
Gabriel AkowuahUCSI University | ucsi · Faculty of Pharmaceutical Sciences
Gabriel Akowuah
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Publications (68)
To study Cassia alata (CA) (Linnaeus) Roxburgh’s effectiveness towards atopic dermatitis (AD), CA leaf extracts were prepared using three methanol-based extraction solvent systems. Bioactive constituents were characterized and quantified via high-performance liquid chromatography with diode array detection. Antioxidant properties and antimicrobial...
Objectives
Vernonia amygdalina Del. leaves are used in traditional Southeast Asia and Africa medicinal practices. Metformin is used for diabetes management. This study investigated the effect of a single dose of aqueous leaf extract of V. amygdalina on metformin pharmacokinetics in diabetic rats.
Methods
Diabetic rats were randomly assigned to fou...
Objectives
Vernonia amygdalina Del. is a perennial tropical shrub from Asteraceae. The fresh leaf of V. amygdalina is consumed as a vegetable due to its medicinal and nutritional properties. The present study focused on the quantification of bioactive compounds, luteolin-7-O-glucoside, luteolin-7-O-glucuronide, and 1,5-O-dicaffeoylquinic acid from...
Cassia alata, a traditional herb with a global presence, is renowned for its anti-inflammatory, antibacterial, and antifungal properties, making it a go-to remedy for skin ailments. While it has demonstrated wound healing capabilities in both in vitro and in vivo studies, the precise mechanisms remain elusive. This review aims to highlight its key...
Hair shampoos containing botanical ingredients without synthetic additives, such as parabens, petrochemicals, sulfates and silicones are more skin- and environmentally friendly. In recent years, there is a growing demand for shampoo products with botanical extracts. Shampoos with botanical extracts are well-known for their perceived health benefits...
In recent decades, there has been a growing demand for shampoos derived from botanical sources due to their avoidance of synthetic and highly allergenic chemicals used as bioactives and excipients. These hair care products are free from sulfates, parabens, silicones, synthetic fragrances, and artificial colours. Natural shampoos are sustainable, sk...
The study aimed to investigate the effects of different extraction methods on the content of thymoquinone using UV-Vis
spectroscopy and the antioxidant activities of thymoquinone by measuring the free radical scavenging activity. One gram of
powdered Nigella sativa L. black seed was added to 20 mL of solvents (hexane and methanol) into a conical fl...
The major complaint that most of the schizophrenic patients’ face is the cognitive impairment which affects the patient’s quality of life. The current antipsychotic drugs treat only the positive symptoms without alleviating the negative or cognitive symptoms of the disease. In addition, the existing therapies are known to produce extrapyramidal sid...
The purpose of the present study was to compare nitric oxide scavenging and hemolytic activities of dry leaf extracts and fresh leaf juice of Clinacanthus nutans (Burm.f) Lindau. Methanol and cold aqueous extracts of the dry leaf were prepared by macerating in the respective solvent at room temperature. Hot aqueous extract was prepared by mixing th...
INTRODUCTION: Phosphodiesterase10A (PDE10A) is a dual-substrate enzyme that catalyses the inactivation of cAMP and cGMP and is expressed most prominently in the striatum. The inhibition of PDE10A results in the elevation of cAMP and cGMP, activating the direct and indirect pathways in striatum. Activation of these pathways provides significant impr...
INTRODUCTION: Phosphodiesterase 10A (PDE10A) is a dual substrate enzyme that catalyzes the inactivation of both cAMP and cGMP in to AMP and GMP respectively. This enzyme is expressed mainly in striatum. Thus inhibition of PDE10A results in elevation of cAMP and cGMP which activate the direct and indirect pathways in striatum. Activation of these tw...
The purpose of this study was to investigate the effect of Manganese ions (Mn 2+) on colour development of ninhydrin by alendronate for the spectrophotometric analysis of alendronate sodium in tablets. The analysis was based on the reaction of ninhydrin with the primary amino group in alendronate in the presence of 0.01 M sodium bicarbonate solutio...
Background:
Clinacanthus nutans Lindau (family: Acanthaceae), also known as “Sabah Snake Grass” or “Belalai Gajah” in Malaysia, has been widely used by Malaysians due to its anticancer property. However, the anticancer activity of C. nutans leaves extract and its safe use need to be further investigated. The objectives of the present study were to...
Background: Alendronate sodium (the sodium salt of 4-Amino-1-hydroxy-1-bisphosphonic acid) is a potent anti-resorptive drug that is widely used for the treatment of osteoporosis and Paget’s disease. Its analysis is challenging due to the lack of chromophore in its chemical structure. This study describes a quick and simple attenuated total reflecta...
