Sibtain Ahmed | University of California, San Diego (original) (raw)

Papers by Sibtain Ahmed

Results in Chemistry, 2025

In the current study, parietin was extracted aerobically from lichen and quantified using parieti... more In the current study, parietin was extracted aerobically from lichen and quantified using parietin activity tests. Different parameters were optimized to extract parietin, viz. suspending 1.5 g biomass of lichen in 15 mL methanol and incubating it for 45 min at 37 • C. Parietin-mediated AgNPs were synthesized by 30-minute procurement period with 3 mL of AgNO 3 (3 mM) solution. Visual observations and ultraviolet-visible (UV-Vis) spectra demonstrated that the Ag precursor's treatment changed the color of fresh methanolic extract to greenish-brown. Fourier transfer infrared (FTIR) spectroscopy was used to identify lichen secondary metabolites. The effective synthesis of Xa-AgNPs was further validated by X-ray diffraction patterns and scanning electron microscopy. The free parietin extract and synthesized nanoparticles (Xa-AgNPs) were evaluated for antimicrobial activity against selected bacterial isolates; S. aureus, B. subtilis (gram-positive), E. coli, Pseudomonas sp. (gramnegative) by agar well diffusion method. The results indicated that free parietin extract and synthesized nanoparticles (Xa-AgNPs) have potential antimicrobial activity against selected gram-positive and gram-negative bacterial isolates. The current results exhibited that Xa-AgNPs are potent bactericidal agents and should be considered a promising candidate to combat bacterial infections.

Physica Status Solidi A: Applications and Materials Science. , 2024

This work is devoted to studying and manufacturing a highly sensitive nonenzymatic glucose biosen... more This work is devoted to studying and manufacturing a highly sensitive nonenzymatic glucose biosensing system of metal oxides via the sol–gel technique. The X-ray diffraction patterns of all the prepared samples confirm that the samples present hexagonal crystal lattice structures of ZnO and Ag–ZnO nanoparticles. Ultraviolet (UV) analysis of all the samples is carried out to evaluate the absorption of silver in the UV region for electrical and chronoamperometric analysis. The transmittance of all the samples is observed, and the maximum transmittance is 11% for 4% AgZnO. Fourier transform infrared spectroscopy reveal the functional group stretching and vibration of the particles at different wavelength ranges. Scanning electron microsocpy analysis reveals the grain size and morphology of the samples, which decrease with increasing doping agent. Chronoamperometric analysis of all the samples reveals that the value increases with time for the 4% doped sample. The sensing response is also observed and is enhanced with increasing temperature for the 4% doped sample. The sensing response of the samples coated with carbon fiber electrodes is assessed from −0.2 to +0.5 V at a scan rate of 50 mV s−1.

PeerJ, 2024

Itaconic acid is an industrially crucial organic acid due to its broad range of applications. The... more Itaconic acid is an industrially crucial organic acid due to its broad range of applications. The main hurdle in itaconic acid production is the high cost of the substrate, i.e., pure glucose, required for the fermentation process. Pakistan annually produces about 1.7 to 1.8 million metric tonnes of mango fruit. Keeping this in view, the potential of a sugar-rich fruit by-product, i.e., mango peels, was analyzed to be used as a substrate for the biosynthesis of itaconic acid using Aspergillus niger by submerged fermentation. Different physicochemical parameters (incubation period, temperature, agitation rate, inoculum size, and pH) were optimized using the central composite design (CCD) design of response surface methodology (RSM). The maximum production of itaconic acid, i.e., 4.6 g/L, was analyzed using 10% mango peels w/v (water hydrolysate), 3 mL inoculum volume after 5 days of fermentation period at pH 3, and a temperature of 32 C when the media was kept at a 200-rpm agitation speed. The itaconic acid extraction from mango peels was done using the solvent extraction method using n-butanol. The identification and quantification of itaconic acid produced in the study were done using the Fourier Transform Infrared Spectroscopy (FTIR) spectrum and the High-Performance Liquid Chromatography (HPLC) method. According to HPLC analysis, 98.74% purity of itaconic acid was obtained in the research. Hence, it is concluded from the results that sugar-rich mango peels can act as a promising substrate for the biosynthesis of itaconic acid. Further conditions can be optimized at the bioreactor level to meet industrial requirements.

