Premila Perera

Evaluation of some Samoan and Peruvian medicinal plants by prostaglandin biosynthesis and rat ear oedema assays

In our ongoing program to find new anti-inflammatory compounds, 58 extracts from 46 different medicinal plant species, used in treatment of inflammatory disorders-38 plants from the traditional medicine of Western Samoa and eight originating from the indigenous medicine of the Shipibo-Conibo tribe of Peruvian Amazonia-ere evaluated. The ability of all extracts to inhibit cyclooxygenase-1 catalysed prostaglandin biosynthesis in vitro was examined. Of the plant species tested 14 showed moderate to strong inhibition; including 11 Samoan and three Peruvian species. Further, 12 Samoan and all eight Peruvian species were investigated on their inhibitory activity of ethyl phenylpropiolate induced rat ear oedema in vivo. Significant activity was shown by 10 of the Samoan and by all eight Peruvian species. An additional evaluation of the most active species was provided through a compilation of existing literature documenting traditional medicinal uses, pharmacological activity and chemical constituents. Several known cyclooxygenase-1 inhibitors were reported to which the observed pharmacological activity can be attributed at least partly. The combination of chemical and pharmacological literature data and our experimental data may help to explain the anti-inflammatory use of these species in indigenous medicine.

Alkaloids of stem and rootbark of Tabernaemontana dichotoma

Abstract During chemical investigation for compounds possessing biological activity in the stem and rootbark of Tabernaemontana dichotoma, 22 alkaloids were isolated. Ten monomeric alkaloids were identified, viz. (−)-apparicine, coronaridine, 3-oxocoronaridine, 3-ketopropylcoronaridine, 19R-heyneanine, 3-ketopropyl-19R-heyneanine, ibogamine, isomethuenine, perivine and vobasine. Two of the monomeric alkaloids isolated were new, one was identified as 3,19R-oxidocoronaridine and the other one is not yet identified. The other ten alkaloids isolated were dimeric compounds, three were identified as tabernamine, voacamine and 3′R/S-hydroxyvoacamine. Five of the dimers were new alkaloids related to tabernamine and ervahanine type structures and identified as 3′R/S-hydroxytabernamine, 3′R/S-hydroxy-N4-demethyltabernamine, N4-demethyltabernamine and 3′R/S-hydroxy-N4-demethytervahanine A and B. The remaining two alkaloids are partially characterized.

Muscle relaxant activity and hypotensive activity of some Tabernaemontana alkaloids

Stemmadenine, the major alkaloid from the seeds of Tabernaemontana dichotoma, showed hypotensive activity and weak muscle relaxant activity. Perivine, vobasine, coronaridine and dichomine, some of the alkaloids found in the leaves, fruits and bark of T. dichotoma, also showed hypotensive and muscle relaxant activity.

Cyclopeptide alkaloids from Heisteria nitida

Abstract Integerrenine, and a new cyclopeptide alkaloid, containing the unusual amine oxide function, anorldianine 27-N oxide, stigmasterol, β-sitosterol, lupeol, (+)-catechin, (—)-epicatechin and 4-hydroxy-2-methoxy benzoic acid were isolated from the Ecuadorian medicinal plant Heisteria nitida (Engl.), Olacaceae. The structures were determined by UV, IR, NMR and mass spectroscopic investigations and chemical transformations. The cyclopeptide alkaloids have been isolated and characterized for the first time in the family Olacaceae.

Alphitol, a phenolic substance from Alphitonia zizyphoides which inhibits prostaglandin biosynthesis in vitro

The new phenolic compound, 3,5-dihydroxy-4-methoxy phenethyl alcohol, named alphitol, and betulinic acid were from the bark of Alphitonia zizyphoides. The chemical structure of alphitol was determined by mass spectrometry in combination with one and two dimensional NMR, including HMBC. Both compounds inhibited prostaglandin biosynthesis in vitro, alphitol with an IC50 value of 0.66mM, which is of the same magnitude as acetyl salicylic acid.

Monogagaine, a Novel Dimeric Indole Alkaloid from Tabernaemontana chippii and Tabernaemontana dichotoma [1]

Abstract From the rootbark of Tabernaemontana chippii and the stembark of T. dichotoma a novel dimeric indole alkaloid was isolated which was named monogagaine. It was assigned structure 1 on the basis of spectral data. It showed antimicrobial activity against Bacillus subtilis.