Research on african medicinal plants - xiii+nyasicoside, a new glucoside of bak

Norlignan glucosides from Hypoxis hemerocallidea and their potential in vitro anti-inflammatory activity via inhibition of iNOS and NF-κB

Eleven diarylpentanoid/norlignan glucosides, along with five other specialized metabolites, were isolated and characterized from the hydro-alcoholic extract of Hypoxis hemerocallidea corms. Hypoxhemerolosides A-F were found to be undescribed compounds. Curcapicycloside was isolated and identified for the first time in its original form, previously it was reported as a methylated derivative. In addition, (1S,2R)-1-(3,4-dihydroxyphenyl)-5-(4-β-D-glucopyranoxy-3-hydroxyphenyl)-1-methoxypent-4-yn-2-ol and (1S,2R)-1-(3,4-dihydroxyphenyl)-1-ethoxy-5-(4-β-D-glucopyranoxy-3-hydroxyphenyl)pent-4-yn-2-ol were isolated and characterized as artifacts, generated during extraction/isolation procedures from possible 1-(3,4-dihydroxyphenyl)-5-(4-β-D-glucopyranoxy-3-hydroxyphenyl)pent-4-yne-1,2-diol. Structure elucidation was mainly achieved by the interpretation of 1D and 2D NMR and HRESIMS data. The isolated compounds were screened for anti-inflammatory activity in terms of iNOS and NF-κB inhibition as well as for cytotoxicity. Hypoxhemerolosides C-E and obtuside A moderately inhibited nitric oxide production in LPS-stimulated mouse macrophages (RAW 264.7).

Nor-Lignans: Occurrence in Plants and Biological Activities-A Review

In this review article, the occurrence of nor-lignans and their biological activities are explored and described. Nor-lignans have proven to be present in several different families also belonging to chemosystematically distant orders as well as to have many different beneficial pharmacological activities. This review article represents the first one on this argument and is thought to give a first overview on these compounds with the hope that their study may continue and increase, after this.

Hypoxis (Hypoxidaceae) in African traditional medicine

ETHNOPHARMACOLOGICAL RELEVANCE

Hypoxis species (Hypoxidaceae) are popular medicinal plants used in the African traditional medicine to treat numerous ailments and are reported to have a wide spectrum of pharmacological properties. In this paper we reviewed and evaluated the traditional uses, pharmacological, phytochemistry and toxicity aspects of the genus Hypoxis. Potential medicinal prospects and possible knowledge gaps and pitfalls are discussed.

MATERIALS AND METHODS

A comprehensive and systematic review of literature on Hypoxis species was done using numerous resources such as books and scientific databases that include Pubmed, Scopus, Scirus, Google scholar, Web of Science and others. Information on the various pharmacological and chemical properties of Hypoxis extracts was critically analysed and discussed under the various topics.

RESULTS

The literature indicated a broad range of uses, pharmacological and toxicological properties of different Hypoxis species extracts and their relevance to African healthcare systems. Several compounds, mostly glucosides, sterols and sterolins, have been isolated, identified and tested in various in vitro and in vivo models as well as in a couple of clinical trials with a lot of promising prospects reported in some studies.

CONCLUSION

A critical analysis of the available literature and studies identifies positive potential for the future use of Hypoxis species in both traditional and modern medicine and concurrently so with possible pitfalls and research gaps in current knowledge. An integrated and holistic approach to addressing research issues, particularly toxicology aspects could be more effectively applied and incorporate conservation strategies for the species.

Studies on vasoconstrictor activity of Curculigo pilosa extracts and of its isolated compounds

The Curculigo pilosa total extract, its butanolic fraction (0.5 microg-100 mg/kg) and the most active in vitro compound structurally similar to adrenaline, pilosidine (10 ng-l mg/kg), caused a reversible and dose-dependent increase in blood pressure in anaesthetized rat. This hypertensive effect is partially reversed (90%) by the prior administration of phentolamine (1 mg/kg) and abolished by pre-treatment with phentolamine (1 mg/kg) and atenolol (100 microg/kg). Neither tachiphylaxis nor any toxic effects were observed. These experimental findings suggest an interaction between C. pilosa and the peripheral adrenergic system (particularly with alpha1 and beta1 receptors); the structure of the bioactive glucosides could be important in evoking this effect.

Three novel constituents from curculigo capitulata and revision of C-2 stereochemistry in nyasicoside

Continuing study of the constituents of the rhizomes of Curculigo capitulata provided three novel compounds, including two norlignan glucosides, curcapicycloside (2) and (1S,2R)-O-methylnyasicoside (3), and a phenanthrofuran, curcapital (9). The former two compounds were characterized as their tetra-O-methyl derivatives. Compound 2 possesses a glucosyl-fused skeleton with 1R,2R configuration. Biogenetic consideration led to a revision of the previously assigned 2S configuration of nyasicoside (1) to 2R, which was confirmed by NOE studies of the acetonide of its tetra-O-methyl derivative. The 2R configuration in tetra-O-methyl-1-O-methyl curculigine (7a) and isocurculigine (8a) was also established by chemical correlation of the former with (1R, 2R)-tetra-O-methyl-1-O-methylnyasicoside (10a). Curcapital (9) represents the first natural product having a phenanthro[9,10, b]furan skeleton.