Investigation of Phenolic Contents and TLC-Direct Bioautography Screening of Four Nigeria Plant Extracts for Antioxidant Activities

In search of lead compounds with no side effect, four medicinal plants; Euadenia trifoliata, Lactuca capensis, Alstonia boonei and Ficus platyphylla were screened for antioxidant activity. Dried leaves of the four plants were extracted with EtoAc/MeOH (1:1) and the extracts obtained were screened by TLC-Direct bioautography method (TLC-DB) to identify the most promising extract from the four plants for antioxidant property. The TLC chromatogram revealed that the extract from the leaf of Euadenia trifoliata was the most promising and was thus fractionated into  dichloromethane, methanol and hexane soluble fractions. The fractions along with the crude extract were investigated for their phenolic contents and antioxidant potentials. Total phenolic content, TPCs, of the dichloromethane, methanol, crude and hexane extracts were 44.37, 28.83, 24.79 and 19.91 mg/g of gallic acid equivalents of extract, respectively. Antioxidant activities of the fractions using phosphomolybdate and free radical scavenging assays were in the order of methanol ˃ dichloromethane > crude ˃ hexane extract. The results of our finding indicated that methanol was the most suitable solvent to extract polyphenols and other antioxidant compounds from E. trifoliata leaves. In conclusion high polyphenols content of E. trifoliata leaves is an indication that the plant could potentially provide a remedy against disorders caused by oxidative stress. Keywords: Antioxidant, Euadenia trifoliata, Phenolics, Radical, TLC-Bioautograph

Variation in pre-extraction processes influences the differences in chemical constituent, quantity and biochemical activities of volatile oils from Crinum jagus (Th.) D.: Gas Chromatography-Mass Spectrometry analysis

A comparative study performed on essential oil composition, cytotoxic and antioxidant activities of fresh and dried samples involving leaf and bulb of Crinum jagus (Th.) D. were reported. Qualitative and quantitative variations in the composition of oils were investigated using GC and GC-MS. The oil extracted from the leaf of C. jagus's was characterized by high proportions of beta-ocimene (10.0–13.8%), followed by hexadecane (2.6–11.1%), tetramethylpentadecane (9.3–10.4%) and phytol (7.0–9.0%). Bulb oil is rich in 14-methylpentanedecanoic acid methyl ester (20.6–22.5%), tetratetracontane (7.9–10.0%) and 9,12-octadecadinenoic acid (14.0–14.2%). Dried leaves and dried bulbs exhibited the highest cytotoxic activity (IC50 of 0.002 and 0.003 µg/mL, respectively) followed by fresh leaves 0.033 µg/mL and fresh bulb 0.55 µg/mL. The essential oils at 1.0 mg/mL displayed significant antioxidant activities. The level of antioxidant capacity varied according to samples. The chemical constituents and quantities significantly varied based on sample pre-extraction processing, thus affecting the biochemical activities

Immunomodulatory activities of isolated compounds from the root-bark of Cussonia arborea

Context: Cussonia arborea Hochst. ex A. Rich (Araliaceae) is a folk medicine used to treat various diseases. However, there is no report of the root phytochemistry. Objective: This study isolates and identifies the immunomodulatory compounds from root-bark of C. arborea. Materials and methods: The methanol extract (18 g) was subjected to repeated column chromatography resulting in isolation of five compounds (1–5). Structure determination was achieved by analysis of their 1 D and 2 D NMR, and mass spectroscopy. The compounds (100–1.0 μg/mL) were examined immunomodulatory for effect on production of reactive oxygen species (ROS) from whole blood phagocytes and on proliferation of T-cells. The compounds cytotoxicity (100–1.0 μg/mL) was evaluated on NIH-3T3 normal fibroblast cells. Results: Three pentacyclic triterpenoids [3, 23-dihydroxy-12-oleanen-28-oic acid (1), 3β-hydroxylolean-12-en-28-oic (2) and 23-hydoxy-oxo-urs-12-en-28-oic acid (5)], two phytosterols: [stigmasterol (3)] and [3-O-β-d-glucopyranosyl stigmasterol (4)] were all isolated from the methanol soluble extract. All the tested compounds (1–4) were found to be nontoxic on NIH-3T3 cells. Compound 1 and 2 moderately inhibited the production of ROS (IC50 = 24.4 ± 4.3 and 37.5 ± 0.1 μg/mL, respectively) whereas compound 2 exhibited the highest inhibitory effect (IC50 = 12.6 ± 0.4 μg/mL) on proliferation of phytoheamagglutinin (PHA) activated T-cells. Conclusions: The isolated compounds (1–5) are reported for the first time from this species. In addition, compound 2 with suppressive potential on production of intracellular ROS and proliferation of T-cells could be of immense value in control of autoimmune diseases as well as in immune compromised patients

Dioclins A and B, new antioxidant flavonoids from <i>Dioclea reflexa</i>

<p>Dioclins A <b>(1)</b> and B <b>(2),</b> the new flavonoids, have been isolated from the ethyl acetate soluble fraction of the roots of <i>Dioclea reflexa</i> along with 3,5-dihydroxy-4 methoxybenzoic acid (<b>3)</b>, lupeol (<b>4</b>) and the rare dipeptide, auratiamide acetate (<b>5</b>). Their structures have been elucidated by spectroscopic techniques. The compounds <b>1</b> and <b>2</b> showed a significant antioxidant activity in DPPH radical scavenging assay.</p