Desarrollo reproductivo del “amancay” Ismene amancaes (Amaryllidaceae) en su ambiente natural / Reproductive development of “amancay” Ismene amancaes (Amaryllidaceae) in its natural environment

Ismene amancaes “amancay” es una especie bulbosa característica de las formaciones vegetales denominadas “Lomas” de la costa central del Perú. Emerge al iniciar el periodo de neblina que ocurre en junio, durante el invierno. Presenta flores grandes amarillas y con agradable aroma, muy apreciadas y de valor ornamental. A fin de conocer el desarrollo reproductivo de Ismene amancaes en su ambiente natural se hicieron muestreos mensuales de sus bulbos durante todo un año. Se realizaron observaciones del interior del bulbo para determinar el inicio de la formación y desarrollo de las yemas florales y se relacionó con la formación de sus hojas y la humedad edáfica. Se puede indicar que las primeras yemas florales se hacen evidentes el año anterior a su emergencia, en el mes de diciembre, alcanzando el máximo número de yemas florales en febrero (periodo de verano). La diferenciación de las yemas florales se inicia luego de haberse formado las hojas que saldrán el siguiente año y en el periodo de máximo descenso de la humedad edáfica y de incremento de la temperatura (noviembre). La inflorescencia es la única ramificación que se forma mientras que la yema apical continua formando hojitas. En junio, la pequeña inflorescencia alcanza el cuello del bulbo y avanza seguido por las hojas formadas antes de la inflorescencia siendo envolventes a la inflorescencia misma y a la yema foliar apical. La yema foliar continuará su desarrollo y en julio dos de sus hojas salen del bulbo, las siguientes aun pequeñas quedan dentro y brotarán en el periodo de Lomas del siguiente año. Se puede señalar que el éxito reproductivo de Ismene amancaes en su etapa inicial es dependiente de los fotoasimilados acumulados como biomasa del bulbo en el periodo de Lomas anterior.

Ismene amancaes “amancay” is a bulbose species typical of the central coast vegetation of Peru called “lomas”. This species sprouts in June during the beginning of the winter-fog period. It has large yellow, aromatic flowers valued for their ornamental value. Our goal was to examine the reproductive development of Ismene amancaesin its natural environment, and we recorded monthly observations during a yearlong study. Observations of the interior of the bulbs allowed recording of the beginning of floral bud formation and development, relating them to leaf formation and edaphic humidity. We found that the first floral buds develop the year before their emergence in December, reaching a maximum number of floral buds in February, during the Summer. Floral bud differentiation starts after leaves that will emerge the following year have developed. This occurs during a period of maximum decrease in edaphic humidity and an increase in air temperature (November). The inflorescence is the only branching that develops while the apical bud continues developing leaves. In June, the small inflorescence reaches the neck of the bulb and surpasses it followed by those leaves developed before the inflorescence that surround both the inflorescence and the apical foliar bud. The foliar bud will continue its development, and in July two of the leaves expand, while the smaller ones remain inside the bulb until the following year’s Lomas season. It can be noted that the reproductive success of Ismene amancaes in its initial development depends on the photoreserves accumulated in the bulb the previous growth period.

Acetylcholinesterase-inhibiting alkaloids from Zephyranthes concolor.

The bulbs and aerial parts of Zephyranthes concolor (Lindl.) Benth. & Hook. f. (Amaryllidaceae), an endemic species to Mexico, were found to contain the alkaloids chlidanthine, galanthamine, galanthamine N-oxide, lycorine, galwesine, and epinorgalanthamine. Since currently only partial and low resolution (1)H-NMR data for chlidanthine acetate are available, and none for chlidanthine, its 1D and 2D high resolution (1)H- and (13)C-NMR spectra were recorded. Unambiguous assignations were achieved with HMBC, and HSQC experiments, and its structure was corroborated by X-ray diffraction. Minimum energy conformation for structures of chlidanthine, and its positional isomer galanthamine, were calculated by molecular modelling. Galanthamine is a well known acetylcholinesterase inhibitor; therefore, the isolated alkaloids were tested for this activity. Chlidanthine and galanthamine N-oxide inhibited electric eel acetylcholinesterase (2.4 and 2.6 × 10(-5) M, respectively), indicating they are about five times less potent than galanthamine, while galwesine was inactive at 10(-3) M. Inhibitory activity of HIV-1 replication, and cytotoxicity of the isolated alkaloids were evaluated in human MT-4 cells; however, the alkaloids showed poor activity as compared with standard anti-HIV drugs, but most of them were not cytotoxic.