Terpenoids from the Stems ofDrypetes congestiflora

Triterpenoids

This review covers newly isolated triterpenoids that have been reported during 2015.

Eudesmanolides and Other Constituents from the Flowers of Wedelia trilobata

Two eudesmane sesquiterpene lactones, wedetrilides B (1) and C (2), along with five known analogues (3 - 8), an ent-kaurane diterpenoid (9), a steroid (10), as well as cinnamic acid derivatives (11 - 13), were isolated from the flowers of Wedelia trilobata. Their structures were elucidated on the basis of extensive spectroscopic analyses and by comparison of their NMR data with those of related compounds. Furthermore, the structures of 1 and 3 - 5 were confirmed by X-ray single-crystal diffraction analyses. Compounds 4 and 5 exhibited weak cytotoxic activities against the MCF-7, HeLa, and A549 cell lines. Compounds 3 - 5 were also evaluated for their inhibitory effects against HIV lytic replication.

Phytochemistry and pharmacology of the genus Drypetes: A review

AIMS

Traditional medicinal use of species of the genus Drypetes is widespread in the tropical regions. The aim of this review is to systematically appraise the literature available to date on phytochemistry, ethnopharmacology, toxicology and bioactivity (in vitro and in vivo) of crude extracts and purified compounds.

ETHNOPHARMACOLOGICAL RELEVANCE

Plants of the genus Drypetes (Putranjivaceae) are used in the Subsaharan African and Asian traditional medicines to treat a multitude of disorders, like dysentery, gonorrhoea, malaria, rheumatism, sinusitis, tumours, as well as for the treatment of wounds, headache, urethral problems, fever in young children, typhoid and several other ailments. Some Drypetes species are used to protect food against pests, as an aphrodisiac, a stimulant/depressant, a rodenticide and a fish poison, against insect bites, to induce conception and for general healing. This review deals with updated information on the ethnobotany, phytochemistry, and biological activities of ethnomedicinally important Drypetes species, in order to provide an input for the future research opportunities.

METHODS

An extensive review of the literature available in various recognized databases e.g., Google Scholar, PubMed, Science Direct, SciFinder, Web of Science, www.theplantlist.org and www.gbif.org, as well as the Herbier National du Cameroun (Yaoundé) and Botanic Gardens of Limbe databases on the uses and bioactivity of various species of the Drypetes was undertaken.

RESULTS

The literature provided information on ethnopharmacological uses of the Subsaharan African and Asian species of the genus Drypetes, e.g., Drypetes aubrévillii, D. capillipes, D. chevalieri, D. gerrardii, D. gossweileri, D. ivorensis, D. klainei, D. natalensis, D. pellegrini (all endemic to Africa) and D. roxburghii (Asian species), for the treatment of multiple disorders. From a total of 19 species, more than 140 compounds including diterpenes, sesquiterpenes, triterpenes (friedelane, oleanane, lupane and hopane-type), flavonoids, lignans, phenylpropanoids and steroids, as well as some thiocyanates, were isolated. Several crude extracts of these plants, and isolated compounds displayed significant analgesic, anthelmintic, antidiabetic, anti-emetic anti-inflammatory, antioxidant, antiparasitic, central nervous system depressant, cytotoxic, and insecticidal activities both in vitro and in vivo. Some toxicities associated with the stem, bark, seed and leaf extracts of D. roxburghii, and the flavonoid, amentoflavone, isolated from the stem extract of D. littoralis as well as D. gerrardii, were confirmed in the animal models and in the rat skeletal myoblast cells assays. As a consequence, traditional medicine from this genus should in future be applied with care.

CONCLUSIONS

Plants of this genus have offered bioactive samples, both from crude extracts and pure compounds, partly validating their effectivity in traditional medicine. However, most of the available scientific literatures lacks information on relevant doses, duration of the treatment, storage conditions and positive controls for examining bioefficacy of extract and its active compounds. Additional toxicological studies on the species used in local pharmacopeia are urgently needed to guarantee safe application due to high toxicity of some crude extracts. Interestingly, this review also reports 10 pimarane dinorditerpenoids structures with the aromatic ring C, isolated from the species collected in Asia Drypetes littoralis (Taiwan), D. perreticulata (China), and in Africa D. gerrardii (Kenya), D. gossweileri (Cameroon). These compounds might turn out to be good candidates for chemotaxonomic markers of the genus.

Antimicrobial Compounds from Drypetes staudtii

Antimicrobial-directed phytochemical investigation of the MeOH extract of Drypetes staudtii afforded two new compounds, 4,5-(methylenedioxy)-o-coumaroylputrescine (1), 4,5-(methylenedioxy)-o-coumaroyl-4'-N-methylputrescine (2), along with seven known natural products 4α-hydroxyeremophila-1,9-diene-3,8-dione (3), drypemolundein B (4), friedelan-3β-ol (5), erythrodiol (6), ursolic acid (7), p-coumaric acid (8), and β-sitosterol (9). Structures of compounds 1 - 9 were elucidated with the aid of extensive NMR and mass spectral studies. All of the isolates exhibited antibacterial activity against Gram-positive and Gram-negative bacteria with minimum inhibitory concentration (MIC) in the range of 8 - 128 μg/ml. Compounds 1 - 2 were also moderately active against Candida albicans with an MIC value of 32 μg/ml.