Phosphodiesterase 4 (PDE4) has been established as a drug target for inflammatory diseases of respiratory tract like asthma and chronic obstructive pulmonary disease. The selective inhibitors of PDE4B, a subtype of PDE4, are devoid of adverse effect like nausea and vomiting commonly associated with non-selective PDE4B inhibitors. This makes the dev...
Pleurotus porrigens and Schizophyllum commune contain high amounts of dietary antioxidants such as flavonoids and phenolic acids. Identification of major antioxidative components of selected fractions of P. porrigens and S. commune was determined by high performance liquid chromatography - ion trap tandem mass spectrometry (HPLC-IT/MS). In addition...
Hazelnut (Corylus cornuta) is good source of natural antioxidants. Natural antioxidants are very important in the food industry for preparation of functional foods. The aim of this study was to evaluate antimicrobial activity against selected bacteria and antiradical potency of ethyl acetate and methanol extracts of dehulled hazelnut kernel. Dried...
Vernonia amygdalina or commonly known as “bitter leaf” in Malaysia has been widely used for the treatment of malaria and diabetes mellitus. The objective of this study was to examine the possible toxic effect of methanol leaves extract of V. amygdalina after 28 days oral administration in female Sprague Dawley rats. This 28 days toxicity study of V...
Antioxidative potentials of peel extracts of rambutan (Nephelium lappaceum), mangosteen (Garcinia mangostana), and langsat (Lansium domesticum) in experimental rats were investigated. Antioxidant activities were evaluated using liver enzymatic and non-enzymatic systems. Rats were treated with fruit peel extracts for 14 and 30 days. Blood was collec...
Partially purified fraction E, dichloromethane extract of leaves from Labisia Pumila has been shown to possess anti-ulcer, anti-inflammatory, anti-asthmatic activities among others. Naringin has been identified by LC-MS and HPLC as the major compound present in fraction E. The present study reports the development and validated TLC densitometric me...
Citrus fruits are known to possess high antioxidant activity due to active compounds present in it such as vitamins, carotenoids, flavonoids, and phytochemicals. The present study aimed to evaluate the antioxidant activity and total phenolic content of chloroform fraction from ethanol extract of peel of Citrus hystrix. The peel of C. hystrix was ex...
Attenuated total reflectance Fourier transform infrared spectrometric method for determination of crocin in commercial saffron samples was studied. Calibration models were built based on the peaks at spectral region of 1700-900 cm−1 and spectral wavenumbers with correlation coefficient (r) greater than 0.99 were selected for quantification of croci...
High-performance liquid chromatography (HPLC) and ultraviolet (UV) spectrophotometric methods were developed for analysis of berberine, the principal bioactive constituent, in Coscinium fenestratum extracts. The HPLC and UV spectrophotometric determinations were performed at 226, 270, and 340 nm. The methods were validated by assessing linearity, s...
The oxidative properties of sunflower oil supplemented with rambutan extract,
(crude extract and its fractionated fraction, SF II) in comparison with synthetic antioxidant
were investigated. The supplemented sunflower oils were stored under accelerated
conditions for 24 days at 60 °C. For every 6-day interval, the oxidative properties of the
supple...
Labisia pumila, LP (Myrsinaceae), is a popular herb among the women in Malaysia known locally as ''Kacip Fatimah. It has been claimed by the traditional medicinal practitioner as a pain reliever, treat inflammatory disorders, such as rheumatism and fever. This study was aimed to investigate the partially purified crude extracts of Labisia pumila (D...
Partially purified fraction E “SNP E”, dichloromethane extract of leaves from Labisia Pumila has been shown to possess anti-ulcer, anti-inflammatory, anti-asthmatic activities among others. Naringin has been identified by LC-MS and HPLC as the major compound present in “SNP E”. The present study reports the development and validated TLC densitometr...
The objective of this study was to evaluate antiradical activities of methanol and 50% aqueous methanol extracts of dehulled kernels of almond, apricot and pumpkin. All the extracts showed 2,2-diphenyl-1-picryhydrazyl, superoxide anion, and nitric oxide radicals scavenging activities. The activities of the methanol extracts were higher than 50% aqu...
The oxidative properties of sunflower oil supplemented with rambutan extract, (crude extract and its fractionated fraction, SF II) in comparison with synthetic antioxidant were investigated. The supplemented sunflower oils were stored under accelerated conditions for 24 days at 60 °C. For every 6-day interval, the oxidative properties of the supple...
