Centrifugal partition chromatography for antibacterial bio-guided fractionation of Clidemia hirta roots

Development of Hinoline® as a natural preservative for cosmetic product using bioinspiration and Greenpharma Database

AIMS

The cosmetic industry needs new preservatives that are effective, natural, safe, cost effective, sustainable and compliant with regulatory standards. This necessity has posed challenges requiring obligations, bioinformatics and bioinspiration as driving forces.

METHODS AND RESULTS

Twenty natural extracts were selected from the Greenpharma Database with parameter filters corresponding to development constraints and antimicrobial properties. We confirmed using minimum inhibition concentration (MIC) assays that eight of the extracts have good bactericidal properties and that one has a high antifungal activity. The latter was purified hinokitiol, a bioproduct from Aomori Hiba wood. This substance provides high resistance against putrefaction; for instance, old Japanese temples were made of Aomori Hiba wood. The combination of hinokitiol with levulinic acid, another bioproduct, demonstrated complementary antimicrobial activities and synergistic effects in MIC studies and measurements according to Kull synergy index. Further, the mixture Hinoline® was tested at 2% in challenge tests and fulfilled criteria A of different standards. It also exerted complementary preservative effects with potassium sorbate and beneficial effects in unbalanced skin microbiota.

CONCLUSION

Hinoline, a new effective preservative from renewable bioresources, was developed.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study accelerates the development of a preservative solution for cosmetics selected from Greenpharma Database, through bioinspiration and the identification of cost-effective investments and resources.

Secure and Sustainable Sourcing of Plant Tissues for the Exhaustive Exploration of Their Chemodiversity

The main challenge of plant chemical diversity exploration is how to develop tools to study exhaustively plant tissues. Their sustainable sourcing is a limitation as bioguided strategies and dereplication need quite large amounts of plant material. We examine if alternative solutions could overcome these difficulties by obtaining a secure, sustainable, and scalable source of tissues able to biosynthesize an array of metabolites. As this approach would be as independent of the botanical origin as possible, we chose eight plant species from different families. We applied a four steps culture establishment procedure, monitoring targeted compounds through mass spectrometry-based analytical methods. We also characterized the capacities of leaf explants in culture to produce diverse secondary metabolites. In vitro cultures were successfully established for six species with leaf explants still producing a diversity of compounds after the culture establishment procedure. Furthermore, explants from leaves of axenic plantlets were also analyzed. The detection of marker compounds was confirmed after six days in culture for all tested species. Our results show that the first stage of this approach aiming at easing exploration of plant chemodiversity was completed, and leaf tissues could offer an interesting alternative providing a constant source of natural compounds.

Green Ultrasound Assisted Extraction of trans Rosmarinic Acid from Plectranthus scutellarioides (L.) R.Br. Leaves

Painted nettle (Plectranthus scutellarioides (L.) R.Br.) is an ornamental plant belonging to Lamiaceae family, native of Asia. Its leaves constitute one of the richest sources of trans-rosmarinic acid, a well-known antioxidant and antimicrobial phenolic compound. These biological activities attract interest from the cosmetic industry and the demand for the development of green sustainable extraction processes. Here, we report on the optimization and validation of an ultrasound-assisted extraction (USAE) method using ethanol as solvent. Following preliminary single factor experiments, the identified limiting extraction parameters (i.e., ultrasound frequency, extraction duration, and ethanol concentration) were further optimized using a full factorial design approach. The method was then validated following the recommendations of the association of analytical communities (AOAC) to ensure the precision and accuracy of the method used to quantify trans-rosmarinic acid. Highest trans-rosmarinic acid content was obtained using pure ethanol as extraction solvent following a 45-minute extraction in an ultrasound bath operating at an ultrasound frequency of 30 kHz. The antioxidant (in vitro radical scavenging activity) and antimicrobial (directed toward Staphylococcus aureus ACTT6538) activities were significantly correlated with the trans-rosmarinic acid concentration of the extract evidencing that these key biological activities were retained following the extraction using this validated method. Under these conditions, 110.8 mg/g DW of trans-rosmarinic acid were extracted from lyophilized P. scutellarioides leaves as starting material evidencing the great potential of this renewable material for cosmetic applications. Comparison to other classical extraction methods evidenced a clear benefit of the present USAE method both in terms of yield and extraction duration.

