Chrysen-2-ol derivative from West Indian wood nettle Laportea aestuans (L.) Chew inhibits oxidation and microbial growth in vitro

Bio-active compounds present in West Indian Wood Nettle Laportea aestuans (L.) Chew (Urticaceae), used in ethno medicine as antioxidant and antimicrobial were studied. The aim of this research work was to isolate and characterize the bio-active compounds in the n-hexane fraction of L. aestuans, determine the toxicity and subject it to in-vitro antimicrobial and free radical scavenging activities. The chemical constituents were isolated by gradient elution column chromatographic technique and Ultra Violet/visible (UV), Infrared (IR) and Nuclear Magnetic Resonance (NMR) spectroscopies were used for structural elucidation. The free radical scavenging activity of the isolate was assessed using three methods; scavenging effect on 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), hydroxyl radical generated from hydrogen peroxide and ferric thiocynate method. Antimicrobial screening was done by agar well diffusion method while toxicity was determined by Brine shrimp lethality test. Structures were proposed for the white crystalline solids isolated; (4E)-3,6-dimethylhep-4-en-3-ol (AB) and 1,2,3,4,4a,4b,5,6,6a,7,8,9,10,10a,10b,11-hexadecahydro-1,1,6a,10b-tetramethyl-7-((E)-4,7-dimethyloct-5-enyl) chrysen-2-ol (AC). Percentage yield of AC was 91.2 and was non-toxic with LC50 (μg/ml) value of 1581233000.0. AC significantly scavenged free radical at 0.0625 mg/ml in the DPPH (64.73 %) and hydrogen peroxide (99.22 %) tests. It also showed 65.23 % inhibition at 1.0 mg/ml in the ferric thiocyanate test. AC also inhibited microbial growth significantly when compared with gentamicin and tioconazole which are antibacterial and antifungal standards respectively. The presence of Chrysen-2-ol derivative in L. aestuans which was non-toxic and possessed significant antimicrobial and antioxidant activities supports its ethno medicinal application

Synthesis, ionization constant, toxicity, antimicrobial and antioxidant screening of 1-Phenyl-3-(phenylamino) propan-1-one and Phenyl (2-[phenyl amino) methyl] phenyl) peroxyanhydride Mannich bases

Synthesis of 1-Phenyl-3-(phenylamino) propan-1-one (BO1) and Phenyl (2-[phenyl amino) methyl] phenyl) peroxyanhydride (BO2) both of which are Mannich bases were achieved in this study. Analysis and characterisation of the Mannich Bases were also achieved by UV, IR, and NMR Spectroscopy. The ionization constant (pKa) of the products is also reported.  The pKa at 8.1 obtained by non-aqueous titration may enable the lone pair of electron on nitrogen in the compounds to be protonated at physiological pH. The result of the Brine shrimp lethality test showed that both BO1 and BO2 with LC50 values 17345.1µg/ml and 33520µg/ml respectively, were non – toxic. The result of the antimicrobial screening of BO1 and BO2 using Escherichia coli, Staphylococcus aereus, Bacillus subtilis, Pseudomonas aeruginosa, Klebsiellae pneumoniae, Salmonellae typhi, Candida albicans, Rhizopus stolonifer, Aspergillus niger and Penicillum nonatum showed that the two compounds possess significant antimicrobial activity when compared with the standards, Gentamicin and Tioconazole. In vitro antioxidant screening of both compounds by DPPH free radical scavenging method, scavenging effect on Hydrogen peroxide and peroxide oxidation by Ferric thiocyanate method showed that the compounds possessed significant antioxidant activity when compared with antioxidant standards Ascorbic acid, BHA and ?-Tocopherol . They possessed the highest %inhibition in peroxide oxidation by Ferric thiocyanate method. Keywords: Mannich bases, 1-Phenyl-3-(phenylamino) propan-1-one, Phenyl (2-[phenyl amino) methyl] phenyl) peroxyanhydride, ionization constant, antimicrobial, antioxidan

Chemical composition, antioxidant and antimicrobial activities of volatile oils of Periscopsis laxiflora leaf and stem

ABSTRACT. Pericopsis laxiflora (Fabaceae) is a savannah shrub used traditionally to treat headache, stomach ulcers, heart pain and abdominal pain. Air-dried leaves and stem of the plant were extracted by hydrodistillation and the oils obtained were characterized using gas chromatography-mass spectrometry. Antimicrobial assay was carried out by agar well diffusion method against Pseudomonas aeruginosa, Escherichia coli, Klebsiellae pneumonia, (gram negative bacteria), Staphylococcus aureus,  Salmonella typhi, Bacillus subtilis, (gram positive bacteria);  Candida albicans, Aspergillus niger, Penicillum notatum and Rhizopus stolonifer (fungi) while antioxidant activity was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical method. Oxygenated monoterpenes (32.92%), monoterpenes (22.58%) and sesquiterpenes (21.63%) hydrocarbons dominated the leaves’ oil and monoterpenes (33.63%), sesquiterpenes (18.42%) and diterpenes (21.48%) hydrocarbons dominated the stem’ oil. The leaf oil showed better scavenging activity at 1.0 mL (60.56%) than the stem oil (46.58%) comparing activity with ascorbic acid and butylated hydroxyl anisole (BHA) in the antioxidant assay. P. laxiflora stem oil showed highest activity against K. pneumonia and E. coli at 100 µg/mL and 50 µg/mL with comparable activity to gentamicin and tioconazole which are antibacterial and antifungal standards respectively. This study therefore showed that the colourless volatile oils exhibited comparable bioactivity with standards thus, justifying the plant’s ethno medicinal application.   KEY WORDS: Pericopsis laxiflora, Fabaceae, Monoterpenes hydrocarbons, Antimicrobial, antioxidant  Bull. Chem. Soc. Ethiop. 2022, 36(3), 717-725.                                                               DOI: https://dx.doi.org/10.4314/bcse.v36i3.20                                                     &nbsp

