Bays by the Bay

Anyone for soup?

No need to go to the store for bay leaves, California residents; we have our own more potent variety right here!

Like Laurus nobilis, the Mediterranean bay leaf we more commonly eat, the California bay is in the Lauraceae (Laurel) family, but bears the rather delightful Latin name Umbellularia californica.  It came out way ahead of the California poppy in nomenclature.  It’s the only member of the genus Umbellularia, which seems like kind of a shame.

Leaves of the California bay, Umbellularia californica. The bottom leaf is creased where I bent it to take a whiff.

California bay trees (aka California bay laurels, or California laurels) grow in the coastal woods around the bay here, but are more abundant further north where it’s more moist, and also in Oregon (where they’re called “Oregon myrtles” which seems a bit like cheating.  It’s U. californica after all, Oregon).  They’re also sometimes used as ornamentals, so I’m not sure whether the ones we’ve got growing at Stanford (where it’s drier) are wild or planted.

Some of the foliage sprouting from the base of a bay tree near the hospital Emergency parking lot.

In my opinion California bays don’t have a hugely distinctive morphology–the trees are tallish, the leaves are 2-4″ long, glossy, slim and pointed like other bay leaves.  The wood is supposed to be very fine as a tonewood for making guitars, but that’s not necessarily obvious as you saunter by the tree.  In the spring when they’re in flower they’re more obvious: the flowers are yellow-green and small, and grow right where the leaves meet the stems.  Later the fruit grows as a walnut-sized green oval (Wikipedia describes it as like a tiny avocado and that seems very apt).  But if you’re in doubt, just crinkle a leaf and smell it–the fragrance is unmistakable.

A stately bay tree towers above the path near the Stanford mausoleum. There are a few more tucked in behind the mausoleum, too.

And you can eat it!

You can use California bay leaves as a flavoring, but I can vouch that they’re much stronger than store-bought bay leaves, so experiment with caution–use half a leaf to start where you would normally use 1 or 2.  The fruit is also edible, but I haven’t tried it personally.

Extra nitty-gritty: a note of caution to migraineurs or other headache sufferers

Unfortunately, the fragrance of the California bay isn’t universally loved, and for some people it’s downright noxious, leading to the nickname “headache tree.”  The compound responsible for this effect is a monoterpene ketone called Umbellulone.

Umbellulone: shortcut to a headache

In a recent paper, Italian neurobiologists investigated the basis for headaches caused by Umbellulone, and found that its inhalation triggered pain in rats by stimulating trigeminal ganglion neurons via the pain receptor ankyrin 1/TRP1A.  A similar response was evoked from other headache triggers like cigarette smoke, chlorine, and formaldehyde.  So if you’re headache-prone, take a cautious whiff before you stick some in your food.  Speaking as a migraineur myself, I’ve never found bay to be a trigger, but scents aren’t generally triggers for me and I’d hate to have any of you guys knocked into an attack by incautious bay-huffing.

Want more details? Here’s the reference:

Nassini R, Materazzi S, Vriens J, Prenen J, Benemei S, De Siena G, la Marca G, Andrè E, Preti D, Avonto C, Sadofsky L, Di Marzo V, De Petrocellis L, Dussor G, Porreca F, Taglialatela-Scafati O, Appendino G, Nilius B, & Geppetti P (2011). The ‘headache tree’ via umbellulone and TRPA1 activates the trigeminovascular system. Brain : a journal of neurology PMID: 22036959


Poppies part deux: taxonomical embarrassment

Botanical illustrators go crazy for poppies, so when I was looking for pictures to put in Monday’s post, there was one particular botanical illustration of Papaver somniferum I was looking for–one I’ve seen in maybe a dozen places, so I thought it must be the iconic, quintessential opium poppy illustration.  And I spent like half an hour on Google images, digging through variations on “Papaver somniferum red,” Papaver somniferum botanical,” Papaver somniferum painting…drawing…red…poppy…opium poppy red…opium poppy drawing….aaaarrggghhh!  Couldn’t find it anywhere.