Objective
To examine the possible sub-acute toxic effect after 14 d oral administration with 0.3 g/kg, 0.6 g/kg and 0.9 g/kg of methanol leaves extract of Clinacanthus nutans (C. nutans) on liver and kidney functions in young male Sprague Dawley (SD) rats.Methods
This study was carried out according to OECD 407 guideline. A total of 24 young health...
Objective
To investigate the effects of standardized dichloromethane (DCM) extract of Cosinium fenestratum (C. fenestratum) stem bark on liver and kidney function parameters in streptozotocin (STZ)-induced diabetic rats.
Methods
Standardization of the extract was performed through high performance liquid chromatography (HPLC) using berberine (BE)...
Clinacanthus nutans is a medicinal herb found in South East Asia. It has been traditionally used for skin infections. Hence, this study aimed to investigate the antibacterial effect of C. nutans against selected bacteria. C. nutans leaf was extracted with methanol. The dried methanolic extract was qualitatively screened for the presence of phytoche...
Nasopharyngeal carcinoma (NPC) is a malignancy that occurs in the epithelium of the nasopharynx. The standard treatment of NPC patients with locoregionally advanced stages is problematic and is often associated with toxicities. Therefore, it is essential to screen for naturally occurring compounds with strong apoptosis-inducing activity and minimal...
Nasopharyngeal carcinoma (NPC), prevalent in Southeast Asia and Southern China, is a cancer that develops from the epithelium of the nasopharynx. Current treatments of NPC patients produce undesirable complications. There is growing interest in natural products with anti-proliferative potential to circumvent toxicity associated with synthetic anti-...
Labisia pumila, LP (Myrsinaceae), is a popular herb among the women in Malaysia known locally as ''Kacip Fatimah. It has been claimed by the traditional medicinal practitioner as a pain reliever, treat inflammatory disorders, such as rheumatism and fever. This study was aimed to investigate the partially purified crude extracts of Labisia pumila (D...
The aim of this study was to determine the major boactive constituents, trans-cinnamic acid and transcinnamaldehyde, and anti-oxidative activities of 50% aqueous methanol and water extracts of Cinnamomum burmannii Blume stem bark. Gas chromatography-mass spectrometry (GC-MS) was used to analyse the extracts. The content of trans-cinnalmadeyde quant...
Objective
The aim of the present study is to develop liquid chromatography (LC)/Time-of-flight mass spectrometry (TOF/MS) profile for methanol and water extracts of Orthosiphon stamineus leaf using SEN and RA as flavonoid and non-flavonoid polyphenolic markers in the extracts. The study also evaluates in vitro nitric oxide radical scavenging effect...
The effect of extraction solvents (methanol, 95%ethanol, and water) on total phenolic contents and free radical scavenging activity (FRSA) of Gynura procumbens leaf was investigated. The contents of total phenolic and in vitro FRSA were significantly higher in the methanol extract compared to the 95% ethanol and water extracts. Consequently, the ef...
Coscinium fenestratum (CF) (Gaertn.) Colebr traditionally has been used for the treatment of many diseases including diabetes Mellitus. In the present study, we investigated the effects of crude dichloromethane (DCM), Ethyl Acetate (EA), and Butanol (BuOH) extract of CF on streptozotocin-induced diabetic rat's models. The crude stem extracts at con...
Labisia pumila, LP (Myrsinaceae), is a popular herb among the women in Malaysia known locally as "Kacip Fatimah". It has been used by many generations of Malay women to induce and facilitate child birth as well as a post partum medicine. This study was aimed to investigate the partially purified crude extracts of DCM from the leaves of LP for its a...
Labisia pumila is a popular medicinal plant in Malaysia and has been used in the treatments of various health complications. In this study, the in vitro anti‐histaminergic and anti‐cholinergic antioxidant and mast cell stabilizing effect of Labisia pumila crude leaf extract and partially purified fractions were investigated on guinea pig ileum. HPL...
The effect of extraction temperature on the stability of polyphenols and free radical scavenging activity of Orthosiphon stamineus leaf extract was investigated. Sinensetin (SEN) and rosmarinic acid (RA) were selected as flavonoid and non-flavonoid polyphenolic markers of the extract, respectively. The levels of the markers were significantly (p <...
The dichloromethane (DCM) extract of Labisia pumila leaves were investigated for its anti‐inflammatory (acetic acid‐induced writhing and carrageenan‐induced paw oedema test), antinociceptive (hot‐plate and formalin test) and anti‐pyretics (yeast‐induced hyperpyrexia test) effects. The phytochemical screening of the extract was also investigated. In...
