Bioassay-guided isolation of cytotoxic constituents of Aframomum melegueta K.Schum. seeds

The seeds of Aframomum melegueta are used extensively in the Nigerian ethnomedicine for the management of cancer. This study therefore aimed at isolating and characterizing its cytotoxic constituents. Methanol extract of the seed was obtained through cold maceration, and it was further partitioned into n – hexane, dichloromethane and ethylacetate. The most active fraction was purified on repeated chromatographic techniques, using vacuum liquid chromatography (VLC), column (CC), and high-performance liquid chromatography (HPLC). The extract, purified fractions and isolated compounds were tested for their cytotoxic activities against the human Rhabdomyosarcoma (RD) and breast (MCF-7) cancer cell lines, using MTT assay. The crude extract and n-hexane fraction were found to be selectively cytotoxic to the cancer cell lines. Bioassay-guided fractionation of the n-hexane fraction led to the isolation of three compounds, which were identified as 6-shogaoal, 6-paradol, and 1-dehydro-6-gingerdione.  6-shogaoal   demonstrated the highest cytotoxicity with CC50 values of 0.11 ± 0.02 and 0.25 ± 0.05ìg/mL against RD and MCF-7 cell lines  respectively, and these were higher in activity when compared with cyclophosphamide (CC50 = 1.98 ± 0.15 and 0.71 ± 0.7ìg/mL). The presented data validates the  ethnomedicinal use of A. melegueta in the treatment of cancer and is also indicative of the potential of 6-shogaol as an anticancer agent

Molecular identity and cytotoxicity of Lenzites quercina macrofungus extracts toward cancer cell lines

The medicinal uses of wild macrofungi have been attributed to their accumulated bioactive compounds. Several mushrooms have been reported to possess antitumor activity, but little, in this regard, is known about Lenzites quercina collected from Akure in Nigeria. Hence, the molecular identification and cytotoxic activity of extracts obtained from raw and fermented Lenzites quercina were assessed. The macrofungus Lenzites quercina was identified using Internal Transcribed Spacers (ITS) sequence analysis. The basic local alignment search tool (BLAST) analyzed on NCBI GenBank data revealed that the Lenzites species from Nigeria – accession number, JF689829.1 – was closely related to Lenzites quercina (a 100% relationship match). The cytotoxic activity of raw and fermented Lenzites quercina extracts was tested against human cervical cancer (HeLa), habdomyosarcoma (RD) and African green monkey kidney (VERO) cell lines. A tetrazolium yellow 3-(4,5-dimethyl thiazol-2-yl)-2,5- diphenyl tetrazolium bromide (MTT) colorimetric assay was used to evaluate the reduction in viability of cell cultures with or without the extracts of Lenzites quercina . Extracts of Lenzites quercina exhibited cytotoxic activity (6.0-84.5%) against the tested cancer cell lines (HeLa, VERO and RD). The concentration of the bioactive compounds in the crude extract ranged from 0.01 to 1000 μg/ml. The results revealed that bioactive compounds in Lenzites quercina possess cytotoxic properties. These bioactive compounds may be isolated and used as alternative therapies to currently available anticancer drugs