**Author details**

Alkyl protocatechuates act as both lipoxygenase inhibitors and scavengers. Safety is a primary consideration for antioxidants in food products. After ingestion, the alkyl proto‐ catechuates are likely hydrolyzed, at least in part, to protocatechuic acid and the corre‐ sponding alcohols that are common in edible plants. For example, pecan nuts contain protocatechuic acid as a one of predominant phenolic acids [28]. If alkyl protocatechu‐ ates can reach the sites where antioxidants are needed, a more lipophilic alkyl side chain may partition into lipophilic membranes of cells and organelles, where it presumably ex‐ erts its antioxidant activity, similar to the phytyl chain in tocopherols and tocotrienols [29]. The site of antioxidant location is known to be important, however, it is not clear if alkyl protocatechuates can reach, without being metabolized, the sites where antioxidants are needed for protection from oxidative damages. It should be noted, however, that the role of alkyl protocatechuates in the human body is unknown when orally ingested. It is not clear if alkyl protocatechuates are absorbed into the system through the intestinal tract and delivered to the places where lipoxygenase inhibitors are needed without being

A Comprehensive Survey of International Soybean Research - Genetics, Physiology, Agronomy and Nitrogen

**Chemicals.** A series of alkyl protocatechuates was available from our previous study [17]. **Enzyme Assay.** The assay was performed as previously reported [11]. The soybean lipox‐ ygenase 1 (EC 1.13.11.12, Type I) used for the bioassay was purchased from Sigma Chemical Co. Linoleic acid (**30**) was used as a substrate. The reaction mixture consisted of 1.2 mM linoleic acid (**30**), 60 mM phosphate buffer (pH 7.0) and different concentra‐ tions of sample. At zero time, the enzyme solution (100 units) was added to the reaction mixture. The lipoxygenase activity was measured polarographically with an oxygen elec‐ trode(YSI 53, Yellow Springs Instrument Co., Yellow Springs, OH) at 25 °C. Calibration of a Clark-type oxygen electrode was performed by using 4-tert-butylcatechol.The native enzyme is quite capable of producing 13-HPOD (**27**) directly from linoleic acid (**30**) with‐

The work was presented in part at the Symposium of Diet and the Prevention of Gender Re‐ lated Cancers in Division of Agricultural and Food Chemistry for the 222nd ACS National

LDL, low-density lipoprotein; SAR, structure and activity relationships; NDGA, nordihy‐ droguaiuretic acid; DPPH, 1,1-diphenyl-2-picrylhydrazyl; EDTA, ethylenediaminetetraace‐

metabolized.

Relationships

194

**4. Materials and methods**

out any prior activation.

**Acknowledgements**

Meeting in Chicago, Il.

**Abbreviations**

Isao Kubo, Tae Joung Ha and Kuniyoshi Shimizu

Department of Environmental Science, Policy and Management, University of California, Berkeley, California, USA