Biology, 2024

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

PLoS One, 2024

Viral diseases pose a serious global health threat due to their rapid transmission and widespread... more Viral diseases pose a serious global health threat due to their rapid transmission and widespread impact. The RNA-dependent RNA polymerase (RdRp) participates in the synthesis, transcription, and replication of viral RNA in host. The current study investigates the antiviral potential of secondary metabolites particularly those derived from bacteria, fungi, and plants to develop novel medicines. Using a virtual screening approach that combines molecular docking and molecular dynamics (MD) simulations, we aimed to discover compounds with strong interactions with RdRp of five different retroviruses. The top five compounds were selected for each viral RdRp based on their docking scores, binding patterns, molecular interactions, and drug-likeness properties. The molecular docking study uncovered several metabolites with antiviral activity against RdRp. For instance, cytochalasin Z8 had the lowest docking score of-8.9 (kcal/mol) against RdRp of SARS-CoV-2, aspulvinone D (-9.2 kcal/mol) against HIV-1, talaromyolide D (-9.9 kcal/mol) for hepatitis C, aspulvinone D (-9.9 kcal/mol) against Ebola and talaromyolide D also maintained the lowest docking score of-9.2 kcal/mol against RdRp enzyme of dengue virus. These compounds showed remarkable antiviral potential comparable to standard drug (remdesivir-7.4 kcal/mol) approved to target RdRp and possess no significant toxicity. The molecular dynamics simulation confirmed that the best selected ligands were firmly bound to their respective target proteins for a simulation time of 200 ns. The identified lead compounds possess distinctive pharmacological characteristics, making them potential candidates for repurposing as antiviral drugs against SARS-CoV-2. Further experimental evaluation and investigation are recommended to ascertain their efficacy and potential.

Pharmaceuticals, 2024

Breast cancer is a prevalent and potentially life-threatening disease that affects women worldwid... more Breast cancer is a prevalent and potentially life-threatening disease that affects women worldwide. Natural products have gained a ention as potential anticancer agents due to their fewer side effects, low toxicity, and cost effectiveness compared to traditional chemotherapy drugs. In the current study, the network pharmacology approach was used following a molecular docking study to evaluate the therapeutic potential of N. sativa-derived phytochemicals against breast cancer. Specifically, the study aimed to identify potential anticancer agents targeting key proteins implicated in breast cancer progression. Five proteins (i.e., EGFR, MAPK3, ESR1, MAPK1, and PTGS2) associated with breast cancer were selected as receptor proteins. Fourteen phytochemicals from N. sativa were prioritized based on drug-likeness (DL) and oral bioavailability (OB) parameters (with criteria set at DL > 0.18 and OB > 30%, respectively). Subsequent analysis of gene targets identified 283 overlapping genes primarily related to breast cancer pathogenesis. Ten hub genes were identified through topological analysis based on their significance in the KEGG pathway and GO annotations. Molecular docking revealed strong binding affinities between folic acid, betulinic acid, stigmasterol, and selected receptor proteins. These phytochemicals also demonstrated druggability potential. In vitro experiments in the MDA-MB-231 breast cancer cell line revealed that betulinic acid and stigmasterol significantly reduced cell viability after 24 h of treatment, confirming their anticancer activity. Furthermore, in vivo evaluation using a DMBA-induced rat model showed that betulinic acid and stigmasterol contributed to the significant recovery of cancer markers. This study aimed to explore the mechanisms underlying the anticancer potential of N. sativa phytochemicals against breast cancer, with the ultimate goal of identifying novel therapeutic candidates for future drug development. Overall, these results highlight betulinic acid and stigmasterol as promising candidates to develop novel anticancer agents against breast cancer. The comprehensive approach of this study, which integrates network pharmacology and molecular docking study and its experimental validation, strengthens the evidence supporting the therapeutic benefits of N. sativa-derived phytochemicals in breast cancer treatment, making them promising candidates for the development of novel anticancer agents against breast cancer.

