Biologically active compounds in Melia volkensii

Abstract

Melia volkensii extracts were tested for the first time under field conditions in the southern Tamesna Desert (Republic of Niger). S. gregaria larvae caught in the field and larvae hatched from egg pods brought from Germany to Agadez were both treated with these extracts. Although these experiments had pilot character in every respect, a number of important findings were made, some of them unexpected. Application of an oil‐based formulation containing 1000 ppm of biologically active compounds (10 liters per hectare) caused retarded growth and a considerable delay in the onset of sexual maturity in the imagoes, i.e. it was possible to reduce by 30–40 days the potential reproductive period of adult S. gregaria individuals that had been treated with Melia extract as larvae. Moreover, initial studies indicated a high likelihood that active compounds contained in Melia extracts are capable not only of halting the feared gregarization process that S. gregaria undergoes, but indeed of reversing it. Zusammenfassung Biologisch aktive Inhaltsstoffe aus Melia volkensii. Ihre Wirkung als Wachstumshemmer und Phasenmodulatoren der Wüstenheuschrecke Schistocerca gregaria (Forskal) (Orth., Cyrtacanthacrinae) Melia volkensii‐Extrakte wurden zum ersten Mal unter Freilandbedingungen in der südlichen Tamesna‐Wüste (Republik Niger) getestet. Appliziert wurden diese Extrakte sowohl gegen im Freiland gefangene S. gregaria‐Larven als auch in Agadez gezüchtete Locusts. Obwohl diese Experimente in jeder Hinsicht Pilotcharakter besaßen, wurden wichtige und z. T. überraschende Ergebnisse erzielt. Die Applikation einer 1000 ppM‐haltigen öligen Formulierung (10 l/ha) bewirkte ein retardiertes Larvenwachstum sowie eine erst sehr spät einsetzende Geschlechtsreife der Imagines, d. h. die mögliche Reproduktionsdauer adulter S. gregaria, als Larven mit Melia‐Extrakt appliziert, konnte um 30–40 Tage verringert werden. Weiterhin machten es erste Untersuchungen äußerst wahrscheinlich, daß in Melia‐Extrakten Wirkstoffe enthalten sind, die den gefürchteten Gregarisierungsprozeß von S. gregaria nicht nur anhalten, sondern auch umkehren können.

Antimycobacterial Triterpenes from Melia volkensii

“…A tea prepared from the bark is used in local folk medicine to alleviate pain, but it is poisonous at higher dose levels . Extracts of seed kernels possess potent antifeedent activity against the desert locust, Schistocerca gregaria , , and fruit kernel extracts have also demonstrated growth-inhibitory activity against larvae of the mosquitoes Aedes aegypti and Anopheles arabiensis . , Chemical investigations of the fruits have resulted in the isolation of the insect antifeedants volkensin; salannin; and 1-cinnamoyl-, 1-tigloyl-, and 1-acetyl-trichilinin. , More recent chemical investigations of M. volkensii have focused on the activity against the human breast-tumor cell line (MCF-7), studies which resulted in the isolation of meliavolin; meliavolkin; meliavolen; melianinone; 3-episapelin A; nimbolin B; meliavolkensins A and B; melianins A, B, and C; meliavolkinin, 1,3-diacetylvilasinin; and meliavolkenin. − …”

“…A tea prepared from the bark is used in local folk medicine to alleviate pain, but it is poisonous at higher dose levels. 1 Extracts of seed kernels possess potent antifeedent activity against the desert locust, Schistocerca gregaria, 2,3 and fruit kernel extracts have also demonstrated growth-inhibitory activity against larvae of the mosquitoes Aedes aegypti and Anopheles arabiensis. 4,5 Chemical investigations of the fruits have resulted in the isolation of the insect antifeedants volkensin; salannin; and 1-cinnamoyl-, 1-tigloyl-, and 1-acetyltrichilinin.…”

The Phytochemical Composition of Melia volkensii and Its Potential for Insect Pest Management

“…Repellency effect, decreased mobility, retarded development and reduced fecundity were observed against S. gregaria when seed extract was applied to their preferred host plants mainly Schouwia thebaica Webb, Fagonia olivieri DC (fagonbush plant) and Hyoscyamus muticus Linnaeus (Egyptian henbane) in a field trial experiment [26]. Although the mode of action of the extracts is still unknown, it is postulated that the active compounds in M. volkensii extracts could affect hormone levels in S. gregaria larvae [27]. In fifth-instar nymphs of S. gregaria, 80% mortality was recorded 48 hours after injection with crude ethanolic and methanolic extracts at a concentration of 30 µg/g of the insect [19].…”

Effect of Different Neem Products on the Mortality and Fitness of Adult Schistocerca gregaria (Forskal)

“…The precise mode of action of the active substances contained in neem products -primarily azadirachtinis not known. It has been suggested, however, that azadirachtin directly interacts with the endocrine events responsible for the ecdysteroid and juvenile hormone titres [31,46,[61][62][63] . The relation between the respective concentrations of these hormones regulates the growth and development processes which take place during insect metamorphosis.…”

“…It is also known that neem products cause antifeedant effects in S. gregaria nymphs and adults [18,[59][60][61] . The precise mode of action of the active substances contained in neem products -primarily azadirachtinis not known.…”