But! I knew I had it in one of my botanical books at home.  So once I got back, I pulled out my copy of Wilfrid Blunt’s “The Illustrated Herbal,” found “poppy” in the index, turned the page, and cried out to JMG: “Ha!  See!  It’s right here, by Rinio!  Why was this not findable in Google?? Everybody loves this painting, it’s like the perfect painting of an…oh.  OOOOOhhhh.  It’s a corn poppy.  Well, dammit.”

Rinio's "Papaver rhoeas," the corn poppy. Not an opium poppy, it turns out.

Corn poppies are the ones from the poem “Flander’s fields” (the WWI poem you may have been forced to memorize in high school).  They grow wild in much of Europe.  And while the deep evolutionary conservation of alkaloid biosynthesis machinery in the Papaveraceae means they probably make a bit of the opiates their sibling species is known for, it doesn’t count as an opium poppy.  Hrmph.

In my defense, they look awfully darn similar.  As far as I can tell the main differences are the anther distribution and color in the center of the flower, and the size and roundedness of the seed capsule.  The foliage looks more feathery in the corn poppy too, but I think this varies among subtypes of the two species.

Why I am not a taxonomist: Opium poppies, Papaver somniferum, var "cherry glow" for purchase from Capital Gardens in the UK.

Poppies: You’re getting sleepy…very sleepy…

No you’re not, wake up! You haven’t even started reading yet!

I suffered a nasty shock recently when I discovered that the audaciously sunny California poppy is called “Eschscholzia californica.” Eschscholzia? Bleh. Such a slushy mouthful to hang on a cute little flower. But despite the disservice done to it by Linnaeus, the California poppy has held up bravely, bringing sunshine and some surprising biochemical utility to our coast.

Undaunted by its miserable Latin name, a California poppy brightens up the median.

Doped up on poppy seeds

Ever since I watched the Mythbusters episode where Adam and Jaime were able to make themselves test positive for morphine and codeine by gobbling poppy seed cake and bagels, I’ve been curious about how widespread the expression of narcotics in related flowers actually is. The first surprise was that the poppy seeds we eat are straight from Papaver somniferum, the same opium poppy used to make, well, opium. Can someone with FDA expertise please explain how possession of poppy seeds is no problem, and growing opium poppies in your yard is totally cool (really, some of my neighbors have them right out front), but you could never do that for cannabis or coca plants?

Meanwhile, both California poppies (genus Eschscholzia) and opium poppies (genus Papaver) are members of the Papaveraceae family, which has been around for 70 million years or so, and these two genera are roughly 30-50 million years distant from each other in evolutionary time. So what is the likelihood that the biosynthetic machinery for morphine and codeine and the like is shared between them? Surprise #2: quite high!

Morphine and codeine are both alkaloids made via several steps from the amino acid tyrosine. California poppies have all the enzymes involved in this pathway, but because of the bias in the way those enzymes are used, very little of these narcotics are made in California poppies, with several other alkaloids being favored instead. (Everybody got that?  So don’t go off and start smoking CA poppies now, ok?) One of the benzophenanthridine alkaloids made by California poppies, sanguinarine (named for the bloodroot where it was first found), is worth a little more discussion.

Do I have any poppy seeds stuck in my teeth?

In the 1990s, sanguinarine was found to be a potent antimicrobial, and so effective against plaque bacteria that the company Viadent added it to their toothpaste and mouthwash for several years…until it was found that it also killed off human cells, leading to precancerous mouth lesions. Yuck.

mmm...toothsome sanguinarine

But wait! That actually was handy for sanguinarine, because in the course of characterizing its toxicity to human cells, it was found to preferentially target dividing cells, and where are dividing cells a problem? In cancer of course! Consequently, sanguinarine and a related E. californica alkaloid, chelerythrine, are under investigation for their antiproliferative and pro-apoptotic effects in prostate cancer.

Extra nity-gritty: Poppies in the lab

At the same time, the actual yield of any of these compounds from living poppy plants is pretty low, so a fairly rigorous side discipline has sprung up around trying to get E. californica to make more of sanguinarine and other useful alkaloids. One approach has been to find the rate-limiting enzymes of benzophenanthridine alkaloids and force the plant to express more of them. Another has taken advantage of the fact that all these alkaloids are made as a stress response in plants, and has involved stressing the plant with everything from aspirin to yeast extract in order to drive up their production.  Both approaches use a cell culture system based on small chunks of E. californica tissue, and I derive a small amount of joy from imagining racks of agar petri dishes filled with poppy plantlets.

