Antioxidant and Quinone Reductase-Inducing Constituents of Black Chokeberry (Aronia melanocarpa) Fruits

Using in vitro hydroxyl radical-scavenging and quinone reductase-inducing assays, bioactivity-guided fractionation of an ethyl acetate-soluble extract of the fruits of the botanical dietary supplement, black chokeberry (Aronia melanocarpa), led to the isolation of 27 compounds, including a new depside, ethyl 2-[(3,4-dihydroxybenzoyloxy)-4,6-dihydroxyphenyl] acetate (<b>1</b>), along with 26 known compounds (<b>2</b>–<b>27</b>). The structures of the isolated compounds were identified by analysis of their physical and spectroscopic data ([α]_D, NMR, IR, UV, and MS). Altogether, 17 compounds (<b>1</b>–<b>4</b>, <b>9</b>, <b>15</b>–<b>17</b>, and <b>19</b>–<b>27</b>) showed significant antioxidant activity in the hydroxyl radical-scavenging assay, with hyperin (<b>24</b>, ED₅₀ = 0.17 μM) being the most potent. The new compound (<b>1</b>, ED₅₀ = 0.44 μM) also exhibited potent antioxidant activity in this assay. Three constituents of black chokeberry fruits doubled quinone reductase activity at concentrations <20 μM, namely, protocatechuic acid [<b>9</b>, concentration required to double quinone reductase activity (CD) = 4.3 μM], neochlorogenic acid methyl ester (<b>22</b>, CD = 6.7 μM), and quercetin (<b>23</b>, CD = 3.1 μM)

Pyrrole Alkaloids with Potential Cancer Chemopreventive Activity Isolated from a Goji Berry-Contaminated Commercial Sample of African Mango

Bioassay-guided fractionation of a commercial sample of African mango (Irvingia gabonensis) that was later shown to be contaminated with goji berry (Lycium sp.) led to the isolation of a new pyrrole alkaloid, methyl 2-[2-formyl-5-(hydroxymethyl)-1<i>H</i>-pyrrol-1-yl]­propanoate, <b>1</b>, along with seven known compounds, <b>2</b>–<b>8</b>. The structures of the isolated compounds were established by analysis of their spectroscopic data. The new compound <b>1</b>g showed hydroxyl radical-scavenging activity with an ED₅₀ value of 16.7 μM, whereas 4-[formyl-5-(methoxymethyl)-1<i>H</i>-pyrrol-1-yl]­butanoic acid (<b>2</b>) was active in both the hydroxyl radical-scavenging (ED₅₀ 11.9 μM) and quinone reductase-induction [CD (concentration required to double QR activity) 2.4 μM)] assays used. The isolated compounds were shown to be absent in a taxonomically authenticated African mango sample but present in three separate authentic samples of goji berry (Lycium barbarum) using LC-MS and ¹H NMR fingerprinting analysis, including one sample that previously showed inhibitory activity in vivo in a rat esophageal cancer model induced with <i>N</i>-nitrosomethylbenzylamine. Additionally, microscopic features characteristic of goji berry were observed in the commercial African mango sample

New Bioactive Lupane Triterpene Coumaroyl Esters Isolated from Buxus cochinchinensis

Five new lupane triterpene coumaroyl esters (1–5), together with betulin (6) and a known Buxus alkaloid, N-3-benzoyldihydrocyclomicrophylline F (7), were isolated from a CHCl(3)-soluble partition of a methanol extract of Buxus cochinchinensis Pierre ex Gagnep. (Buxaceae) collected in Vietnam. Isolation work was monitored using human colon cancer cells (HT-29). The structures of the new compounds (1–5) were determined on the basis of spectroscopic data interpretation. In addition to their cytotoxicity against HT-29 cells and NF-κB (p65) inhibitory activity in an ELISA assay, all isolates, as well as two semi-synthetic compounds derived from betulin and 5, respectively, were also evaluated for their in vitro antiplasmodial activities against the drug-resistant Dd2 strain of Plasmodium falciparum and antifungal effects on the growth of the pathogenic yeast Candida albicans. The new lupane triterpene coumaroyl esters (1–5), along with a betulin derivative and the known Buxus alkaloid, were found to show significant in vitro antimalarial activities, with IC(50) values ranging from 0.26 to 2.07 µM

Bioassay-Guided Isolation of Antioxidant and Cytoprotective Constituents from a Maqui Berry (<i>Aristotelia chilensis</i>) Dietary Supplement Ingredient As Markers for Qualitative and Quantitative Analysis

Bioassay-guided phytochemical investigation of a commercially available maqui berry (<i>Aristotelia chilensis</i>) extract used in botanical dietary supplement products led to the isolation of 16 compounds, including one phenolic molecule, <b>1</b>, discovered for the first time from a natural source, along with several known compounds, <b>2</b>–<b>16</b>, including three substances not reported previously in <i>A. chilensis</i>, <b>2</b>, <b>14</b>, and <b>15</b>. Each isolate was characterized by detailed analysis of NMR spectroscopic and HRESIMS data and tested for their in vitro hydroxyl radical scavenging and quinone-reductase inducing biological activities. A sensitive and accurate LC–DAD-MS method for the quantitative determination of the occurrence of six bioactive compounds, <b>6</b>, <b>7</b>, <b>10</b>–<b>12</b>, and <b>14</b>, was developed and validated using maqui berry isolates purified in the course of this study as authentic standards. The method presented can be utilized for dereplication efforts in future natural product research projects or to evaluate chemical markers for quality assurance and batch-to-batch standardization of this botanical dietary supplement component

Computer-Assisted Structure Elucidation of Black Chokeberry (<i>Aronia melanocarpa</i>) Fruit Juice Isolates with a New Fused Pentacyclic Flavonoid Skeleton

Melanodiol 4″-<i>O</i>-protocatechuate (<b>1</b>) and melanodiol (<b>2</b>) represent novel flavonoid derivatives isolated from a botanical dietary supplement ingredient, dried black chokeberry (<i>Aronia melanocarpa</i>) fruit juice. These noncrystalline compounds possess an unprecedented fused pentacyclic core with two contiguous hemiketals. Due to having significant hydrogen deficiency indices, their structures were determined using computer-assisted structure elucidation software. The in vitro hydroxyl radical-scavenging and quinone reductase-inducing activity of each compound are reported, and a plausible biogenetic scheme is proposed