I have leaves of plants that start to dry out at the end of the branches. Could this be over watering? These are place at corrider with no direct sunlight and some indirect sunlight throughout the day, and 2 fluorescent lights above the plants for 12hr at night time.

Thanks in advance.

Has the soil been oversaturated? Overwatering kills roots and makes them unable to deliver moisture to the foliage, so that the plant looks like it is dying of thirst. If the soil has not been oversaturated, it could just be dying of thirst. Spider mites can also ruin tips like that.

Are you able to add pics of the whole plants with the pots?

If that is a breathable clay pot with a drain hole, it would be hard to overwater a plant of that size. I suspect it may not be getting enough water. Might also need a bigger pot & fresh soil.

Indeed it's a clay pot with drainage hole. Since it's received minimum indirect sunlight, I would just water a bit(around 100ml) twice per day, worrying that it might cause root rot.

If it needs water that often, I would move it to a bigger pot if it was my plant. When you do water, thoroughly moisten all of the soil, then add more water before it gets completely dry.

Your plant is seriously light-deprived, water-deprived and pot bound. Needs a bigger pot, more soil, more light, more water.

I can't actually tell what it is. Can you tell us?

When you water, make sure all of the soil to the bottom of the pot is wet. 100ml (less than half a cup) is just a tease. The roots are in the bottom of the pot and you are watering the top of the soil only.

It's Bougainvillea.

The first plant looks like a Katuk plant (Sauropus androgynus / Breynia androgyna) is it?

If yes, both Bougainvillea and Katuk requires lots of lights and good flowing air. Bogaivillea loves direct sunlight, while Katuk loves dappled sunlight, both need good air circulation. Not a sturdy plant indoor, but when they are outdoor both are very tolerant plant, under or over watered.
I also grow one of Katuk plant indoor since it is a variegated mutant, and too small to be grown out door, affraid of loosing this mutant I need to keep it indoor for a while. In the future it will be grown outside.
And yes, it is chalenging plant indoor, often showing under/overwatering symptoms. Bringing them out door occasionally in the afternoon after going back home from work, seems helps alot, or putting them very close to windows might work.

Here is my little variegated katuk plant, it is in sleeping mode now since it is night here at my place. hence the closing foliages