Synthesis, Microbial Growth and Oxidation Inhibitory Properties of Three Mannich Bases

Diseases, infections and unhealthy diet serve as threat to human existence. Bases obtained from Mannich reaction have been found to have pharmacological application as antioxidant, antimicrobial, anti-cancer, anti-hypertensive, antiviral and anti-inflammatory in drugs and as food additives. Biologically active 4-(3-oxo-1,3-diphenyl propylamino) benzoic acid (A1), N-phenyl-3-(phenylamino) propanamide (A2) and 3-(p-tolylamino)-N-phenylpropanamide (A3) were synthesized and their purity confirmed by melting point determination and Thin layer chromatography. Characterization of the Mannich bases by spectroscopic methods: Infrared and Ultraviolet spectroscopy confirmed the presence of C=O, O-H, N-H typical of Mannich bases. They are also readily soluble in organic solvents. Antioxidant activity of A1, A2 and A3 involving the use of 2,2- diphenyl-1-picrylhydrazyl radical (DPPH) and hydrogen peroxide was significant when compared with antioxidant standards: ascorbic acid, butylatedhydroxylanisole and α-tocopherol. Compounds A2 and A3 gave percentage inhibition of 90.37 and 90.11 at 0.0625 mg/ml in the hydroxyl radical scavenging activity, a better percentage inhibition than ascorbic acid and α–tocopherol at the same concentration. Antimicrobial activity of the three compounds against bacterial and fungal strains; Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomona aeruginosa, Klebsiellae pneumoniae, Salmonellae typhi, Candida albicans, Aspergillus niger, Rhizopus stolonifer and Penicillium notatum showed moderate microbial inhibition when activity was compared with standard drugs: gentamicin and tioconazole for bacteria and fungi respectively. The ionization constant (pKa) values at 6.01, 8.15 and 7.23 reported for compounds A1, A2 and A3 respectively indicates that they would be readily metabolized at physiological pH. Keywords: Mannich bases; spectroscopy; oxidation; antimicrobial; ionization constan

Antioxidant, Toxicity and Phytochemical Screening of Extracts Obtained from Mariscus alterifolious Vahl

The plant Marisus alternifolious Vahl is a weed used in ethno medicine for the treatment of wounds, bacterial and gonorrheal infections. The dried whole plant was extracted with methanol (MMA) and partitioned using hexane (HMA), ethylacetate (EMA) and butanol (BMA). The fractions were subjected to phytochemical screening, antioxidant assay by the free radical scavenging effect on 2,2-diphenyl picryl hydrazyl radical and hydrogen peroxide while toxicity assay was by Brine shrimp lethality test. Phytochemical screening revealed the presence of alkaloids, flavonoids, cardiac glycosides, phenolics, steroids, saponins, tannins, terpenoids and reducing sugars as secondary metabolites. Brine shrimp lethality assay revealed that the hexane fraction was toxic with LC50 of 106.98 µg/ml while the ethylacetate, methanol and butanol fractions were non toxic with LC50 values >1000 µg/ml. HMA (76.22%), EMA (72.80%), MMA (76.04%), BMA (77.94%) at 0.0625 mg/ml scavenged free radicals better than ascorbic acid (AA) (44.0%) at the same concentration. In the hydrogen peroxide test, HMA (73.25%); EMA (79.55%); MMA (77.49%) and BMA (81.64%) scavenged hydroxyl radical at 0.25 mg/ml better than ascorbic (AA) (66.45%) even at its highest concentration (1.0 mg/ml). Phytochemicals like flavonoids, tannins and phenolics present in this plant may be responsible for its antioxidant activity and the wound-healing ability of the plant in ethno medicine. Keywords: Mariscus alterifolious, phytochemicals, antioxidants, free radicals, toxicit

Cytotoxicity and Acute Oral Toxicity Study on Quassin and Fractions of Quassia amara Extract

Different fractions of Quassia amara and its bioactive compound quassin have been implicated in male reproductive toxicology. Toxicity results obtained from brine shrimp lethality test on chloroform, methanol and hexane fractions of Quassia amara gave LC50 value of 93.456

Chemical composition, toxicity and antioxidant activities of essential oils of stem bark of Nigerian species of guava (Psidium guajava Linn.)

