Stories: The Cat's Whiskers

Today's story is one from my personal experience and it's about a health giving herb that almost turned deadly. 

 

The cat's whiskers (Orthosiphon stamineus, Lamiaceae)

Long ago, I adopted this lovely plant from a friend of my grandmother. It's called the cat whiskers or misai kucing (local Malay) for obvious reasons. We were told that the cat's whiskers works wonders for people with high blood pressure and kidney stones. We're recommended to make a herbal tea out of it to be drank daily for good health. And so we did, but only for a few days because the cat whisker's tea is a most bitter substance! But as the old Chinese saying goes 'bitterness makes a good medicine', or is it?

A few months later, my grandma's friend who gave us the cat whiskers came to us for the plant because hers died due to some reasons. Most importantly, she had a friend who was diagnosed with high blood pressure, and she was willing to give the herbal tea a try. Without further hesitation, we supplied our friend with a huge load of cat whiskers, amounting to 3-4 kg fresh weight. After all, we have no use for it. Little did we know that our kind intention was about to take a nasty turn! One week later, we collected more of the ever flourishing cat whiskers to supply that our friend in need. But what we learnt was shocking because the patient (also of old age) who was taking the cat whiskers almost passed out after drinking. If it weren't for the people around her at the moment, she could have hit her head, injured herself and died! Not surprisingly they decided NOT to drink this 'wonderful' bitter tea anymore. Funnily enough, some other aunties came knocking at our doors for cat's whiskers only a few months after the incident.

Eventually, we were told by a local herbal practitioner that one mustn't cook the cat's whiskers over boiling water for long. In fact, it should be just a steep in warm water. If the taste of the tea is intensely bitter, that's overdo, which I suppose he meant poisonous! Thus, even today my grandmother is happily giving away herbs, but she will always provide this warning. Back then, I hadn't even started college but I agreed with the herbal practitioner because after all, percolating the cat's whiskers in hot water for extended period might just extract toxins out of it? Who knew at that time, it would take me about eight years before I finally revisit this story, and shed light on its possible causes.

Fast forward twelve years later and now that I have a PhD in phytochemistry,  let's do some detectives work. Why would someone pass out after drinking a supposedly healthy herbal tea? Turns out, the reason is  because the cat whiskers can lower your blood pressure and fix kidney stones. It does so by making you pee a lot, being what pharmacists call a diuretic (diuresis is the medical term for passing of urine). The active constituents of cat whiskers are not well characterised, but as a whole, the tea (water extract) has been consistently proven by different research groups to produce a diuretic effect on animal models. It's true, I've tried the bitter concentrated tea and I was running the loo back and forth for a few hours. While we are not entirely sure what chemicals cause this, the cat's whiskers make you pee.

I guess it's conceivable that passing a lot of urine can aid in excreting kidney stones, but how can it cause someone to faint suddenly?  To get around this, we need to look at how diuretic drugs work. Based on animal studies of cat's whiskers, I would compare its activity to a well known diuretic (out of different classes) called Lasix or furosemide. Lasix is an invaluable drug that is currently used to treat water retention due to heart or liver failure, as well as some forms of high blood pressure. This drug was very dear to me because it was prescribed to my late uncle and I had to remind him to take Lasix for almost a year. What a nice name, Lasix. Anyways, Lasix and presumably cat's whiskers act on our kidney, a most precious organ that filters our blood of wastes like urea, creatinine and urobilin (which makes your urine yellow). Our body uses water to dissolve these wastes that would otherwise become toxic and excrete them as urine. To promote the passing of urine, we need to promote a flow of water and that in turn is done by using a salt gradient (mainly sodium and potassium ions). Essentially where salt goes, water follows to balance out their concentration differences. At the end of the day, our smart kidneys recycle the water and salt by using special pumps in the cells of the kidney. It is this crucial pump that Lasix and many diuretics inhibit or stop them from functioning. Without those pumps, your body loses a lot of water, as well as a lot of salt. When our body loses salt, our blood pressure decreases and the blood volume gets lower (higher volume, higher pressure in blood vessels). For old patients or people with postural hypotension, this dangerous side effect is intensified for diuretic drugs. Mind you, people have died as a result of falling or injuries due to hypotension from diuretics use! Therefore, it's absolutely conceivable that the cat's whiskers can produce this adverse reaction in an overdose.

Finally, speaking of overdose, if there's one thing to take away from my story, it is that dose is what makes a difference. Get the dose right, and you have a medicine; get the dose wrong, you get either no effect or a deadly poison! As with drugs like Lasix, pharmacists know exactly what is a right dose for you, and it is safe and effective almost all of the time. In contrast, the cat's whiskers and many herbs or traditional medicines suffer from this very issue of dosage control. I honestly don't know what's a useful or dangerous dose for cat's whiskers, and we usually titrate its dosing according to clinical effects. Besides, different plants may have different concentration (dosage) of active ingredients, making it trickier to dose. I used to look down on herbs and traditional medicine because of this, and come to the conclusion that they are inferior to modern medicine. However, that's not to say that traditional herbs don't have a value. Who knows, better or even novel diuretics still reside in the cat's whiskers? If anything, it deserves more scientific study and better dose recommendations.

That's it for today, and next time we will explore a local vegetable that yields a very unforgiving dose window of toxicity vs. medicinal effects. If you think the cat's whiskers can make you run for the washroom,  wait until you meet our next customer.