Iron chelating-mediated antioxidant activity of Plectranthus barbatus extract on mitochondria

Chemical characterization and antioxidant potential of Arthrospira sp., Thalassiosira sp., and Raphidonema sp

Microalgae are emerging as valuable sources of bioactive compounds. This study evaluates hexane extracts from Thalassiosira sp. and Raphidonema sp., and Arthrospira sp., for their bioactive potential. Saturated fatty acids predominated in Arthrospira sp. and Thalassiosira sp. while Raphidonema was rich in polyunsaturated fatty acids. Carotenoids, such as carotenes and xanthophylls, were abundant in Arthrospira sp., while Thalassiosira sp. contained chlorophylls and fucoxanthin derivatives, and Raphidonema sp. showed high levels of chlorophylls and xanthophylls. Antioxidant assays revealed up to 70 % radical scavenging activity, 60 % iron chelation, and up to 67 (μM) ferric-reducing power. Dose-dependent protective effects were observed in Schizosaccharomyces pombe and HepG2 cells, with viability improvements up to 50 %, indicating their potential as antioxidant-rich ingredients for functional foods, promoting health and disease prevention. This study enhances our understanding of Thalassiosira sp. and Raphidonema sp. while underscoring the promising applications of microalgae extracts in functional foods.

Antifungal activity of 4-hydroxy-3-(3-methyl-2-butenyl)acetophenone against Candida albicans: evidence for the antifungal mode of action

The main secondary metabolite of Senecio nutans is 4-hydroxy-3-(3-methyl-2-butenyl)acetophenone (4HMBA). The antifungal activity of this compound and three derivatives was assessed using Candida albicans. 4HMBA exhibited the highest antifungal activity among the assayed compounds. The Fractional Inhibitory Concentration (FIC = 0.133) indicated a synergistic fungicidal effect of 4HMBA (5 mg L(-1)) and fluconazole (FLU) (0.5 mg L(-1)) against the C. albicans reference strain (ATCC 10231). Microscopy showed that 4HMBA inhibits filamentation and reduces cell wall thickness. Our findings suggest that 4HMBA is an interesting compound to diminish resistance to commercial fungistatic drugs such as fluconazole.

Inhibition of HIV-1 enzymes, antioxidant and anti-inflammatory activities of Plectranthus barbatus

ETHNOPHARMACOLOGICAL RELEVANCE

Plectranthus barbatus is widely used in African countries as an herbal remedy to manage HIV/AIDS and related conditions.

AIM OF THE STUDY

To investigate the HIV-1 inhibitory, anti-inflammatory and antioxidant properties of P. barbatus and thereby provide empirical evidence for the apparent anecdotal success of the extracts.

MATERIALS AND METHODS

Ethanolic extract of P. barbatus's leaves was screened against two HIV-1 enzymes: protease (PR) and reverse transcriptase (RT). Cytotoxicity of the extract was determined through measuring tetrazolium dye uptake of peripheral blood mononuclear cells (PBMCs) and the TZM-bl cell line. Confirmatory assays for cytotoxicity were performed using flow cytometry and real-time cell electronic sensing (RT-CES). The free radical scavenging activity of the extract was investigated with 2,2-diphenyl-1-picrylhydrazyl while the anti-inflammatory properties of the plant extract were investigated using a Th1/Th2/Th17 cytometric bead array technique.

RESULTS

P. barbatus extract inhibited HIV-1PR and the 50% inhibitory concentration (IC50) was 62.0 µg/ml. The extract demonstrated poor inhibition of HIV-1 RT. Cytotoxicity testing presented CC50 values of 83.7 and 50.4 µg/ml in PBMCs and TZM-bl respectively. In addition, the extract stimulated proliferation in HIV negative and positive PBMCs treated. RT-CES also registered substantial TZM-bl proliferation after extract treatment. The extract exhibited strong antioxidant activity with an IC50 of 16 µg/ml and reduced the production of pro-inflammatory cytokines indicating anti-inflammatory potential.

CONCLUSION

This is the first demonstration of the in vitro anti HIV-1 potential of P. barbatus including direct activity as well as through the stimulation of protective immune and inflammation responses. The low cytotoxicity of the extract is also in agreement with the vast anecdotal use of this plant in treating various ailments with no reported side-effects.

Matrix solid-phase dispersion extraction for chromatographic analysis of labdane diterpenoids in Coleus forskohlii

INTRODUCTION

The quality of Coleus forskohlii is often evaluated by high performance liquid chromatography (HPLC), using bioactive labdane diterpenoids as chemical markers. However, the existing sample preparation methods for the analysis of diterpenoids in C. forskohlii are generally labour-intensive, time-consuming and require large volumes of solvents.

OBJECTIVE

To establish an efficient matrix solid-phase dispersion (MSPD) extraction method for the simultaneous analysis of five bioactive diterpenoids in C. forskohlii by HPLC.

METHODOLOGY

Herbal samples were prepared by an optimised MSPD procedure using C(18) as the sorbent. The quantification of the diterpenoids was achieved by HPLC with evaporative light scattering detector (ELSD), and the identification of the five compounds was performed by HPLC with tandem mass detector (MS/MS). The efficiency of the MSPD method was also compared with other extraction techniques including Soxhlet extraction, heat reflux extraction, ultrasonic-assisted extraction and microwave-assisted extraction.

RESULTS

The MSPD extracted five diterpenoids with satisfactory recoveries ranging from 98.36% to 102.08%. Compared with other extraction methods, the proposed MSPD method had the advantages of combining extraction and clean-up into a single step, consuming less time and requiring lower solvent volumes.

CONCLUSION

The MSPD method is simple, rapid and efficient for the extraction of labdane diterpenoids from C. forskohlii. The MSPD procedure coupled with HPLC-ELSD or HPLC-MS/MS is suitable for the quantification and identification of the diterpenoids in C. forskohlii.

Towards a unifying, systems biology understanding of large-scale cellular death and destruction caused by poorly liganded iron: Parkinson's, Huntington's, Alzheimer's, prions, bactericides, chemical toxicology and others as examples

Exposure to a variety of toxins and/or infectious agents leads to disease, degeneration and death, often characterised by circumstances in which cells or tissues do not merely die and cease to function but may be more or less entirely obliterated. It is then legitimate to ask the question as to whether, despite the many kinds of agent involved, there may be at least some unifying mechanisms of such cell death and destruction. I summarise the evidence that in a great many cases, one underlying mechanism, providing major stresses of this type, entails continuing and autocatalytic production (based on positive feedback mechanisms) of hydroxyl radicals via Fenton chemistry involving poorly liganded iron, leading to cell death via apoptosis (probably including via pathways induced by changes in the NF-κB system). While every pathway is in some sense connected to every other one, I highlight the literature evidence suggesting that the degenerative effects of many diseases and toxicological insults converge on iron dysregulation. This highlights specifically the role of iron metabolism, and the detailed speciation of iron, in chemical and other toxicology, and has significant implications for the use of iron chelating substances (probably in partnership with appropriate anti-oxidants) as nutritional or therapeutic agents in inhibiting both the progression of these mainly degenerative diseases and the sequelae of both chronic and acute toxin exposure. The complexity of biochemical networks, especially those involving autocatalytic behaviour and positive feedbacks, means that multiple interventions (e.g. of iron chelators plus antioxidants) are likely to prove most effective. A variety of systems biology approaches, that I summarise, can predict both the mechanisms involved in these cell death pathways and the optimal sites of action for nutritional or pharmacological interventions.