A number of aposematic butterfly and diurnal moth species sequester unpalatable or toxic substances from their host plants rather than manufacturing their own defensive substances. Despite a great diversity in their life histories, there are some general features in the selective utilization of plant secondary metabolites to achieve effective protection from predators. This review illustrates the biochemical, physiological, and ecological characteristics of phytochemical-based defense systems that can shed light on the evolution of the widely developed sequestering lifestyles among the Lepidoptera.

Sequestration of defensive substances from plants by Lepidoptera.

Recent advances in natural product synthesis by using intramolecular Diels-Alder reactions.

Simple indole alkaloids and those with a nonrearranged monoterpenoid unit

Ellagitannins (ETs) from pomegranate juice (PJ) are reported to have numerous biological properties, but their absorption and metabolism in humans are poorly understood. To investigate the pharmacokinetics of pomegranate ETs, 18 healthy volunteers were given 180 mL of PJ concentrate, and blood samples were obtained for 6 h afterwards. Twenty-four-hour urine collections were obtained on the day before (-1), the day of (0), and the day after (+1) the study. Ellagic acid (EA) was detected in plasma of all subjects with a maximum concentration of 0.06 +/- 0.01 micromol/L, area under concentration time curve of 0.17 +/- 0.02 (micromol x h) x L(-1), time of maximum concentration of 0.98 +/- 0.06 h, and elimination half-life of 0.71 +/- 0.08 h. EA metabolites, including dimethylellagic acid glucuronide (DMEAG) and hydroxy-6H-benzopyran-6-one derivatives (urolithins), were also detected in plasma and urine in conjugated and free forms. DMEAG was found in the urine obtained from 15 of 18 subjects on d 0, but was not detected on d -1 or +1, demonstrating its potential as a biomarker of intake. Urolithin A-glucuronide was found in urine samples from 11 subjects on d 0 and in the urine from 16 subjects on d +1. Urolithin B-glucuronide was found in the urine of 3 subjects on d 0 and in the urine of 5 subjects on d +1. Urolithins, formed by intestinal bacteria, may contribute to the biological effects of PJ as they may persist in plasma and tissues and account for some of the health benefits noted after chronic PJ consumption. Whether genetic polymorphisms in EA-metabolizing enzymes (e.g., catechol-O-methyl transferase and glucuronosyl transferase) are related to variations in response to PJ remains to be established.

Pomegranate Juice Ellagitannin Metabolites Are Present in Human Plasma and Some Persist in Urine for Up to 48 Hours

Alkaloids of Crinum pratense

Isocarbostyril alkaloids from Haemanthus kalbreyeri

Fulvic acids (FA) and 4′-methoxy-6-carbomethoxybiphenyl (MCB, 1), two major organic compounds isolated from Shilajit (a humus product), were screened for anti-ulcerogenic activity in albino rats. Both FA and MCB showed significant anti-ulerogenic effects in the battery of tests accepted for this purpose. The mechanism of anti-ulcerogenic action was studied with MCB on the basis of its effects on mucin content (gastric juice carbohydrates and carbohydrate/protein ratio) and on the concentration of DNA and protein in the gastric juice. The MCB-induced changes in the mucosa provided resistance against the effect of ulcerogens and also against shedding of mucosal cells. A preliminary acute toxicity study indicated that both FA and MCB had a low order of toxicity.

Yatendra Kumar

Papers

Alkaloids of Crinum pratense

Isocarbostyril alkaloids from Haemanthus kalbreyeri

Anti‐ulcerogenic activity of fulvic acids and 4′‐methoxy‐6‐carbomethoxybiphenyl isolated from shilajit

Glucosyloxy alkaloids from Pancratium biflorum

The role of ungeremine in the growth-inhibiting and cytotoxic effects of lycorine: evidence and speculation.