Want more detail? Here are references!

Adhami VM, Aziz MH, Reagan-Shaw SR, Nihal M, Mukhtar H, & Ahmad N (2004). Sanguinarine causes cell cycle blockade and apoptosis of human prostate carcinoma cells via modulation of cyclin kinase inhibitor-cyclin-cyclin-dependent kinase machinery. Molecular cancer therapeutics, 3 (8), 933-40 PMID: 15299076

Cho, H., Son, S., Rhee, H., Yoon, S., Lee-Parsons, C., & Park, J. (2008). Synergistic effects of sequential treatment with methyl jasmonate, salicylic acid and yeast extract on benzophenanthridine alkaloid accumulation and protein expression in Eschscholtzia californica suspension cultures Journal of Biotechnology, 135 (1), 117-122 DOI: 10.1016/j.jbiotec.2008.02.020

Takemura T,, Chow YL,, Todokoro T,, Okamoto T,, & Sato F (2010). Over-expression of rate-limiting enzymes to improve alkaloid productivity Methods Mol Biol, 643, 95-109 DOI: 10.1007/978-1-60761-723-5_7

Mung Beans: From Dinner Table to Lab Bench

So today I was doing an experiment, and realized the tube I was pipetting from was a perfect plant topic: mung bean nuclease!

You know mung beans.  You’ve probably eaten them recently, especially if you like Asian food or if you’re on a strict diet.  Mung bean sprouts are the popular white bean sprouts found in every grocery store, and their crisp crunch is a familiar texture in stir-fries, spring rolls and salads. Although they’re native to India, their use is widespread across Asian cuisine.  The beans’ starch is used to make bean thread noodles, and the beans themselves are used to make the paste that fills Chinese mooncakes, or for some kinds of the Indian dish dal (although I’m used to the lentil variety.  Has anyone had mung bean dal—does it taste similar?).

Mung bean sprouts. Fresh, crisp, tasty, and chock-full of nuclease. (Open source photo by Kwantonge).

But mung beans are also a surprising component of every molecular biologist’s toolkit, because they produce a useful enzyme (mung bean nuclease).  There are quite a lot of applications for which this handy tool can be used, but I generally use it for cutting away dangling single-stranded tails of DNA.  A huge, huge part of practical molecular biology is playing cut-and-paste with DNA: I have a piece of DNA over here, and I want to put it into a different piece of DNA over there.  This requires the molecular equivalent of scissors and glue—something that will cut DNA apart, and something else that will glue it back together.  Mung bean nuclease is a very specialized pair of molecular scissors.

Any other favorite uses from the biologists out there?

On my bench: a few precious drops of molecular scissors.

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Lavender at the lab

If Stanford isn’t running a bustling underground soap and sachet business, it should be.

The grounds near the med school have stands of lavender large enough to comfortably carpet my entire house (ok, granted my house is the size of some people’s bedrooms, but that is not the point.  The point is that there’s a lot of lavender).

A mere sampling of all the lavender that populates our section of campus. It's listed as Lavandula "var," which seems only fair since apparently fighting over Lavandula species and subspecies names is a popular botanical pastime.

This hardworking Mediterranean mountain native is probably most famous for its use in bath oils, soaps, and fragrances (its name, after all, comes from the Latin lavare: “to wash”), but I like it best as a food flavoring—it’s great with chicken (see recipe, below), but also chocolate and other dessert items.

A closer look at the flower spikes

Extra nitty gritty:

The fragrance we associate with lavender in its essential oil comes from several compounds, mainly terpenes, but the biggest single component is probably linalool.  Linalool is made by a diverse array of sweet-smelling plants, including many others of the mint family to which Lavandula belongs.

linalool by any other name woud almost certainly still smell as sweet

Lately, the commercial and therapeutic utility of lavender has driven a more molecular approach to its cultivation, with scientists characterizing the expression levels of genes contributing to the biosysnthesis of linalool and other terpenes.  By studying how Lavandula angustifolia regulates production of its essential oil normally, new cultivars could be developed with greater essential oil output, and even more of a fragrant pop.

