O-α-dirhamnoside (4), and isorhamnetin-3-O-α-(4″-acetylrhamnoside)-7-O-α-rhamnoside (5). The inhibitory activities of these compounds were tested in vitro against several enzymes involved in diabetes management. Only the relatively less polar methoxylated flavonol glycosides (4, 5) showed mild to moderate α-amylase and α-glucosidase inhibitory activities. Compounds 1-4 displayed remarkable inhibition of dipeptidyl peptidase IV (DPPIV) enzyme (IC50 0.194 ± 0.06, 0.573 ± 0.03, 0.345 ± 0.02 and 0.281 ± 0.05 µg/mL, respectively) comparable to vildagliptin (IC50 0.154 ± 0.02 µg/mL). Moreover, these compounds showed high potential in preventing diabetes complications through inhibiting aldose reductase enzyme and combating oxidative stress. Both isorhamnetin glycoside derivatives (2, 3) exhibited the highest activities in aldose reductase inhibition and compound 2 (IC50 5.45 ± 0.26 µg/mL) was even more potent than standard quercetin (IC50 7.77 ± 0.43 µg/mL). Additionally, these flavonols exerted excellent antioxidant capacities through 2, 2-diphenyl-1-picrylhydrazil (DPPH) and ferric reducing antioxidant (FRAP) assays.

Analgesic, Anti-Inflammatory, Cytotoxic Activity Screening and UPLC-PDA-ESI-MS Metabolites Determination of Bioactive Fractions of Kleinia pendula.

Kleinia pendula (Forssk.) DC. is a prostrate or pendent dark green succulent herb found in the southwestern mountain regions of Saudi Arabia. The literature survey of the plant reveals a lack of phytochemical and pharmacological studies, although traditional uses have been noted. The objective of the present work was to assess the in vivo analgesic and anti-inflammatory activities, as well as, the in vitro cytotoxic potential of the fractions of Kleinia pendula, and correlate these activities to the plant metabolites. The methanolic extract of Kleinia pendula was subjected to fractionation with n-hexane, ethyl acetate, chloroform, n-butanol, and water. The fractions were screened for their analgesic and anti-inflammatory activities, as well as cytotoxic activity against breast, liver, and colon cancer cell lines. The n-hexane and chloroform fractions of Kleinia pendula showed significant cytotoxic activity against all three cancer cell lines tested. The ethyl acetate and chloroform fractions showed significant analgesic and anti-inflammatory activities. The metabolites in these three active fractions were determined using UPLC-PDA-ESI-MS. Thus, the analgesic and anti-inflammatory activities of the plant were attributed to its phenolic acids (caffeoylquinic acid derivatives, protocatechuic, and chlorogenic acids). While fatty acids and triterpenoids such as (tormentic acid) in the hexane fraction are responsible for the cytotoxic activity; thus, these fractions of Kleinia pendula may be a novel source for the development of new plant-based analgesic, anti-inflammatory, and anticancer drugs.

Antiviral potential of green synthesized silver nanoparticles of Lampranthus coccineus and Malephora lutea.

BACKGROUND: Viral and microbial infections constitute one of the most important life-threatening problems. The emergence of new viral and bacterial infectious diseases increases the demand for new therapeutic drugs. PURPOSE: The objective of this study was to use the aqueous and hexane extracts of Lampranthus coccineus and Malephora lutea F. Aizoaceae for the synthesis of silver nanoparticles, and to investigate its possible antiviral activity. In addition to the investigation of the phytochemical composition of the crude methanolic extracts of the two plants through UPLC-MS metabolomic profiling, and it was followed by molecular docking in order to explore the chemical compounds that might contribute to the antiviral potential. METHODS: The formation of SNPs was further confirmed using a transmission electron microscope (TEM), UV-Visible spectroscopy and Fourier transform infrared spectroscopy. The antiviral activity of the synthesized nanoparticles was evaluated using MTT assay against HSV-1, HAV-10 virus and Coxsackie B4 virus. Metabolomics profiling was performed using UPLC-MS and molecular docking was performed via Autodock4 and visualization was done using the Discovery studio. RESULTS: The early signs of SNPs synthesis were detected by a color change from yellow to reddish brown color. The TEM analysis of SNPs showed spherical nanoparticles with mean size ranges between 10.12 nm to 27.89 nm, and 8.91 nm 14.48 nm for Lampranthus coccineus and Malephora lutea aqueous and hexane extracts respectively. The UV-Visible spectrophotometric analysis showed an absorption peak at λmax of 417 nm.The green synthesized SNPs of L. coccineus and M. lutea showed remarkable antiviral activity against HSV-1, HAV-10, and CoxB4 virus. Metabolomics profiling of the methanolic extract of L. coccineus and M. lutea resulted in identifying 12 compounds. The docking study predicted the patterns of interactions between the compounds of L. coccineus and M. lutea with herpes simplex thymidine kinase, hepatitis A 3c proteinase, and Coxsackievirus B4 3c protease, which was similar to those of the co-crystal inhibitors and this can provide a supposed explanation for the antiviral activity of the aqueous and nano extracts of L. coccineus and M. lutea. CONCLUSION: These results highlight that SNPs of L. coccineus and M. lutea could have antiviral activity against HSV-1, HAV-10, and CoxB4 virus.