Sesquiterpenes as immunosuppressants.

BACKGROUND: The search for new immunosuppressive drugs is a high priority. Sesquiterpenes constitute a family of compounds with a great variety of biological activities due to their reactive moieties. METHODS: Human tumor cell lines and murine primary cells and human peripheral blood mononuclear cells or primary CD4+ cells from healthy individuals were stimulated in the presence of sesquiterpenes. Cell division was analyzed by 5-(and-6)-carboxyfluorescein diacetate succinimidyl ester, cell cycle progression by Hoecht, and cell death by Anexin-V and propidium iodine staining. Cytokine secretion was analyzed by means of a bioplex assay. RESULTS: Two sesquiterpene derivatives of the 18 previously shown to inhibit vegetal cell growth are shown to block cell division and cell cycle progression in human and murine cell lines and primary cells. Cytokine secretion is also impaired on stimulation in the presence of sesquiterpenes. CONCLUSIONS: Here, we show that sesquiterpenes heliannuols constitute a novel family of molecules with potential use as immunosuppressants. Moreover, we show that an assay based on the allelopathic effect of plant leads can be used as a cost-effective screening previous to studies in mammalian cells.

Isolation and synthesis of allelochemicals from gramineae: benzoxazinones and related compounds.

Compounds with a (2H)-1,4-benzoxazin-3(4H)-one skeleton have attracted the attention of phytochemistry researchers since 2,4-dihydroxy-(2H)-1,4-benzoxazin-3(4H)-one (DIBOA) and 2,4-dihydroxy-7-methoxy-(2H)-1,4-benzoxazin-3(4H)-one (DIMBOA) were isolated from plants belonging to the Poaceae family. These compounds exhibit interesting biological properties, such as phytotoxic, antimicrobial, antifeedant, antifungal, and insecticidal properties. These chemicals, in addition to a wide variety of related compounds involved in their metabolism, detoxification mechanisms, and degradation on crop soils and other systems, have high interest and in some cases potential agronomic utility. This paper presents a complete review of the methods employed for their synthetic obtention in addition to some of the authors' own contributions to their chemistry. The degradation and phytotoxicity experiments carried out in ongoing research into the potential agronomic utility of these compounds required large amounts of them, which were obtained from natural sources. This paper presents a modified methodology to access DIMBOA from Zea mays cv. Apache and to obtain 2-O-beta-D-glucopyranosyl-2,4-dihydroxy-(2H)-1,4-benzoxazin-3(4H)-one (DIBOA-Glc) and DIBOA from Secale cereale L. New synthetic methodologies were employed for the obtention of the lactams 2-hydroxy-(2H)-1,4-benzoxazin-3(4H)-one and 2-hydroxy-7-methoxy-(2H)-1,4-benzoxazin-3(4H)-one and the malonamic acids N-(2-hydroxyphenyl)malonamic acid and N-(2-hydroxy-7-methoxyphenyl)malonamic acid. The aminophenoxazines 2-amino-7-methoxyphenoxazin-3-one and 2-acetamido-7-methoxyphenoxazin-3-one have been synthesized in the authors' laboratory by novel procedures. All of the methodologies employed allowed the desired compounds to be obtained in high yield and in an easy-to-scale manner.