Pollenopyrroside A and B, Novel Pyrrole Ketohexoside Derivatives from Bee-Collected Brassica campestris Pollen

Abstract

NoteBee-collected pollen is a hive product that bees pack pollen grains from the flower into pollen pellets on their hind legs with the help of combs and hairs, to feed their larvae in the early stages of development. The constituents of pollen are different according to the floral species or cultivars, 1) while flavonols are commonly encountered in the pollen of flowering plants and perform an essential physiological function in pollen germination and pollen tube growth. Brassica campestris L., also called rape, belongs to Brassica genus (Crucifer) and is widely grown in south of China as an economic crop. Bee-collected Brassica campestris pollen is often used in China as a healthy food and an herbal medicine in strengthening the body's resistance against disease. It has already been found to possess a wide range of biological activities, including antioxidant, 2) antitumor, 3) regulating serum lipids, 4) and treatment of prostatitis. 5) Up to date, bee-collected Brassica campestris pollen are known as a rich source of protein, polysaccharide, fatty acid and flavonoids.6) In our study on the active components of bee-collected Brassica campestris pollen, two novel pyrrole ketohexoside derivatives, named pollenopyrroside A (1) and pollenopyrroside B (2), were isolated from it. Their structures were identified on basis of spectroscopic data (UV, IR, MS, NMR and X-ray) and chemical evidence. Compounds 1 and 2 are two novel pyrrole ketohexoside derivatives with five-six and six-six member dioxaspirocycle, respectively (Fig. 1). Their cytotoxicities were evaluated against A549, Bel7420, BGC-823, HCT-8, and A2780. Restults and DiscussionCompound 1 7) These were supported by heteronuclear multiple bond connectivity (HMBC) correlations (Fig. 2) of H-7 with C-2 and C-3, of H-6 with C-4 and C-5, of H-3 with C-2, C-4, and C-5, and of H-4 with C-5 and C-2. In addition, the 1 Hand 13 C-NMR spectra showed the resonances of two methylene carbons at d C 52. 3.76 (1H, dd, Jϭ10.5, 10.5), 3.53 (1H, m)], one quaternary carbon at d C 95.0. These NMR data suggested that a deoxyketohexose moiety existed in 1. The connectivity of aglycone and sugar moiety was established on the basis of HMBC experiment. In the HMBC spectrum (Fig. 2), correlations of H-1Ј with C-5 and C-2Ј, and H-6 protons resonating at d H 4.93 (1H, d, Jϭ16.0 Hz) and 4.86 (1H, d, Jϭ16.0 Hz) with the quaternary carbon C-2Ј were observed. This quaternary carbon was also correlated with some protons of sugar. The above evidence confirmed that the deoxyketohexose moiety fused to the 5-oxymethy1-2-formyl-pyrrole fragment through oxygen and nitrogen atoms and an oxazine ring was formed. The addi- 983-985 (2010)

Xylapyrrosides A and B, two rare sugar-morpholine spiroketal pyrrole-derived alkaloids from Xylaria nigripes: isolation, complete structure elucidation, and total syntheses

“…However, due to the shortage of singlecrystal data, determination of the absolute configuration at C-9 in 1b and 2a seems to be challenging. Interestingly, after careful analysis of the optical rotations of compounds 1, 1a, 2−4, and their diastereoisomers reported in the literature, [3][4][5] we reasoned that the absolute configuration at the spiro-center (C-9) would be the key factor to influence the sign ( The above synthetic route could efficiently afford the target compounds (only six steps from the commercially available 9), along with three new analogues (1a, 1b, 2a) for potential structure-activity relationship (SAR) studies. In Scheme 2, TBS was employed to protect the secondary hydroxyl group in 10, yielding an inseparable epimeric mixture of 11 (Schemes 2 and 3).…”

“…This includes a very small class of sugarmorpholine spiroketal pyrrole-derived alkaloids that emerged only in recent years. Capparisines A and B from the fruits of Capparis spinosa, 3 pollenopyrrosides A and B from the beecollected Brassica campestris pollen, 4 and acortatarins A and B from the rhizomes of Acorus tatarinowii, 5 were independently reported by three Chinese research groups in 2010. About two years later, acortatarins A and C were isolated from the crust of whole wheat bread by Peterson, et al 6 In general, this group of ---* Corresponding authors.…”

Spiroalkaloids from Shensong Yangxin capsule

“…The structure of 1 could be A or C, as H-4 0 was situated in axial bond. [5]. As compound 1 gave a negative optical rotation f½a 27 D 2 12:7 ðc ¼ 0:05; MeOHÞ}, which was opposite to that of capparisine B f½a 25 D þ 37:9 ðc ¼ 0:009; MeOHÞ}, the absolute configuration of 1 was assigned as C (2 0 S, 4 0 S).…”

Optimized Extraction and High Selective Purification of Flavonoids and Intermediate Polar Nitrogen-Containing Constituents fromBrassica campestrisL. Pollen

“…Ceramide and coumaroylspermidine are intermediate polar nitrogen-containing compounds. Except that, other nitrogen-containing constituents (polar ones), such as pollenopyrrosides (9), uridine, xanthosine, guanosine, adenosine (10), and cerebroside (6), were also isolated from the pollen. And they were tested to be negatively bioactive during the biological assays.…”