Senecipyrrolidine, an unusual pyrrolidine alkaloid isolated from Jacobaea gigantea (Desf.) Pelser (Asteraceae)

Alkaloids and phenolic compounds are among the most biologically active natural products from the Jacobaea/Senecio genera (Asteraceae). To isolate original natural products directly from Jacobaea gigantea crude polar extracts, centrifugal partition chromatography (CPC) was used. Previously, we reported the phytochemical study of J. gigantea (syn. Senecio giganteus) n-butanol extract using various classical chromatographical techniques combined with CPC. Herein major constituents from the J. gigantea crude ethyl acetate extract and further compounds from the n-butanol extract were purified in only one step using this technique. A new pyrrolidine alkaloid, named senecipyrrolidine was isolated along with thirteen known compounds - chiro-inositol, three phenolic acids, six flavonoids, two quinones and emiline, another pyrrolidine alkaloid - from crude n-butanol or ethyl acetate extracts. Pyrrolidine alkaloids were isolated for the first time in the Jacobaea/Senecio genera and were probably biogenetically related to the two isolated quinones derivatives jacaranone and 3a-hydroxy-3,3a,7,7a-tetrahydrobenzofuran-2,6-dione, isolated in this species.

In vitro and in vivo anti-malarial activity of plants from the Brazilian Amazon

BACKGROUND

The anti-malarials quinine and artemisinin were isolated from traditionally used plants (Cinchona spp. and Artemisia annua, respectively). The synthetic quinoline anti-malarials (e.g. chloroquine) and semi-synthetic artemisinin derivatives (e.g. artesunate) were developed based on these natural products. Malaria is endemic to the Amazon region where Plasmodium falciparum and Plasmodium vivax drug-resistance is of concern. There is an urgent need for new anti-malarials. Traditionally used Amazonian plants may provide new treatments for drug-resistant P. vivax and P. falciparum. Herein, the in vitro and in vivo antiplasmodial activity and cytotoxicity of medicinal plant extracts were investigated.

METHODS

Sixty-nine extracts from 11 plant species were prepared and screened for in vitro activity against P. falciparum K1 strain and for cytotoxicity against human fibroblasts and two melanoma cell lines. Median inhibitory concentrations (IC50) were established against chloroquine-resistant P. falciparum W2 clone using monoclonal anti-HRPII (histidine-rich protein II) antibodies in an enzyme-linked immunosorbent assay. Extracts were evaluated for toxicity against murine macrophages (IC50) and selectivity indices (SI) were determined. Three extracts were also evaluated orally in Plasmodium berghei-infected mice.

RESULTS

High in vitro antiplasmodial activity (IC50 = 6.4-9.9 µg/mL) was observed for Andropogon leucostachyus aerial part methanol extracts, Croton cajucara red variety leaf chloroform extracts, Miconia nervosa leaf methanol extracts, and Xylopia amazonica leaf chloroform and branch ethanol extracts. Paullinia cupana branch chloroform extracts and Croton cajucara red variety leaf ethanol extracts were toxic to fibroblasts and or melanoma cells. Xylopia amazonica branch ethanol extracts and Zanthoxylum djalma-batistae branch chloroform extracts were toxic to macrophages (IC50 = 6.9 and 24.7 µg/mL, respectively). Andropogon leucostachyus extracts were the most selective (SI >28.2) and the most active in vivo (at doses of 250 mg/kg, 71% suppression of P. berghei parasitaemia versus untreated controls).

CONCLUSIONS

Ethnobotanical or ethnopharmacological reports describe the anti-malarial use of these plants or the antiplasmodial activity of congeneric species. No antiplasmodial activity has been demonstrated previously for the extracts of these plants. Seven plants exhibit in vivo and or in vitro anti-malarial potential. Future work should aim to discover the anti-malarial substances present.