Functional food components of Antigonon leptopus tea

The Isolation of Hypoglycaemic Compounds from Desmodium canum and Their Synergistic Effect on Blood Glucose Levels in Euglycaemic Sprague Dawley Rats

Desmodium canum (Strong back) commonly consumed as a tea or tonic is believed to possess hypoglycaemic activity. This paper sets out to isolate potential hypoglycaemic compounds present within the plant and investigate their synergistic effects on blood glucose levels in euglycaemic Sprague Dawley rats. The milled plant was sequentially extracted using hexane, ethyl acetate and methanol. The ethyl acetate extract was subjected to column chromatography yielding seven major fractions and were subsequently bioassayed using the Oral Glucose Tolerance Test (OGTT). Further chromatographic separation and analysis using Gas Chromatography–Mass Spectroscopy and Fourier Transform Infrared Spectroscopy enabled the identification of two hypoglycaemic compounds, oleic acid (OA) and succinic acid (SA). These were bioassayed individually and as a cocktail to determine the synergistic effects using OGTT. Intravenous administration of these compounds individually indicated both are very potent in retarding blood glucose levels. However, the most significant activity was observed on synergistic administration. The cocktail (1 : 1) displayed significant hypoglycaemic activity throughout the entire study. It also significantly differed from OA at the 120 min interval (3.43 ± 0.22 mmol/L vs. 4.98 ± 0.19 mmol/L, resp., p=4.29 × 10⁻⁷) and significantly differed from SA at 30 min (3.95 ± 0.43 mmol/L vs. 5.17 ± 0.32 mmol/L, resp., p=0.003), 90 min (4.35 ± 0.36 mmol/L vs. 5.49 ± 0.69 mmol/L, resp., p=0.04), and 120 min intervals (3.43 ± 0.22 mmol/L vs. 4.94 ± 0.31, resp., p=1.54 × 10⁻⁵). Oral administration of the cocktail showed comparable potency to that of metformin (p > 0.05) throughout the OGTT curve. The synergistic effects of the naturally isolated compounds yielded higher potency levels than individual administration and when administered orally, the hypoglycaemic effect was similar to that of metformin. This may assist in paving a way to attempt a novel method in approaching antidiabetic therapy.

Green synthesis of silver nanoparticles by coral vine and assessment of their properties

Aqueous extracts of all parts (leaves, stem and roots) of the invasive terrestrial plant coral vine (Antigonon leptopus; Polygonaceae) were used to synthesise silver nanoparticles (AgNPs) in a rapid and single-step process at ambient temperature and pressure. The effect of several key variables that influenced the shape and/or size of the AgNPs was studied – including metal–extract stoichiometry, temperature, interaction time, stirring and pH – on the basis of ultraviolet-visible spectrophotometry, scanning electron microscopy, transmission electron microscopy, dynamic light scattering and X-ray diffraction. The study has yielded a template with which processes for synthesising AgNPs of desired shapes and sizes can be developed using A. leptopus as the bioagent. Besides being simple, non-polluting, inexpensive and non-hazardous, the template makes available a means with which it may become possible to utilise the weed A. leptopus on a large scale, thereby opening an avenue to reducing the ecological degradation that it causes. The synthesised AgNPs showed potential to scavenge free radicals and also had catalytic activity.

Phenanthrenes in Chinese Yam Peel Exhibit Anti-inflammatory Activity, as Shown by Strong in Vitro Cyclooxygenase Enzyme Inhibition

Chinese yam ( Dioscorea opposita), peeled or whole, is a popular food item that is considered to be healthy. Often, the yam is peeled before cooking. However, it is also consumed with peel. Therefore, in this study, the peel of this yam was extracted sequentially with n-hexane, ethyl acetate and methanol, and studied for its health-benefits, using in vitro bioassays. Bioactivity-guided purifications of extracts of the peel afforded phenanthrenes (1-4), as characterized by spectroscopic methods. Phenanthrene 1 is a novel analogue. The extracts and isolates were tested for anti-inflammatory activity using cyclooxygenase enzyme (COX-1 and -2) inhibitory assays. All phenanthrenes isolated from the yam peel showed higher inhibition of COX enzymes than the over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs) aspirin, ibuprofen and naproxen.

Antioxidant and anti-inflammatory assays confirm bioactive compounds in Ajwa date fruit

Ajwa, a variety of date palm Phoenix dactylifera L., produces the most expensive date fruits. Percentages of seed, moisture, fructose, glucose, soluble protein, and fiber in Ajwa dates were 13.24, 6.21, 39.06, 26.35, 1.33, and 11.01, respectively. The ethyl acetate, methanolic, and water extracts of Ajwa dates, active at 250 μg/mL in the MTT assay, inhibited lipid peroxidation (LPO) by 88, 70, and 91% at 250 μg/mL and cyclooxygenase enzymes COX-1 by 30, 31, and 32% and COX-2 by 59, 48, and 45% at 100 μg/mL, respectively. Bioactivity-guided purifications afforded compounds 1-7, in addition to phthalates and fatty acids. Compounds 1-3 showed activity at 100 μg/mL in the MTT assay; inhibited COX-1 enzyme by 59, 48, amd 50% and COX-2 enzyme by 60, 40, amd 39% at 50 μg/mL; and inhibited LPO by 95, 58, amd 66% at 100 μg/mL, respectively. The soluble protein fraction was also very active in both antioxidant and anti-inflammatory assays.