Journal of Food Quality, 2024

Te increasing world population needs a standard balanced diet to address malnutrition problems. F... more Te increasing world population needs a standard balanced diet to address malnutrition problems. For this purpose, seed priming is one of the best techniques, which helps to increase the production of functional and nutritional food crops. Diferent techniques have been used for seed priming, but biological priming is the most frequently used because biocontrol agents ofer a friendly environment for the growth of food crops. In this study, Momordica charantia L. seeds were subjected to a strain of Enterobacter sp. FD17 as a biocontrol agent at diferent time exposures (i.e., 24 h, 48 h, and 72 h). Leaf growth, favonoids, chlorophyll content, amino acids, soluble sugars, protein, and total soluble phenolics were studied in the vegetative stage. Te yield of nutritive components was evaluated from fruit, peel, and pulp of M. charantia. Biopriming was revealed to improve the fnal emergence rate, mean emergence time, seedling vigor, emergence index, and vigor indices I and II. Among the growth parameters, the root (0.45 ± 0.045 g) and shoot fresh weight (1.23 ± 0.05 g), leaf area (15.52 ± 1.5 cm), shoot length (30.33 ± 0.58 cm), number of fowers (6 ± 1.0), fruit weight (96.33 ± 1.15 g), and germination percentage (56.67 ± 11.55%) were also improved. Among biochemical analyses, biopriming improved chlorophyll a (6.33 ± 0.58 mg/g) and b (8.58 ± 2.5 mg/g), total soluble sugar (33.13 ± 2.24%), and total chlorophyll content (9.0 ± 1.5 mg/g). Te nutritional analysis showed that free amino acids (1.43 ± 0.02 mg/g), total soluble sugar (42.53 ± 1.65%), ash (20.53 ± 2.57%), and catalase (347.47 ± 34.76 U/g) were increased in fruit, while crude fber (3.62 ± 0.1%) and peroxidase (5.61 ± 0.34 U/g) in peel and protein and metabolizable energy in peel and fruit were increased. Among the water, acetone, and methanol extracts, the maximum antibacterial activity was shown by methanol extracts of leaves against Gram-negative and Gram-positive bacterial species (i.e., Pseudomonas aeruginosa and Staphylococcus aureus, respectively) with inhibitory diameters of 3 mm. Biopriming also improved the phenolic contents in the leaves and fruits of M. charantia. Biopriming treatment was also revealed to be directly correlated with antiglycation activity. Terefore, biopriming treatment on seeds could be used to manipulate plant cell metabolism with a substantial improvement in phenolic content, antibacterial activity, and growth of M. charantia.

Molecules, 2023

Infertility is a well-recognized multifactorial problem affecting the majority of people who stru... more Infertility is a well-recognized multifactorial problem affecting the majority of people who struggle with infertility issues. In recent times, among infertility cases, the male factor has acquired importance, and now it contributes to approximately half of the infertility cases because of different abnormalities. In the current study, we used natural phytochemicals as potential drug-lead compounds to target different receptor proteins that are involved in the onset of male infertility. A set of 210 plant phytochemicals were docked counter to active site residues of sex hormone-binding globulin, a disintegrin and metalloproteinase 17, and DNase I as receptor proteins. On the basis of binding scores and molecular dynamics simulation, the phytochemicals tricin, quercetin, malvidin, rhamnetin, isorhamnetin, gallic acid, kaempferol, esculin, robinetin, and okanin were found to be the potential drug candidates to treat male infertility. Molecular dynamics simulation showed tricin as a strong inhibitor of all selected receptor proteins because the ligand–protein complexes remained stabilized during the entire simulation time of 100 ns. Further, an in vivo study was designed to evaluate the effect of tricin in male rats with nicotine-induced infertility. It was explored that a high dose of tricin significantly reduced the levels of alanine transaminase, aspartate transaminase, urea, creatinine, cholesterol, triglyceride, and low-density lipoprotein and raised the level of high-density lipoprotein in intoxicated male rats. A high dose of tricin also increased the reproductive hormones (i.e., testosterone, luteinizing hormone, follicle-stimulating hormone, and prolactin) and reduced the level of DHEA-SO4. The phytochemical (tricin, 10 mg/kg body weight) also showed significant improvement in the histo-architecture after nicotine intoxication in rats. From the current study, it is concluded that the phytochemical tricin could serve as a potential drug candidate to cure male infertility.