Interested in the details?  Here’s the reference:

Lane A, Boecklemann A, Woronuk GN, Sarker L, Mahmoud SS.  A genomics resource for investigating regulation of essential oil production in Lavandula angustifolia. Planta. 2010 Mar;231(4):835-45.

 And you can eat it!

So here’s my favorite lavender recipe, does anyone have a favorite of their own? Post a comment or a link–I’d love more!

Lavender chicken recipe:

4 Boneless Chicken Breasts

3 Tbsp Butter

1 clove garlic, chopped

1 large shallot, chopped

3-4 spikes lavender flowers (plus a few more for garnish)

1/2 cup pinot grigio or sauvignon blanc (we avoid chardonnay for cooking because the oak taste becomes too strong when the wine reduces)

1 tsp. Fines Herbes ( or a mix of marjoram, thyme, rosemary and a bay leaf or two works well)

2 Tbsp honey (clover or wildflower. Don’t use orange blossom; it turns out yucky)

juice of 1/2 lemon

Salt, pepper

Pat the chicken dry and rub with 1-2 Tbsp butter (or olive oil if that’s more your style), then sprinkle with salt and pepper.  Place so they fit fairly snugly in a baking dish.

Saute the garlic and shallot together in the remaining butter just until the shallot turns soft.  Then add wine, lavender, herbs, honey, and lemon juice and bring to a simmer.  Let simmer, stirring occasionally, until slightly reduced—about 5-10 minutes.  Slosh the resulting sauce over the chicken breasts and cook at 375 for 45-50 minutes, basting occasionally toward the end.  If needed, broil 4-5 minutes to brown chicken nicely.

Garnish with lavender and serve with the rest of the wine.  A big chunk of crusty bread is handy for sopping up the extra sauce.

Lavender chicken, my favorite brassicate, fresh-baked bread and a generous glass of sauvignon blanc. Dinner!

Roadside edibles: missed one!

As I was jogging through the Berkeley marina yesterday, I realized I left a roadside edible out of last week’s post!  How could I forget the bright and peppery nasturtium?  It’s pretty much everyone’s favorite edible flower, an easy garnish to dress up your salad.

Tropaeolum majus, or Nasturtium to its friends. I found this one at the Berkeley marina near the parking lot of the Doubletree hotel.

The leaves are good too, but quite spicy.  I just learned that the flowers I know as nasturtium are from Tropaeolum genus (this one is most likely T. majus), but are named for the Nasturtium genus that includes watercress, because they produce a similar peppery-flavored oil.

Nasturtiums are native to Central and South America, but grow easily here. They’re popular not just because they’re pretty and hardy, but also because they deter many types of insect pest, and can act as a “trap crop” for pests (specifically aphids) that would have a more devastating effect on other crops.  Pretty and selfless!

Oleander: backyard killer has a softer side?

A murderer lurks in your neighborhood.  It’s Nerium oleander, and it’s everywhere. Great swaths of it envelop LA freeways.  It’s littered across backyards, and encircles parking lots.  And it’s deadly poisonous to humans, animals and especially kids so don’t taste it, don’t sniff it, don’t even touch it, OMG I brushed against it AAAHHHH!!!

Don't be fooled by the sweet pink exterior. It's totally out to get you. (Photo by Servophbabu, Creative commons attribution 3.0 unported license)

Actually, it may not be quite that big a deal.  Although all parts of the oleander plant are toxic, and quite a lot of people are treated for oleander poisoning in the US, there have actually been only a handful of adult deaths from oleander poisoning in the last 25 years.  Most of these were deliberate self-poisonings, with the exception of a young couple of vegans who got lost while hiking and ate a whole mess of oleander leaves.  Estimates I’ve seen suggest that a lethal dose to a child would be about one whole leaf, and several leaves for an adult, and the potential for poisoning by skin contact is minimal.  So, while you should definitely watch out for your kids around oleander, you don’t have to be quite as afraid of it as I always thought. The urban legend about a troop of boy scouts who died after roasting their marshmallows on oleander sticks, for example, is almost certainly bunk.