In this study we evaluated dichloromethane (DCM) extract obtained from C. fenestratum , for its ability to protect the gastric mucosa against injuries caused by necrotizing agents (0.3M HCl/60% EtOH), hypothermic restraint stress, and non‐steroidal anti‐inflammatory drugs (NSAID, indomethacin). Total phenoic content and free radical scavenging effe...
Gynura procumbens (Merr.), which is known as "Sambung nyawa", is widely used in South East Asian countries in the traditional treatment of many ailments. However, there is little toxicological information available regarding safety following repeated exposure. The present investigation describes the toxicity of a methanol extract of Gynura procumbe...
A simple and validated high-performance liquid chromatography (HPLC) method with UV detection has been used to determine the content of andrographolide (AP) and 14-deoxy-11,12-didehydroandrographolide (DIAP) in rat plasma after oral dose of methanol extract (1 g/kg body weight) of Andrographis paniculata leaf. An increase in plasma concentration of...
The effect of extraction temperature on total phenolic contents and free radical scavenging activity of Gynura procumbens leaf extract was investigated. The content of total phenolic were not significantly different (P > 0.5) at the extraction temperature of 40 °C and 50 °C. However, decrease in total phenolic content was observed from extraction t...
A simple high-performance liquid chromatography (HPLC) method to determine the content of betulinic acid (BA) in rat plasma collected at different times (0-8 h) after oral administration of Orthosiphon stamineus leaf extract was developed. The features of the assay include protein precipitation using acetonitrile and isocratic elution using reverse...
The current study evaluated the antioxidant and hepatoprotective activities of Elephantopus tomentosus. L. (Asteraceae) ethanol extract (ET). In the experiment, total antioxidant capacity, reducing capacity, DPPH* and hydrogen peroxide scavenging, and Fe3 +-induced lipid peroxidation inhibiting activities of ET were determined. The results indicate...
Orthosiphon stamineus. Benth. was cultivated at different locations in Malaysia to compare the xanthine oxidase inhibitory potential of the methanol extracts of the leaf. The extracts showed superoxide scavenging and xanthine oxidase inhibitory activities using in vitro. methods. By means of HPTLC densitometric technique and UV-Vis spectra, sinense...
The antioxidant activity of methanol extracts of Orthosiphon stamineus. Benth (Lamiaceae), cultivated in different regions of Malaysia, was determined by measuring the scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and on superoxide anion. The results showed a variation in free-radical and superoxide-anion scavenging activities o...
A simple high-performance liquid chromatography (HPLC) method was developed to determine the content of andrographolide (AP) and 14-deoxy-11,12-dideoxyandrographolide (DIAP) in a pooled urine of rat obtained within 24h after an oral dose of Andrographis paniculata leaf extract at 1g/kg body weight. Cumulative urinary excretion of AP and DIAP in 24h...
The methanol extract of the leaves of Gynura procumbens was partitioned between chloroform, ethyl acetate and n -butanol. Qualitative HPLC identification of the major flavonoid constituents in the n -butanol fraction and separation of standard mixture of isolated compounds from the n -butanol fraction are given. Blood glucose levels in streptozotoc...
Andrographis paniculata is a Malaysian traditional herb for treatment of fever-causing diseases and diabetes. The aim of the present study was to
examine the antihyperglycemic effects of different extracts (95, 50, and 20% ethanol extracts and water extracts) of A. paniculata in normal and streptozotocin-induced diabetic rats. Only the treatment wi...
A rapid method based on HPTLC and RP-HPLC with UV detection for quantitative determination of two major bioactive compounds in Andrographis paniculata, andrographolide and 14-deoxy-11, 12-didehydroandrographolide, is described. The recoveries of the two compounds were between 96.5–99.0% by HPTLC method and 98.1–99.2% by HPLC assay. The relative sta...
Leaf powder of Orthosiphon stamineus was extracted with the following solvents; distilled water, 50% aqueous methanol, methanol, 70% aqueous acetone and chloroform, at 2, 4 and 8 h, respectively, on a water bath at 40 °C. The extracts were subjected to qualitative and quantitative HPLC analyses of the polyphenols, the most dominant chemical constit...
An HPLC method was developed for the separation and determination of three methoxylated flavones:sinensetin (SEN), eupatorin (EUP) and 3′-hydroxy-5,6,7,4′-tetramethoxyflavone (TMF) and rosmarinic acid (RA), a caffeic acid derivative in Orthosiphon stamineus (OS). All the compounds were separated using a reversed phase C18, Lichrosorb column with th...