Microorganisms, 2023

Pharmaceuticals, 2023

Hepatocellular carcinoma (HCC) is the fifth most common and fatal cancer reported, representing 7... more Hepatocellular carcinoma (HCC) is the fifth most common and fatal cancer reported, representing 72.5% of malignancies around the world. The majority of HCC incidents have been associated with infections caused by hepatitis B and C viruses. Many first- and second-line conventional drugs, e.g., sorafenib, cabozantinib, or ramucirumab, have been used for the management of HCC. Despite different combinational therapies, there are still no defined biomarkers for an early stage diagnosis of HCC. The current study evaluated the potential of Bergenia stracheyi, Bergenia ciliata, Bergenia pacumbis, and Bergenia purpurascens, which belong to the family Saxifragaceae, to treat HCC using an integrated network pharmacology and molecular docking approach. Four active phytochemicals were selected based on oral bioavailability (OB) and drug likeness (DL) parameters. The criteria of phytochemical selection were set to OB > 30% and DL > 0.18. Similarly, the gene targets related to Bergenia spp. and the genes related to HCC were retrieved from different databases. The integration of these genes revealed 98 most common overlapping genes, which were mainly interrelated with HCC pathogenesis. Ultimately, the 98 Bergenia-HCC associated genes were used for protein–protein interaction (PPI), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and Gene Ontology (GO) enrichment analyses. Finally, the topological analysis revealed the top ten hub genes with maximum degree rank. From the top ten genes, STAT3, MAPK3, and SRC were selected due to their involvement in GO annotation and KEGG pathway. To confirm the network pharmacology results, molecular docking analysis was performed to target STAT3, MAPK3, and SRC receptor proteins. The phytochemical (+)-catechin 3-gallate exhibited a maximum binding score and strong residue interactions with the active amino acids of MAPK3-binding pockets (S-score: −10.2 kcal/mol), SRC (S-score: −8.9 kcal/mol), and STAT3 (S-score: −8.9 kcal/mol) as receptor proteins. (+)-Catechin 3-gallate and β-sitosterol induced a significant reduction in cell viability in HepG2 after 24 h of treatment in a dose-dependent manner. The results of this study explore the potential of (+)-catechin 3-gallate and β-sitosterol, which can be used in the future as potential drug candidates to suppress HCC.

Cellular and Molecular Biology, 2021

ancer is the leading cause of death, accounting for approximately one out of six people dying wit... more ancer is the leading cause of death, accounting for approximately one out of six people dying with this disease worldwide. Among all, the breast and ovarian cancers are top-ranked causes of women mortalities compared to other disorders. Although, there is advancement in technologies, but still, there are unresolved concerns to overcome the global disease burden. Currently, plants are being explored as a natural remedy to cure disorders. This research was planned to explore phytochemicals in methanolic extracts of Zizyphus mauritiana and Triticum aestivum, and their pharmacological activities were studied through Agrobacterium tumefaciens bacteria, in vitro breast cancer cell line and ovarian cancer cell line to find out novel candidates in disease control and prevention. Eleven different types of bioactive compounds were analysed in the tested extracts. The highest crude extracts percentage (75±0.02) was observed with Z. mauritiana. The extracts showed promising cell growth inhibiti...

Molecules, 2023

Diabetes mellitus is a chronic metabolic disorder defined as hyperglycemia and pancreatic β-cell ... more Diabetes mellitus is a chronic metabolic disorder defined as hyperglycemia and pancreatic β-cell deterioration, leading to other complications such as cardiomyopathy. The current study assessed the therapeutic effects of phenolic acids extracted from Jasminum sambac phenols of leaves (JSP) against diabetes-induced cardiomyopathy in rats. The rats were divided into four groups, with each group consisting of 20 rats. The rats were given intraperitoneal injections of alloxan monohydrate (150 mg/kg) to induce diabetes. The diabetes-induced groups (III and IV) received treatment for six weeks that included 250 and 500 mg/kg of JSP extract, respectively. In the treated rats, the results demonstrated that JSP extract restored fasting glucose, serum glucose, and hyperlipidemia. Alloxan induced cardiomyopathy, promoted oxidative stress, and altered cardiac function biomarkers, including cardiac troponin I, proBNP, CK-MB, LDH, and IMA. The JSP extract-treated rats showed improved cardiac func...

