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5. Several African plants are used topically to treat wounds and angiogenesis is an important sub-phase of the proliferative stage of wound healing. Using a zebrafish model we confirmed pro-angiogenic properties of several plant species that promoted the growth of new capillaries from pre-existing blood vessels.
6. There has been renewed interest in the discovery of antiepileptic compounds of natural origin. Using the zebrafish model, several "mind-and-mood" plants used in African traditional medicine were screened to confirm their use in treating epilepsy.
7. Traditional healers rarely rely on a single species to treat disorders but most often administer polyherbal formulations to patients. The value of synergy studies to enhance pharmacological efficacy will be demonstrated.
The premise for studying the plants mentioned above is all based on very rich (yet fragile) indigenous knowledge systems. An urgent need exists to explore the unique South African flora with the ultimate goal of improving the quality of life of mankind and to stimulate the bio-economy of the region.
THE EFFECT OF DIFFERENT SOLVENTS ON PHENOLIC AND FLAVONOID CONTENTS AND FREE RADICALS SCAVENGING ACTIVITY OF MACLURA COCHINCHINENSIS STEM EXTRACTS
© Boonyadist Vongsak1, Nutsuda Inson1, Savita Chewchinda2
1 Faculty of Pharmaceutical Sciences, Burapha University, Saensook, Muang, Chonburi, Thailand;
2 Department of Food Chemistry, Faculty of Pharmacy, Rajathevi, Mahidol University, Bangkok, Thailand
Maclura cochinchinensis Corner have been used as traditional herbal medicine throughout tropical and subtropical countries. The stem of this plant has traditionally been used to treat, skin infection, fever and jaundice. Based on recent study, M. cochinchinensis has in vitro prominent value of antioxidant and free scavenging activity. The bioactive compound in this plant was found to be morin, a class of flavonols. To obtain the maximum yields of the compound, which consequently influence the free radicals scavenging activity, varying extraction solvents; distilled water, 70 percent ethanol, and ethyl acetate, were examined by soxhlet extraction method. The contents of total phenolics and total flavonoids, free radical scavenging activity using DPPH and ABTS free radical scavenging methods and ferric reducing antioxidant power (FRAP) assay of each extract were quantitatively determined. Seventy percent ethanol extract gave the highest yields of crude extract (25.23% dry weight), while ethyl acetate extract
gave the lowest yield (11.33% dry weight). The 70% ethanol extract exhibited significantly different amount of total phenolic contents (4.88 ± 0.25 gram Gallic acid equivalent/100 gram dry powder) and total flavonoid contents (2.80 ± 0.22 gram Morin equivalent/100 gram dry powder). For free radicals scavenging activity, the extracts from these various solvents revealed slightly different activity (IC50 16.39 - 18.87 ig/mL, IC50 7.05 -9.52 ig/mL and 0.82- 1.08 mmol Fe2+eqivatent/100 gram extract for DPPH, ABTS and FRAP assays, respectively), while ascorbic acid, a positive control, displayed the activity with IC50 5.10 ig/mL, 5.42 ig/mL and 5.56 mmol Fe2+eqivatent/15000 gram extract for DPPH, ABTS and FRAP assays, respectively. Thus, the results point that M. cochinchinensis stem extracts illustrated strong free radicals scavenging activity and 70 percent ethanol extract should be recommended as the extraction solvent because of maximum contents of phenolics and flavonoids for pharmaceutical development.
ISOLATION OF THREE NEW FLAVONOID C-GLYCOSIDES FROM IRIS LACTEA
© Whaley A.K., Luzhanin V.G.
St. Petersburg State Chemical-Pharmaceutical Academy, St. Petersburg, Russia
Iris lactea Pall. is a rhizomatous perennial flowering plant distributed throughout mostly temperate and some tropical areas of Asia. Early research of plants from the Iris genus mainly focused on the rhizomes, of which flavonoids were reported to be the major secondary metabolites. In previous phytochemical publications flavone C-glycosides
have been found in the aerial parts of Iris lactea. Previous study on Iris lactea suggested the presence of flavone C-glycosides derivatives of embinin [1].
Up to now, three rhamnose-residue acetate ester derivatives of embinin, 5-hydroxyl-7,4'-dimethoxyflavone-6-C-[O-(a-L-2-acetylrhamnopyranosyl)-1^2-p -D-
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glucopyranoside], 5-hydroxyl-7,4'-dimethoxyflavone-6-C-[O-(a -L-3-acetylrhamnopyranosyl)-1 ^2-p -D-glucopyranoside], and 5-hydroxyl-7,4'-dimethoxyflavone-6-C-[O-(a-L-2,3-diacetylrhamnopyranosyl)-1^2-p-D-glucopyranoside]2 have been isolated and described in literature [2, 3].