That having been said, getting sick from incidental leaf consumption would be no fun, and oleander really is everywhere, so here’s what to look for:  it’s a tall shrub, 2-6m high, often used in neighborhood hedges.  If you live anywhere in southern California (or some places in northern California, like along the 80 between Davis and Sacramento), you’ve seen it lining the freeways and medians.

A menacing stretch of median oleanders. (Photo borrowed from, but original photographer unknown).

The flowers are vibrantly pink or red or sometimes white, and grow in bunches.  Most distinctive are the leaves, which are dark green and leathery, and shaped like thin daggers about 4-8 inches long (there’s that assassin imagery again).  The leaves and flowers are poisonous because of several compounds, but notably the cardiac glycoside oleandrin/oleandrine and its metabolites.  Cardiac glycosides interfere with the Na+/K+ ATPase pump in heart muscle cells, throwing off the balance of ions inside the cell, and ultimately leading to it contracting faster and more strongly than it’s supposed to.  So oleander poisoning can result in irregular heartbeat, poor circulation, seizures, coma, and death.

Oleandrin. My heart's all a-flutter just looking at it.

Myth busting

While I was in college near LA, I encountered a rumor that oleanders were heavily planted along the local freeways because they were able to metabolize carbon monoxide (CO) emissions from cars, thus cleaning the air.  Turns out, the rumor may have had it exactly backwards.  A whole litany of plants, maybe all of them, can take up and metabolize small amounts of CO from the air—this was determined by Canadian botanists Bidwell and Fraser in the 1970s, who put radioactive C14-labeled CO into the air around plant samples, and recovered the C14 label from the plant later.  But the only study that talks specifically about oleander and CO is by Fischer and Luttge in 1978, who found that oleander was actually a net producer of CO through C1 metabolism of glucose.  That is to say, they might take up a little CO from the air, but then they actually make more of it in their own metabolism.  So no air-quality help there.

Extra Nitty-Gritty: Plant crossover!

One of the treatments for oleander poisoning is a digoxin immune fab, using antibodies raised against a similar glycoside from the plant foxglove called digoxin.  Apparently, oleandrin and digoxin are similar enough that antibodies raised to the latter will also bind the former.  The antibodies work by binding to the glycoside and preventing it from reaching its target in the body and causing harm–it’s the same principle used to make snake or spider antivenom.

Oleandrin and digoxin. You can see how the pink-highlighted parts are almost identical, so that some antibodies that are made to bind to digoxin will also bind the corresponding parts of oleandrin.

Anything oleander is good for?

In previous centuries, oleander was used as an herbal medicine to treat everything from headaches to eczema, which makes me queasy to think about.  Since digoxin is used therapeutically for some heart conditions, I thought oleandrin might be the same, but its therapeutic index seems pretty limited in that context.  However, it does appear that the same Na+/K+ ATPase pump interfering properties that make oleandrin so dangerous to heart cells also make it effective at killing off some kinds of cancer cells when used in concert with chemo- or radiotherapies.  But a drug based on oleandrin called Anvirzel stalled after Phase I clinical trials in Ireland (due to poor performance–no reduction in solid tumors was seen but side effects were, and at least one company trying to inflate claims of its efficacy and continue to sell it got in serious trouble with the FDA). Now it’s the subject of an alarming cancer home-remedy fad based on making oleander extract at home.  People, please don’t poison yourselves!

Want more detail?  Here are the references:

Fab antibody fragments: some applications in clinical toxicology.  Flanagan RJ, Jones AL. Drug Saf. 2004;27(14):1115-33.

Cardiac glycosides in cancer research and cancer therapy. Winnicka K, Bielawski K, Bielawska A. Acta Pol Pharm. 2006 Mar-Apr;63(2):109-15.

Phase 1 trial of Anvirzel in patients with refractory solid tumors.  Mekhail T, Kaur H, Ganapathi R, Budd GT, Elson P, Bukowski RM. Invest New Drugs. 2006 Sep;24(5):423-7.