ACS Food Science & Technology , 2023

Studies investigating the bioactivity application of Streptococcus thermophilus FUA329, a potenti... more Studies investigating the bioactivity application of Streptococcus thermophilus FUA329, a potential urolithin Aproducing strain isolated from human breast milk in a previous study, are insufficient. We here investigated the changes in polyphenols and antioxidant activities of pomegranate peels before and after fermentation by S. thermophilus FUA329. Liquid chromatography−mass spectrometry was used to detect the polyphenols in the fermentation broth. Total phenolic and flavonoid contents were used as indicators of the antioxidant activity of the broth. The results revealed that the total phenolic and flavonoid contents of the fermented pomegranate peels peaked at 48 h (122.54 ± 0.93 mg GAE/100 mL and 26.09 ± 1.11 mg RE/100 mL, respectively), and urolithins, especially urolithin A, produced by the strain during fermentation were considered a new and primary metabolite that enhances the antioxidant ability of the fermentation broth. Thus, as a potential probiotic, S. thermophilus FUA329 can transform ellagic acid in pomegranate peels to urolithin A and improve the antioxidant power of natural foods.

Microorganisms, 2023

Levan is a homopolysaccharide of fructose units that repeat as its structural core. As an exopoly... more Levan is a homopolysaccharide of fructose units that repeat as its structural core. As an exopolysaccharide (EPS), it is produced by a great variety of microorganisms and a small number of plant species. The principal substrate used for levan production in industries, i.e., sucrose, is expensive and, hence, the manufacturing process requires an inexpensive substrate. As a result, the current research was designed to evaluate the potential of sucrose-rich fruit peels, i.e., mango peels, banana peels, apple peels, and sugarcane bagasse, to produce levan using Bacillus subtilis via submerged fermentation. After screening, the highest levan-producing substrate, mango peel, was used to optimize several process parameters (temperature, incubation time, pH, inoculum volume, and agitation speed) employing the central composite design (CCD) of response surface methodology (RSM), and their impact on levan production was assessed. After incubation for 64 h at 35 °C and pH 7.5, the addition of ...

Molecules , 2023

Animals , 2023

Journal of Microbiology and Biotechnology, Apr 28, 2022

Chitin deacetylase (CDA) inhibitors were developed as novel antifungal agents because CDA partici... more Chitin deacetylase (CDA) inhibitors were developed as novel antifungal agents because CDA participates in critical fungal physiological and metabolic processes and increases virulence in soilborne fungal pathogens. However, few CDA inhibitors have been reported. In this study, 150 candidate CDA inhibitors were selected from the commercial Chemdiv compound library through structure-based virtual screening. The top-ranked 25 compounds were further evaluated for biological activity. The compound J075-4187 had an IC50 of 4.24 ± 0.16 μM for AnCDA. Molecular docking calculations predicted that compound J075-4187 binds to the amino acid residues, including active sites (H101, D48). Furthermore, compound J075-4187 inhibited food spoilage fungi and plant pathogenic fungi, with minimum inhibitory concentration (MIC) at 260 μg/ml and minimum fungicidal concentration (MFC) at 520 μg/ml. Therefore, compound J075-4187 is a good candidate for use in developing antifungal agents for fungi control.

Fermentation

Vanillin is a secondary metabolite of plants and the major organoleptic aroma component of natura... more Vanillin is a secondary metabolite of plants and the major organoleptic aroma component of natural vanilla. Nowadays, the chemical synthesis method used for vanillin production has been rejected by the United States and European legislation, while plant-derived vanillin is expensive. The current study demonstrates vanillin production via solid-state fermentation (SSF) by Enterobacter hormaechei using different ferulic acid-rich fruit peels as substrates. From different ferulic acid-rich fruit peels (pomegranate, banana, and orange) screened Punica granatum (pomegranate) peels yielded maximum biovanillin (0.09 mg/g) after 24 h. Different bioprocess parameters, including moisture content, inoculum size, pH, and temperature, were optimized using central composite design (CCD) of the response surface methodology (RSM). The maximum biovanillin yield (0.462 mg/g) from Punica granatum peels was achieved at 60% moisture content, 2 mL inoculum size, 6.5 pH, and 32 °C temperature. An F-value ...