As a result of phytochemical analysis of Iris lactea three new C-glycoside flavonoid compounds were isolated from Iris lactea. All of the isolated compounds shared similar UV absorption and NMR spectra. Their hydrolysis afforded a-L-rhamnose and embigenin, suggesting them to be derivatives of embinin. Further analysis using HRESIMS, COSY, HMBC and HSQC showed the three compounds to be 5-hydroxyl-7,4'-dimethoxyflavone-6-C-[O-(a-L-2,4-diacetylrhamnopyranosyl)-1^2-p-D-glucopyranoside], 5-hydroxyl-7,4'-dimethoxyflavone-6-C-[O-(a -L-4-acetylrhamnopyranosyl)-1 ^2-p -D-glucopyranoside] and 5-hydroxyl-7,4'-dimethoxyflavone-6-C-[O-(a-L-4-acetylrhamnopyranosyl)-1 ^2-p -D-6-acetylglucopyranoside].
O-glycosyl flavones are known as one of the major components in genus Iris, which were mainly isolated from leaves and flowers. There are few reports about C-glycosyl flavonoids from this genus. C-glycosylflavonoids are found to be minor constituent in the extract and their roles in plant physiology needs further research. Inspection of their NMR data revealed the duplication of the signals, indicating the presence of rotamers. This is caused by the rotational hindrance at the C(6)-C(1') linkage, which cannot be found in mono-6-C-substituted derivatives.
References:
1. Reynaud J, Guilet D, Terreux R, Lussignol M, Walch-shofer NI. 2005. Nat. Prod. Rep. 22/504-515.
2. Pryakhina NI, Sheichenko VI, Blinova KF. 1984. Chem. Nat. Compd. 20:554-559.
3. Shen WJ, Qin MJ, ShuP, Zhang CF. 2008. Chin. Chem. Lett. 19:821-824.
HOW FAR DEEP CAN PLANT METABOLITE PROFILING CAN BE PERFORMED? IMPLICATIONS FOR DRUG DISCOVERY AND QUALITY CONTROL OF HERBALS
© Jean-Luc Wolfender, Pierre Marie Allard, Emerson Ferreira Queiroz
School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland
With the recent progresses made in metabolite profiling methods and miniaturization of bioassays, a question that arises is: do we still need to perform conventional large scale bioactive guided-isolation of natural products to characterise the extract composition of an herbal drug and identify its active ingredients?
High resolution mass spectrometry (HRMS) and data dependent MS/MS analyses provide very valuable information on secondary metabolites for in-depth metabolome annotation studies [1]. The recent development of molecular network (MN) approaches for the mining of such data in combination with spectral database generated in silico [2] gives the possibility to establish relationships between metabolites thus significantly improving the efficiency of dereplication when combined with high quality chemotaxonomic data [3]. Such types of information can be generated with a few mg of extract only and are readily applicable to herbarium scale samples.
For complete de novo identification of new compounds MS-targeted micro-isolation can be performed and sensitive 1D and 2D microNMR with microgram amounts of purified metabolites can be acquired. For bioactivity determination, many bioassay fit also to this scale. Using an ideal combination of methods it is this virtually possible to fully identify any bioactive principles in this way. Integration of other filters to this approach such as permeation studies on extracts additionally provide key
information on the possible bioavailability of NPs prior to their isolation. Furthermore the link of a given bioactivity result to those previously reported for compounds similar to those identified can be rationalised through in silico chemical space approaches.
Ideally a combination all these state-of-the-art methods should enable to identify and localise valuable NP efficiently at the analytical scale. In such a way large scale MS-targeted isolation of valuable NPs only can become a very rational way to conduct investigations. Different recent applications of our metabolomics and phytochemical investigations will illustrated these aspects.
Such strategies have different implications for drug discovery but also for quality control of herbal and such issues will be discussed. A summary of what could be an ideal workflow will be presented and discussion on what is readily implemented and what is still required will be made.
References:
1. Wolfender JL, Marti G, Thomas A, Bertrand S. 2015. J Chromatogr A. 1382:136-164.
2. Allard PM, Peresse T, Bisson J, Gindro K, Marcourt L, Pham VC, Roussi F, Litaudon M, Wolfender JL. 2016. Anal. Chem. 88:3317-3323.
3. Wolfender JL, Genta-Jouve G, Allard PM. 2017. Curr. Opin. Chem. Biol. 1 (in press).
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