DHOK Exerts Anti-Cancer Effect Through Autophagy Inhibition in Colorectal Cancer

DHOK (14,15β-dihydroxyklaineanone) is a novel diterpene isolated from roots of Eurycoma longifolia Jack, a traditional herb widely applied in Southeast Asia. It is reported that DHOK has cytotoxic effect on cancer cells, but its anti-cancer mechanism has still been not clear. In our study, we first observed that DHOK inhibits cell proliferation of colorectal cancer cells in a time- and dose-dependent manner. Next, we performed transcriptome sequencing to identify the targets of DHOK and found that autophagy-related signaling pathways are involved under DHOK treatment. Indeed, in DHOK-treated cells, the level of autophagosome marker LC3 and the formation of GFP-LC3 puncta were decreased, indicating the reduction of autophagy. Moreover, confocal microscopy results revealed the lysosomal activity and the formation of autolysosomes are also inhibited. Our western blotting results demonstrated the activation of mammalian target of rapamycin (mTOR) signaling pathway by DHOK, which may be attributed to the enhancement of ERK and AKT activity. Functionally, activation of autophagy attenuated DHOK-caused cell death, indicating that autophagy serves as cell survival. In xenograft mouse model, our results also showed that DHOK activates the mTOR signaling pathway, decreases autophagy level and inhibits the tumorigenesis of colon cancer. Taken together, we revealed the molecular mechanism of DHOK against cancer and our results also demonstrate great potential of DHOK in the treatment of colorectal cancer.

Identification of Phytochemicals from the Water Extract of Eurycoma longifolia Roots using Solid-Liquid and Liquid-Liquid Extraction Based Fractionation Techniques

Phytochemicals in the water extract of Eurycoma longofolia roots were identified using both solid-liquid and liquid-liquid extraction based fractionation techniques. A reversed phase C18 solid phase extraction (SPE) was used as solid-liquid extraction, whereas solvent partition was applied as liquid-liquid extraction. Total saponin was increased after fractionation. A few known quassinoids; eurycomanone, 13α(21)-epoxyeurycomanone, pasakbumin D, 13β,18-dihydroeurycomanol and 13β,21-dihydroxyeurycomanol were identified from the 40% and 60% methanol fractions of SPE. Solvent partition extract using ethyl acetate was found to have the highest saponin content compared to butanol and chloroform fractions. Subsequent acetone precipitation of the organic fractions recovered a formylated hexose trimer and other saccharide-containing compounds. Ethyl acetate effectively recovered saponins from E. longofolia water extract using liquid-liquid extraction followed by acetone precipitation.

Woody Species Stand Structure and Regeneration Status in Long Jack (Eurycoma longifolia Jack) Habitat in Batang Lubu Sutam Forest, Padang Lawas, North Sumatra

Long jack (Eurycoma longifolia) is a medicinal plant that has become a common target for exploitation, leading to a population decline in natural forests. This study aimed to determine the stand structure and regeneration status of E. longifolia tree habitat in Batang Lubu Sutam Forest, Padang Lawas, North Sumatra. The research was performed through vegetation analysis using a purposive sampling technique with a randomized sample plot based on the presence of E. longifolia. A total of 181 plots were established in this study. The results showed that the horizontal structure of tree species in the research area had an inverted J-shape pattern, indicating that the number of trees decreased as the diameter increased. The vertical structure showed that all strata were found in the research location, dominated by stratum C. This condition indicated that the forest was in good condition. The regeneration status of 48 species in the location showed different categories. Thirty species (62.50%) were classified as good regeneration, ten species (18.75%) as new regeneration, and four species (8.30%) as poor and no regeneration. The high proportion of trees with good regeneration showed that the forest community could survive despite environmental or anthropogenic stress. Keywords: long jack (Eurycoma longifolia), regeneration, species composition, vegetation structure

Distribution and association pattern of pasak bumi (Eurycoma longifolia) in Batang Lubu Sutam District, Padang Lawas, North Sumatra

Pasak bumi (Eurycoma longifolia) is a medicinal plant with various benefits and has long been used to cure various diseases such as cancer, gingivitis, intestinal worms, and anti-inflammatory anti-malarial, and tonic after childbirth. The root has high economic value leading to unsustainable harvest and drastic population decline. As initial data in conservation activities, information regarding the association of pasak bumi in Batang Lubu Sutam natural forest has not been obtained. Therefore, this research was conducted to determine the pasak bumi distribution and its association within their natural habitat in Batang Lubu Sutam forest. The study was conducted by using the vegetation analysis method using a plotted path determined by purposive sampling. Data analysis was performed by calculating association indices, including the Ochiai index (Oi), Dice index (Di), and Jackard index (Ji). The results showed that pasak bumi were found in the seedling and sapling stage in the research location and form a degree of association with several plants. The species that formed the highest degree of association with the pasak bumi at both levels of regeneration was Shorea leprosula with an Ochiai index value of 0.85 at the seedling level and 0.94 at the sapling level.

Characterization of phosphate solubilizing and cellulolytic fungi isolated from soil under Eurycoma longifolia stands

Eurycoma longifolia is one of the potential medicinal plants and has a high economic value if developed. The bioactive compound produced by E. longifolia has potential as medicine, thus causing increased exploitation of their habitat. This condition resulted in the decreasing population of E .longifolia in nature. The distribution of E. longifolia is influenced by soil fertility conditions. The presence of phosphate solubilizing fungi and cellulolytic fungi in the soil can support the growth of E. longifolia in nature. The purpose of this study was to calculate the population of phosphate solubilizing and cellulolytic fungi and to identify the types of phosphate solubilizing and cellulolytic fungi found in the soil under E. longifolia stands. Soil samples were taken randomly at a depth of 0–20 cm in a natural forest of Papaso Village, Lubu Sutam District, Padang Lawas Regency, North Sumatra. Population and isolation of phosphate solubilizing and cellulolytic fungi were obtained by dilution methods. The isolates obtained were identified morphologically to the genus level by macroscopic and microscopic observation of colonies. The results showed that the population of phosphate solubilizing and cellulolytic fungi were 6.64 × 104 CFU/mL and 9.31 × 103 CFU/mL, respectively. The isolation results in 11 isolates of phosphate solubilizing and 10 isolates of cellulolytic fungi. Based on the morphological identification of phosphate solubilizing fungi isolates consisted of 5 genera, namely Aspergillus, Penicillium, Rhizopus, Fusarium, and Mucor, while isolates of cellulolytic fungi also included 5 genera, namely Aspergillus, Cladosporium, Penicillium, Rhizopus, and Mucor.