Journal of Traditional Chinese Medicine , 2022

Introduction: Withania somnifera (W. somnifera) is a plant with remarkable pharmacological proper... more Introduction: Withania somnifera (W. somnifera) is a plant with remarkable pharmacological properties. The plant has an impressive profile of medicinal uses in the folk medicine system of several civilizations.

Aim: This comprehensive study is aimed to characterize phytochemicals in fruit of W. somnifera and tested for anticancer potential to find out active candidate in disease prevention and treatment.

Methods: The bioactive components from W. somn-ifera fruit were extracted with polar and non-polar solvents. Anticancer potential of the isolated bioactive was assessed against different cancer cell lines through MTT assay and Incucytes imaging analysis. The extracts were characterized for secondary metabolites using GC-MS (gas chromatography-mass spectrometer), LCMS (liquid chromatography-mass spectrometry)-ESI (electrospray Ionization) and 1H-NMR (electrospray Ionization) techniques.

Results: Both freeze-dried and rotary evaporator con-densed extracts exhibited anticancer potential against MDA-MB-231, MCF7- SKOV3 and SKBR3 cell lines. The tested extracts have cell growth inhibition potential ag-ainst mammalian cancer cell line. Hexacosanedioic acid purified from -hexane extract through HPLC was inves-tigated for its cytotoxicity against breast cancer cell line SKBR3 by using Incucytes imaging analysis.

Conclusion: We found that a variety of bioactive compounds existed in this plant. One identified compound that was not investigated for cytotoxicity in previous studies was purified and its application showed cytotoxicity on breast cancer cell lines. A number of bioactive identified from fruit may have an effective potential for development into chemotherapy drugs.

Indian Journal of Pharmaceutical Sciences, 2021

Mushtaq et al.: Characterization of Subtilisin Gene from Bacillus subtilis Fibrinolytic therapy p... more Mushtaq et al.: Characterization of Subtilisin Gene from Bacillus subtilis Fibrinolytic therapy progressed by the evolution of different strategies that helped in enhancing its efficacy and specificity. The use of microbial fibrinolytic enzymes is leading to a promising direction for the treatment of cardiovascular diseases. Subtilisin, a member of subtilases is a fibrinolytic enzyme abundantly found in Bacillus species. The isolation of subtilisin gene (quaking homolog) from Bacillus subtilis was attempted in the present work. The genomic deoxyribonucleic acid extraction was done following Yamada protocol and used as a template for polymerase chain reaction amplification of the target gene using specifically designed primers. The polymerase chain reaction product was ligated into cloning vector pTZ57R/T followed by its transformation into Escherichia coli top 10 strain. A 1090 base pair, partial gene sequence was amplified coding for subtilisin protein of 363 amino acids with molecular weight of 37550.7 Daltons. The nucleotide sequence revealed significant evolutionary relationships with subtilases from other strains of Bacillus subtilis. Our study confirms the presence of subtilisin (quaking homolog) gene in local Bacillus species suggesting economical way to produce important thrombolytic agents of commercial and pharmaceutical worth.

Results in Chemistry, 2025

Physica Status Solidi A: Applications and Materials Science. , 2024

PeerJ, 2024

Biology, 2024

PLoS One, 2024

Pharmaceuticals, 2024

Journal of Food Quality, 2024

Molecules, 2023

Microorganisms, 2023

Pharmaceuticals, 2023

Cellular and Molecular Biology, 2021

Molecules, 2023

ACS Food Science & Technology , 2023

Microorganisms, 2023

Molecules , 2023

Animals , 2023

Journal of Microbiology and Biotechnology, Apr 28, 2022

Fermentation

Journal of Traditional Chinese Medicine , 2022

Aim: This comprehensive study is aimed to characterize phytochemicals in fruit of W. somnifera and tested for anticancer potential to find out active candidate in disease prevention and treatment.

Indian Journal of Pharmaceutical Sciences, 2021