Health-Beneficial Phenolic Aldehyde in Antigonon leptopus Tea

Tea prepared from the aerial parts of Antigonon leptopus is used as a remedy for cold and pain relief in many countries. In this study, A. leptopus tea, prepared from the dried aerial parts, was evaluated for lipid peroxidation (LPO) and cyclooxygenase (COX-1 and COX-2) enzyme inhibitory activities. The tea as a dried extract inhibited LPO, COX-1 and COX-2 enzymes by 78%, 38% and 89%, respectively, at 100 μg/mL. Bioassay-guided fractionation of the extract yielded a selective COX-2 enzyme inhibitory phenolic aldehyde, 2,3,4-trihydroxy benzaldehyde. Also, it showed LPO inhibitory activity by 68.3% at 6.25 μg/mL. Therefore, we have studied other hydroxy benzaldehydes and their methoxy analogs for LPO, COX-1 and COX-2 enzymes inhibitory activities and found that compound 1 gave the highest COX-2 enzyme inhibitory activity as indicated by a 50% inhibitory concentration (IC(50)) at 9.7 μg/mL. The analogs showed only marginal LPO activity at 6.25 μg/mL. The hydroxy analogs 6, 7 and 9 showed 55%, 61% and 43% of COX-2 inhibition at 100 μg/mL. However, hydroxy benzaldehydes 3 and 12 showed selective COX-1 inhibition while compounds 4 and 10 gave little or no COX-2 enzyme inhibition at 100 μg/mL. At the same concentration, compounds 14, 21 and 22 inhibited COX-1 by 83, 85 and 70%, respectively. Similarly, compounds 18, 19 and 23 inhibited COX-2 by 68%, 72% and 70%, at 100 μg/mL. This is the first report on the isolation of compound 1 from A. leptopus tea with selective COX-2 enzyme and LPO inhibitory activities.

Analgesic and Anti-Inflammatory Properties of Extracts from the Bulbils of Dioscorea bulbifera L. var sativa (Dioscoreaceae) in Mice and Rats

The aqueous and methanol extracts from the dry bulbils of Dioscorea bulbifera L. var sativa (Dioscoreaceae)—evaluated orally at the doses of 300 and 600 mg/kg against pain induced by acetic acid, formalin, pressure and against inflammation induced by carrageenan, histamine, serotonin and formalin in mice and rats, showed a dose dependant inhibition of pain and inflammation with a maximum effect of 56.38%, 73.06% and 42.79% produced by the aqueous extract, respectively on pain induced by acetic acid, formalin and pressure while the methanol extract at the same dose respectively inhibited these models of pain by 62.70%, 84.54% and 47.70%. The oral administration of aqueous and methanol extracts caused significant anti-inflammatory activity on paw oedema induced by histamine, serotonin and formalin. The present results show that the bulbils of Dioscorea bulbifera var sativa possess potent analgesic and anti-inflammatory activities. These activities may results from the inhibition of inflammatory mediators such as histamine, serotonin and prostaglandins. Thus, the analgesic activity of the bulbils of Dioscorea bulbifera may be at least partially linked to its anti-inflammatory activity.

Inhibitory Effects of Black Pepper (Piper Nigrum) Extracts and Compounds on Human Tumor Cell Proliferation, Cyclooxygenase Enzymes, Lipid Peroxidation and Nuclear Transcription Factor-kappa-B

Black pepper ( Piper nigrum) and hot pepper ( Capsicum spp.) are widely used in traditional medicines. Although hot Capsicum spp. extracts and its active principles, capsaicinoids, have been linked with anticancer and antiinflammatory activities, whether black pepper and its active principle exhibit similar activities is not known. In this study, we have evaluated the antioxidant, antiinflammatory and anticancer activities of extracts and compounds from black pepper by using proinflammatory transcription factor NF-κB, COX-1 and -2 enzymes, human tumor cell proliferation and lipid peroxidation (LPO). The capsaicinoids, the alkylamides, isolated from the hot pepper Scotch Bonnet were also used to compare the bioactivities of alkylamides and piperine from black pepper. All compounds derived from black pepper suppressed TNF-induced NF-κB activation, but alkyl amides, compound 4 from black pepper and 5 from hot pepper, were most effective. The human cancer cell proliferation inhibitory activities of piperine and alklyl amides in Capsicum and black pepper were dose dependant. The inhibitory concentrations 50% (IC50) of the alklylamides were in the range 13-200 μg/mL. The extracts of black pepper at 200 μg/mL and its compounds at 25 μg/mL inhibited LPO by 45-85%, COX enzymes by 31-80% and cancer cells proliferation by 3.5-86.8%. Overall, these results suggest that black pepper and its constituents like hot pepper, exhibit antiinflammatory, antioxidant and anticancer activities.

An efficient and economical MTT assay for determining the antioxidant activity of plant natural product extracts and pure compounds

Antioxidants scavenge free radicals, singlet oxygen, and electrons in cellular redox reactions. The yellow MTT [3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide] is reduced to a purple formazan by mitochondrial enzymes. NADPH is the basis of established in vitro cell viability assays. An antioxidant assay has been developed utilizing the redox reaction between MTT and selected natural product extracts and purified compounds. This simple, fast, and inexpensive MTT antioxidant assay is comparable with the lipid peroxidation inhibitory assay and can be mechanized to achieve high throughput.