Essential oil from the stem bark of Nigerian species of Psidium guajava of the family Myrtaceae was obtained by hydro-distillation using an all-glass Clavenger apparatus. GC and GC/MS analysis were carried out on the essential oil and was found to contain 62 compounds constituting 99.98 % of the total oil composition. The principal constituents are hydrocarbons, amines, amides and esters with 3,6-dioxa-2,4,5,7- etraoctane,2,2,4,4,5,5,7,7-octamethyl (11.67 %) and cyclononane (10.66 %) dominating the total essential oil. Brine shrimp lethality test was carried out to determine the toxicity of the oils to living organisms (shrimps). LC50 value (μg/ml) of 1.0009 obtained showed that the essential oil of P. guajava stem bark was toxic. The antioxidant property of essential oil was investigated by measuring the decrease in absorption at 517 nm of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) in a UV/visible spectrophotometer. The oil showed better activity as a radical scavenger than α-tocopherol. The oil activity was 71.83 % at 0.2 mg/ml and the absorption is stoichiometric with respect to the number of electron taken up. Thus, the results of this study showed that the essential oil from P. guajava was not only toxic; it possessed antioxidant activity, which could exert beneficial actions against pathological alterations caused by the presence of highly reactive free radicals. The toxicity of the oil can be taken advantage of in the therapy of diseases involving cell or tumor growth

Variation in chemical composition, insecticidal and antioxidant activities of essential oils from the leaves, stem barks, and roots of Blighia unijugata (Baker) and B. sapida (K. D. Koenig)

Blighia unijugata (Baker) and B. sapida (K.D. Koenig) (Sapindaceae) are forest trees widespread in Tropical Africa. They are used in folk medicine for the treatment of rheumatism, cardiovascular diseases, yellow fever, dysentery, and epilepsy. The essential oils of the air-dried leaves, stem bark, and roots of the plants were extracted using the hydrodistillation method and were analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). The antioxidant activity was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical method using α-tocopherol and ascorbic acid as standards. The insecticidal activity of the oils was investigated by determining the percentage mortality of the grain insects (Sitophilus zeamaise). Results showed that the yield of the colorless oils (% w/w) from the leaves, stem bark, and roots of the plants were 0.91%, 0.42%, and 0.34% for B. unijugata and 0.67%, 0.32%, and 0.48% for B. sapida, respectively. The most abundant compounds in B. unijugata leaves were pentadecanoic acid (14-methyl-, methyl ester) (38.34%), carbonic acid, propyl-en-2-yl undecylpropyl ester (36.79%), and 9-octadecanoic acid (Z)-methyl ester (24.86%). The stem bark was rich in 1,3-dimethoxybenzene (79.01%) while the root contained limonene (20.51%), trans-13-octadecanoic acid (16.74 %), and cis-vaccenic acid (9.50%). The leaf essential oil of B. sapida had hexahydrofarnesyl acetone (21.43%), phytol (20.45%), geosmin (16.258%), and α-ionone (8.271%) as the major constituents. The stem bark had cholesterol (38.66%) as the major constituent while the root contained nonanal (18.09%) and 4-cyclopropyl carbonyl tetradecane (11.6%). The antioxidant analysis revealed that B. unijugata root had 83.96% inhibition at 100 mg/ml, while B. sapida stem had 79.73% inhibition, better than α-tocopherol. No significant insecticidal activity was observed in the essential oils of the plants against S. zeamaise except for B. sapida stem which showed 50% toxicity to the maize weevils. However, the two plants can be the source of antioxidant agents against oxidative stress and related diseases

Toxicity, antimicrobial and antioxidant activities of methyl salicylate dominated essential oils of Laportea aestuans (Gaud)

The colourless essential oils obtained by hydro-distillation from the whole plant of Laportea aestuans (Gaud) were analysed by GC and GC/MS. The major constituents in the oil were methyl salicylate (54.50%), fenchol (10.59%), 1, 2-cyclohexanedione dioxime (9.40%), 1, 4-octadiene (8.86%) and linalool (3.26%). The toxicity results obtained from brine shrimp lethality test gave LC50 value of 367.1805 μg/ml indicating that the oil is toxic. The oils showed appreciable antimicrobial activity against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella typhi, Candida albicans, Rhizopus stolon, Aspergillus niger and Penicillium nonatum at 200 mg/ml when compared to standards; gentamicin for bacteria and tioconazole for fungi. The oil was however very active against the fungi R. stolon and A. niger at 25–200 mg/ml. While the in vitro antioxidant activities of the oils determined by scavenging effect on 2, 2-diphenyl-1-picryl hydrazyl radical method showed that the oils have promising antioxidant activity as a free radical scavenger. At 0.1 and 0.2 mg/ml, the % inhibition of the essential oil (84.46% and 86.87%, respectively) was discovered to be higher than the % inhibition of α-tocopherol (15.4% and 12.4%)